基于DFR法的螺栓连接件疲劳性能研究  

Investigation of fatigue properties of bolted connectors based on detail fatigue rating

作　　者：陶雪菲 王瑞[1] 高玉魁 黄甫[4] 陈禹锡 TAO Xuefei;WANG Rui;GAO Yukui;HUANG Fu;CHEN Yuxi(Tongji University,School of Aerospace Engineering and Applied Mechanics,Shanghai 200092,China;Tongji University,School of Materials Science and Engineering,Shanghai 201804,China;Shanghai Key Laboratory of R&D for Metallic Function Materials,Shanghai 201804,China;Shanghai Aircraft Design and Research Institute,Shanghai 201210,China)

机构地区：[1]同济大学航空航天与力学学院,上海201804 [2]同济大学材料科学与工程学院,上海201804 [3]上海市金属功能材料开发应用重点实验室,上海200092 [4]上海飞机设计研究院,上海201210

出　　处：《民用飞机设计与研究》2021年第4期28-36,共9页Civil Aircraft Design & Research

摘　　要：针对螺栓连接件在服役过程中易产生疲劳损伤的问题,采用有限元模拟、理论分析和试验测试相结合的方法探究试验件厚度以及螺栓连接间隙对构件疲劳性能的影响规律。有限元模拟结果表明,由于构件几何形状的不连续性以及螺栓连接间隙的存在使得连接件中的铝合金板孔边产生较为明显的应力集中现象,在循环载荷作用下易在该处萌生疲劳裂纹导致构件的损伤失效,而施加螺栓预紧力可以通过摩擦传载改善孔边的受力情况。在静力分析的基础上,采用有传载紧固件双剪接头结构细节疲劳额定值(DFR)理论计算方法估算不同类型试验件的DFR值。理论估算结果与通过双点法确定的试验件DFR值基本吻合,相对差异在10%以内,可以验证该理论方法有较好的工程适用性。分析结果表明,试验件的连接间隙会影响螺栓的受载情况,在拉伸过程中先发生接触的螺栓处有较大的应力集中,最终导致连接件的疲劳失效;当试验件的厚度增加,铝合金板所承受的附加弯矩增大,会影响孔边的应力分布,在一定程度上降低试验件的疲劳性能。试验件厚度和连接间隙对试验件疲劳性能的影响可通过应力集中系数来综合体现,试验件DFR值近似随应力集中系数呈线性降低。本工作的研究成果可为螺栓连接件疲劳性能研究提供参考。Aiming at problems of fatigue damage of bolted connections during services,the influences of plate thickness and connection gap were investigated via the combination of theoretical,numerical and experimental methods.Numerical results indicated that there was stress concentration by the bolt holes of aluminum plates because of the existence of geometry incontinuity and the connection gap.Under cyclic loads,fatigue cracks were easily to be initiated near these holes,leading to the damage and fracture of components.However,the loading conditions around the holes can be improved through the frictional effects induced by the application of bolt load.Based on static analysis,the detail fatigue rating(DFR)values were calculated according to the theory of the double-shear joint with load-transmitting fastener structures.The estimated values were consistent with experimental results derived from the two-point method and the relative differences were within 10%.This implied that the theoretical method had good engineering applicability.Results showed that the connection gap would affect the load of bolted connectors.There can be a large stress concentration at the bolt that first contacts the plate during the stretching process,which would eventually lead to the fatigue failure of the component.Furthermore,the increment of thickness would cause additional bending moment that could affect the stress distribution at the edge of the hole and diminish the fatigue performance of components.In this case,the effects of plates thickness and connection gap can be comprehensively embodied through stress concentration factors.The increment of stress concentration factors would approximately lead to the linear diminution of components’DFR values.As a result,this work can provide references for further investigation of fatigue performances of bolted connection structures.

关 键 词：螺栓连接件 疲劳性能 细节疲劳额定值 

分 类 号：V262.3[航空宇航科学与技术—航空宇航制造工程]