A multiscale approach for the development of a nonlinear viscoelastic friction-and-cavitation-based model for solid propellants

Solid composite propellants present a highly nonlinear viscoelastic behavior when submitted to cyclic loadings. To model these nonlinearities, it is proposed to use two internal variables representing friction and cavitation. A homogenization approach is set to determine the evolution equations of these variables and their mathematical relationships with the material's macroscopic properties. Then, a macroscopic step allows the construction of a thermomechanically consistent viscoelastic model containing the new internal variables. Numerical parameters are identified through propellant characterization tests. Validations on cyclic experiments show the model's ability to reproduce and to predict the material's behavior correctly outside this identification range.