No abstract

We present a parallel computational strategy for carrying out 3-D simulations of parachute¯uid±structure interaction (FSI), and apply this strategy to a round parachute. The strategy uses a stabilized space-time ®nite element formulation for the¯uid dynamics (FD), and a ®nite element formulation derived from the principle of virtual work for the structural dynamics (SD). The¯uid±structure coupling is implemented over compatible surface meshes in the SD and FD meshes. Large deformations of the structure are handled in the FD mesh by using an automatic mesh moving scheme with remeshing as needed. Ó

No abstract

Membrane structures have been used since the earliest of times. Until recently, their analysis has relied chiefly on trial and error; however, modern methods of analysis are evolving. The deformations are nearly always of the large rotation and/or strain type and are thus inherently nonlinear. Static analysis can be considered as a special case of the dynamic analysis. This paper is concerned then with reviewing methods of nonlinear dynamic analysis of membrane structures. Two problems of analysis are associated with membrane structures: (i) shape (or form) finding; (ii) response (deformation and/or stress) analysis. Shape finding (ie, determination of the surface geometry given an initial prestress, generation of cutting patterns, etc) is nontrivial but well documented in the literature and is not considered in this paper. In this review attention is instead focused on formulation of field equations, wrinkling analysis, fluid/structure interactions, material nonlinearities, and computational methods.

A parallel computational technique is presented for carrying out three-dimensional simulations of parachute uid-structure interactions, and this technique is applied to simulations of airdrop performance and control phenomena in terminal descent. The technique uses a stabilized space-time formulation of the time-dependent, three-dimensional Navier-Stokes equations of incompressible ows for the uid dynamics part. Turbulent features of the ow are accounted for by using a zero-equation turbulence model. A nite element formulation derived from the principle of virtual work is used for the parachute structural dynamics. The parachute is represented as a cable-membrane tension structure. Coupling of the uid dynamics with the structural dynamics is implemented over the uid-structure interface, which is the parachute canopy surface. Large deformations of the structure require that the uid dynamics mesh is updated at every time step, and this is accomplished with an automatic mesh-moving method. The parachute used in the application presented here is a standard U.S. Army personnel parachute.