# Search results

1. ### Clamping force needed?

Say you have a piece of flat bar stock bolted to the end of a 3 x 3 x .25 HSS. A force of 900 pounds is exerted on the flat bar approx. 19" away from the center of where it is bolted. What clamping force would be needed to prevent the bar from rotating? My attempt at this was to first...
2. ### Direct stiffness method

Let's say you have part of frame contacting the ground, such as the feet on the base of the tripod. Assuming each leg is equally spaced around a center post, how would you go about analyzing this type of structure? I'm trying to teach myself how to use the stiffness method, but all the examples...
3. ### Force Couple on Frame

1. Homework Statement A force couple acts on the frame, which is fixed at the base. Find the moment(s) and reaction(s) at the fixed locations. 2. Homework Equations ΣMa = 0 ΣMb = 0 ΣFy = 0 ΣFx = 0 3. The Attempt at a Solution Since it would be statically indeterminate, assumptions would be...
4. ### Force couple

Suppose you had a bar that spinned due to a torque load applied, but the pivot was not centered at exactly the middle of the bar. If you arrested the bar with your hands, obviously you are applying a couple to counter the torque to stop it from moving, but your hands are not at equal distances...
5. ### FBD for tri-pod jack stand?

1. Homework Statement A jack-stand with three equally spaced legs (120 degrees) are connected to a center tube is loaded axially with 36,000 pounds. Each leg has a horizontal cross member 11 inches from the ground. All connections are welded. Set up FBD and find reaction forces. 2. Homework...
6. ### ANSYS analysis

If I am doing a simple, static analysis on something like a table, or tripod with a vertical force acting on it, what support condition do I assign to the base at which the legs contact the ground? I feel like it is incorrect to specify this as "fixed," since that would be like saying the legs...
7. ### Compression load in jack stand leg

If I have a jack stand that is essentially a tri-pod, with all legs at the base equidistant from the center tube, and a 36,000 pound load on the jack. What is the compression in each leg given these dimensions? My attempt: Each reaction in the vertical direction is 1/3 the load, and there...
8. ### Bearing stress

For a hollow tube inside a hollow tube, with a pin passing through both and a force pushing down on the innermost tube, what would the bearing stress be on the holes (assuming tube wall thickness is equal)? Would the equivalent reaction force be F/4 since the pin is passing through 4 holes? So...
9. ### Dezincification of brass?

I have a brass part that is showing signs of corrosion, namely the appearance of dark red spots. Through research I've learned that this is probably caused by dezincification, which can occur after exposure to water, acid, or salt. My question is I have noticed brass corrosion also involves...
10. ### Location of bend line on sheet metal flat layout?

For a flat layout sheet metal part, is the bend line located directly in the middle of the bend allowance section, or is it inset from one side by a distance of the bend radius? So for a U-channel with an opening of approx. 4.56" (distance between inside of legs), would the distance between the...
11. ### Bending stress on handle

I have a problem where I'm considering a curved member of circular cross section bent in the shape of a half circle and fixed at the base. A force is applied perpendicular to it (so in the picture, the dot is the force going 'into' the screen at the top view) and I'm trying to find the bending...
12. ### Torque question involving gears

Lets say you have two sets of gears with a combined 200:1 ratio. There's a worm and worm gear + two spur gears that rotate a welding table via a hand crank going to the worm. If the torque load from the weldment on the table was, say, 9375 in-lbs... then to calculate the force needed on...
13. ### Goodness factor for fan cooling performance

I have a set up which is basically a small wind tunnel (single rectangular channel) with an axial fan at the inlet. The experiment is testing the effect of various shaped "shrouds" that constrict flow around an inductor to improve the convective cooling. I have heat transfer coefficients and...
14. ### Program used to generate schematics?

http://img607.imageshack.us/img607/8638/schematics.jpg [Broken] Could someone tell me what software was used to make these? I need to create similar schematics of a DAQ system but don't know the name of the program used to do it. Thanks.
15. ### Reynolds number question

