2
$\begingroup$

Which type of support should I use when trying to simulate stress in structure that is lifted. Lifting is done by using four lifting lugs and chain angle is 45 degrees. What type of support to use on this surface:

enter image description here

Lifting chains (ropes) are not modeled.

EDIT

Structure is loaded with force of 20 000 [N] acting on plate shown on picture. Lug will be welded to plate.

$\endgroup$
  • $\begingroup$ Are you applying load to the lug, or are you constraining it? $\endgroup$ – user2790167 Oct 24 '16 at 0:38
  • $\begingroup$ I am constraining it. $\endgroup$ – Sysrq147 Oct 24 '16 at 13:29
1
$\begingroup$

I would put a pin through the hole with the proper clearances. The include a contact condition with friction between the pin and the hole. Otherwise the stresses on the lifter will be way off.

You can then apply the load on the ends of the pin. If you don't care for stresses on the pin, make it rigid so the bending does not cause edge stress on the hole.

If you want to simulate lifting you need to include standard gravity and constrain the ends of the pin instead.

You don't want to constrain the lugs because then you are over-constraining the structure as it won't be allowed to flex properly. As a last resort you might try a remote displacement in the center of the holes with deformation on. If the lifting is done with a bolt, then a coupled condition on the remote displacement would do the trick also.

| improve this answer | |
$\endgroup$
  • $\begingroup$ I was adding remote displacement, with point defined in center of lifting ropes (imaginary chains) intersection. As Geometry for remote displacement I have selected four inner cylindrical surfaces of lifting lugs, but my Behavior was set to rigid :/. In case of pin what supports (constrains) can be used on them. Fixed on both sides ? Making Stiffnes behavior on body asks for asymetric contact behavior. Will that make problems ? Thank you very much. $\endgroup$ – Sysrq147 Oct 24 '16 at 19:10
  • $\begingroup$ The rigid constraint is not going to let the hole go out of round as expected. Change it to deformable. Asymmetric contact is fine to use. I try to apply the least amount of constraints overall, but in this case fixing the pin would be fine. You care about the plate, not the pin. Correct? $\endgroup$ – John Alexiou Oct 24 '16 at 20:17
  • $\begingroup$ Yes, about plate, lugs and sub-structure made of I-beam, or C-chanel, on which plate is laying. My question is general so that's why I did not want to overdetail it. I want to find stress distribution (Von-Misses) in state when structure is lifted, pin and chains are not in point of my interest right now. $\endgroup$ – Sysrq147 Oct 24 '16 at 20:19
  • $\begingroup$ Do you have any symmetry planes? If yes, them with a symmetry constraint a) less elements to solve and b) fixes the part with frictionless planes and avoids an unconstrained condition. $\endgroup$ – John Alexiou Oct 24 '16 at 20:24
  • $\begingroup$ Generaly speaking I will use remote force to represent weight of equipment that is not distributed uniformly on structure, so load is not symetric. But in case that equipment is uniformly distributed I would use symmetry with frictionless suport on symmetry faces. $\endgroup$ – Sysrq147 Oct 24 '16 at 20:29

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.