SPH-based framework for modelling fluid-structure interaction problems with finite deformation and fracturing

Understanding crack propagation in structures subjected to fluid loads is crucial in various engineering applications, ranging from underwater pipelines to aircraft components. This study investigates the dynamic response of structures, including their damage and fracture behaviour under hydrodynamic load, emphasizing the fluid-structure interaction (FSI) phenomena by applying Smoothed Particle Hydrodynamics (SPH). The developed framework employs weakly compressible SPH (WCSPH) to model the fluid flow and a pseudo-spring-based SPH solver for modelling the structural response. For improved accuracy in FSI modelling, the $\delta$-SPH technique is implemented to enhance pressure calculations within the fluid phase. The pseudo-spring analogy is employed for modelling material damage, where particle interactions are confined to their immediate neighbours. These particles are linked by springs, which don't contribute to system stiffness but determine the interaction strength between connected pairs. It is assumed that a crack propagates through a spring connecting a particle pair when the damage indicator of that spring exceeds a predefined threshold. The developed framework is extensively validated through a dam break case, oscillation of a deformable solid beam, dam break through a deformable elastic solid, and breaking dam impact on a deformable solid obstacle. Numerical outcomes are subsequently compared with the findings from existing literature. The ability of the framework to accurately depict material damage and fracture is showcased through a simulation of water impact on a deformable solid obstacle with an initial notch.