New answers tagged

1

When the arm is straight out it has a torque $T= mg*L \quad $with L the distance between arm's CG and rotation center. Your stepper motor should provide this torque to keep the arm in balance. if you need to rotate the arm up and down you need an additional torque such that if you rotate the arm with angular acceleration, $\alpha$ $$T_{rotation}=I\alpha$$ ...


1

To paraphrase https://www.controleng.com/articles/stepper-motor-torque-basics/, holding torque is the amount of torque required to turn a stationary rotor. As long as this is higher than the torque provided by your "arm" when it is extended, it should remain in the position you set it. To determine the maximum torque needed, multiply the weight of your arm ...


1

I discovered the solution method through more banging head against a wall: You have to do a double-substitution of velocity and chord, together, and you only need to focus on the prototype. Solve Reynolds equation for uc (uc = Re*(mu)/(rho)) Use Aspect ratio to find area in terms of chord only (S = c^2 * (AR)) Plug area into lift force equation Rearrange ...


2

to prevent the nut from unscrewing, you must use either 1) a thread-locking compound (Loctite or equivalent) on the threads during assembly, 2) split lock washers, 3) an aircraft-grade castellated nut-and-safety-wire assembly, or 4) a nut with a nylon insert to prevent unscrewing (Nylock or equivalent).


1

No and yes; and no. Pearlitic grey freezes as austenite plus graphite. It shrinks as it cools until the austenite transforms to pearlite , this causes expansion over a very short temperature range . Then the pearlite and graphite continue to shrink. This is a higher strength grey iron. The other grey iron ( most common): Ferritic iron probably freezes as ...


1

The thermal expansion coefficient for grey cast iron is ~ 10.8 in/(in*degR) see: list of expansion coefficients. This would indicate that expansion is expected from ambient temperature to melting temperature so the reverse would be to expect shrinkage while cooling to ambient temperature. Slightly related note, I was taught that gray cast iron is more ...


0

The quench all depends on the grade of steel that you are working with. Each steel is specially formulated to be used for a specific type of application. As others have stated you need to narrow down your material then investigate from that point. I don't know how anyone could answer this vague of a question with any accuracy. The following list gives a ...


2

Are you are using the outer race as a "wheel". Sounds like an unusual design , maybe a steel tire should be put over the outer race. The steel tire could easily be any hardness you want. It would be poor judgement to mess with the rolling element bearing hardness. The heat-treatment has been developed over decades. One factor is the residual compressive ...


1

If it is a double-acting cylinder then possibly fine, BUT you will need to check the seals are not going to be damaged by the oil and make sure that the pressure inside the cylinder, on both sides of the piston, is greater than the oil pressure so oil is less likely to make its way past the seals. A single acting cylinder needs to be able to fill or expel ...


1

You could try pressing the yoke rollers into plastic sleeves, essentially giving the yokes plastic ODs and thus a softer surface. We tried experimenting with this a few years ago at a bearing manufacturer I worked at. Typical materials are Acetal resin and Nylon 6/6. It's also possible only the bearing races are heat treated, leaving the OD would be softer. ...


0

I tried very large strap wrenches, a heat gun, the lot. In the end, nothing short of an angle grinder would do the job. Be careful with the depth of your cut, to avoid hitting the valve. I would not try this on any cylinders containing flammable gases or oxygen!


1

First, go take a look at some documentation on the servo PWM signal. The gist of it, is that a PWM signal is a pulse between 1000us and 2000us, repeated every 20ms. The signal is interpereted as 0 when the pulse it 1500us. More than that is positive, and less negative (or the reverse, can't remember). How you convert your output signal to this format will ...


1

Does the stacking of peltiers device shows promising results in achieving the cryogenic temperature? If you consider actually working in devices that are working in satellites to be "promising", then yes. I have tried doing the experiment, the overall temperature of the system increased around 80ºC and then the dissipation of that heat was the prime ...


2

Your controller output needs to be converted to the PWM signal your RC motor can understand and what your controller can output, so you can use a simple linear function like $y(x)=m*x+b$ to achieve this, your x-axis being your position, and your PWM in bits (8, 10, 12, etc) along the y-axis. $b$ if you happen to be off hazy in your linear functions is your ...


2

In order to supplement @fred_dot_u's answer and add a few details on the nature of the problem that these devices address I'll add a bit of additional material. For a description of a numerical model of how Stockbridge dampers work and ANSYS simulation results, see for example Aeolian vibration of a single conductor with a Stockbridge damper, Oumar Barry, ...


3

There is no way to get around the physics in this case. The fundamental issue here is that peltier effect refrigerators are individually extremely inefficient, and stacking them in essence "stacks" their inefficiencies. Why are they inefficient? Because the material they are made from ideally should have zero electrical resistance and infinite thermal ...


2

Yes. To reduce wear, material fatigue, and strength needed to turn it, you should use a couple coils of the spring, leave enough play so it won't seize when tensioned, and obviously the disc needs to sit on an independent bearing/bushing/hinge to turn, spring only providing tension - it's no replacement for a bearing.


