考虑围压效应的N15固体推进剂本构模型

利用自制围压试验系统,完成了不同围压下N15固体推进剂的力学性能测试,结果显示:围压对推进剂初始模量影响不大,但最大抗拉强度、断裂强度、最大伸长率和断裂伸长率均随着围压的增大而增大;结合推进剂细观结构及断面分析,初步揭示了围压对推进剂力学性能的影响机理,由于围压的存在,推进剂内部颗粒脱湿度降低,孔洞由于受到压迫,其形成扩展过程延缓,裂纹萌发扩展被抑制,从细观结构上证明了围压对推进剂具有强化效果;根据弹性-黏弹性对应原理建立了考虑围压效应的N15推进剂本构模型,结果表明所建立的本构模型准确度较好,能够准确描述围压对N15推进剂力学性能的影响。 

Constitutive model of N15 solid propellant considering confining pressure effect

Mechanical properties of N15 solid propellant under different confining pressures were obtained by using the confining pressure test system. Result showed that the initial modulus of the propellant did not change with the confining pressure, but the maximum tensile strength, rupture strength, the maximum elongation and elongation at break increased with the increase of confining pressure; combined with propellant’s mesoscopic structure and cross section analysis, the mechanical mechanism of confining pressure effect on the propellant was revealed preliminarily; as a result of the existence of confining pressure, the particle dewetting inside the propellant was reduced, the holes’ propagation delayed due to the pressure, and its crack extension and germination was inhibited, which proved that the confining pressure had strengthening effect for propellant; according to the elastic-viscoelastic correspondence principle, a constitutive model considering the confining pressure effect was established for N15 propellant. The results showed that accuracy of the constitutive model was good, and it can describe the influence of confining pressure on the mechanical properties of N15 propellant accurately.