texts: Rotating Control Panel for Arcade Cabinet

texts:
I am building an Arcade cabinet with a 3-sided rotating control panel. I want the rotation of the control panel will be automated. Here's a render:

However, I have a problem: locking the control panel in place. It needs to be able to hold in place against the force of players leaning on the control panel (and angry players pounding on it). It also needs to have no play and feel very solid. It can't be rocking while players are pushing the joystick up and down (some people push somewhat hard). The front panel prevents it from rotating forward, but there is nothing preventing it from rotating backwards. Note that this will be made from wood in my shop, so exact tolerances can not be expected (may be off by up to 1/8"-1/4").

I created a test setup for my original idea that used a tension latch to secure the control panel to the front. That worked well, but I would like the whole thing to be automated. Here's a video of that: http://www.youtube.com/watch?v=KK2Xa4psLp0

I have had a couple ideas but I am not sure how feasible they are or exactly how to implement them.

One idea was to use an indexing/dividing head like the one in my lathe. The rod that locks it in place could be automated via an actuator or something. But, I am not sure how to obtain one. I don't have the tools to machine anything.

Another was to use a worm screw to drive the rotation of the control panel as I have read they are supposed to provide holding strength. However, I am not sure how much holding strength and how much play will be present.

I thought about an electromagnetic brake, but I think one that would provide enough force would be way too big (and could interfere with the CRT).

I also figured solutions could be combined. One component could be responsible from preventing the control panel from turning freely under large forces (like leaning/pounding) and another component could be used to prevent the control panel from rocking due to the smaller forces (like pushing on the joystick).

I assume the problem of holding a rotating joint in place is one that has been readily solved by robotics. But I am a babe in the woods with this stuff and I have not been able to find a good solution in my research. I am completely new to automation/ME. Please let me know if there is a better place to post this question and sorry if this is not the correct place.

Edit: While posting this I had another idea: is there a way to automate the tension latch?


texts: What is the Best Heat Resistant Translucent Material?

texts:
I am looking for a material that can be used in a non commercial environment that will allow all (or nearly all) light to penetrate but will be heat resistant (By heat resistant I mean it will not allow the heat to penetrate to the other side, not that the materiel itself won't get hot - although they may be dependent on each other).

To better understand my requirements, I am trying to illuminate a room with 40,000 lux of light using a few metal halide (MH) bulbs, for a scientific experiment. The bulbs will consume 1800 - 2400 watt which means it will produce a lot of heat. Since real people will partake in the experiment (sitting about 6-12 inches from the light source in order to increase the amount of lux reaching the subject) I am concerned the heat produced by the bulbs will be too difficult to bear. Therefore, I want to place some material (such as a glass or plastic) in between the subject and the light source so maximum light penetrates with minimum heat.

What is the best way to do this?


texts: What fundamentally distinguishes cavitation and boiling as different phenomena?

texts:
Cavitation and boiling are names for phenomenon that both involve sudden appearance of bubbles of vapor within a liquid, and in both cases they happen when the local hydrostatic pressure is lower than the vapor pressure of the fluid, but that doesn't necessarily mean they are the same thing.

In this video of an electrical heating element in water, between 01:00 and 02:00 the sound produced by rapid bubble collapse gets louder and louder but there are few visible bubbles. Is the process that produces this sound considered boiling or cavitation? What is the distinction?

I've left a provisional answer to the related question on another SE site: How (actually) do sub-cooled propellants reduce cavitation within turbo pumps and make feed easier? I couldn't bring myself accept the answer on that question that starts with the claim, "cavitation is boiling."

Although they are related, what fundamentally distinguishes cavitation and boiling as different phenomena?


texts:
Since the Equation for the Angular velocity of Precession of a Spinning Disk is:

$$\omega _{p}=\frac{m*g*r}{I*\omega _{spin}}$$

Where,

  m -> Mass of the spinning Disk. [$kg$]

  g -> Acceleration due to Gravity. [$m/(s^2)$]

  r -> Distance of the Centroid of disk from the pivot. [$m$]

  I -> Mass moment of inertia of the Disk. [$kg*m^2$]

  $\omega _{spin}$ -> Angular velocity of the disk. [$rad/s$]

$$\therefore \, \, \omega _{p} (unit) = \frac{kg*\frac{m}{s*s}*m}{kg*m*m*\frac{rad}{s}}$$

Simplifying,

$$\omega _{p} (unit) = \frac{1}{rad*s}$$

Shouldn't it be:

$$\omega _{p} (unit) = \frac{rad}{s}$$

The Answer that I got is 'Since radian is the ratio of lengths, it has no dimension. Which means the expression $\frac{1}{rad*s}$ Simplifies to $\frac{1}{s}$ and again could be written as $\frac{rad}{s}$

So, instead of $\frac{rad}{s}$, I could write $\omega _{p} (unit) = \frac{rev.}{s}$, which are similar.

Now, I want to solve a problem with this.

A gyroscope has a 1-kg disk that spins at 100 rev/s. The center of mass of the disk is 10 cm from a pivot which is also the radius of the disk.

To find the precession angular velocity.

  m = 1 [$kg$]

  g = 9.8 [$m/(s^2)$]

  r = 0.1 [$m$]

  I (Disk) = $\frac{mr^2}{2}$ = $5*10^{-3}$ [$kg*m^2$]

  $\omega _{spin}$ = 100 [$rev/s$]

On Solving, $$\omega _{spin} = 1.96 \, \frac{rev}{s}$$

since, 1 rev/s = 2$\pi$ rad/s

$$\omega _{spin} = 12.315 \, \frac{rad}{s}$$

Now, instead I want to give the input for $\omega _{spin}$ as $2 \pi * 100$ [$rad/s$]. (Solving the problem again with all the above given data.)

Which gives $$\omega _{spin} = 0.31194 \, \frac{rad}{s}$$

Which is kinda Contradictory.

Since rev/s and rad/s are similar units.

I used the same method above to derive the unit of $\omega _{p} (unit) \,\, as \,\, \frac{rev}{s}$

Now, please explain the catch in here..


texts: Best way to connect electric motor and differential in a tight space

texts:
I want to know, what the best way to connect an electric motor to a differential in a tight space. I first thought of a drive shaft, but the angle is to steep. The diff would be of a BMW E46 320d and the shaft of the motor has an outer diameter of 19.75mm and min 24.5mm depth and DIN 5480 teething.

Here is the side view of the setup

And the top view of the setup

Here's more info about the electric motor


texts:
I'm trying to build a filament extruder with some basic available tools and materials. Simply the main principle of the machine is to insert some amount of plastic raw material ( ABS in our Case ) to a hopper , move them inside a barrel with the help of helical screw which is derived by a motor, heating the material and extruding it from a predefined hole size.

lets assume that these are our givens:

Tube inner diameter: 20 mm
Helical screw outer diameter: 18 mm
Helical screw body diameter: 15 mm
Helical screw pitch: 30 mm
ABS density @ melting: 0.97 gr/cc
Motor speed: 30 RPM
Material output hole: 3 mm

Now what is the proper power of the motor to drive the machine?


texts: Adaptive downsampling of time-series data?

texts:
I’ve been tasked with developing software to (among other things) log temperature data from samples in a furnace. Generally the temperatures are very steady, but can, at times, experience dramatic changes.
I’ll be storing the data in SQLite, which is more than adequate for millions of rows, but this will be running on something like a Raspberry Pi with 8 GB of RAM. I’m doing testing now, but I’d rather not store data I don’t need to store.
The data should be easy to downsample regions of data without going below Nyquist, but when I search for “adaptive decimation” or “adaptive sampling,” I get some pretty weighty scholarly articles. I would have thought this wasn’t so hard to do, and widely available. I can do it after the fact, I don’t need to predict what my data is going to do. I don’t mind periodically going over older data to do the decimation.
It’s possible Pandas or some other Python library can do it with a simple call, so that might be a starting point for me (half the battle is figuring out what the technique is called). I’m writing this in Swift, so I don’t expect a ready-made solution, but if I knew what to implement, I could.
Any suggestions on how to accomplish this?


texts:
Question: Is 56 Nm enough torque for a delta robot with the below dimensions and specs? If not, what would be the minimum torque needed? Thank you in advance for your help.

I am working on a rotary delta arm design and needed help sizing the correct motor and gearbox. Below are the mechanical dimensions of the arm and application info.

Delta Arm Specs:

Base Radius (Center to Motor): 200 mm
Primary Arm Length: 279.4 mm
Secondary Arm Length: 441.96 mm
End Effector Radius: 100 mm
The arms are carbon fiber: Weight of arms is approx: 445 grams
The gripping mechanisms weight between 300 grams to 1 kg

Application Info:

Type: Pick and Place
Max Payload: 3 kg
Min picks per minute: 60
Max pick per minute: 100

I have been looking at using Teknic Clearpath motors with a planetary gearbox from Anaheim Automation.

Teknic NEMA 23 Motor Peak Torque: 5.8 Nm | Const (RMS) Torque: 1.2 Nm | Max RPM: 1860 with a 10 to 1 single stage gearbox Anaheim Automation Gearbox Arc-Min: 3.  At gear output expecting: Peak Torque: 56.26 Nm and Const Torque: 11.64 Nm. RPM Expected: 186

Here is a gif of the delta arm and its movement (Wikipedia) Delta Arm Sketch


texts: Thermoelectric Module Not Working Properly!

texts: I have a TEC-12706 thermoelectric peltier module. I am making a mini refrigerator (simple box refrigerator). I'm using this peltier and heatsink of equal size as compared with the peltier. I have given the picture of the heatsink attached with the hot side of the peltier. I'm facing a very big problem. While I connect this peltier with a DC source, it works properly for some time, i.e., the cold side of the peltier gets cool and the heatsink starts becoming hot. But just after a few time the peltier starts working in a different way. That is, the cold side of the peltier also gets some heated and the heatsink stops or reduces absorbing heat from the hot side of the peltier. I think the heatsink compound (or thermal paste) which I'm using is not proper. What do you think, what may be the problem? Please help me, I'm struck and am not able to make my refrigerator.!See this picture


texts: How to model ball joint in Patran/Nastran?

texts:
I would like to model below mechanical system in Patran.