5

According to the wiki, these are called Stockbridge dampers. The design is tuned for a specific length and one might also expect a specific mass/material. The weights are mounted on flexible arms, typically a length of stiff cable, which allow the assembly to absorb energy that might otherwise be imparted to the longer power lines, or more accurately, that ...


0

It is the Kelvin-Planck Statement which gives your answer: It is impossible to construct a device which operates on a cycle produces work continuously while interacting with a single Thermal Energy Reservoir or in lay man terms: Heat being a low grade energy, we cannot completely convert it into work and some heat has to be rejected. Now have a look at ...


4

Use two strap wrenches or an equivalent - one on the tank and one on the cap. You won't crush the tank :) If you need to make one, then a length of 4*2 and some old car seat belt bolted to one end works well enough - it did when I had to do something similar.


1

It is more question of the friction than torque. The truck with the greater torque will be pushed back the moment its tires start to skid. Torque on a tire will be delivered to the pavement very effectively as long as static friction conditions are involved (no slipping). But in the case of slipping the kinetic friction is the active force and most of the ...


2

I think the problem is just that you're expecting the solution to be more elegant; it looks like you already have it pretty much figured out.


1

Symbol 23 is just a plugged cavity. The two incoming hydraulic lines are both blocked. No flow is exchanged between them. The designer's intent for the cavity is future use. Various cartridge valves can be inserted into the cavity for either pressure control, flow control, directional control, or other purposes. You can search "DCP-2 cavity plug" or see this ...


0

To summarize your problem description, you have ... 3 HP, 1200 RPM electric motor 40 MPa (400 bar) pump rated 4 LPM @ 40 RPM Gearbox ratio TBD between motor and pump Desired operation of 20MPa (200bar) at 4 LPM First, we can make a few observations from the problem data. The full-load torque of your electric motor. Note that this number is a nominal ...


2

In your example 2, Nastran is scaling both loads as part of the buckling load. In your first case, you have buckling with $90\times 1 = 90$N axially plus $90\times 1=90$N laterally. In the second, you have buckling with $9.5\times 10 = 95$N axially plus $9.5\times 1 = 9.5$N laterally. From example 1 you have a buckling load of 100N axially plus zero ...


1

In addition to the other answers, water is commonly used as a primary working fluid in industrial hydraulic systems with additives to prevent the issues mentioned above. Typical applications include furnaces, foundries, plastic extrusion, etc. Anywhere that standard hydraulic oil represents a major fire or contamination hazard, yet operating costs do not ...


0

On a typical hydraulic press, there is negligible danger of motor overloading. However your instincts are correct. Consider the operating sequence of a press. An electric motor drives a pump. The pump drives oil into a cylinder. The cylinder extends until no more motion is possible. What happens after that? Oil must escape somewhere, or pressure will build ...


0

Because of the symmetry, you have zero slope over the support and if you draw the FBD at the support you see it is like a cantilever beam with half of the length of the beam. Let's call the uniformly distributed load $w$ and length $2L$ for convenience. $$ M_{max}=\frac{wL^2}{2} \; and\; V{max}= 2wL $$ Maximum moment and shear happen over the support. ...


2

From my location it appears the image is broken, however I can assume with my imagination and the comments it’s a pretty big bolt. Exceptionally large bolts are surprisingly not that uncommon. They often show up in oil industry to bolt flanges and for use in huge structures. But they are usually custom low production bolts designed for a specific use case ...


-1

Hurstwic has been doing some interesting work with basic iron/steel smelting. Not an answer to your question, but, Yes, you can smelt your own Iron/Steel at home with relative safety (your mileage may vary). You'd have to figure out what additional properties you'd need to add in the smelt, and the refinement work would take additional research, but it's ...


0

In control systems, the main focus is the design of a controller for machines or robots, here we mainly deal with linear systems application of linear control theory. While non-linear systems is an advanced topic, where we deal with advance and mathematically more complex systems. If its ur first course in control systems or automatic control. Go for the ...


1

There are at least 3 factors that influence the damping Internal material damping within the membrane. For a single ply drum head, this is probably small, but if you are using a multi-ply head (e.g. the batter head on a typical snare drum), it will be larger and could get pretty complicated to model Friction at the interface of the drum head to the drum. ...


0

To accurately measure the time of a system is no causal task. You cannot taken samples and extrapolate since you will be ignoring far too many variables such as material thickness linear acceleration/deceleration Jerk Material heat absorption Curve accel/decel The best way to do this would be to read generated gcode and calculate your time with a script ...


0

As the submersible pump is designed to be located inside water, the water will be natural cooler to the pump. If it is not located inside the water, clearly it will be overheat immediately just after started. Unless you modify the pump by adding cooling oil inside the tube/body, it will be just fine. But keep in mind that adding oil inside the body will add ...


1

Just buy a step switch and use it as your axle - it has the notches ready-made and costs a few dollars, at most.


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