Hi, 

I am trying to model a human aortic tissue with linear material that has poisson's ratio of 0.49 loaded with internal pressure.

I have two parts surface to surface tie contact is defined between them (as seen in the figure), the tetrahedral elements (blue part) has C3D10H element type, While I have some issues in selecting the proper element type for the hexahedral elements (red part), I tried C3D20H, C3D20R, C3D20RH, the results are not close to my ground truth which is the same model but instead of the hexahedral red elements I have them as tetrahedral elements with C3D10H element type.

Appreciate your help,

Farah