Abstract: In order to achieve mechanical properties of HTPB composite base bleed grain (CBBG), quasi-static uniaxial compressive and tensile experiments were conducted at room temperature (28℃). Based on the analysis of HTPB CBBG’s nonlinear mechanical properties at finite deformation, a five-component viscoelastic-viscoplastic damaged constitutive model was developed. Model predictions present that the developed model can characterize well both compressive and tensile mechanical responses of HTPB CBBG. Damage evolution curves indicate that the increment of cumulative damage value D and damage factor f is approximately linearly dependent on the increment of strain ε when ε is larger than yield strain ε_y. When strain rate decreases by upto four orders of magnitude, the damage degree at the compressive strain of -0.62 and tensile strain of 0.24 increases by a factor of 10.64 and 22.28, respectively. Tensile stress can lead to much severer damage than compressive stress. The user subroutine VUMAT was then written according to the developed model and implemented into the finite element program ABAQUS/Explicit to simulate uniaxial tension experiments. Simulation results indicate that numerical stress-strain curves show satisfactory agreement with experimental data and the accuracy of the VUMAT is verified.

Key words: HTPB composite base bleed grain;Viscoelasticity;Viscoplasticity;Damage;Constitutive model;Numerical implementation

摘要： 为研究HTPB复合底排药（Composite Base Bleed Grain，CBBG）力学性能，进行了室温（28℃）下准静态单轴压缩和拉伸实验。基于对HTPB CBBG有限变形过程的非线性力学响应分析，建立了五元件黏弹-黏塑-损伤本构模型。模型预测结果表明，所建模型能够准确描述HTPB CBBG压缩和拉伸力学性能。获得的损伤演化律表明，达到屈服应变ε_y后，累积损伤值D和损伤因子f随应变ε近似线性增长，应变率降低4个量级，压应变为-0.62时、拉应变为0.24时的损伤程度分别增加了10.64倍和22.28倍，拉应力引起的材料损伤较压应力严重。结合所建模型编写了用户子程序VUMAT，利用ABAQUS/Explicit模拟了单轴拉伸实验。计算结果表明，应力应变曲线数值解与实验结果吻合良好，验证了VUMAT的正确性。

关键词: HTPB复合底排药;黏弹性;黏塑性;损伤;本构模型;数值应用