Recent content by gomerpyle

  1. G

    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. G

    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. G

    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. G

    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. G

    Direct stiffness method

    Here is the drawing
  6. G

    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. G

    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. G

    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. G

    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. G

    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. G

    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. G

    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. G

    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. G

    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. G

    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...
Top