Structural components may experience extreme large deformations and multi-mode failure under complex service loads, which poses major challenges for predictive simulation and design optimization. This talk presents a unified material point method (MPM) framework that integrates large-deformation dynamics, fracture modelling, and structural optimization in a consistent computational setting. For finite deformation, a total Lagrangian MPM (TLMPM) formulation is adopted to reduce algorithmic complexity associated with repeated configuration updates. Fracture is described using a phase-field model coupled with a phase-field-driven adaptive mesh refinement strategy to enhance resolution near evolving crack fronts. To improve robustness for nearly incompressible materials, a constitutive-independent hybrid F‑bar formulation is introduced to alleviate volumetric locking; the volumetric strain-energy contribution is further degraded consistently with the phase-field variable to avoid enforcing incompressibility on fully damaged (cracked) regions. To enable unified mixed-mode failure prediction, a volumetric–deviatoric stress (or energy) decomposition is incorporated to represent both spall fracture and adiabatic shear banding within a single phase-field setting. Building on this solver, we formulate a dynamic topology optimization approach under large deformation within TLMPM, where compliance is minimized to improve impact resistance. Sensitivities are evaluated using an adjoint method, and evolving material boundaries are resolved using adaptive refinement. The resulting framework provides an efficient and robust toolset for multi-mode fracture simulation and large-deformation topology optimization, supporting structural design under extreme loading and failure scenarios.