material behaviour

[Ale22pic]

Hello, I'm working on a sandwich material where one of the two faces consists of a material that has different traction and compression behaviour. how could I do that? Could I create a field where inside I insert the sigma-epsilon curve of this material?

 

[Onda]

you can use a material with elastic bilinear module. but it depends a little on which is the goal of your analysis. if you already know which face is in traction and which in compression you should create two different materials. then how do you model the sandwich? with a solid in thickness or with a pcomp? in the second case it seems to me that you cannot use a bilinear material but pcomp only accepts linear materials.
In the first case, then modeling the sandwich with three elements in thickness, one shell per side and one solid in the center, I think you can use a pshell, and to give it a bilinear material.

 

[Ale22pic]

hello wave, thank you for the answer. the idea was to model the heart with 3d elements and faces with shell elements. the idea was to use a bilinear so that you don't have to always first understand what was in traction and compression. At this point I believe that it is the same thing to see first the areas where you have traction and compression with a simple model and then go to insert "different" materials according to that element as you work.

 

[Onda]

you can model with a bilinear and do a non-linear analysis (a linear does not work with a bilinear material) which is not linear by definition. or model by putting different materials and performing a linear analysis.
depends on the complexity of your model. generally the sandwich does not model with solids, except on very special occasions.
depends on whether you are interested only in a stress analysis or you have to do even an instability, in such case you can not turn for a search for autovalues with a nonlinear material, you have to put instead stress stiffening (or binding in compression) and turn until the non-linear convergence. much more complex.