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no matter what setting, I have, I cant stop attached parts from going through each other by some amount. There is a bearing pushing on a lever, making the lever rotate.
Hi @ym16 ,
Is the model constrained by a prescribed motion that causes the bodies to intersect? For example, I have two objects that are initially 50 mm apart. One object is grounded, and the other is constrained to move only translationally in one direction (toward the other block). If I apply a prescribed displacement of 60 mm and define contact between the two surfaces, the moving block will penetrate the other block because the solver is instructed to move it 60 mm regardless of the contact condition.
Are you able to share the model?
Best,
Christopher Fadanelli
please take a look. I am new to inspire so every advise is a win
Hello @ym16 ,
I took a look at your model and made a few modifications to minimize penetration. It appears that the model is very stiff. Both springs have high stiffness values, and there is also a very large preload applied. When I removed the preload, I observed a noticeable reduction in penetration. I also increased the contact stiffness between the two bodies.
If you lower the stiffness of the second spring, the intersection should be further reduced (should this be a torsional spring instead of a coil spring?). You may also have noticed the warning about intersecting parts. We try to avoid initial intersections as much as possible. This can be achieved by repositioning the parts so there is either very minimal or no initial overlap.
When an initial intersection exists, the contact force increases to repel the bodies from each other. However, if the model is highly constrained or excessively stiff, it may not allow the bodies to separate as intended.
Attaching the updated model.
We do have a free self paced learning for Inspire Motion. You can access it here: https://learn.altair.com/courses/motion-analysis-with-inspire-elearning
3D Contact tricks and tips: https://help.altair.com/hwsolvers/ms/topics/solvers/ms/best_practices_for_modeling_3d_contacts_ms.htm
Thanks for the stiffness tip, instead of changing the forces, which are required as per the realistic model. I was able to remove any collision simply by choosing the poission setting with very high stiffness. It didn't have very high sim time penalty as its still a very simple model.
Can you please tell me if this was the write approach and any and all problems or unrealistic Scenarios it might cause.
Also, why isn't there a setting that completely removes collisions. I understand these contact simulations have to be done by inserting very stiff springs between the surfaces. Is there an alternative?
Please find the new model in attachment.
Hallo,
I now see very good results, very close to expected. This is however considering every body and joint is rigid and no friction is present. Which tool would be ideal if I want to do the same motion analysis with deformation and friction
Glad to hear! You can convert rigid bodies to linear flexible bodies in inspire Moiton. If you are using versions 2025.0 and below. You can access the flexbody tool in the main ribbon.
If you are using 2025.1 and above. You will need to switch from the designer to Analyst profile and enable the Flexbody tool.
https://help.altair.com/inspire/en_us/topics/inspire/motion/flexible_bodies_c.htm
If the flexbodies are engaged in contact, you will need to enable FlexContact in the run analysis settings.