But, I don't know how to configure boundary condition of ball joint.

The ball joint is spherically rotated.

When the described system is in gravity, the upper beam and supports would be deformed, then contact point of ball joint would be slightly rotated.

In my model, I just rigidly connected the ball joint by using RBE 2.

But, with my model, I can not consider rotation of ball joint.

Could anyone explain how to model this kind of ball joint, or give me some sources about this issue?


texts: Buckling vs. Yielding Failure of Columns

texts:
As I have been working through examples of construction projects, I've noticed that in nearly every case of a structural column (sample size considers only homogeneous material columns, no composite structures) the materials chosen to construct the beam will yield before the beam design chosen will experience Euler buckling. I may not be considering all use cases but is it easier (or more likely, safer) to design for yield failure modes than for buckling failure modes?

Perhaps manufacturing tolerances on mass produced steel beams are sloppy enough compared to material composition that it requires a larger Factor of Safety?


texts: Does the the field of tribology include the study of adhesives?

texts: Does the field of Tribology include the study of adhesives in addition to the study of lubricants?


texts: What is the gray-body emissivity value of air

texts:
Wonder if anyone would know what is the average thermal emissivity value of air relative to blackbody at near room temperatures? I am looking for that magical number between 0 and 1. Looked everywhere but couldn't find the value.

I am trying to enumerate thermal losses when heating air inside an envelope made of Polyethylene with very high transmissivity and hence low emissivity. I am thinking that actual radiative thermal losses of air itself might play an important role with regard to the temperature of the heated air. I am completely neglecting convective and conductive heat loss at this stage. (I understand that these are actually major contributors to the thermal balance.)


texts: Is there a rule of thumb to construe a screw

texts:
When your first idea is drafted you calculate which forces/pressures and so on are working on your system. And then you break the forces down into the single screws which are built in your device.

Exemplary let’s say, that screw is loaded axially with $8000 \ N$ – the transverse load could be unattended.

How do you decide to take the right screw dimension?
Things that should in my opinion be also considered are:

How is the load working on the screw?

concentrically vs. eccentrically
static vs. dynamic

How is the montage of the screw realized?

Simple tightening spindle vs. tightening by angle monitoring in the plastic range

What degree of utilization is allowed?
What is the strength grade of the screw?
And perhaps many more points…

The aim that I’m expecting is, something like: With these forces, this montage, this strength grade and … (simple calculation) … you have to take a screw M16x2  10.9

I’m curious to hear your experiences.

Thanks in advance for your help.


texts:
I've read this:
"A microphone converts sound into a small electrical current. Sound waves hit a diaphragm that vibrates, moving a magnet near a coil. In some designs, the coil moves within a magnet. Other microphones, such as condenser microphones, work on the principle of capacitance."
And I get how that converts sound to current. I've also read that speakers work by converting this current back into vibrations which then cause sound waves.
Here is what I am confused about: consider something like Siri, where a microphone interfaces directly with software. How does Siri/etc convert the current from the microphone to sound wave data (i.e a .mp3 file)? Is this just a shift/scale from the current waves? How are those factors calculated. I'm not confused on what Siri does with the sound wave data.
Thanks.


texts: Comparing EPA emission limits between wood stoves and wood furnaces

texts:
Emission limits set by the EPA were updated in 2020.
Currently, "Wood-burning stoves" are allowed 2.5 grams/hour of smoke emission [1]. On the other hand, "Wood-burning forced-air furnaces" are limited to 0.15 pounds per million BTU heat output [2].
Comparing these two units would require knowing how much heat output (in BTU) a stove outputs per hour. This must vary quite a bit, simply by how much wood you happen to be burning.
Are there general statements that can be made regarding this comparison? I'd love to know, for example, if one is always better (i.e. less smoke output) than the other.
Or am I going to have to start digging into spec sheets and doing conversions?


texts: Best reactor for solubility-limited reaction?

texts:
I have a reaction where component X is required to react with formic acid producing a solid precipitate. The main problem is that component X has very low solubility in formic acid and the reaction takes almost 10 hours to reach completion.

I am trying to improve the reaction time but all I can come up with as of yet:
1. run reactor at high temperature - 120 degC with reflux
2. use multiple smaller CSTRs to reduce mass/heat transfer limitations
3. ensure particle distribution of component X is neither too large nor too small causing it to float on the surface.

are there any other simple techniques to improve this reaction? perhaps a different mixer/impeller design?

I don't know of any catalysts that apply to this reaction and an investigation is not possible at this time.


texts: Generating a IES file from an illuminaire and a lens

texts:
I have a IES luminaire file of a lamp and some polar candela distribution plots of lenses like:

How can I create a new luminaire file combining the lamp with every lens?

I could manually sample the plots in order to retrieve the information from the plot but I haven't been able to fully understand how to weight the candelas values from the IES using the lens plots. I assume the plots are representing the iluminare of an ideal candela through a lens, but I'm not sure. Even if I were correct, there's various distributions (ways to weight each candela value of an IES) that for an ideal candela will output that plot.


texts: I am newbie to embedded programming. My problem is I can write and read data to ds1307(by saying using I2C debugger). But my received data on LCD showing 0xE1 constantly for every changing second. Is it I2C debugger showing wrong data as reading data? Or my conversion is wrong, if it so, my data should change but it doesn't. I'm stuck here so hard.please comment where did I go wrong.


texts: How do I interpret the following Bode, Nyquist and Nichols diagrams?

texts:
I am working with an arbitrarily complicated and long-winded transfer function that looks something like this:
$$
H(s) = \frac{as^4+\cdots+b}{cs^6+\cdots+ds^2}
$$
where letters represent constants. First I have the bod plot which has a consistently decreasing magnitude which indicates that t acts similar to an integrator for magnitude, but I am unsure about what the almost constant -180 degree phase margin indicates and why there could be this trough and peak around 10 rad/s.

This Nyquist diagram is below as well.  I think this is showing that the system is stable as expected as no open-loop poles appear on the right-hand real axis.

I zoomed in on the origin and this is what I was able to see. It seems like it does not ever cross into the positive real axis.

Nichols diagrams are something I have not worked with before and so am trying to understand their significance. This certainly mirrors the bode plot where a -180 degree phase dominates but is this saying that the phase is about -180 degrees for pretty much all open-loop gain values?


texts: How did Al-jazary's "castle clock" work?

texts: My question is what are the ideas behind the complicated historical water clocks. According to wikipedia, modern versions of the historical water clock rely on the principle of the syphon. So I ask how to translate it to the mechanical language. In particular, as is evident from my question, I'm very interested in knowing the inner-workings of al-jazary's "castle clock", which is an early example of programmable analog computer.


texts: Historical data for using supervised learning algorithm in the field of Mechanical Engineering

texts:
Being a student in the field of Mechanical Engineering, I am very new to Machine Learning.I did a couple of basic online courses of Machine Learning (including the one by Andrew Ng on Coursera). So, I am a bit curious about using Machine Learning in this field.

What I want to know is where can I find monitoring data in large quantities related to the use of any mechanical component  so that I can use it to train and predict results(just for practicing so as to know how everything works)

Also any other tips/tutorials/guidance on how to start working on the combination of these two fields would be helpful.


texts:
I am currently designing a planetary gear set, and I have designed the sun gear with a module of 2.25 and 35 teeth. Is there any formulae to calculate the internal gears size and amount of teeth?

Ideally I had like to have 3 small planet gears and 1 central gear.


texts: What is the meaning of line and points in the schematic of a polymer

texts:
In the engineering material book. It shows the following figure

The following is the text to depict the picture
"The origin of rubber elasticity is more difficult to picture than that of a crystal or glass. The long molecules, intertwined like a jar of exceptionally long worms, from entanglements—points where molecules, because of their length and flexibility, become knotted together (Figure 25.6)."

But I still don't know the point and line.


texts: Do ships powered by nuclear reactors use water for shielding?

texts:
On a different Stack, I encountered an answer that was making a comparison to nuclear powered naval ships. It was stated that the physical shielding being used was various kinds of metals. This seems... odd to me.

I assume that water is probably being used to cool the reactors in ships. But, water is also excellent at shielding. Considering how abundant water is for the environments that naval ships operate in, do the ships use water for shielding? And if not, why?


texts: Calculate MPH on the tire based on RPM of the hub?

texts:
I’m building a pitching machine that has an 8” wheel (16” OD tire) that is directly mounted to a 1/2” motor shaft.

Most similar questions reference a gearbox or pulpy system, but my situation is directly mounted to a 12v motor shaft.

Due to motor/fabrication design, the closest I can get my magnetic rpm sensor is a radius of 5” from the shaft.

So known variables for the calculation will be RPM at a diameter of 10” and the OD of the tire at 16” all on the same wheel.

How do I calculate the speed (MPH) of the tire?

I would imagine the OD of the tire runs slower than the shaft.

I hope this makes sense.


texts:
I have a complicated cylindrical geometry with a speaker mounted on somewhere middle of the rig. The one end is closed, the other is open. Sweeping the speaker frequency from 0 to 1000 Hz, I tried to find the acoustic resonance frequency of this geometry from several sensors at different location. It is found that there are some frequencies that give the local peak amplitudes. I thought those frequencies are the resonance frequencies, but when I compared the signals from two different sensors, the phase difference was neither in phase nor out of phase, but like 120 degree.  This result is counter-intuitive to me because I thought the resonance always happens with the standing wave, which gives only in phase or out of phase between two sensors. If the end boundary conditions are hard or soft BCs, the resonance theoretically occurs with the standing wave pattern. So I think my open end is not actually sound soft BC, but rather have low impedance BC.
Anyway, the below is my questions:

Does resonance always happen with the standing wave?
What properties affect the end impedance. Is it function of temperature? Frequency?


texts:
I paddle several different types of small craft in the ocean and bays near my home.  One phenomenon I've observed is beyond my understanding of drag on a narrow displacement hull.  When paddling in water less than maybe 6 feet in depth, there is a very noticeable increase in drag, which increases as the depth decreases.  This is true for all the types of boats I paddle, from a large 6-person Hawaiian outrigger canoe (L=40', width=2', draft=0.67') to a one-person racing kayak (L=20', width=1.5', draft=0.33').  I should add that hull speeds are generally in the 6-8 mph range.  I've read that rowing shells also encounter this same drag and they are longer, narrower, but with drafts in more or less the same range.

