I'm having difficulty modeling a right-circular-cylindrical, silicone-rubber bushing bonded on both disk faces, possibly because I don't understand how to enter mutually compatible material properties or possibly because SolidWorks is having difficulty computing stress/strain solutions for soft, essentially incompressible elastomers. Here are the "stiffness" parameters I'm using in psi:

Elastic Modulus in X (I assume this means Young's modulus): 210

Poisson's Ration (sic.) in XY: 0.499

Shear Modulus in XY: 70.1

The results I get depend strongly on the density of nodes in the bushing. For example, with only 3 layers of nodes axially (many more transversely) I get shear essentially the same as predicted by a semi-empirical formula I looked up and compression within about a factor of two of the corresponding formula. For much higher density of nodes, however, I get orders of magnitude smaller shear and compression for the same applied forces. Any thoughts? -- John Willett

P.S. -- If you only specify two of the three "stiffness" parameters (actually there are four, counting the bulk modulus -- say you specify Young's modulus and Poisson's ratio, leaving the shear modulus blank), does SolidWorks automatically calculate the missing one from the two available analytical formulae, or what? It still seems to run... -- J.W.

John: I highly suspect that the finite element formulations (of the type used in this specific software) are not quite appropriate to model some nonlinearities very well - I've come to the conclusing using this software with plasticity modeling (i.e., a near 'flowing' material). I don't believe it's the software developers at fault here - just the appropriate math used in the finite elements. The elements get too stretched or compressed and they tend to 'lock' or not provide realistic results, or the program 'exits' (i.e., crashes). I know there is other software called: Adina and MARC and Abaqus that have element formulations specifically designed to handle these types of nonlinearities.

To suggest a solution other than that, this type question should go to the developers - the software should handle it: it should only be a matter of twiddling the knobs on their math models, which I'm not good at.

I hope that helps (a little). I'm trying to prevent you from going down a rabbit hole (which I've done many times with this software).

Anthony