New Structural Model for Parachute Inflation Simulations

The goal of this project has been to develop a new robust structural model that is being coupled with existing computational fluid dynamics CFD codes to accurately simulate the dynamics of parachute and parafoil systems. This research will allow the Army to reduce the time and cost of developing new airdrop systems and retrofitting existing systems for new applications. Parachute dynamics is an extremely complex process. This process is governed by nonlinear time dependent coupling between the parachute and surrounding airflow and involves large canopy shape changes and unconstrained motion of the parachute in the fluid medium. To successfully simulate this complex process, a robust structural model is essential. The following capabilities were added to the structural model 1 membrane wrinkling, 2 material orthotropy, 3 local bending and damping elements, 4 user defined time dependent element properties, 5 various nonlinear transient solution algorithms, 6 approximate fluid forces, 7 stress projection algorithms, and 8 local nodal coordinate systems. It has been demonstrated that large scale finite element modeling of parachute dynamics is feasible using this structural model. Significant transfer of this basic research was accomplished. New structural model features have continuously been incorporated into a finite element code which has been used extensively by Army engineers to perform simulations of Army parachute systems.