I've read one explanation that the boundary layer on the hull makes contact with the bottom and the bottom increases the drag on the outer part of the boundary layer which in turn is transmitted to the hull.  This seems highly unlikely to me, especially when the water is more than a maybe a foot deep.  I don't believe the boundary layer from a 20 foot kayak extends that deep.  As I said, this is noticeable at water depths up to 6 feet or more.

I've also heard that pressure waves from the hull bounce off the bottom and reflect back up to the hull and cause drag but as an engineer that doesn't really sound very rigorous to me.

It seems to me there might be some interaction between the bow wave of a boat and the bottom, since I know that the dynamics of surface waves do extend approximately as deep as their wavelength, and at these speeds the wavelength of a bow wave is certainly on par with the water depth.  Can anyone give me a properly defensible answer to this?


texts: How do you call the intersection with barrier and you can always right turn?

texts:
In the photo above I can name the first 3 intersection

a) Regular intersection

b) T intersection

c) Skewed intersection

I am having a hard time on identifying the fourth intersection, what do you call that one?


texts: Viscosity is resistance to the motion of fluid layers sliding over one another. Density is a measure of forces of attraction between atoms or molecules of same species. Is there any relation between the two?


texts: Pneumatic actuator capable to achieve 5m/s?

texts: Is there a pneumatic actuator capable to achieve 5m/s and will be good idea for constant work? I know SMC have up to 3m/s, but I can't find faster.


texts: Is stroboscope a useful device to control the translational vibrations?

texts:
There is few material on net related to stroboscope applications. since it is an optical device, it is best used to control the vibrations of rotary devices like turbine blades electromotors etc.
but is it also useful if you want to control the vibrations of a lump mass ( big and heavy structure) doing very small vibration in its place in very high frequencies ? I don't give a number of how much or how big ( up to you to consider  the proportions)


texts: AC Motor On/OFF Control using SSR instead of contactor

texts:
I would like to control a 1-phase 3HP motor using a SSR ( the reason being, I need to switch it on/off using a signal (0-5VDC).

Are normal SSRs (ex:Fotek 40A model) capable of handling the starting  current of a 3HP motor?

What are the protection devices that I need to use in the circuit.

I guess a Motor MCB is required. Is anything else required?

All opinions/suggestions are welcome.
Thanks in advance


texts: Can pinned support / pin joint transfer moments in 3D?

texts:
What's an authoritative definition of whether the idealized pinned support and pin joint can transfer moments in 3D?

Most sources say both of them cannot transfer moments but are apparently only considering 2D. A real pin joint obviously can transfer moments about all axes normal to the pin's axis. So is an implementation of the ideal pin joint really more like a ball joint than a pin joint?

I assume a pinned support is the same as a pin joint but with one end fixed to ground. But maybe they have different numbers of degrees of rotational freedom?

For example, if this support can carry moments about two perpendicular axes (red arrows), would it be correctly called a pinned support?

In comparison, this one has all 3 rotational degrees of freedom, so is it still a pinned support?


texts:
(This is a follow-up to the previous question I posted.) I'm basically trying to control three different tempeartures on a single PCB. It looks like the following:

The middle pattern heats up to about 75 deg. Celsius, while the far-right and far-left ones heats up to 95 deg. Celsius. The ones between them are supposed to be controlled to 55 deg. Celsius.

This is where I'm facing problems. I think, because of the relatively high temperatures of the surrounding areas, I'm not able to control the 55 deg. heater, and the temperature keeps rising. (I'm using thermocouples to measure the temperature)

As a solution, I thought of removing the area between the heaters, so that the heat gets dissipated into the air. However, I'm not entirely sure of that theory, and needed some opinions about that. Also, the design cannot be changed at this point, so the spacing between them is pretty much a constant.


texts:
What are the various lumped element dynamic system models called?  By lumped element dynamic system models, I mean the various nodal models comprised of things that look like capacitors, inductors, resistors, etc.  In other words, the models where these analogies occur. For example, for electrical systems, we just call them circuits.  In heat mass transfer, I sometimes see them called thermal nodal models or thermal circuits.

Basically, I'm trying to study bond graphs, which talks about these analogies, but has its own notation.  Generally, in the bond graph literature, I see various diagrams and how they relate to bond graphs, but I'm not familiar with the various diagrams outside of electrical circuits.  For example, I see similar diagrams for mechanical systems with dampers.  I see diagrams for hydraulic components.  I'm pretty sure that there's even some kind of diagram that uses chemical potential for for current and molar flow for voltage.  The problem is that I'm not familiar with these diagrams and notation.  I'd look them up, but I'm not sure what they're called and I'm having a difficult time determining the common use names for the lumped element models in various domains.


texts: Calculating the diameter of screws that are on radius 160mm from axis of rotation. I need help - I don't know If I'm thinking in the right way

texts:
First of all, english is not my first language so if there are some mistakes I made - I'm sorry and I hope everything is understandable.
The example I am trying to solve reads the following:
The gear is loaded with torque of M=500Nm it is connected with a clutch with 8 screws made from ST5(S275) steel. The screws are distribiuted on diameter D=320mm.
Calculate the diameter of the screws.

So what I think I should do here is to use the definition of torque and calculate the value of the force that is distributed equally between the screws, so it would look like this:
$$F=\frac{M}{D/2}$$
$$F_{\tau} = \frac{F}{8}$$
where 8 is  the quantity of the screws/
and then calculate the diameter using shear condition
$$\frac{F_{tau}}{A}=<k_t$$
where

$A$ - cross section area of the screw
$k_t$ - admissible stresses on shearing

Am I right? Or am I doing a mistake somewhere? If all above is correct is it all I have to do or is there something other to calculate?
Thanks in advance for your help!


texts:
One night, raining, crossing a street, I noticed strange thing about one of the stopped cars: In front of that car's headlamps, it rained dashed lines. I assumed that the car used LED for lights, running on AC, all with the same phase. (I couldn't recognize the model of the car.)

But what benefit do the AC headlights give? Most car lights run on battery so you can use it even when the engine is off. What powers AC car lamps when the engine is off?


texts: Could a Fuel Breathing Engine Rather Than an Oxidizer Breathing Engine Work?

texts: Here on Earth, the atmosphere is ideal for jet engines which combust a fuel using the native oxygen as an oxidizer. On another planet, might it make sense to carry oxidizer in the fuel tanks and scoop the fuel from the air (assuming the planet contained some suitable Fuel in its atmosphere)? This is just the reverse of what jets here on Earth do. Would there be some reason for this to not work?


texts:
I have a 12" flow meter that uses a float on a stem and whenever gas is supplied, the initial flow spikes the float to the top and gets wedged. The flow meter is plumbed downstream of a control valve and ball valve that is being used to regulate the flow at 40 cfm. The supply side is helium that can range between 60 - 80 psig and the outlet of the meter is plumbed to a chamber at half atmosphere, ~ 400 Torr.

I'm aware that a ball valve should not be used to fine tune flow, that's why I need some clarification to properly correct this issue. I attached an image to help better explain my current setup.


texts:
I am trying to make a MOSFET switching circuit where its gate input is 12V clock pulse. Now when I put the load between (Vdd) and (Drain), there is no drop voltage VDS, but when the gate input falls down to 0, there still a voltage between (Vdd) and (Drain) (across the load).  - - - - - - case (1).

When I put the load between (Source) and (Ground), the situation is reversed so that there is a voltage drop VDS, but when the input falls down to 0 the load voltage also becomes 0 (pulled down) . - - - - - - case (2).

Now what is better, putting the load on case 1 or case 2 ?


texts: what means Probablity of event excedence of so many years

texts: I like to know about occurrence of earthquake events when we say that earthquake of 0.5 g will occur in 50 years in excedence of.


texts: What affects an internal-combustion engine's efficiency?

texts:
For a gasoline internal-combustion engine, used in accordance with the manufacturer's instructions (specified quality oil, fuel, etc. used), what changes the efficiency of the motor?

For example at higher RPM, more heat generated due to friction would mean it isn't as efficient as at lower RPM, since some energy is lost as heat.

The engine's alignment would also have an impact on the efficiency of the engine – for example if a car's motor is mounted upside down (i.e., 180° rotated from the camshaft's axis of rotation) it won't be as efficient as it would be the right side up.  So there is some relationship between engine tilt/misalignment and efficiency.

Another factor could be the temperature: hot engine vs cold engine vs overheating engine.  Also does ambient temperature affect the efficiency – e.g., if the same engine is running in Antarctica vs the Sahara desert?

What other factors might have an influence on the engine's efficiency (disregarding fuel types E10, U95, U98, etc.), and are they also valid for diesel motors?

I've been looking for references with Google's aid, but I haven't found anything that is conclusive.


texts:
Major questions:

Are 0.028 locating tolerances divided by two for left/right shift?
Do overall drawing tolerances apply to a thru hole with a locating tolerance of 0.028 (max material condition)?
If a part is dimensioned off a theoretical center, does the overall dimension apply to the stackup?


texts: How are tunnels dug from two endpoints joined?

texts:
Let's assume I want to build a subway system. I dig two subway stations and now I start digging a tunnel from both of these endpoints simultaneously.

How can I ensure that the two tunnels dug from the different endpoints meet in the middle? I don't believe I can use GPS underground. What methods do professionals use to ensure that the two tunnels meet? Are there some positioning technologies that work underground?


texts: How I can separate a matrix into two matrices in Matlab?

texts:
I want to separate  into two  matrices in Matlab like this:
$$
Q=Sq^{T}Sq
$$
for example this matrix:
$$
Q=\Biggm[\matrix{92.316 &31.78&240.417\cr
31.78 &194.66 &275.47\cr
240.417 &275.47 &938.99}\Biggm]
$$


texts: Multi-gas barometric height formula in isotope separation devices?

texts:
What is the barometric height formula for a mixture of gases?

The main problem I can see, the curves describing the minimal energy (kinetic + gravitational/centrifugal) won't be any more a simple derivative, but a functional equation.

