Mechanical Properties of Z-Fold Membrane under Elasto-Plastic Deformation

Abstract

This paper addresses a elasto-plastic behavior of creasing process for a z-fold membrane to examine the mechanical properties of the crease, which determine the folding and deployment characteristics of a large membrane. To examine the elasto-plastic behavior in terms of the layer pitch and the contact force for creasing the membrane, fold experiments are performed. The experimental results are evaluated numerically by demonstrating elasto-plastic FEM analyses, and examined theoretically by introducing a mathematical model. In the FEM analyses, the precision is improved by investigating numerical parameters; the penalty stiffness for the contact analyses, the numerical damping in the equilibrium equation, and the size of the finite element mesh, which are dominant parameters in non-linear FEM analyses. In the mathematical model, the mechanics of the creasing process is formulated for elastic deformation. These results indicate that the loading process of the creasing properties is confirmed in terms of the contact force and the layer pitch. On the other hand, the further examinations are requested for the unloading behavior to determine the mechanical properties of the crease precisely.