关键词: 黏弹性, 微裂纹, 偏折扩展, 损伤映射张量, 裂纹扩展模型

Abstract: A constitutive model for the Hydroxyl Terminated PolyButadiene (HTPB) propellant with damage is developed by using a macro-micro coupled method. The micro-damage mechanism was considered as the kinking growth of microcracks. First, based on the dilute estimation theory of microcracks, the general form of the damage mapping tensor in the Abdel-Tawab's macro-constitutive equation was derived, which maps the multiaxial loading on an anisotropic material in the true stress space into more complicated multiaxial loading on an isotropic material in the effective stress space. Second, the kinking growth of a 3D penny crack was analyzed based on the energy release rate criterion and maximum circumferential stress criterion, and a penny microcrack was used to approximate the kinked one by a two-step equivalent method. Finally, a rate equation for stable growth of a microcrack was derived based on the Schapery's crack tip model. Numerical results indicate that the model can effectively reflect the anisotropic damage feature of the material, and the dependence of damage on strain rate and temperature.

Key words: viscoelasticity, microcrack, kinked growth, damage mapping tensor, crack growth model