Hi Fernando: I believe you should be able to do it with the "Drop Test" study in Simulation (Simulation Professional), if you can build a plastic deformation rule. There is a material model in Simulation (in the materials dialog) that has a drop-down under heading "Model Type" that is labeled "Plasticity -von Mises". The rule allows for input of a tangent modulus and hardening rule. This is a kind of bi-linear stress-strain curve that's meant for typical metals - I'm assuming you have a metal roof. Hope that helps get started. Tony
I have done these before. You need to do a NL static analysis. You apply a force at the impact location and then run the analysis untill the displacement times the force gives the same anergy as the impact (ie its potential - mass x drop hieght). You typically need a plasticity model.
Thanks for the comments and suggestions.
I'm doing an nonlinear dynamic analysis but the model fails to converge and takes a long time, I'm having trouble setting the appropriate time steps, I will continue doing tests and I will be reporting