An axisymmetric parachute model with wrinkling

The deformation and stresses in a parachute canopy are analyzed, using an axisymmetric model. The canopy is modeled as an ideal or nearly ideal elastic membrane shell. Steady state is assumed. No restriction is imposed on the size of the deformation, and thus the problem is strongly nonlinear. Wrinkles which form over parts of the surface are taken into consideration approximately via the use of wrinkle fields (tension fields). The solution is obtained by a double-iteration numerical procedure, based on a shooting technique and incremental loading. First a basic parachute model is considered in which the material is assumed isotropic and Hookean, the pressure distribution is assumed uniform (but with unknown magnitude), and the canopy is assumed to have a small central hole. Later all these assumptions are relaxed. Numerical examples are presented for some representative cases.