运输过程火箭战斗部装药振动疲劳的数值分析

摘要

In order to understand the structural reliability of the solid rocket warhead in transport,the frequency domain method is used to evaluate the fatigue damage degree.The simplified kinetic model of the rocket launcher was built and the base excitation PSD (power spectrum density) of the charge was calculated by the transfer function and road load PSD;the finite element model of the charge was established and dynamic responses were solved by mode superposition methods;the fatigue damage degree was evaluated by Steinberg's 3-σ Law.Results show that the random vibration of the warhead charge causes the dynamic stress,and the inner face of the top hole is the danger place with the stress peak value of 4.86 MPa.When the loading time reaches 250 h the damage degree is 1.12,which reveals that the warhead charge has been broken.The road roughness load can bring about the fatigue damage of the warhead charge,which has negative impacts on the structural reliability.%为深入了解运输环境下火箭战斗部装药的结构可靠性,利用频域方法对其随机振动特性及疲劳损伤情况进行了研究.建立了发射车简化动力学模型,由传递函数及路面载荷求得装药基础激励功率谱;根据装药有限元模型,利用模态叠加法求出了结构随机振动响应,并通过Steinberg 3-σ法则估算疲劳损伤量.计算结果表明:运输过程中装药会发生随机振动,结构内部会产生动应力,危险点位于顶部圆孔内侧,应力峰值为4.86 MPa.当加载时间达到250 h时累积损伤量为1.12,表明装药已经发生结构破坏.路面激励会引发装药疲劳损伤,影响其结构可靠性.