I'm trying to calculate the reynolds number for flow inside an air duct with an obstruction. Basically the set up involves cooling electronics by placing aerodynamic "shrouds" over the device to improve the heat transfer. So far a cube is being used to approximate the shape of the device. The...
16. ### Fan curve question

If I had a fan sitting in a small duct, and used several different sized orifice plates to create different restrictions, how would I find the fan curve? I run the fan at the same RPM each test. The problem I run into is using the equation for orifice flow that relates pressure drop, area...
17. ### Themocouple calibration question

One method I've found is putting the thermocouple in an ice bath, then boiling water and plotting actual temperature vs. measured TC temperature. A linear curve fit is then applied between the two reference points, and used in a DAQ program to 'correct' the TC measurement coming into the DAQ...
18. ### Air Flow Straightener question

Any HVAC experts in the house? Does anyone know of any engineering standards concerning the placement of flow straighteners downstream of a fan in a duct? I'd hate to just choose an arbitrary distance without any justification other than "well, it just seemed like it was good enough." So...
19. ### PWM fan control?

Excuse my lack of knowledge on PWM and fans, but can a fan configured with 4 wires (power, ground, tach. signal, and PWM input) be run off of a DC power supply without using the PWM to control its speed? As in, not using the PWM lead and just hooking up power/ground and controlling fan speed...
20. ### Sign convention spring/mass

If a mass was hanging vertically from a spring under its own weight. In the static equilibrium position, using up as positive, the spring force is +kx and gravity is -mg. Add them up to get: kx - mg = 0. Using down as positive, the spring force is -kx and gravity is +mg. Add them: -kx + mg =...
21. ### Calculating heat transfer

1. Homework Statement << Oversize image deleted by Moderator >> From this problem statement I am to find the heat transferred to the oxygen stream and the hydrogen stream. 2. Homework Equations q''_0 = q''_oxygen + q"_hydrogen 3. The Attempt at a Solution I first drew a...
22. ### Question about minor losses

I'm working on a research project dealing with cooling an electrical component in an air duct with a fan. I'm experimenting with different shrouds and directional vanes around the component to see which offers the best cooling. Obviously this has to be judged against the pressure drop caused...
23. ### Shear stress?

1. Homework Statement I just want to know the difference between certain equations for shear stress. I'm trying to find the factor of safety for pins that are in double shear and have a circular cross section. 2. Homework Equations So far I've used stress = 2F/pi*d^2 for double...
24. ### Bending stress in gear/bearing puller

1. Homework Statement I have a project where I have to determine the bending stress on a gear/bearing puller. It looks like this: http://www.posilock.com/PDFs/106.pdf [Broken]. The free body diagram I'm pretty sure would look something like this...
25. ### Dynamics question (kinetics and energy)

1. Homework Statement The two blocks are connected by a light inextensible cord, which passes around small massless pulleys as shown below. If block B is pulled down 500 mm from the equilibrium position and released from rest, determine its speed when it returns to the equilibrium...
26. ### Dynamics Question (Kinetics& energy)

1. Homework Statement The two blocks are connected by a light inextensible cord, which passes around small massless pulleys as shown below. If block B is pulled down 500 mm from the equilibrium position and released from rest, determine its speed when it returns to the equilibrium...
27. ### Differential equation linear input/output

1. Homework Statement Given the equation my'' + cy' + ky = ku + cu' explain why the size of the output scales linearly with the size of the input. In your argument, do NOT actually try to find the solution(s) to the equation, rather use the definition of what it means to be a solution to a DE...
28. ### Spring-damper system with sine input

1. Homework Statement http://s3.amazonaws.com/answer-board-image/ad36bcba0e2d0b49d556f054de19d124.jpg Variable y(t) is the position of the block of mass m, and u(t) is the position of the plate on the right. The spring is unstretched when y = u. We can think of u(t) as the input and y(t)...
29. ### Atwood machine Force & Motion problem

1. Homework Statement Figure 5-53 shows Atwood's machine, in which two containers are connected by a cord (of negligible mass) passing over a frictionless pulley (also of negligible mass). At time t = 0, container 1 has mass 1.30kg and container 2 has mass 2.80kg, but container 1 is losing...