Position-based finite element formulation for the analysis of wrinkled membranes

The paper illustrates the application of the position-based finite element formulation to the nonlinear analysis of hyperelastic membranes. The formulation adopts the nodal position vectors in the current configuration as the main unknowns of the problem instead of the nodal displacements. As a result, simple analytical expressions are deduced of the secant and tangent stiffness matrices, which enable straightforward implementation of any hyperelastic constitutive law. Here, Ogden’s material model is adopted in conjunction with Pipkin’s concept of relaxed energy. In this way, the effects of wrinkling and buckling are automatically taken into account and treated as material nonlinearities. As an illustrative example, a polyurethanic rectangular membrane in bending is analysed. The obtained results are in good agreement with experimental and analytical results of the literature.