I think, this or similar equations could be useful in very separate areas (isotope separation, estimating high atmosphere components of planets, etc.) Despite I couldn't find anything with google about this.

So, the question is: we have a high gas mixture in constant g gravity and T temperature. We know the $p_1$, $p_2$, ... partial pressures of the gases on the $h=0$. Of course we know every relevant constants of the gases, too. What is their minimal-energy, isothermic, height-dependent partial pressure function $p_n(h)$?


texts: Does a rotating bar experience lateral force?

texts:
Let's say I have a bar attached to the rim of a rotating wheel, , and it's in a vacuum so we can ignore drag.

If the wheel is rotated, does the bar experience a lateral force (perpendicular to the bar)? What if the rotation speeds up impulsively: will the bar experience a lateral force then?


texts: What is a Spiral Curve, and How is it Different from a Normal Curve?

texts:
I've heard the term spiral curve used to describe a section of highway that is more aesthetically pleasing to the driver's eye. However, I believe I've driven on enough road to say that I can't definitively tell the difference between any given curve other than how "sharp" it is.

Could anyone explain how one can determine if a section of curve on a highway is classified as a "spiral" curve, and are there other advantages besides "making it look good"?


texts: What's the name of the calculus used to make smooth transitions in roads?

texts:
So I'm not actually an engineer, I'm a novice computer programmer but I think in order to solve a problem I have I'm going to need some help from the world of engineering.
I remember in high school they were teaching a civil engineering calculus class and one thing they spent a lot of time on was how to figure out the perfect curve for the perfect slope to transition the road to a bridge smoothly. My computer program is a digital paint and photo software which may include 3D sculpting and modeling later on. There is an existing tool that I don't know a ton about but it does something kind of similar called a Bézier curve and basically, it lets you find smooth curves. But I'm looking for something else as well, I think.
Here's a rough picture of what I'm trying to do. Imagine this is someone's face. It is showing a mid-tone and a shadow. The green circle is where an AI-powered healing stamp will attempt to conceal a blemish. But there's a problem. There's both shadow and midtone in the same area as the stamp, and we're basically inventing contours in the skin. The robotic way to do it would be to just B-line between both instances of shadow, but maybe it would look more organic if there was a smooth transition between the external shadow's slope going in and the artificial shadow that continues.
So, what math would you use to figure that out, and does anybody know of any good place to learn it? Could I do it with just Calculus I under my belt?


texts: Is it possible to replicate a Tesla valve in large scale?

texts:
Supposedly a Tesla valve will impede fluid or air flow in one direction whilst allowing flow to move freely through the valve entering from the opposite direction, without using any moving parts. Also the alleged effectiveness of the valve is based on its length, with a longer configuration being more efficient.
Does anyone know if such a valve is scalable or does the properties of the valve diminish with greater size?


texts: What is the maximum temprature that could be achieved by compressing air?

texts: We know that compressing air produces heat but is it possible to achieve temprature of 700degree C just by compressing air. If not what will be the maximum temprature that could be achieved?


texts:
There is this problem I can't figure out. One measurements wheel needs to be attached to a slowly moving but wildly shaking and twitching construction machinery. I am trying to greatly absorb the shocks by means of a spring pictured below (and a damper not pictured). The wheel also needs to move in parallel with the machinery.

In this design I have coupled the wheel to the machinery by a guided spring. The spring stretches and compresses between two metal plates with the upper plate sliding over rod1 and rod2. I am not a mechanical engineer, but I think there will be problems due to the way the wheel is dragged alongside the machinery, i.e. there will be some friction between the two rods and the upper metal plate, causing the spring guide not to work very well.

If this is the case, what is a standardized known to work manner to approach this problem - shock reduction / isolation between the machinery and such a wheel ?


texts: Lintel construction technique in UK in 80s using blockwork

texts:
An issue has been raised when replacing windows that the blockwork inner leaf is missing a lintel.

The hollow blocks have been in-filled with concrete which makes me believe that this is a ‘cast-it-yourself’ lintel where blocks have been hollowed out, rebar inserted and concrete cast.
Can anyone confirm whether this was a valid construction technique in the 1980s in the UK?
If so can you provide more information such as the size and expected quantity of reinforcing bar?


texts: Why are both conductors in a High Voltage Direct Curent powerline isolated from ground?

texts:
Picture of a High Voltage Direct Curent powerline (HVDC line) on the Læsø Island, Denmark (from Google Street View):

We can observe that there are 2 conductor cables, and that both are insulated from the tower (which is grounded). Because the line is in DC it makes sense to have 2 cables.
However, I see no reason why one of those conductors would not be grounded. For example on railway electrification, one of the conductors (the overhead line or 3rd rail) is always isolated and the other of the conductors is the rail track itself and is grounded.
Grounding one of the conductors on the HVDC line might save money on isolators, not to mention electric and safety issues if the HVDC line as a whole recieves a too large voltage offset compared to ground.


texts: How do I separate these powerful magnets from their base plates?

texts:
Old hard drives are my favourite source of super-powered fridge magnets. I have a bunch of them holding up countless childrens' drawings. But the magnets themselves are stuck to base plates of various shapes, some with pins and protrusions which are sometimes unhelpful.

I am wondering what the best process would be to remove the magnets from those plates? They're definitely not stuck on solely by their own magnetism, so my best guess is "some sort of glue". I don't want to take a saw or screwdriver to them, because they're probably way too firmly stuck and also too brittle -- I'd just break them (possibly spectacularly so). I have tried sawing off the odd parts of one base plate, but getting the metal particle sawdust away from (or off of) the magnet is quite a challenge. I have also tried to twist and pry those pins off, but they're stuck in their holes better than my measly DIY-ers toolbox can undo (I don't have access to a metalworking shop).

So ... Heat? Acid? Magic? Some other SE stack?


texts:
I have a fresh feed (stream 1) entering a reactor . This fresh feed consists 225kg/h of iso-butane , 225kg/h of butylenes and
50kg/h of n-butane .

In the stream table I need to add in a flowrate value . How do I calculate this ? Do I take the average ?

And also the composition (wt%) how do I calculate them ?

Do I calculate the percentage ?
This means iso-butane and butylenes have 45% each and 10% for the n-butane in the mixed fresh feed .

This is a question I have to solve . I'm not given wt% . So can I calculate the wt% by knowing the flowrate of all the products in the fresh feed ?


texts: Nusselt number for partially adiabatic tubes / rectangular ducts

texts:
I am trying to model laminar, forced convection heat exchange for water in a round pipe and rectangular duct. In both cases, a portion of tube / duct is maintained at a constant surface temperature while the rest of the tube / duct is insulated. I have two questions:

Is there a reference that gives the Nusselt number for fully-developed, laminar flow in a round tube when a portion of the tube is insulated? (What I'm looking for would be similar to the results presented here: http://www.dtic.mil/dtic/tr/fulltext/u2/736260.pdf in Table 14 pg. 151, but for round pipes instead of rectangular ducts)
Is there a reference that gives the Nusselt number for either Graetz flow, or simultaneously-developing flow in a tube / duct when one or more of the sides are insulated?

Thanks.


texts: Spring Loaded Pin with Chamfered Pin Finish?

texts:
I would like to try out a component that operates like a combination of the two pictures provided - spring loaded pull pin, with a pin finish like a tubular latch (chamfered/filleted finish).

Do these exist?

If somebody can tell me their correct name or better still, provide me with a link to a manufacturer's site that would be great.

Thank you


texts: Running a well pump rated for 230V on 208V power

texts:
I have a well with a 1.5 HP pump. The pump is rated for 240V input. At the moment, the only nearby available power is 4-wire 208Y 3phase. I am considering connecting two of the three phases to the well pump, so it receives 208V where it is expecting 240V.

To what extent, and by what mechanism, will it hurt the pump if it is powered by 208V instead of 240V? Are there warning signs I can observe (like something electrical I can measure, or something I can observe about the flow of water) that would indicate whether this lower voltage is causing problems?

More generally, when an AC motor says it's rated for a certain voltage, without specifying a range, how tight is that calibration? Like, what is the "probably not much worse" voltage range? My intuition says "ohh eee ah around 15%" but I'm realizing I have no actual basis for that sentiment.


texts:
When looking at various small fans (like those found in a computer or the bathroom) you often see in their specifications the type of bearings they use. And the typical values there are either "sleeve bearing", "1 ball bearing" and "2 ball bearing".
Now I can imagine what a "sleeve bearing" is - it just means that the axis of the fan is stuck in a hole, maybe with a bit of lubricant, and that's that. In essence, it means "no bearing". But what are "1 ball" and "2 ball" bearings? I know what a "ball bearing" is in general, but how do you make that with just 1 or 2 balls? I think that the very minimum theoretical amount would be 3 balls but in practice I don't think I've seen anything less than 6 or so.


texts: How to put the green diamond back in it's original position in AutoCAD 2018

texts:
How would I go about resetting the position of the green diamond which acts as an anchor point for these text objects?
The idea is to be able to move the text box around with the green diamond in it's original position where it moves around with the text box, as it is by default.


texts: How to compute heat produced by 2.5kw heating element

texts: Lets say the following is limited to 2.5 kW only and the thermostat and flow switch failed during use. After water is boiled away and bit of steam released. What would happen to the heating element inside? Can it just stay inside getting hot like a lamp? How do you compute the heat of the 2.5 kW heating element?


texts: Thoriated tungsten TIG electrodes were in use 45 years ago.What were their specific use and problems?

texts: Some TIG electrodes in use in the early 1970's were marked Thoriated Tungsten and Non-Thoriated Tungsten. What were the specific purposes or properties for these TIG welding electrodes?


texts: Can I use 220-12v,1.5 Amps Stepdown transformer along with 12V 2A (KBP200) bridge rectifier to build a charger for 12v, 7.5AH battery or I should use transformer with Higher output, maybe 15V


texts: Transferring the project from "Altium Design" to "SolidWorks" while maintaining silk-screen printing, sizes and everything else

texts:
I want to transfer the PCB project to solidwork from altium design, I read forums on how to do it better, and so:

Save to STEP. The option is good and working, but I did not like the option, since silk-screen printing and tracks on the PCB are not drawn. The PCB itself is just like a block, very unrealistic. Adding PCB tracks by overlaying a photo is not an option.

