How to model a silent block

Francesco Cataldi_20856

Hi, I have to model this silentblock. Is there a way to use simplified elements? I was told I should use the CBUSH elements but I can not really understand how they work. I already know the eleastic properties of the component. Thank you!

Adriano_Koga

The CBUSH/PBUSH element is suitable for your application. (created as a spring element)

It works like a 6-dof spring, and you can assign the stiffness into the PBUSH property.

If you use a linear loadcase (static, modal, FRF, etc). then the stiffness is fixed during the analysis.

If you use into a NL loadcase, you could create a TABLED1 and assign a non-linear curve for it (force x displacement).

https://community.altair.com/community/en/how-to-model-non-linear-spring-in-optistruct?sys_kb_id=021d0ee81bfbad10c4dfdbd9dc4bcb01&id=kb_article_view&sysparm_rank=2&sysparm_tsqueryId=076c25881b92b110507ca6442a4bcb70

For dynamic analysis, you could also assign a dynamic behavior, frequency dependent (force x frequency)

 

Francesco Cataldi_20856

Thank for your answer. My doubt is how to use the CBUSH element to model my silentblock. My idea was to create a rigid spider connecting all the nodes of the hole and then to add a 0D CBUSH element on the center node. Is it correct?

Adriano_Koga

Francesco Cataldi_20856 said:

Thank for your answer. My doubt is how to use the CBUSH element to model my silentblock. My idea was to create a rigid spider connecting all the nodes of the hole and then to add a 0D CBUSH element on the center node. Is it correct?

yes, it is possible to do that.

You could also create a '0D' spring, that has only 1 node, and the other node is implicitely grounded.

The behavior is the same, and you wouldn't need to define a constraint on the other end.

the CBUSH can be attached to a RBE2 spider, with no problem.