Solid Propellant Micro-scale Failure Mechanisms and Their Influence on Progressive Damage Propagation and Accumulation

A microscale random Representative Unit Cell (RUC) of solid propellant internal structure was developed to study solid propellant failure mechanisms and progressive damage propagation and accumulation on the macro-scale level. Two different types of RUC were proposed, a rectangular tension model and a cylindrical sector model, representing internal SRM bore location. Spherical solid particles embedded in a rubber binder were modeled. A nonlinear hyperelastic material model for the binder was adopted to permit micro- and macroscale high strains. A bilinear cohesive contact model was adopted for the particle-binder interface and interface failure mechanism. Microscale level failure of the particle-binder interface was detected under tension. On the macroscale level, stress strain curves were obtained with particle-binder interface failure detection and clear influence of particle random scatter. The presented results were obtained for a plane strain model, which describes "infinite fibers" instead of real spherical 3D particles, but this simplified model permits a study of applicable models and methods.