本项目旨在多轴疲劳实验研究基础上，系统分析增材制造材料在多轴疲劳荷载作用下的力学性能，区别并量化不同加载方向及微观缺陷形式对材料损伤的影响，构筑基于能量法的多轴疲劳损伤参量，进而建立可靠的疲劳寿命预测方法。主要有三部分内容：(1) 实验研究，包括测试不同多轴疲劳加载路径下的非比例度，测量各种强化效应下的疲劳裂纹萌生寿命，观测材料微观缺陷形态及疲劳断口形貌。(2) 微观缺陷的宏观表征，包括分析缺陷形态、荷载形式以及材料破坏状态的相互影响，量化微观缺陷与工艺参数以及与材料力学性能之间的关联度，深入研究微观缺陷对于材料破坏的损伤机理，建立考虑微观缺陷影响的多轴疲劳强度模型。(3) 寿命预测方法研究，研究不同加载路径下材料疲劳总体损伤的演化规律，构建有效的考虑微观缺陷影响并体现非比例强化效应的材料总体损伤参量模型，在此基础上建立针对增材制造材料的精确的多轴疲劳寿命预测方法。

Based on multiaxial fatigue experimental research, this project is aimed to systematically study mechanical properties of additive manufacturing materials under multiaxial fatigue loading, distinguish and quantify the effect of different loading directions and micro-defects on material damage, construct energy-based multiaxial fatigue damage parameters, and establish a reliable fatigue life prediction method as well. It consists of three main parts. The first one is experimental measurements, which include the measurement of the non-proportional factor under different multiaxial fatigue loading paths, the detection of fatigue crack initiation under various hardening effects and the observation of micro-defect morphology and fatigue fracture morphology of materials. The second one is macro characterizations of micro-defects, which include the analysis of the interaction mechanism of defect shape, load form and material failure state, the quantification of relationship between micro-defects, process parameters and mechanical properties of materials, the in-depth study on damage mechanism of micro-defects to material failure and establishment of multiaxial fatigue strength model considering the effect of micro-defects. The third one is research on life prediction method, which includes evolution of total fatigue damage of materials under different loading paths, construction of effective damage parameter model of material considering the effect of micro-defects and reflecting non-proportional hardening effect and on that basis, we can establish accurate multiaxis fatigue life prediction method for additive manufacturing materials.