SPRING_PLASTICITY-TRY.pmx (467.1 KB)
I make a plasticity test model, a displacement is add to a spring. and 2nd step I removed the displacement, with this model I can see the set of the spring.It worked well if Nlgeom is Off.
But if I “On“ the Nlgeom , the 2nd step will not worked. Here is the model uploaed.The total run time is within 1 min.
Try refining the mesh (and use a hex or hex-dominated mesh - change recombination to avoid getting only wedge elements). Also, use different incrementation settings - increase max increments, decrease initial time increment, and reduce minimum time increment significantly. Finally, make sure that the Nlgeom setting is consistent across both steps.
Thank you very much for your suggestion. It has given me a clear direction. I will modifying the model and try again.
That won’t be easy to compute with an implicit solver. I’ve always wanted to try using inp2rad to convert a case from Prepomax to OpenRadioss, so here’s an example. I applied a very quick 1e-3 s loading and 1e-3 s unloading. The material is steel with noticeable plasticity.
I kind of worked around it — instead of applying a prescribed deformation, I first determined the force needed to achieve approximately the desired deformation, and then applied that force with an amplitude going from zero to one and back to zero.
Typically, displacement control is much better for the convergence of nonlinear problems than load control, but indeed, amplitude could be used (also for displacement) to simulate loading and unloading in one step. However, it might be good to spread it across a small surface instead of an edge.
Definitely, but there is a first step with displacement control, and in the second step the prescribed displacement is removed, which causes convergence problems. A slow decrease of the force to zero resolves this.
Thank you for your effort on this topic. This analysis primarily focuses on the plastic deformation of a metal spring and the contact force.
Additionally, I also utilized force amplitude to conduct this non-linear geometry (Nlgeom) analysis, but the results showed only a minimal difference compared to when Nlgeom was disabled. And the result is very same with a sheet metal company result.
