不同温度下混合材料机械连接结构疲劳分析的SSF法

SSF Method for Fatigue Analysis of Mechanically Fastened Hybrid-material Structures at Different Temperatures

为评估环境温度变化对混合材料机械连接结构疲劳性能的影响,提出了混合材料机械连接结构疲劳性能分析的应力严重系数(Stress-severity-factor,SSF)方法。考虑不同材料在不同环境温度下的热变形,建立混合材料多排钉连接结构的钉传载荷和旁路载荷计算模型,然后定义并计算危险细节的SSF值,结合材料的S-N曲线可以估算连接结构在不同环境温度下的疲劳寿命。采用7050-T7451铝合金/CFRP层合板三钉单搭混合连接试件在不同环境温度下开展疲劳试验,对提出的疲劳寿命分析方法进行验证。结果表明,不同材料的热变形差异会影响结构的传力行为,进而使得结构在不同环境温度下表现出不同的SSF值,疲劳寿命预测结果与试验结果之间的相对误差小于20%,该方法便捷高效,为复杂环境下混合材料机械连接结构的疲劳寿命分析提供了有力的支撑。

To evaluate the influence of ambient temperature change on fatigue performance of mechanically fastened hybrid-material structures,a stress-severity-factor(SSF)method is proposed for the fatigue analysis of mechanically fastened hybrid-material structures.Considering the thermal deformations of different materials at different ambient temperatures,the calculation model of bolt loads and bypass loads for the multi-row-bolt-fastened hybrid-material structures is established.Then,the SSF value of hazard details is defined and calculated,and fatigue lives of fastened structure at different ambient temperatures can be estimated based on S-N curves of the materials.Fatigue tests of 7050-T7451 aluminum alloy/CFRP laminate three-bolt single-lapped hybrid fastened specimens are carried out at different ambient temperatures to verify the proposed fatigue life analysis method.The results show that the thermal deformation difference of different materials will affect the force-transfer behavior of structure,and then the structure show different SSF values at different ambient temperatures.The relative errors between the prediction results and test results of fatigue lives are less than±20%.The method is convenient and efficient,which provides a strong support for the fatigue life analysis of mechanically fastened hybrid-material structures under the complex environments.