应变率对高固含量HTPB推进剂力学特性与破坏机制的影响

Effect of Strain Rate on Mechanical Properties and Failure Mechanisms of HTPB Propellant with High Solid Content

通过不同拉伸速率下的单轴拉伸力学性能试验,研究了应变率与90%固含量(固体颗粒的质量分数)HTPB推进剂力学性能之间的相关性,并采用扫描电镜对拉伸断面进行了观察,分析了应变率对推进剂力学性能和破坏机制的影响。结果表明,在低应变率条件下,推进剂的应力—应变曲线出现了弧段现象;随着应变率增加,推进剂应力—应变曲线逐渐由5段式变为4段式;推进剂的初始模量、最大抗拉强度随应变率的增大呈现出上升趋势;推进剂的最大延伸率随应变率增大呈现出降低趋势,在应变率为1190.48×10^(-4)s^(-1)时最大延伸率仅为33.9%;随着应变率增大,高固含量HTPB推进剂的破坏机制逐渐由颗粒“脱湿”转变为基体撕裂,无颗粒破碎产生。

The correlation between strain rates and the mechanical properties of HTPB propellant with 90%solid content(mass fraction)was investigated by uniaxial tensile tests at different tensile rates,and the tensile fracture surface was observed by scanning electron microscope(SEM).The effects of strain rate on the mechanical properties and failure mechanisms of the propellant were analyzed.The results show that the stress—strain curve of the propellant appears an arc segment phenomenon at low tensile rates.With the increase of tensile rates,the stress—strain curves of propellant gradually changes from 5 segment to 4 segment.The initial modulus and the maximum tensile strength of the propellant show an increasing trend with an increase in the tensile rates.The maximum elongation of the propellant decreases with an increase in the strain rate,and the maximum elongation of propellant is only 33.9%when the strain rate is 1190.48×10^(-4)s^(-1).With the increase of strain rate,the failure mechanism of propellant gradually changes from particle dehumidification to matrix tearing,without particle fragmentation.