Save to PDF3D. It also works well, but there are also problems, namely:

The board opens in the form of Graphics bodies, if you open it as a solid body or surface, then the solid simply hangs and that's it.
The size of the fee changes completely. There should be a length of 100 mm, and it is 9 with something, that is, the point is not in the correct translation of inch-centimeter-meter-millimeter.
When drawing, all colors are lost, the board and elements are just gray, although in the working environment the model can be rotated and it is colored. You can manually sit to paint all the conductors and radioelements, set the material for them. Yes, it works, after painting, the model can be drawn very well, but it is long and wrong to sit and paint what I have already painted in another program.

Although everything looks great here, for example:
But I need to be sized, not just have a pretty picture.

And the last option, as the most developing one at the present time, is "Collaborating between Altium Designer and SOLIDWORKS". This is the cloud storage of the project. I simply did not manage to do it, it’s something difficult, I need a paid registration and I cannot do it.

the "SOLIDWORKS PCB Add-in" also requires registration and it is very difficult.
It also exists, but it seems to me that this is something old and does not receive development: "Solidworks modeler for Altium"


texts: Casting a phone screen using fiberglass resin?

texts:
My phone is pretty smashed up and I won't be able to buy a new one for quite a while. I know you can buy a phone for ~$30, but I'm in an extremely tight situation and I just can't afford that right now. I do, however, have some Protite (clear-casting/embedding) fibreglass resin and catalyst. So my question is, if I were to cast a (temporary) new screen, how safe would it be to use? Would I even be able to attach it to the digitiser without losing functionality? And, if anyone could even approximate, how long could I expect it to last?  I know an epoxy bond would be stronger but aside from that I'm not sure how it would go enduring heat from the phone, or if it might pose any other risks. I live an hour out of town and rely on my phone greatly, it's kind of essential, so any help would be greatly appreciated.
NB: I posted here because I felt this query pertained most to 'a specific engineering problem' and didn't fit the criteria for the electrical engineering site, nor do I believe it is specific to a particular type of device e.g. iPhone or Android. I apologise if that is not correct. I'm new to SE and definitely no expert in such matters.


texts: Why have some Hyperloop researchers abandoned the air bearings initial idea?

texts: Air bearings are a cheap solution for Hyperloop, unlike the costly magnetic levitation system. I'm consulting some sources and it seems there's enough air in the tube at 100 Pa to feed the air bearings.


texts:
I was referring to some Thermodynamics text books and found that their definitions of a "pure substance" seem very subjective.
"Air, for example, is a mixture of several gases, but it is often considered
to be a pure substance because it has a uniform chemical composition" (Fundamentals of thermal-fluid sciences, fifth edition - YUNUS A.
ÇENGEL, JOHN M.
CIMBALA, ROBERT H.
TURNER)
"A system consisting of air can be regarded as a pure substance as
long as it is a mixture of gases; but if a liquid phase should form on cooling, the liquid would
have a different composition from the gas phase, and the system would no longer be considered a pure substance" (Fundamentals of
Engineering Thermodynamics - Michael J. Moran, Howard N. Shapiro)


texts: Help with Engineering Mathematics, Struggling to determine coefficients using methods detailed in this research paper

texts:
I am struggling with a curve fitting calculation below. the part I am stuck with is arguably the simplest part, which is determining the coefficients $\\K_3$ and $\\K_4$. It seems like it should be simple/straightforward but it's not clear cut at this stage. some clarity would be appreciated on what I am missing in terms of defining the coefficients of the equation assuming that $\\p = 5$ just to keep it simple.

I am trying to calculate $\\I_s$ using equation (II.10) assuming that $\\I_h$ = 0 and $\\I_s = I_0$

if $\lambda\ = \lambda\ _m $  $\sin(\omega t)$

$\lambda\ ^5\ = \lambda\ _m^{5} $  $\sin^{5}(\omega t)$

using the trigonometric power formula:

$\lambda\ ^5\ = \lambda\ _m^{5} $  $\sin^{5}(\omega t)$ =
$\dfrac{1}{16}(10\lambda_m^{5}sin^5(\omega t)-5\lambda_m^{5}sin(3wt)+\lambda_m^{5}sin(5wt))$

note: I used wolfram alpha to complete this formula and couldn't figure out how to use subscript, for this equation $\lambda\ = \lambda\ _m $

I could use some help with determining the coefficients $\\K_3$ and $\\K_4$
what am I missing ?


texts: Why is the Poisson's ratio for isotropic 1/4 and the maximum value 1/2 (when there is no net volume change)?

texts:
It sounds logical untill I tried some thought experiments. So I must be doing something wrong. Or I am missing a fundamental aspect.

What I thought of was:

-lets say you have an orthogonal parallelepiped which is pulled in tension by a stress-strain test. (in the long axis or z-direction).

the lateral sides are 5 mm and 4 mm and the axial length is 7 mm.

-It has been elongated by the test untill the specimen had an axial length of 11 mm and hypothetically the 4 mm lateral side did not change.

So the original volume was 4x5x7= 140 mm^3 and since there is no net volume change the final length of the lateral side that did change has to be:
140= a x 11 x 4 -> a= 35/11 mm

now if you calculate the poisson's ratio: v= - Ex/Ez

-> Ex = (35/11 -5)/5= -4/11 and Ez= (11-7)/7= 4/7

v= 4/11 : 4/7 = 7/11 = 0.64 > 0.5

How I understood it: There is no volume change, so when you elongate one direction the other two will compensate this by compressing. And this poisson ratio of 1/2 is in the extreme case that one direction does not compress and so the other side has to take all the compression. Like in the situation that you elongate the axial side to twice it's orginal length, then in order to have same volume the two other directions have to become each 1/4 of their orginal length or one direction has to become 1/2 it's orginal length. This will indeed then give poisson ratio of 1/4 and 1/2. So I don't get why with other numerical examples I don't get this same 1/4 and 1/2 ratio.


texts: Structural Analysis of an RC plane in flight

texts:
I am working on structural analysis of an RC plane in a symmetrical maneuver. There are two types of loads on the structure a) aerodynamic loads and b) inertial loads.

I have determined the aerodynamic loads by performing CFD analysis on Fluent. Mapping of aerodynamic loads from CFD mesh to structural mesh in MSC Patran is easy. The details of the load mapping are given in link [1].

The maximum inertial loads in any maneuver can be determined using analytical calculations or directly from different handbooks/standards including FAR 25 etc.

I have read somewhere that I can perform static analysis of unconstrained system using inertia relief. However, from what I have learnt from link [2], the inertial loads cannot be used in inertia relief analysis.

Question#1: Is it possible to perform the static structural analysis of an unconstrained object subjected to aerodynamic loads (which are nothing more than a pressure distribution) coupled with inertial loads? If yes, how?

Question#2: If static structural analysis cannot be performed, do I have to perform a dynamics analysis?

LINKS

1- https://www.eng-tips.com/viewthread.cfm?qid=446687

2- https://pdfs.semanticscholar.org/6e7c/9a0ba36d86ac73b3e2e213fa64e3b6c5b988.pdf


texts: Penetration depth and weld deposition rate in Welding

texts:
What factors affect the penetration depth and weld deposition rate in arc welding?
How does polarity affect the penetration depth and weld deposition rate?
My lecturer said that penetration depth is higher when using straight polarity when compared to reverse polarity.
But I've read in a textbook that it's the opposite.


texts: What are the some of the best (dis)engagement mechanism for small gears?

texts:
I’m planing to build a robot out of gears.  I was wondering what kind of (dis) engagement mechanism would be suitable for gears that are about 2.5cm (1 inch) in diameter.

PS: preferably, (dis)engagement of gears accomplished without stopping.

Thanks!


texts: Is there a formula for the burst working pressure of a spherical pressure vessel that takes into account its material peoperties? It should be noted that this is not a concentric sphere design (it has only one radius) .This is a formula for a pipe: http://www.engineersedge.com/calculators/pipe_bust_calc.htm


texts: Larger battery from 18650 batteries - using a case?

texts: I want to build a battery for an electric bicycle using 18650 batteries. But I'm not into spot welding so much. Would it be possible to build a large case for the 18650 batteries with these types of black plastic cases serial connected together and then just put the batteries in place when I want to use them instead?


texts: How can I join a 1/2" motor shaft to a gearbox with a 14 mm input?

texts:
I need to join a half-inch motor shaft to a gearbox with a 14 mm input (the input is not a male shaft, but a female collar with a 14mm hole). I'm considering using a sleeve with a wall thickness of 0.026" (0.6604 mm) but not sure it will be strong enough.

If it will work to sleeve this, what material should I make the sleeve out of?


texts: What's the name of the white lubricant that children's toys often use?

texts: When I was little I would often take apart my toys and found that if they contained any gears or motors they'd always be coated in a white lubricant. What is this substance?


texts: Can redundancy be used instead of periodic calibration?

texts:
A lot of production equipment requires periodic calibration as part the documentation that the equipment is under control. The companies selling the equipment knows this and sometimes lowers the price of the equipment and offer an expensive service agreement (better to sell a long time service than a product once).

But wouldn't it be valid to use redundancy and drop calibration - what are the chances that both drift or breaks at the same time (AND that the process comes out of control). If one goes out then it just time to order a calibration..

An example could be monitoring systems like temperature loggers. Having two loggers (perhaps from different manufactures) and just drop calibrating.

Do anyone have some arguments why this would NOT be such a good idea?

Update

Thank you very much for the big interest in the topic!

I changed the header to use the term periodic calibration instead of just calibration - in order to be more clear. I would also like to elaborate here a bit more on what I mean by periodic calibration and proven state of control.

In EU GMP guidelines for process equipment the following is stated:

  5.3 Calibration

  5.30 Control, weighing, measuring, monitoring and test equipment that is critical for assuring the quality of intermediates or APIs should be calibrated according to written procedures and an established schedule.

  5.31 Equipment calibrations should be performed using standards traceable to certified standards, if existing.

  5.32 Records of these calibrations should be maintained.

  5.33 The current calibration status of critical equipment should be known and verifiable.

  5.34 Instruments that do not meet calibration criteria should not be used.

  5.35 Deviations from approved standards of calibration on critical instruments should be investigated to determine if these could have
  had an impact on the quality of the intermediate(s) or API(s)
  manufactured using this equipment since the last successful
  calibration.

