FLUID STRUCTURE INTERACTION SIMULATION BASED ON IB-LBFS AND NFE FOR LARGE DEFORMATION MEMBRANE

In the field of aerospace engineering, the nonlinear dynamic response and complex flow characteristics of flexible fabric aircraft, such as parachutes and airships, under unsteady aerodynamic forces represent a frontier challenge in the study of large deformation fluid-structure interaction (FSI). The coupling phenomena of geometric nonlinearity, material nonlinearity, and boundary nonlinearity for hyper-elastic membrane structures subjected to aerodynamic loads have introduced significant technical challenges to traditional numerical simulation methods, including issues related to mesh distortion, interface tracking, and energy conservation. In this paper, we address the numerical simulation requirements of such FSI problems by integrating the Immersed Boundary-Lattice Boltzmann Flux Solver (IB-LBFS) method with the nonlinear finite element (NFE) method for membrane structures. This integration establishes a fluid-structure coupling computational framework that achieves four core functionalities: Dynamic deformation boundary identification for viscous flows, dynamic reconstruction of fluid-structure loads and surfaces, solution of hyper-elastic material irregular membrane structures, and large-scale parallel computing. Using a constant-pressure inflated bag as the research object, we analyze the fluid-structure coupling effect between the airbag and the viscous fluid under free incoming flow conditions. The results demonstrate that the predicted data from the model align well with the flow field distribution characteristics and the development trends of structural responses. The developed fluid-structure coupling computational program can be further utilized for evaluating the FSI effects of inflatable aircraft, such as aviation parachutes and airships, providing a theoretical basis for structural design, strength verification, and flight reliability assessment of future flexible aircraft.