压印接头微动损伤与疲劳寿命预测研究

As an emerging sheets joining technology, mechanical clinching was widely used due to a series of advantages. The applications of the clinched joints including the automotive industry, aerospace and machinery manufacturing, etc. In this reason, the clinched joints are inevitably working under cyclic loading. Therefore, the research of the fatigue properties of clinched joints is of great importance. However, the specific position of the fretting wear and the location of the crack initiation are difficult to confirm due to the material deformation state of the joint, the properties of the material and the magnitude of the applied loads. In addition, the fretting wear is an inevitable factor affecting the fatigue failure of the clinched joint, which makes the fatigue life of the clinched joint difficult to predict. Therefore, this project will study the deformation process of the double-half-section clinched joint and the clinched joint after fatigue failure with the aid of the failure image detecting method and the microanalysis method. Exploring the initiation, propagation and fracture process of fatigue cracks, studying the fatigue fracture mechanism of the clinched joints considering fretting wear conditions. Then finally establishing the fatigue life-estimating model of the clinched joints based on theoretical analysis, experiment and simulation. To achieve the goal of predicting the fatigue failure location and life of the clinched joints, which would provide theoretical support and reference basis for the wide application of the mechanical clinching technology and the improvement of product quality.

压印连接作为一种新兴的板材连接技术，被广泛应用在汽车、航空航天和机械制造业等领域，压印接头不可避免的在循环载荷下工作，因此接头的疲劳寿命和失效形式是决定连接点性能的关键因素。除了被连接材料性能、连接点材料变形状态和外加载荷大小等因素，接头裂纹扩展同样会受到微动磨损的影响，但是微动磨损出现的具体位置和裂纹扩展方向往往难以进行有效预测。现今对于压印接头微动磨损的研究较少，其损伤机制不明确，导致很难展开对压印接头的疲劳寿命预测研究。本项目结合失效图像检测技术和微观分析方法，通过对双半剖压印接头的变形过程和疲劳失效后的压印接头开展系统性研究，并对其疲劳裂纹的萌生扩展现象和微动损伤机制进行研究，在理论分析、实验验证和仿真模拟的基础上建立压印接头疲劳寿命估算模型，最终达到准确预测压印接头疲劳失效位置和寿命的目标，为压印连接技术的广泛应用及其产品质量的提升提供理论支撑和实验依据。

压印连接作为一种新兴的板材连接技术，被广泛应用在汽车、航空航天和机械制造业等领域，压印接头不可避免的在循环载荷下工作，因此接头的疲劳寿命和失效形式是决定连接点性能的关键因素。除了被连接材料性能、连接点材料变形状态和外加载荷大小等因素，接头裂纹扩展同样会受到微动磨损的影响。接头的微动磨损具体位置和接头的疲劳寿命往往难以进行有效预测。为此，本项目对轻合金压印接头机械性能及微动疲劳破坏机理方面开展系统性研究，并对其疲劳裂纹的扩展现象和微动损伤机制进行分析，在理论分析、实验验证和仿真模拟的基础上建立压印接头疲劳寿命估算模型。本项目研究了铝合金压印连接过程的塑性变形机理及材料流动行为；得到了压印接头静力学和疲劳状态下的力学性能和失效机理；统计了压印接头疲劳裂纹扩展的行为规律和扩展机制；补充完善了压印接头微动磨损的各类失效形式；揭示了压印接头疲劳状态下微动磨损的破坏机理；得到了压印接头的疲劳寿命估算模型。最终实现了预测压印接头疲劳失效位置和寿命的目标，为压印连接技术的广泛应用及其产品质量的提升提供理论支撑和实验依据。