DEVELOPMENTS IN THE APPLICATION OF LS-DYNA TO FLUID STRUCTURE INTERACTION (FSI) PROBLEMS IN RECOVERY SYSTEM DESIGN AND ANALYSIS

Irvin Aerospace Inc. has used the LS-DYNA Explicit Finite Element Analysis (FEA) tool for over five years for that analysis of static and dynamic fabric problems. The references provide many examples of this previous work. Our first application was the analysis of airbag landings for several spacecraft programs, including Reusable Launch Vehicles (RLV’s), various Unmanned Air Vehicles (UAV’s), Military Airdrop Systems, and planetary exploration systems. These programs are thoroughly covered in the references, including comparisons between simulation and test. Our database of test to simulation comparisons and understanding model details where simulation does or does not apply continues to grow. Additional static and dynamic simulations include various pressurized fabric beams and fabric impact analysis; these are also covered in the references, including another paper presented at this conference. In the past year, Irvin has begun to explore the FSI capability within LS-DYNA through the explicit Navier-Stokes solver, the ALE solutions technique, and the various coupling options. This capability begins to provide Irvin with a capability, which in our industry is currently only available in Government Labs. The interaction of fluid systems and fabric is both the most basic of recovery system (parachute) problems, and perhaps the most difficult fluid structure interaction problem to solve. By beginning with simple problems, and continuously increasing the complexity, we have created early examples of where this simulation technology may lead. Along the way, we will include model size, solution time, and project to problems that will be solvable in the next two years. Additionally, we will report on required algorithmic enhancements and our suggestions on how to approach these. We will also present examples where we begin to apply the recently added Incompressible Navier-Stokes solver in LS-DYNA 960. Unfortunately, we will not report on comparisons to test data as, at the time of this writing, these are not available.