EU Guidelines to GMP vol. 4 part II

This industry commonly uses two calibrations to prove/document that the equipment has been under control the entire production period (the period between before/start and after/end calibrations).

My point is that it seems unlikely that both devices measures wrongly AND that the process is out of control (unless the root cause affects both the measurements and condition). The idea of redundancy instead of calibration is derived from the principle of separating the control and monitoring system - since a drift would not be caught and the process could then go out of control/specs.


texts: How to make a wireless modem using a normal Wi-Fi router and a 4g usb modem

texts: I have a normal TP link (Model: TL-WR841N) router and an USB 4g modem. But the WIFI router does not have any USB port. I want to connect the USB modem with the router, want to share internet wirelessly.  Is it possible to connect?


texts: Control Variations in a Measurement (Temperature Sensor)

texts:
I have a temperature sensor and I want to normalize the sensor values. The measured room has a pretty constant temperature but the sensor shows slightly different values e.g. 30.20, 30.00, 30.30, 30.00. For display reasons, I want to have it less variation. Also sometimes it deviates unreasonable e.g. 30.00, 30.00, 10.00, 30.00, 30.00. But it can change from one moment to another also in a reasonable way e.g. opening a window: 30.00, 30.00, 30.00, 30.00, 25.00, 15.00,10.00

I do not have target curve otherwise I thought about a PID.

At the moment I sum the last values and build an average. What can I do to

normalize the output values
eliminate runaway values


texts: If you have a small fan that blows hot air, and a larger fan that blows cold air against it, what happens to the hot air?

texts:
For context, I have a laptop that has a fan that sucks in cold air from the top on the left side (for cooling the cpu), and a fan that blows hot air out the bottom on the right side (for cooling the gpu). It has problems with heat, so I put a large cooling fan underneath it that sucks in hot air from the bottom and pushes it onto the bottom of the laptop. I'm curious to know if this actually does anything at all.
I apologize if this is a dumb question, as I have a computer programming background and not a physics/engineering background. I simply couldn't find an acceptable answer on google.


texts: Torque Required to Drive Capstan and Bow

texts:
I am trying to find the torque exerted on the shaft of a capstan and bow drive. In particular, the system I'm looking at has two wire rope pulleys, and two idler pulleys, and is used to drive a carriage as seen Below:

In this case the drive pulley consists of two separate pulleys tensioned against one another, with the end of two wire ropes terminated in the pulleys.

Naively, I would assume that the force F is equal to the Torque T * the radius r of the drive pulley.

Are there any additional effects due to a multiple number of wraps on the pulley (one side reels out, while the other side reels in, keeping the total angle of wraps equal throughout the motion)?

Does the capstan effect play a large part with this mechanism? From what I understand the capstan effect should cause less tension at the wire rope stops embedded in the drive pulley, but not effect F.

Thanks!


texts: Mechanism to translate rotation into reciprocating horizontal movement

texts:
I am building a machine, and one of it's components is a mechanism that will convert rotational energy to a reciprocating horizontal movement.

I am aware of various mechanisms such as the Scotch Yoke shown below:

Which perform this translation. In fact, I would have used the Scotch yoke since it is mechanically simpler - however, the problem with the Scotch Yoke is that the extent of the lateral motion is constrained to the diameter of the wheel.

What I want is to be able to create a lateral reciprocating movement of extent NxD where N is a positive real number, and D is the diameter of the wheel.

Is there an existing mechanism that generates lateral displacements that are several times larger than the diameter of the rotating circle/wheel?

2https://imgur.com/a/nYFXKEQ


texts:
I have the following problem: there is a copper pipe getting through a wooden wall. On one side of the wall (hot side), I have elevated temperature which is defined by radiation and convection. On the cold side I have ambient temperature, again defined by radiation and convection (picture in the attachment). It should resemble the experiment done in oven.

However, between the wooden wall and the copper pipe there is a little gap which (in reality) lets some of the hot gasses to pass from one side to another. So far, the temperatures on the cold side are much lower comparing to the experiment.

Is there any way to simulate this stream of hot gasses getting though the gap around the pipe and how to do it? Or if I am doing something completely wrong with defining the parameters? Is this even possible to do with Workbench only?


texts: Arc subtended by stretching of a conical spiral spring

texts:
I'm trying to work out the angle subtended by the stretching of a conical spring and I have a solution but I'm not 100% sure about it so would appreciate some feedback.

An Archimedes spiral spring is shown above with radii at various points. What I would like to come up with is an equation for the angle that each part of the spring gets stretched by as a function of the radius and the distance from rest $x$. I know that for a normal spiral spring of constant radius $R_{ss}$ if it is stretched by a small amount $dx$ then it will subtend an angle $d\theta$ therefore
$$
dx=R_{ss}d\theta \\
\int_0^{x}dx=R_{ss}\int_0^\theta d\theta \\
\therefore \theta=\frac{x}{R_{ss}}
$$

For a spiral conical spring with radius $R_{cs}$ that starts at $R_{cs0}$ and grows to $R_{cs1}$ what I did was integrate the radius:
$$
dx=dR_{cs}d\theta \\
\int_0^{x}dx=\int_{R_{cs0}}^{R_{cs1}} \int_0^\theta d\theta dR_{cs} \\
\therefore \theta=\frac{x}{R_{cs1}-R_{cs0}}
$$
It seems too simple though hence why I would like to check here what the thought is on the solution.


texts: Calculating automotive suspension wishbone loads by considering the structure as a 3D Truss

texts:
I am trying to calculate the loads in the suspension components of a typical car double wishbone setup.  I have found a thread on the www.fsae.com forum, which seems to be exactly the kind of thing I am looking for. It involves considering the assembly as a 3D truss, and building up matrices, containing

the unit vectors and cross products at the mounting points of the struts at the upright
the forces and cross products at the tyre contact patch.  Which when the inverse of matrix 1 is multiplied by matrix 2, results in a third matrix containing the loads on the struts.

My question is, can someone give me the name of this method of truss analysis, and any textbooks / resources that specifically cover this method?


texts:
A colleague of mine sent me this image of some racking and I've been trying to figure out the design intent of some of the features.

Image one (key holes)

Looking at the keyholes on this racking the one side of the lobe is curved while the other side is straight, sloping away from where the skids are going to be placed.

Image 2 (top view paint sketch of the racking profile)

This image is a quick and dirty sketch of the shape of the racking profile,, sort of a W shape.

When I looked at these images I was thinking that the two shapes were made to work together, the straight side of the keyhole being made to slightly pull the shelves of the racking apart when placed in them. I.e. not fully resting on the bottom of the keyholes under their own weight, and then the 'W' shape of the racking uprights being used to act as a bit of a spring/dampener feature. My thinking/reasoning for this is so that when a forklift drops/lowers a skid onto the shelves, the racking uprights will have room to flex slightly and absorb some of the impact (forklifts not being particularly precision instruments). This way the racking pins don't get impact loaded every time a skid gets loaded, and also the flexing of the uprights would allow for a greater tolerance in the levelness of the shelving. (Shelving/racking safety requirements being remarkably strict)

My question is,  does my reasoning sound accurate, or is there another reason for these somewhat 'complicated*' shapes?

note- by complicated I don't mean intricate, these are very simple shapes to make, but they appear to have more design intent because they go beyond simple holes and extrusion processes. I come from industry where all geometry requires justification and calculations not just "because it looks cool".


texts: Calculating Tie Rod Force in Bridge Abutment System

texts:
I have a fairly tall bridge abutment (about 12 ft.). Vertical loads are supported by bearing piles and lateral loads from the retained soil are supported by a sheet pile wall.

However, when I consider just the cantilevered sheet pile wall for the condition where scour has occurred (i.e. maximum exposed height of sheet pile), the sheet pile alone is insufficient to carry the lateral load from retained soil - the deflection at top of abutment cap will exceed the allowable 1/2" for a PZ22 sheet pile section.

In this situation, I've been told to add tie rods to carry some of the lateral load back to a "dead man" / anchor block. Because I already have a grade beam as part of my abutment system, I'm using that as the anchor block...bad idea?

Clarifying "Grade Beam" terminology -- at the end of the bridge deck, there is a separate 20' slab of concrete called the "approach slab" spanning between the abutment and the grade beam. This helps prevent localized settlement at the beginning of bridge, which produces that "kathunk-kathunk" experience as you drive across bridges. The grade beam is just there to support the approach slab (almost like a mini bridge span).

How do I go about calculating the load in each of the tie rods?

Do I completely ignore the contribution of the sheet pile and just assume all the lateral load is transferred through the tie rods? Do I consider the contribution of both the sheet pile and tie rod using strain compatibility?

I put a sketch of the entire abutment system below - in the final configuration it's a pretty rigid system. The abutment / wing / grade beam are tied together with rebar and everything is supported on piles.

Intuitively, it seems like the center tie rods will carry more load than the exterior rods but I'm not sure how to check this mathematically... though I suspect I'm eventually going to end up with some plate approximation and a massive plug-and-chug from Roark's Formulas for Stress and Strain.


texts: To what degree are wind and water turbines exchangeable?

texts:
Assuming maximum efficiency is not the primary concern (but net positive efficiency is), to what extent could a wind turbine operate in water and vice versa?

How do the different turbine types fare in this respect? I.e., HAWT / VAWT (Savonius, Darrieus, Gorlov) for air turbines, reaction (Francis, Kaplan, Gorlov) / impulse (Turgo, Jonval) turbines (Pelton wheels are probably out) for water turbines?


texts:
What is the meaning of power/energy density of an actuator?

Context:
As a novel kind of actuator, the dielectric elastomer ( DE )
demonstrates high-strain response [ 1 ] , high energy densities
( seventy times higher than conventional electromagnetic
actuators ) [ 2 ] , and high energy conversion ef ﬁ ciencies ( 60% –
90% [ 3 ]) .


texts: Aluminum vs Steel rivets/fasteners in a high vibration environment

texts: What are the relative pros and cons between aluminum and steel fasteners when riveting together sheet aluminum (50XX or 60XX) when high amounts of vibration are anticipated? Assuming that the usual guidelines for sheet thickness, hole size and separation are followed, which metal would be the better choice? I don't anticipate atmospheric corrosion to be an issue.


texts: Analizing Vibrations Influence on Dynamic Weighing

texts:
I have a very sensitive scale used for dynamic weighing (by dynamic I mean that the scale and load cells are actually beneath a belt conveyor that actively weight product when it´s being transported along the belt).

