Showing results for 
Search instead for 
Did you mean: 

SOL601/106 - non-linear analysis problems




I am running an analysis of an asssembly that consists of three cartilages and that entails having both an applied and constant and an enforced rotation that reaches a large angle (one case goes from 0 to 45º and another from 0 to 90º, to simulate two types of movements of the human leg).


I set up the models and the meshes (the cartilage is modelled as an isotropic and linear material) and only ticked the large displacements option. I set up the contact surfaces and parameters but I can't seem to obtain a solution due to the lack of convergence, apparently, though the f06 file is not too specific. I am also using some RBE2 elements to apply both the load and the enforced rotation in the centroid of the cartilage, instead of modelling the bone.


I am also curious as to how I can get the output of every time step by the (eventual) end of the analysis because on a previous test I ran, with a different and simpler geometry, not all of them were listed in the solution results.


The f06 file is attached. If someone could lend me a hand, I'd be extremely grateful.



PS: the 3D models used to generate the mesh com from an STL file that was given to me; I did clean it a bit in NX but I think the geometry still has many kinks that could be ironed, eventually, to make for a better mesh. If you want to take a look at the analysis files, I can post them here as well.


Re: SOL601/106 - non-linear analysis problems




It is not really easy to "see" the mechanism but it seems that your model needs to be stabilized by contact. Theses cases are always complicated to deal with. Don't hesitate to reduce the firsts increments of your simulation. You can also activate contact damping for first timestep. Did you also activate "large displacements" in your contact non-linear parameters?


I read in f06 file that a "TIED" contact was created however no nodes were considered in this contact. It may be due to a too low search distance.  Was the TIED contact done on purpose anyway?