Membrane theory compare to solid Theory

[benrb]

Hello,

I use Abaqus Explicit. I have a question about the membrane theory.
I have done simple in plane-shear tests with one element for membrane and solid elements for the same step. The results give strange things for logarithmic principal strains.Normally, I must find the same values of principal strains in the plane. But I don't find the same values between my model with membrane element and solid element. Until a angular value close to 45°, the curve are similar, but with a higher angle, the curve for membrane element go upper.
The principal strain with solid elements follow the analytical values, but not with membrane elements.

Have you any idea which can explain this difference?
Thanks in advance

Ben

 

[xerf]

The membrane theory does not account for bending stiffness and so the elements based on it.