School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, People's Republic of China.
Beijing Institute of Space Long March Vehicle, Beijing, 100070, People's Republic of China.
Sci Rep. 2023 Feb 4;13(1):2049. doi: 10.1038/s41598-023-29214-7.
The development of a nonlinear viscoelastic constitutive model of composite solid propellant (CSP) coupled with effects of strain rate and confining pressure is essential to assess the reliability of solid propellant grains during ignition operation process. In the present work, a nonlinear viscoelastic constitutive model with novel energy-based damage initiation criterion and evolution model was firstly proposed to describe the coupled effects of confining pressure and strain rate on mechanical responses of CSP. In the developed damage initiation criterion and evolution model, the linear viscoelastic strain energy density was introduced as the damage driving force, and the coupled effects of strain rate, damage history and confining pressure on damage growth were taken into account. Then, uniaxial tensile tests from low strain rates to medium strain rates and various confining pressures, and stress relaxation tests were conducted using a self-made active confining pressure device. Finally, the identification procedures of model parameters and validation results of the constitutive model were presented. Moreover, the master curve of damage initiation parameter was constructed through the time-pressure superposition principle (TPSP). The results show that the developed nonlinear constitutive model is capable of predicting the stress-strain responses of CSP under different strain rates and confining pressures.
发展复合材料固体推进剂（CSP）的非线性黏弹性本构模型，并考虑应变率和围压的影响，对于评估点火过程中固体推进剂颗粒的可靠性至关重要。在本工作中，首次提出了一种具有新颖能量型损伤起始准则和演化模型的非线性黏弹性本构模型，以描述 CSP 对围压和应变率的耦合效应。在提出的损伤起始准则和演化模型中，引入了线性黏弹性应变能密度作为损伤驱动力，并考虑了应变率、损伤历史和围压对损伤增长的耦合影响。然后，使用自制的主动围压装置进行了从低应变率到中应变率和各种围压的单轴拉伸试验以及应力松弛试验。最后，给出了模型参数的识别程序和本构模型的验证结果。此外，还通过时间-压力超叠加原理（TPSP）构建了损伤起始参数的主曲线。结果表明，所提出的非线性本构模型能够预测不同应变率和围压下 CSP 的应力-应变响应。
