Numerical computation of mixed mode crack propagation in solid propellant

The viscoelastic finite element method was adopted and the effect of crack tip's deformation is taken into account by various crack tip shapes: sharp angle, ellipse or circular. Maximum tangential stress criterion and the maximum energy release rate criterion were used to estimate the initial crack propagation angle, and J integral criterion was introduced to estimate the initiation of crack propagation. Propagation paths of different cracks were calculated by multiple expanded steps calculation method. Then the cohesive elements were set along the crack propagation path to simulate the dynamic crack propagation process. Results show that, the initial crack propagation angle can be calculated more accurately, considering the crack tip shape's influence. Fracture process of solid propellant can be effectively simulated with multiple expanded step circulation calculation method and cohesive element.