谐振载荷作用下工程结构振动疲劳寿命预估的损伤力学-有限元法

Damage mechanics-finite element method for vibration fatigue life prediction of engineering structures under resonant loading

建立了预估谐振载荷作用下结构振动疲劳寿命的损伤力学-有限元方法。首先根据损伤热力学原理,构建了损伤演化方程,建立光滑试件在恒幅应变交变载荷作用下寿命预估方法;进一步由损伤力学守恒积分原理,得到恒幅重复载荷作用下应力与寿命的关系式;然后根据标准件疲劳试验结果,拟合得到损伤演化方程中的材质参数;最后利用APDL语言编程对ANSYS软件进行了二次开发,借助ANSYS软件对谐振载荷作用下结构振动疲劳裂纹萌生寿命进行预估。作为算例,本文利用该方法预估了LC9CgS1铝合金梁谐振载荷作用下疲劳裂纹萌生寿命。

For predicting vibration fatigue life of engineering structures under resonant loading,damage mechanics-finite element method was constructed.According to the law of thermodynamics,a new damage evolution equation with fractional form was constructed.The fatigue life prediction method for smooth specimen under the repeated loading with constant strain amplitude was constructed.By the theory of conservative integral,the function was derived to express the relation between the stress and fatigue life under the repeated loading with constant amplitude.The material parameters could be obtained by the results of fatigue test of standard specimens.Based on the platform of ANSYS that was the further development of APDL language in ANSYS,damage mechanics-finite element method for vibration fatigue crack initiation life prediction under resonant was used.The vibration fatigue crack initiation life for LC9CgS1 aluminum alloy beam was predicted.This research provides the possibility for predicting the vibration fatigue lives of structure members through the methodology of damage mechanics.