固体推进剂黏弹性参数的确定及细观损伤演化

Accurately determining the model parameters of solid propellant is of great importance for the prediction of its macroscopic mechanical response. A parameter determination method based on multi-step stress relaxation experiments is proposed to calibrate the nonlinear viscoelastic model parameters of solid propellants uncoupled. The proposed method determines the parameters for the elastic part by multi-step stress relaxation equilibrium response and the dimensionless relaxation modulus by stress relaxation in the case of small deformation. The proposed method is then used to analyze the mechanical response of solid propellants. The results show that the predicted results of multi-step stress relaxation and uniaxial tension under different strain rates of the material agree with the experimental results, which verifies the validity of the proposed method. Moreover, since the equilibrium response includes damage, the parameters calibrated by the proposed method can be used to predict the mechanical response of solid propellant with damage. Consequently, the parameters of the composite matrix are derived from the determined parameters of solid propellant, and a viscoelastic debonding criterion-based interface model is introduced to establish a representative volume element (RVE) model, thus achieving the interface debonding analysis in a wide range of strain (~ 100%), which provides an effective method supporting the prediction of mechanical response and microstructural damage evolution of solid propellants.