A finite micro-rotation material point method for micropolar solid and fluid dynamics with three-dimensional evolving contacts and free surfaces

This paper introduces an explicit material point method designed specifically for simulating the micropolar continuum dynamics in finite deformation and microrotation regime. The enables us to simulate large problems while circumventing potential mesh distortion without remeshing. To eliminate rotational motion damping loss of angular momentum during projection, we introduce mapping microinertia between particles grids through affine particle-in-cell approach. curvature at each particle are updated zero-order forward integration microgyration its spatial gradient. We show that conserved projections our formulation. verify formulation implementation by comparing with analytical dispersion relation waves under small strain microrotation, as well soliton solution solids undergoing microrotation. also demonstrate capacity proposed computational framework handle a wide spectrum simulations exhibit size effects geometrical nonlinear regime three representative numerical examples, i.e., cantilever beam torsion problem, fragment-impact penetration fluid discharging problem.