3
$\begingroup$

I'm running a simulation in a CAD on a rather simple assembly with several parts in which a motor effectively rotates a part. If the motor is set to constant 10RPM, the part rotates fine and the max. motor torque is around 500N-mm. However, if it's set to 5RPM, it gets stuck and the motor torque reaches 8000N-mm.

How come a higher RPM could avoid a lock-up? Isn't a higher torque less susceptible to rotational lock-ups, since it's the force to rotate an object?

$\endgroup$
3
$\begingroup$

CAD simulation is not real world. The model may break for a variety of reasons based on your geometry, mesh resolution, time step, software, and assumptions used in writing that software.

When you find something in a model that doesn't match reality, it is time to re-evaluate your model or find different software.

$\endgroup$
0
$\begingroup$

Simulating a process is a big task which includes various preprocessing steps. We try to model the real world yet are not able to do it 100%. So sometimes it’s hard to find errors in your model. Please check for the following errors:

  • Cad Modeling Error
  • Material Properties Error
  • Discretization Errors
  • Other small errors

Check for the modeling error. There may be a problem in the geometry of parts and assembly of your motor. You should check the assembly mates and their constraints. Sometimes constraints are not given correctly which give wrong results while simulating the process.

Check your material properties which you have given to your motor parts. Improper or incomplete material properties will result in different behavior when you will simulate the process. For example, the limit of Poisson’s ratio in isotropic materials.

Your model may have Discretization errors. If you want to run the proper simulation with highly accurate results you can use the ALTAIR Hypermesh for meshing as there may be a possibility that your element size may be too large or too small. After meshing you can use the solver like ALTAIR RADIOSS or LS-DYNA. You can ANSYS workbench to simulate also. These software has better FEM solving capability and provides better meshing options than CAD software. You can use the mesh refinement method. Coarse meshing always gives the false results. Apart from these, you should check for Hourglass effect, element type, contact options, time step, mesh type, damping controls, and erosion controls. Check for proper boundary conditions, if you forget to set boundary conditions you may get wrong results.

If you don’t find any error then try to use different CAE software for simulation. Sometimes CAD software are not able to properly simulate the process. If the error still persists you should consult with a CAD / CAE expert and show him your model. And keep in mind these simulations are approximations.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.