基于J积分分析固体火箭发动机药柱界面裂纹的稳定性

Stability Analysis of the Interfacial Debonded Crack in Solid Rocket Motor Grain with the JIntegral

为探讨某型固体火箭发动机药柱前端壳体/绝热层、绝热层/包覆层、包覆层/推进剂界面裂纹在点火发射时的稳定性,采用3维黏弹性有限元方法,通过在3维J积分柱面内脱黏裂纹尖端上构建奇异界面裂纹单元的方法提高计算精度,分别计算随着界面裂纹沿界面扩展不同深度的J积分,根据J积分随脱黏裂纹深度与位置的变化规律探讨脱黏裂纹的稳定性.结果表明,发动机点火发射时,对应发动机前翼槽结构的各界面裂纹J积分值为全局最大,并且各界面裂纹的J积分值随着脱黏深度的增加呈单调增长趋势,即当界面裂纹脱黏深度到达一定的深度后将失稳扩展.

In order to investigate the stability of the case/insulation,insulation/cladding,cladding/propellant interfacial cracks in the solid rocket motor（SRM）grain when it was lunched,the three-dimension viscoelastic finite element models of the SRM with interfacial cracks were established.The singular interfacial crack elements were included in the 3-DJ-integral loop surface to improve the calculation precision.The three-dimension singular interfacial crack elements at the tips of debonded cracks were established to simulate the crack propagation along the bonded interface.Along the interfacial crack propagation,the J-integral of the interfacial crack tips variation with the debonded length and position were calculated to prejudge its stability.The results show that the maximal J-integral value of the interfacial cracks is located in the position where corresponds to the fore slot of SRM grain.And the J-integral value of the interfacial cracks is monotony increasing with the debonded length.Then the interfacial cracks should be expanded instability at a certain debonded depth.