复合固体推进剂定应变-温度循环加速试验方法研究

Accelerated Test Method of Composite Solid Propellant with Constant Strain-Temperature Cycle

目的建立复合固体定应变-温度循环加速试验方法。方法采用MSC.PATRAN有限元分析软件,仿真计算某型贴壁浇铸固体火箭发动机从零应力温度(68℃)固化降温至常温(20℃)的极值点vonMises应变最大值,利用自制应变加载装置对复合固体推进剂施加定应变。分析固体火箭发动机长期库房贮存的温度变化规律,在兼顾模拟性和加速性的基础上,设计并开展复合固体推进剂在4组不同应力水平下的温度循环加速试验。选用合适的性能退化模型和加速寿命模型,评估复合固体推进剂的可靠库房贮存寿命。结果某型固体火箭发动机从零应力温度固化降温至常温的极值点von Mises应变最大值为9.4%,复合固体推进剂4组温度循环加速试验的最高试验温度分别为75、75、60、60℃,温差分别为5、10、15℃,单个循环时长均为24h。复合固体推进剂在4组温度循环加速试验条件下的老化性能参数均为最大抗拉强度保留率,且在置信度为0.9时,其退化规律均符合指数型性能老化数学模型。结合失效临界值,计算出置信度0.9时的最低加速寿命分别为59、100、203、342 d。基于修正Coffin-Manson模型,利用多元回归分析方法,计算得到复合固体推进剂在长期库房贮存环境(最高温度298 K,年平均温差15 K)下,置信度0.9时的最低贮存寿命为20 a。结论在兼顾模拟性和加速性的基础上,建立了复合固体推进剂定应变-温度循环加速试验方法,并利用指数型性能退化模型和修正Coffin-Manson加速寿命模型,快速获得复合固体推进剂的最低库房贮存寿命,为下一步开展固体火箭发动机装药贮存寿命预估奠定基础。

This paper is to establish a accelerated test method of composite solid constant strain-temperature cycle.The finite element analysis software MSC.PATRAN was used to simulate and calculate the maximum von Mises strain at the extreme point where a certain type of case-bonded casting solid rocket motor solidifies and cools from zero stress temperature(68℃)to normal temperature(20℃).The self-made strain loading device was used to apply a certain strain to the composite solid propellant.The temperature change law of the long-term warehouse storage of the solid rocket motor was analyzed,and then the temperature cycle acceleration test of composite solid propellant under four groups of different stress levels were designed and carried out on the basis of taking into account simulation and acceleration.Appropriate performance degradation model and accelerated life model were selected to evaluate the reliable warehouse storage life of composite solid propellant.The maximum von Mises strain at the extreme point where a certain type of case-bonded casting solid rocket motor solidifies and cools from zero stress temperature to normal temperature was 9.4%.The highest test temperatures of the 4 groups of temperature cycle accelerated tests of composite solid propellants were 75,75,60,60℃,and the temperature differences were 5,10,15℃,and the duration of a single cycle was 24 h.The aging performance parameters of composite solid propellant under four temperature cycle accelerated test conditions were the maximum tensile strength retention rate,and the degradation law of the maximum tensile strength retention rate was conformed to the exponential performance aging mathematical model when the confidence level was 0.9.Combined with the critical value of failure,the minimum accelerated life with a confidence level of 0.9 is calculated to be 59,100,203,and 342 d,respectively.Based on the modified Coffin-Manson model and using the multiple regression analysis method,it was calculated that the minimum storage life of the composite solid propellant in the long-term warehouse storage environment(the maximum temperature was 298 K,and the annual average temperature difference was 15 K)with a confidence level of 0.9 was 20 years.On the basis of taking into account simulation and acceleration,a constant strain-temperature cycle accelerated test method for composite solid propellants was established,and the exponential performance degradation model and the modified Coffin-Manson accelerated life model were used to quickly obtain the minimum warehouse storage life of composite solid propellants and lay the foundation for the storage life estimation of solid rocket motors.