# Search results

1. ### Clamping force needed?

Hollow Structural Steel. I'm mostly trying to figure out how you calculate the resisting frictional torque? I can't find any information about this, only stuff about sliding friction or rotational friction (I.E., stopping a spinning disk). Where is the frictional force acting here? Its...
2. ### 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...
3. ### Direct stiffness method

That's what I tried initially, but what I found running ANSYS simulations was the results yielded noticeably higher stress levels using the above method than if I were to simply analyze the structure as a whole with all three legs connected to a center tube, and with a frictional contact on the...
4. ### Direct stiffness method

Correct, but I'm not sure how applying that restraint would be worked into the stiffness method. The equation to solve for the nodal displacements is: [f] = [K]{u}, where [K] is the master stiffness matrix comprised of the beam properties A, E, I, and L and [f] is the applied loading. Nodes...
5. ### Direct stiffness method

Here is the drawing
6. ### Direct stiffness method

I probably should have included a drawing of what is in my head. This is not a homework problem of any sort, just something I thought up when learning about the direct stiffness analysis. If the tripod had crossmember reinforcements as shown (horizontal to ground) then I believe that would...
7. ### Direct stiffness method

Are you talking about using the equilibrium equations to solve for the forces? My problem is this structure is welded together and so the joints are fixed and not pinned, which in my mind would make the structure statically indeterminate, which is why I'm researching the stiffness method. Also...
8. ### 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...
9. ### Force Couple on Frame

So if it were cut in half what would be the internal shear force acting on it? My guess would be 1430, but then if you did a force balance it wouldn't make sense because you already have the reaction at the base as 1430, and then the applied 1430 in the opposite direction. That would mean the...
10. ### 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...
11. ### 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...
12. ### 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...
13. ### 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...
14. ### Compression load in jack stand leg

Sorry for the rough picture, but that center post actually would not be touching the ground, so the load would have to be transmitted through the legs. Given that, would my approach be correct? Assuming that the legs are welded to the post at the top, there would also be reactive forces there...
15. ### 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...
16. ### 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...
17. ### 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...
18. ### 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...
19. ### 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...
20. ### Torque question involving gears

Right, but there's also a torque requirement to overcome which was my initial calculation. To induce an input torque of 46.88 in-lbs with 9.4 lbs of force, how do I find how what the subsequent shaft RPM would be? Like I said all the relations I can find involve horsepower, which is unknown...
21. ### Torque question involving gears

It would be the load due to the offset of center of gravity for the object on the table. So if the table is at a 90 degree angle to the floor, the object's COG would be say... 4-6 inches away from the pivot (shaft).
22. ### 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...
23. ### Goodness factor for fan cooling performance

The shrouds increase the velocity of the air around the inductor because the cross-sectional area is reduced. Each different shroud shape has a different pressure drop associated with it, and different heat transfer characteristics.
24. ### 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...
25. ### 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.
26. ### 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...
27. ### 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...
28. ### 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...
29. ### 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...
30. ### PWM fan control?

so to run the fan at 100% pwm I would just connect the pwm lead to the + terminal on the power supply?