考虑围压效应的 NEPE 推进剂药柱结构完整性分析

In order to investigate the effects of confining pressure on the structural integrity of NEPE propel⁃ lant grain，the incremental derivation of the nonlinear viscoelastic constitutive model with damage and confining pressure was carried out，and the UMAT subroutine of the propellant material constitutive model was complied. The mechanical responses and structural integrity of NEPE propellant grain under ignition pressurization were evaluated. The results show that the effects of confining pressure on the mechanical response of NEPE propellant grain are associated with damage strain threshold，when the strain response of the grain is less than the damage strain threshold value of NEPE propellant without confining pressure，the confining pressure has little effect on the mechanical response of grain. The stress response of grain increased and the strain reduced compared without confining pressure when the strain response of the grain was higher than damage strain threshold value of NEPE propellant. The maximum equivalent stress increased 26% and maximum equivalent strain decreased 12% with the confining pressure of 5.4MPa. The compacting effect of confining pressure can significantly decrease the dam⁃ age of propellant grain，the damage coefficient reduced about 40% with the confining pressure of 5.4MPa. When considering the confining pressure effect，the safety factor of the grain obtained by twin shear strength criterion and Von Mises stress criterion were 3.06 and 2.11，respectively. When the confining pressure effect was not con⁃ sidered，the safety factor obtained by the traditional Von Mises stress criterion was 1.97. The confining pressure effect can improve safety factor significantly，and the traditional method of structural integrity assessment is con⁃ servative.