温度载荷对固体火箭发动机药柱表面裂纹稳定性影响

Effects of Thermal Loading on Stability of the Surface Crack in Solid Rocket Motor Grains

关键词:  发动机  固体火箭  有限元法  奇异裂纹元  应力强度因子  温度载荷

Key words:  motor  solid rocket  finite element method  singular crack element  stress intensity factor  thermal loading

摘要:

为了探讨环境温度对固体火箭发动机点火发射时药柱内表面裂纹稳定性的影响,以翼锥-过渡伞盘-圆柱组合药型的发动机为例,采用三维有限元方法,在发动机药柱的危险截面上沿危险方向预设裂纹,在裂纹尖端构建奇异三维裂纹元,计算在不同环境温度下点火发射时裂纹的应力强度因子。结果表明,药柱表面裂纹在伞盘顶端和圆柱段表面不会以张开方式扩展,伞盘顶端裂纹不会以滑开方式扩展,圆柱中段表面裂纹除低温外,在高温和常温点火发射时均自动止裂;伞盘裂纹若扩展将以撕开方式失稳扩展,低温较高温点火发射危险,圆柱中段表面裂纹可能以撕开方式扩展,高温较低温更为危险。

Abstract:

In order to judge the stability of the surface crack in solid rocket motor (SRM)grains while the SRM was launched in different environmental temperature. A SRM with the grain configuration of fin cone and umbrella-type trays and column was taken as example.Three-dimension finite elements calculation models of the surface crack were established and three-dimension singular crack elements near the crack tip were set up to simulate the surface crack propagation. Under joint action of thermal loading, working pressure and axial acceleration overloading, aimed at different surface crack depths, the stress intensity factors were calculated respectively and the calculated results could be used to judge the crack stability.The results showed that the umbrella slot and the column section surface cracks would not expend with the opening model.The umbrella slot surface crack would not expend with the sliding model.Except low temperature, under high temperature and normal temperature, the column section cracks would auto stop to expend with the sliding model.If the umbrella slot surface cracks expend, they would expend with the tearing model, and launching in low temperature was more dangerous than high temperature.The column section cracks would expend with tearing model, and launching in high temperature was more dangerous than low temperature.