There´s a lot of variation in the measurements (+- 8g, while the manufacturer says it should be max +-2g).

I want to rule out vibration as a source of enviromental influence, so I gathered some data with a pair of 3 axis accelerometer dataloggers mounted on the structure beneath the load cells.

I analyzed the data in Matlab and found that the maximum vibration frequency when the equipment is being static is 1.066 Hz (EDIT 3); peaks of 1.33 g in the z axis (perpendicular to the floor).

It´s being a while since I´ve done anything with vibrations and I´m a little rusty on the theory and practical experiments.

I´m not sure what I should be looking for and I don´t have (didn´t find) anything about what the normal structural vibrations are for a lab room or specifications from the scale manufacturer on how much vibrations in can withstand or filter out.

I´d appreciate any suggestions.

EDIT:

The Scale is installed on top of a mezanine 5m tall.
The Accelerometer specifications are:
Sensor Type MEMS semiconductor
Acceleration Sampling Rate (Datalogger) 200Hz
Acceleration Range ±18g
Acceleration Resolution 0.00625g
Acceleration Accuracy ±0.5g
Bandwidth 0 to 60Hz
Sampling rate (Software) 500 ms to 24 hours
Memory 4Mbit Flash; 112028 Motion Detection samples per axis,
or 168042 Normal samples
Data Format Time stamped peak acceleration, average and peak vector sum
Dimensions 3.7 x 1.1 x 0.8" (95 x 28 x 21mm)
Weight 1oz (20g)

The FFT results in the X,Y and Z axis were:

EDIT 3: Here´s both time and frequency plots:


texts: Do bolts become tighter or looser at cryogenic temperature?

texts:
In general, will screws tightened at room temperature become tighter or looser at very low temperature (5 K)?

On the one hand, the screw should loosen because it will contract radially, while the surrounding material will contract slightly less (or even expand, in the limit of a very large screw radius and a very thin ring of surrounding material).

On the other hand, the screw should tighten because the screw should contract linearly along its axis, making the threads tighter, while the surrounding material should contract slightly less because it has other boundary conditions.

Is there a general answer, or does it depend on material, screw size, and/or the exact geometry?


texts: Household supplies are 110v AC.  Is it possible to series connect two plug points and get 220v AC?


texts: qualitative influence line of pinned support

texts:
For the highlighted part , why we need to replace the support at A with a roller guide ? We could see at A , it's a pinned support , right ?

Pinned support will resist horizontal and vertical reaction , why the author said it will not resist vertical force ? Is the author wrong ?


texts: Can a hobby gearbox be used to mechanically amplify small forces for better force sensor resolution?

texts: I am trying to configure a force sensor (a piezoresistive force sensor) in a device to measure small forces (less than 0.5 mN). This is difficult due to noise of the system. One of the ways I have considered to address this problem is to mechanically amplify the force applied to the force sensor with a gearbox. The small force applied would be transferred to the gearbox with a gear on a drive bar, and the amplified force from the increased torque would be transferred to the sensor with another gear and drive bar (see schematic). However, I have no experience with gearboxes and would like some opinion on feasibility or if this system even makes sense. I am particularly worried that static friction forces in the gears would cause inaccuracies, especially because gearboxes are designed for a completely different purpose.


texts: How do you calculate the frictional losses in wire ropes over sheaves?

texts:
I am currently pulling a load with a wire rope that is moved through a system of sheaves, but had to replace a smaller wire rope cable (1/2") with a larger wire rope cable (3/4"). The sheave/wire diameter ratio is below the recommended guidelines, which I understand affect fatigue life and strength.

However, I have also noticed that the motor seems to work with a lot more effort than it did before, so I wanted to compare the frictional losses of the smaller cable with those of the larger cable to see if the diameter is making the difference.

Is there any formula, perhaps empirically-derived, or a table that could gauge the relative frictional losses between these two systems?


texts: Does the use of the catenary in an inverted weight model imply a more solid structure?

texts: I am studying Gaudí and how does he created some of his work. I found that he used inverted weight models (as the shown in the picture below) to recreate the catenary. In many articles it is pointed as a good practice to simplify and find a better/more sophisticated and solid structure, but I can't see why.


texts:
IANAE

I want to make an 1/8" steel rotary switch shaft into 1/4" so that it will accept the much more common 1/4" shaft knobs.

If I use McMaster-Carr 92510A422:

which is an aluminum unthreaded spacer that has an ID of 0.115", will heating it expand it enough to fit the 0.125" shaft?

I have a 13" drill press but otherwise, I do not have any ability to mill things so I need to start with off-the-shelf parts.

UPDATE:

I just realized, the nut that goes over the shaft has an ID of only 0.2175". So it would not fit over the new shaft.


texts: Disc Brakes - Swept Area , why is larger better?

texts:
I am trying to understand why a bigger swept area on disc brakes provides higher braking force for the same force being exerted on the brake lever/pedal by the rider.

If we use the same exact brake pad material, same thickness, same disc material/surface treatment etc. and the only variable we change is the width of the brake pads and therefore increase the swept area, would this result in higher braking force for the same lever/pedal input force?
If so, please explain why.
Larger swept area means better cooling of the pads during braking but that shouldn't make a difference when the brakes are still cold.
Larger swept area also means the pad material can be softer since the brake pads are larger so won't wear as quickly as the smaller variety, is this a significant reason why larger swept are provides better braking performance?
Would increasing the length of the pads (thus not increasing swept area) also increase braking performance (braking force higher for same lever/pedal force)? If so, would it have the same effect as making the pads wider?
source: Hydraulic Brakes - Why motorcycle brakes more powerful than bicycle brakes? (check first answer)
Thank you for any input, it is greatly appreciated!


texts: I would like to construct a seconds pendulum. The length of a 1/2 Hz pendulum is 994 mm. My question, is that length the distance to the center of mass? And how does the density of the arm effect the period? e.g.; will the length a steel arm and weight be different than an aluminum of wood arm and weight?


texts:
I want to implement a piece of glass to set various pieces of steel on and take picture through it.

The pieces of steel weigh anywhere between 20-150 lbs.

The purpose of the glass is so pictures can be taken of both sides of the piece at the same time to speed up production instead of having to flip it over by hand.

I'm no expert in this, but I am assuming there are many different compositions of glass as there is steel.  According to Wikipedia, steel has a hardness of 4-4.5 and glass has a hardness of 5.5.  I don't know how true this holds, which is why I'm here.

So what this boils down to is I'm looking for a sheet of glass that will with stand weights over 150 lbs and won't be scratched by constant pieces of steel being laid on it.

This question could be as easy as "All glass will work" but I've seen glass on cars that have been scratched and gouged by other parts, so I wasn't sure how true the Mohs scale I saw was.

Another problem I have thought about is which is better, Anti-Glare or Anti-Reflection.  I would like to try and keep a high quality picture through the glass.

EDIT
Here is a picture as requested.


texts:
I want to know if it is possible to control the gearbox of a car with a manual transmission, specifically one with the shift stick in the steering wheel column.

The idea is using linear actuators or hydraulic cylinders to control the gas / clutch pedals and "some kind of mechanism" to control the shifting stick directly or removing the gear stick and installing the mechanism on the gearbox directly.

Is this idea feasible or has it been done before? Or do all autonomous cars use automatic or "tiptronik" gearbox?

NOTE: I have taken a look at this post before Remote start on a car with manual transmission, but did not find a satisfying answer


texts: How to provide conditional locking to drawers?

texts:
I am designing a device in which I want to lock each drawer until it's time to open them.
Let's say that there are 4 compartments in the device. Each compartment needs to be programmed to open at a pre-programed time.
For example, at T1 time, compartment 1 opens. Then at T1 time, none of the other compartments should be able to open even if pulled by the user. The same should be true for all the other compartments.

My earlier approach included using a solenoidal actuator for this. So, the holding current of the actuator would keep it magnetised and hence latched. And whichever compartment needs to be opened, that actuator is set to low.

However, I am unable to find any solenoidal actuator below 1Amp rating.

I would like to hear if you have any other solutions for this sort of locking mechanism.

Thanks in advance.


texts: According to EN standards, elongation for each material type has been defined, and it varies with different range of thicknesses for the same material. Why is it so? How is this value calculated?


texts: Buckling of a cylinder under bending load

texts: I have a long cylinder with one end fixed and other is free. A bending force is acting on the free edge. I want to simulate the brazier effect under this condition. Every paper that I found talks about the case of pure bending. In my case, the moment is not constant but varying linearly across the length of the cylinder. So, which moment should I take as critical one to compare with brazier analytical solution?One thought is to use the moment at the point of maximum ovalisation.


texts: Does a moving positive charge generate a magnetic field?

texts: I have been wondering about how a positively charged plasma might be used to generate electrical power. So, I was wondering if, similar to a moving negative charge, a moving (or oscillating) positive charge would generate a voltage across a coil.


texts: Why are mass-produced metal parts machined by rotating the part against a stationary tool?

texts:
There's a TV programme called "How It's Made" which often shows automation of mass-produced machined parts. Very often, it seems that metal parts are machined (especially drilled) by rotating the part against a stationary tool rather than holding the part and drilling into it.

What is the advantage of doing it this way? I've never been able to work it out.


texts: I have seen the feature of promoting a point mass to remote point and I cannot figure out what are the use cases of using that feature. I understood that you can add command snippet below remote point but I thought you can do same under point mass.


texts:
Does anybody know what the thread size is on a bicycle pump connector, such as this one?

Note: I'm not talking about the female end that goes on the valve stem on the bike (that's a Schrader valve thread), I'm talking about the male end that connects with the pump. It looks almost like an M5, but doesn't quite fit in an M5 female connector.

