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为研究HTPB推进剂拉伸力学行为的应变速率相关性,采用万能试验机和液压试验机,在室温下开展了不同应变速率(1.2×10~(-4)~80s~(-1))的拉伸实验。结果表明:给定应变对应的应力随应变率对数双线性增加,1s~(-1)为双线性关系的转折点;随应变的减小,HTPB推进剂的应变率敏感性线性增强。在Mohotti建立的模型基础上,结合拉伸力学行为的双线性率相关特性及应变率敏感性的应变依赖性,提出改进的应变速率相关超弹本构模型。该模型以超弹性元件作为基础描述参考应变率下的力学行为,率相关元件乘入超弹性元件描述率相关特性。模型预测与实验曲线对比表明:所提出的率相关超弹本构模型能够描述HTPB推进剂在1.2×10~(-4)~80s~(-1)应变率、30%应变范围内的拉伸力学行为。
In order to study the strain rate dependence of the tensile behavior of HTPB propellants, a universal testing machine and a hydraulic testing machine were used to investigate the strain rates of HTPB propellants at different strain rates (1.2 × 10 -4 ~ 80 s -1) Tensile test. The results show that the stress of a given strain increases logarithmically with logarithm of the strain rate, and 1s -1 is the turning point of the bilinear relationship. As the strain decreases, the strain rate sensitivity of HTPB propellant increases linearly. Based on the model established by Mohotti, an improved strain rate-dependent hyperelastic constitutive model is proposed based on the bilinear rate-dependent properties of tensile mechanics and the strain dependence of strain rate sensitivity. Based on the hyperelastic element, the model describes the mechanical behavior at the reference strain rate and the rate-dependent element times the description of the rate-related properties of the hyperelastic element. The comparison between model prediction and experimental curves shows that the proposed rate-dependent hyperelastic constitutive model can describe the tensile strength of HTPB propellant in the strain range of 1.2 × 10 ~ (-4) ~ 80s ~ (-1) and 30% strain Mechanical behavior.