应力控制下HTPB推进剂的疲劳损伤及寿命研究

Study on fatigue damage and life of HTPB propellant under stress control

为研究HTPB推进剂应力控制下的疲劳特性,在动态热机械分析仪上开展了不同应力幅值的疲劳试验。结果表明,应力幅值增大会使疲劳寿命缩短,应力幅值越大,相同加载次数下的疲劳峰值应变越大,疲劳谷点应变越小,最终断裂应变值基本一样。以疲劳峰值应变作为损伤因子,基于损伤力学理论建立了不同应力幅值下的疲劳损伤演化模型,克服了原有的Chaboche模型不能解释循环应变松弛的缺点,可以很好地表征材料损伤演化规律。

In order to investigate the fatigue properties of HTPB propellant under stress loading,fatigue tests with different stress amplitudes were carried out on the dynamic thermo mechanical analyzer.The results showed that when the stress amplitude increased,the fatigue life was shortened.The bigger the stress amplitude was,the bigger the maximum fatigue strain was,the smaller the fatigue residual strain was,and the ultimate fracture strain value was basically the same.Based on the damage mechanics theory,the fatigue damage evolution model which can consider the stress amplitude was established by using the maximum fatigue strain as damage factor.The model can overcome the shortcomings of Chaboche model that can't explain the cyclic strain relaxation,therefore it can be used to characterize the damage evolution law of materials very well.