I would like to model a dynamic simulation of a drop test on landing gear. The idea is to drop it from something like 20cm height and analyze its transient response.
I would like to model the ground as undeformable body because i’m only interested in landing gear stresses and displacements, something like Abaqus does with its analytical and discrete rigid body. I did some research on CalculiX documentation but only found rigid body constraint, not sure if it is the same thing or how should I apply it to my model in this case.
In the past, I used rigid body constraints to apply load or boundary conditions to model mesh more easily, but if I use it on my model, I would need to mesh the ground region and assign material to it, which will increase model detail and maybe ruin the convergence and/or computational time to solve.
Any ideas on how to do this? I would really appreciate.
Best regards,
Lucas.
Yes, you have to use rigid body constraint for that. It has multiple uses but the main one is simply making parts rigid. Their motion is then controlled by a reference node to which BCs can be applied and this constraint can also be used for nodes instead of elements - that’s what may cause the confusion. In Abaqus there are two ways to model rigid bodies - either by defining them as discrete or analytical rigid from the beginning (then the first type must be meshed with discrete rigid elements) or by defining them as deformable, meshing with regular elements and then applying the rigid body constraint. One of the advantages of the latter approach is that you can easily activate and deactivate the constraint switching between modeling the part as deformable and as rigid. CalculiX doesn’t have discrete rigid elements so you have to use the rigid body constraint.
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Thank you very much for the enlightment, @FEAnalyst . Now I understand the application of rigid body constraint, and agree that it’s approach is good and probably enough for what i’m going to model. Do you know if is it needed to apply a high elastic modulus in this approach? Or assigning hard contact to the pair wheel/ground.
The definition of very high Young’s modulus is an old approach used in software that doesn’t support rigid bodies. Here there’s no need to do this. Contact can be defined normally as well but you should remember the general master-slave assignment rules. In contact with deformable bodies, the surface of a rigid body should be the master surface.
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Again, thanks for the advice. I’ll model it this way.
Hopefully this thread will help somebody in the future.