Hi MES pros,
I am working on Simulation 2012 trying to simulate a roller bearing (static and dynamic) for my project. like it was said to be done here;
On static analysis with linear materials, to find the line contact deformation between one tapered roller and raceways by defining surface contact between roller and raceways. fixed outer race, applied remote load at bearing center and no gap elements, mesh size 0.025" and mesh refinement at nodes on contact line as 0.005"
1) I tried with zero gap on the cad model: contact did not happen.
2) added 0.001" gap, Simulation added gap elements and showed a max stress of 2.7e6 psi
2) changes to 0.0005" gap, Simulation added gap elements and showed a max stress of 2.1e6 psi
which are too abrupt as the expected contact stress is around 1/3rd of (75000psi for cylindrical roller theoretical max Hertz stress)
3) when I changed the gap to 0.002", the cotact did not happen.
I would like to know if I am missing to define mode details or should I try a completely different method.
For the dynamic analysis, I created joint beam elements along the bore and applied prescribed rotation of 1 along the shaft axis.
1) started with 2 full races and one roller defining surface contacts,
2) tried just one roller and inner race, define contact
both tires failed to with some beam element error
3) tried to rotate just the inner race, it did rotate to 0.05s after approx an hour of computing.
If it takes an hour time for jus the inner race it would be impossible to simulate the full bearing in Simulation??
I would like your insight and any kind of help please.
FYI: I used direct CAD models downloaded from bearing manuf. web site and as well as the model I created in Inventor.
Hertz contact cannot be solved adequately with linear stress because of the way contact between parts are handled. You will need to use either MES (preferable) or Static Stress with Nonlinear Materials with surface-to-surface contact. If you are new to MES, I suggest that you go through the tutorials and examples in the Help documentation ("Help > Autodesk Simulation > Examples > Mechanical Event Simulation" does a simple surface-to-surface contact example).
Whenever contact, large deformation, and dynamics are involved, it can take hours to get a solution. So, start with simple models until you get familiar with the setup, and then go into more detailed models.
P.S. It appears that the analyses described in the paper were done on models built by hand. That is, they did not import a CAD model and meshed it. Depending on what you are trying to accomplish, you may need to do the same thing. Contact stress requires a fine mesh (smaller than the area affected) which will be hard to control in a CAD model.
John Holtz, P.E.
Senior User Experience Designer, Simulation
Current version of Mechanical & Multiphysics: 2013 SP1 (2013.01.00.0012 28-Jun-2012)