不同温度下裂纹悬臂梁的模态和疲劳寿命分析

发布时间：2018-05-01 09:24

本文选题：裂纹 + 悬臂梁　；参考：《振动与冲击》2017年08期

【摘要】：基于扭转弹簧模型和修正Paris公式,提出了一种在不同外界温度下含初始裂纹悬臂梁的疲劳寿命估算方法。在模态分析过程中,通过弹性模量引入温度模块,利用扭转弹簧等效该裂纹,将悬臂梁转化为由扭转弹簧联接的两段弹性梁;推导出不同温度下含裂纹梁固有振型的特征方程,分析温度和裂纹几何参数对裂纹梁固有频率的影响。在疲劳寿命分析过程中,利用复弹性模量引入阻尼损耗因子,基于修正Paris方程和同步分析法,考虑裂纹梁振动与疲劳裂纹扩展的相互作用,分析温度、阻尼和悬臂梁根部区域裂纹几何参数对裂纹梁疲劳寿命的影响。结果表明:随着裂纹相对位置的减小以及裂纹相对深度的增大,裂纹悬臂梁的固有频率和疲劳寿命则逐渐降低;而外界温度的升高也会导致裂纹悬臂梁固有频率和疲劳寿命的降低;同时随着阻尼损耗因子的逐渐增大,裂纹悬臂梁的疲劳寿命也会逐渐增加。
[Abstract]:Based on torsional spring model and modified Paris formula, a fatigue life estimation method for cantilever beams with initial cracks at different external temperatures is proposed. In the process of modal analysis, the temperature module is introduced into the elastic modulus and the torsional spring is used to equivalent the crack. The cantilever beam is transformed into a two-segment elastic beam connected by torsional spring, and the characteristic equation of the inherent mode of the beam with cracks at different temperatures is derived. The influence of temperature and geometric parameters of crack on the natural frequency of cracked beam is analyzed. In the process of fatigue life analysis, the damping loss factor is introduced by using complex modulus of elasticity. Based on the modified Paris equation and synchronous analysis method, the interaction between vibration and fatigue crack propagation of cracked beam is considered, and the temperature is analyzed. The effects of damping and geometric parameters of crack at the root of cantilever beam on fatigue life of cracked beam. The results show that the natural frequency and fatigue life of cracked cantilever gradually decrease with the decrease of the relative position of crack and the increase of relative depth of crack. The increase of external temperature also leads to the reduction of natural frequency and fatigue life of cracked cantilever beam, and the fatigue life of cracked cantilever beam increases gradually with the increase of damping loss factor.
【作者单位】：南京航空航天大学机械结构力学及控制国家重点实验室;
【基金】：江苏高校优势学科建设工程基金资助
【分类号】：TB123

【相似文献】