AnsweredAssumed Answered

contact friction force

Question asked by Mark Kamps on Jan 11, 2015
Latest reply on Jan 15, 2015 by Mark Kamps

Hello and thanks in advance for any help or suggestions!


I'm currently working on a simulation with my two parts. The first part is a surface with an representation of a rough surface, while the other part is a rigid top part.

These two parts are joined in an assembly, and the rigid top part will be pushed into the rough surface, causing it to deform. The goal is to extract the forces and the deformed bodies for further analysis. (See parts, attached)


After some testing with coarser meshes and a different surface, I now was ready to go for my final assembly, however this failed.


The results I got were somewhat strange, since the result/contact force response graph was showing weird values. Unfortunately, i didn't get a screenshot, however I did save it as an .csv file (attached). As you perhaps may see, the graph only has some values, while the most values are missing.. How is this possible? The deformation of the body, the stress, the strain all looked good, and I didn't get any errors..


I will explain the simulation and its constrains. When you cant open the files, try to see the simulation as two cubes being pressed into another, where the upper cube is rigid and non deform-able. The parts are 1x1x1mm in size.

- The lower part is fixed on its lowest face. The upper part is fixed in z and x movement (only allowing y movement). The upper part is fixed in y translation (0.04mm).

- A contact set has been made (no penetration) between all the surfaces of the lower part (the rough surface itself) and the lowest surface of the upper part.

- The lower part (surface part) has been divided with split lines to allow for mesh control, the upper part has a 0.015mm mesh, the middle part a 0.05mm mesh and the lowest part has a 0.1mm mesh.


For the settings, the Large Problem Direct Sparse is selected. This best suits the non-linear simulation? The LPDS is better than the Direct Sparse since the computer doens't have that great resources? The meshing results in around 700.000 DoF. My computer is a i5-3570 with 8gb ram and a hd7950 GPU.


So my questions are, how and why are these response graph values missing/incorrect? How can i solve this?

Which solver is best to use and why, I couldn't really find a best answer.

What does the solver Method has for influence? (the Newton-Raphson, or the Modified N-R?) Which should i pick?


Any help is appreciated!