热环境下飞行器壁板的振动疲劳分析

Analysis on Vibration Fatigue of Aircraft Panel under Thermal Environment

针对高超声速飞行器热力环境引起的壁板振动疲劳问题,旨在研究温度变化对壁板结构振动特性及疲劳寿命的影响。首先分析壁板三维瞬态耦合传热和热应力,获得壁板的温度场和应力场;然后依次探讨温度场、应力场及其耦合效应对壁板振动模态与疲劳寿命的影响。分析过程中,考虑温度变化造成弹性模量减小对壁板刚度的影响,引入由热环境引致的附加热应力刚度矩阵以及附加热变形刚度矩阵。结果显示:温度变化引起的材料力学性能退化使壁板结构各阶次模态频率随之下降,温度梯度对振动模态的影响明显,热力耦合效应使壁板的振动疲劳寿命缩短。

According to the vibration fatigue problem of hypersonic aircraft under the thermal-mechanical environment, impacts of the temperature change on vibration properties and fatigue life of aircraft panel are studied. Firstly, the temperature field and stress field are obtained by analyzing three dimension transient coupling thermal conduct and thermal stress. Then, impacts of the temperature and stress and theirs coupling on panel＇ s vibration mode and fatigue life are discussed. During the analysis, the stiffness of panel material influenced by the temperature is considered. Initial stress additional stiffness matrix caused by thermal stress and initial displacement stiffness matrix caused by thermal strain are introduced. Results indicate that different modes the panel are going to be decreased because the performance is worsen by the action of temperature. Impacts of temperature grade on vibration mode are obvious. The vibration fatigue life is shortened because of the coupling effect.