I have spent quite a bit of time googling the question, but have drawn a blank so far.


texts: Knuckle Joint: compressive strength equal to tensile strength

texts:
I was studying the design of joints and came to knuckle joints. Generally  compressive strength is greater than tensile strength, but  considering knuckle joints compressive strength and tensile strength are considered equal (as mentioned below). What are the reasons for assuming equal strengths?

Here is a link to the page, shown above, in Google Books.


texts: Protecting device from microwaves in microwave oven.. but allowing Bluetooth?

texts:
I am building a device that needs to be inside of a microwave oven but somehow needs to communicate with another device outside of the microwave.

How can I reflect microwaves so they don't come into contact with the electronics in the device, while still allowing the device to transmit and receive data?

The frequency of the microwaves in a microwave oven is pretty much the same frequency that is used in Bluetooth. I was thinking the only possible way of doing this is to have an antenna that is small enough that it can slip outside of a microwave oven through the door (but small enough so the door is still able to close properly).

Could I use some material to protect the electronics of the device from microwaves? Is there a way to have this device communicate with another device outside of the microwave oven without the microwaves interfering with it?


texts:
What is meant by shock load in gears?

What are steady, light, medium and heavy shock loads?


texts: Calculating the Motion of a Particle on a Moving Surface Due to the Friction Between Them

texts:
The Basics:
I am trying to come up with an equation describing the motion of a particle resting on a non-stationary surface, given the motion of the surface. Imagine setting a coin on a board and then sliding the board back and forth in an oscillating motion. At a certain rate the coin will start to slip, but will not be completely stationary.

Known Variables:

Static Friction
Dynamic Friction
Motion of the Surface (i.e. the board, x(t), v(t), a(t))

Other Details:
The motion of the board is non-linear and not a 'nice' function (it is a set of data points). I plan to determine the motion of the particle discretely using Scilab (poor man's MatLab). I am only considering 1D motion, forward and backward.

Background Info: I'm a mechanical engineer, but it has been a while since I've used any significant amount of dynamics, calculus, or differential equations. I've tried to research this on my own for a long time, but it seems like I need to re-learn those subjects before even attempting this problem. I'm willing to work for it, but not quit my job and go back to school...

My intent is to use this to model the performance of a machine that I'm working on so that I can optimize the design. I've tried writing an algorithm that looks at the acceleration between each data point and determine whether or not it is slipping. If it is not, I would add the motion traveled by the surface to the position of the particle. That works OK as a very rough estimate, but does not take into account the inertia of the particle or the existing velocity of the particle.

Is there a relatively simple way to do this?


texts: Detecting goals blocked on a foosball table

texts: I am trying to find a way to detect when a goal is blocked on a foosball/kicker table. I have a HD camera  above the table and a laser sensor built into each goal. The lasers can detect when a goal is made and the speed of the ball. The camera was my attempt at ball tracking however the ball speed is upward 30kmh at times. I cannot get the frame rate of the camera high enough to reliably track and detect if a goal was blocked. I can get the frames high enough but with shutter speed that high the ball is too dark to see.  I am looking for an alterative method. Any ideals would be greatly appreciated.


texts: Thermoplastics that are permeable to water - high diffusion coefficient

texts:
I want to know if there are some fairly common thermoplastics that allow water to pass through (by diffusion) at a relatively high rate (on the order of days). For example, PET water bottles leak water by diffusion but it's extremely slow - it will take 100 years to let the water through.

Another way of asking my question is "what are some thermoplastics with very high diffusion coefficient for water?". I thought PMMA (Acrylic) was one but in my experiment it was too slow.


texts: I am currently doing a solar tracker project. Can I use the LDR as position sensor by detecting the sunlight intensity? I mean if light intensity on LDR east is greater than LDR west, the LDR east will send a data to microcontroller and tell the motor where the sun now and rotate to that position.


texts: How do I model a longitudinal tensile strain in a laminate composite using Abaqus software?

texts:
I want to be able to measure the strain response in a material composed of 2 lamina, bottom one (0) top one half (0) half (90), and see the differences in the unidirectional versus the bidirectional area.

I've been trying with the Lamina function, and using a negative pressure at one edge where I want the load, and bounding the other edge with boundary conditions. The error it gives me is (Lamina can only be used with plane stress elements).

How can I get past this error? Do I need to use a different function?


texts: Is epoxy the best way to permanently attach a small PCB to a mechanism that will be vibrating?

texts:
PCB module is about the size of a nickel and has an ARM processor and a sensor chip or two, plus a connector with 5 or 6 wires.

Module must be firmly attached to device because device will be vibrating.  Environment of device may vary: hot/cold, wet/dry, wind/dust.

Cannot modify the target device in any way.

All I can think of is epoxy the bottom (non-circuit side) of PCB to device, which will be metal or plastic, possibly painted.  Specifically, coat entire bottom of PCB with epoxy and stick to device.

Surface of device is flat.  Device surface may be larger or smaller than module diameter, but always big enough for epoxy to work.

If surface of device is conductive, then standoffs would be epoxied between PCB and device surface.

I cannot think of another method to attach module.


texts: How do you calculate the required power of a disk turbine (Rushton turbine) to rotate a fluid at a given speed?

texts: I am designing a potato peeler which is practically a bucket that has a rotating disk (figure below) at the bottom driven by a motor. Water and potatoes are put inside the bucket and the disk rotates creating a swirling motion and peeling the potatoes by rubbing them against an abrasive surface. How do I calculate the power required by the disk to rotate a given weight of water plus potatoes (in kgs) at a given rotational speed (in rpm)?


texts: Name of a keel between the bilge keel and the main keel

texts:
I'm working on a seaplane and find myself doubting about the specific nautical term for a keel placed between the bilge keel and the main keel. This might be a bit academic in nature since I have a working way of naming it, but I'd rather take the chance to find if it's correct or just a fossilized mistake.

My working term is "sister keelson", which is commonplace in seaplane design, but something tells me it's not really right, as in naval engineering a keelson is the inner structural element that holds ribs against a keel.

The second nearest term would be "docking keel", because of its location, but that implies it can be used to beach the craft, which it may not be necessarily designed for.

I can't add images right now, but a google image search for "sister keelson seaplane" will give you pictures of what this is, while a search for "sister keelson" will point you to the inner elements that would be used in a wooden hull boat.


texts: 3 x 1 stone under footing and sump crock

texts:
I am having a house built and the builder found organic soils during the excavation.  They removed the soils and then filled the cavity with 1x3 stone (see picture).  This is the corner where the sump crock is supposed to be and I am concerned that the digging of the hole for the sump will unsettle the stone.  The builder doesn't think so.  My question is should I be concerned about this or will disturbing the stone undermine the foundation.

Thank you.


texts:
Is there a method for plating steel with stainless steel?

If so, is it chemical, electrical, or electrochemical?

I did a quick search on the internet but was unable to find a service. I'm interested in applying a food safe finish to something that would otherwise be cost prohibitive to make out of solid stainless steel.


texts: High-resolution Z stage distance measurement

texts:
I am designing a 3-stage platform like that of a 3D printer. Three stages correspond to X, Y, and Z axis. There is a nozzle with fixed height about the z-stage platform.

The stages are pretty accurate with a resolution of 1 micron.

Now I need to adjust the height of the z stage so that the distance between the nozzle and the stage surface is about 10±1 microns.

I have already checked some of the high-resolution distance sensors, but they are way too expensive.

I wonder if there are any alternate methods to achieve that.


texts: Apply constant load to an electric motor - low tech way

texts:
I want to know how much I can over-drive a small electric motor. Its speed at the rated voltage is too slow, so I want to find a higher voltage that won't blow it. It will only be used intermittently, but I figure if I run it for 100x the max expected duration with the expected load then it will probably survive repeated intermittent use.

So my question is, safety concerns aside, how can I apply a relatively constant load? I can't think of a reliable way of using friction, such as attaching a disk and hold something on it, vaguely resembling a vehicle brake disk. I could attach a weight via a pulley but it would quickly run out of length. I could use a second motor and load that electrically to increase the torque, which is IMO the best idea, but I'm wondering if there are any other mechanical solutions? I think I'm missing something really obvious.


texts: What does "coupling effects" mean in the context of optical systems?

texts: What does it mean to say that there are "coupling effects" between some elements of an optical system? I've searched through the literature, but I cannot find a general explanation of what this means – every mention of it assumes that the reader already knows what it means.


texts: Why does a continuous beam have less deflection than a pair of simply supported beams?

texts:
Inspired by this question, and also this answer to a separate question.

I have two beam models, one with two independent spans (a full hinge), another is a continuous beam over both spans (only column is hinged), the below is the diagram of both beams, and their force/bending moment distribution:

How can I derive from first principles of static analysis or from rules of thumb that continuous beams have a smaller deflection?


texts: How to compare two ANSYS mechanical APDL databases? (.db or .dbb files)

texts:
I am new to using ANSYS. I use the student version.

Is there a way to find what is the difference between two .db or .dbb  files? I have two files say a.db and b.db, which are supposed to be the same exact model for a simple beam structure with one point load on it.

One gives as solution for a deflection, which is a little bit different from the other file.  When I open the .db file inside ANSYS APDL GUI and look at all the listings in the GUI, I can't see any difference any where. I looked at material properties, nodes, elements, solver type, etc... and they are the same. But when I solve the model I get a very small difference in result.

Clearly there should be a better way to compare two .db files than having to open each and look at each listings one by one and do manual comparison like this.

Is there a command to list to a text file, everything inside the db file, all the tables, etc.. so that one can use some diff utility for example to see what is the difference? or is there is some other ANSYS specific tool to do this?

I am using the student version of ANSYS on windows, it is ANSYS APDL mechanical version 16.02.


texts:
There are electronic components like microprocessors which work at 1-2V.

Why do some semiconductor devices have a minimum voltage requirement?
Are there (simple) microcontrollers which work at few tens of millivolts or less?


texts: Calculate the area of the triangular tract of land and its most


texts: What happens if a star lock washer doesn't align properly with the nut?

texts: If I understand correctly, one of the star's teeth is bent into one of 4 nut's slots to secure the nut. What happens if none of the teeth align with the slots? Do you unscrew the nut a bit? Or it is somehow mathematically made that there will always be one slot that aligns properly?