A partitioned fully explicit Lagrangian finite element method for highly nonlinear fluid-structure interaction problems

In this work, a fully explicit partitioned method for the simulation of Fluid Structure Interaction (FSI) problems is presented. The fluid domain is modelled with an explicit Particle Finite Element Method (PFEM) based on the hypothesis of weak compressibility. The Lagrangian description of the fluid is particularly effective in the simulation of FSI problems with free surface flows and large structural displacements, since the fluid boundaries are automatically defined by the position of the mesh nodes. A distinctive feature of the proposed FSI strategy is that the solid domain is modelled using the explicit integration FEM in an off-the-shelf commercial software (Abaqus/Explicit). This allows to perform simulations with a complete and advanced description on the structural domain, including advanced structural material models and contact. The structure-to-fluid coupling algorithm is based on a technique derived from the Domain Decomposition Methods, namely, the Gravouil and Combescure algorithm. The method allows for arbitrarily large interface displacements using different time incrementation and nonconforming meshes in the different domains, which is an essential feature for the efficiency of an explicit solver involving different materials. The resulting fully explicit and fully lagrangian finite element approach is particularly appealing for the possibility of its efficient application in a large variety of highly non-linear engineering problems.