9. Summary of results

This document validates the MEMBRANE element in large deformations, for:

• the laws of behavior of Saint Venant Kirchhoff and Neo-Hookaise,

• linear, quadratic and bi-quadratic elements.

This validation is based on comparison with results from the literature and is complemented by several non-regression tests. The literature elements serving as a reference were also used to implant the membrane element in large deformations in code_aster, so we check the correct location of the element in the code with respect to the sources used.

Given the uncertainty in the reference results, it is not possible to conclude that it is appropriate to use higher order elements to obtain more accurate results with the same mesh size. On the other hand, it can be concluded that all these elements give satisfactory results here, regardless of the law of behavior used.

It is also observed that the membrane element in large deformations is highly non-linear and requires a certain number of Newton iterations (sometimes more than 100) to reach the initial equilibrium.