A unified explicit phase-field material point method framework for fluid-structure interaction with large deformation and dynamic fracture

This work presents a unified explicit phase-field material point method (PF-MPM) framework for fluid–structure interaction (FSI) problems involving large deformations and dynamic fracture. Within a monolithic Lagrangian description, the fluid and solid phases are represented by two independent sets of material points, and their interaction is handled through a resolution-independent particle–particle contact algorithm. This contact strategy strictly enforces local momentum conservation, thereby eliminating numerical “stickiness” at the interface and avoiding the high cost associated with explicit interface reconstruction. To address volumetric locking in explicit FSI solvers, the fluid is modeled using a weakly compressible formulation augmented with a kinematic deformation-gradient correction strategy. This strategy yields a smooth and hydrostatically consistent pressure field while preserving essential transient flow features. For the solid phase, a thermodynamically consistent rate-dependent phase-field fracture model derived from a variational principle is employed to naturally capture crack initiation, branching, and fragmentation without ad hoc failure criteria. Furthermore, quadratic B-spline shape functions are combined with a Taylor Particle-In-Cell transfer scheme to guarantee C 1 continuity and reduce numerical dissipation under severe topological changes. A series of benchmark tests demonstrates that the proposed framework can accurately and robustly resolve catastrophic FSI scenarios characterized by large deformation and complex structural failure.