基于能量耗散镁合金非均质接头微区疲劳裂纹扩展机制及多尺度分析与表征

项目名称： 基于能量耗散镁合金非均质接头微区疲劳裂纹扩展机制及多尺度分析与表征

项目编号： No.51505322

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 机械、仪表工业

项目作者： 闫志峰

作者单位： 太原理工大学

项目金额： 20万元

中文摘要： 镁合金具有轻质、高强、可循环再生等优点，在“陆、海、空、天”等领域有着广泛的应用前景。但因其熔点低、导热快等特点，使其焊接接头的非均质特征更加明显，加载时的断裂行为更加复杂，限制了镁合金构件的安全使用。本项目提出利用能量耗散理论，研究镁合金焊接接头非均质组织的疲劳裂纹扩展机制及多尺度分析与表征。分析裂纹尖端在焊接接头非均质微区（晶粒尺寸、晶界/第二相粒子、位错/孪晶等）的变形行为，建立疲劳裂纹尖端微区累积损伤与能量演化模型。采用微/纳力学方法，测试疲劳裂纹尖端的微区力学性能演变规律，探索疲劳裂纹扩展机制及能量耗散规律的表征。同时探讨缺陷（气孔、夹杂等）对疲劳裂纹尖端变形行为及能量耗散演变规律的影响。探索多尺度下的疲劳裂纹扩展行为及剩余寿命评定方法。研究成果将丰富镁合金构件的疲劳断裂理论，对构件的使用可靠性能评价具有较大科学意义和应用价值。

中文关键词： 镁合金；焊接接头；疲劳裂纹；多尺度分析；能量耗散

英文摘要： Magnesium alloys have broad application prospects in “the land, the sea, the air and the aerospace fields”, with the advantages of light-weight, high-strength and easy recovery. But their characteristics of low melting point and fast heat conduction make the heterogeneity characteristics of the joint more obvious, and lead to complicated deformation behavior, which limits the safe use of magnesium alloy components. This project studies the fatigue crack propagation mechanism of magnesium alloy welded joint with heterogeneous organization, and multi-scale analysis and characterization. In the project, the deformation behavior of the crack tip in welded joint micro heterogeneity (grain size, grain boundarycond phase particles, dislocation/twin, etc.) area will be investigated, and the cumulative damage and energy evolution process will be modeled. Based on the micro/nano mechanics method, it measures the micro zone mechanical properties evolution regularity of the crack tip, and explores the characterization of the fatigue crack propagation mechanism and the energy dissipation law. Meanwhile, it discusses the effect of defects (porosity, inclusions, etc.) on the fatigue crack tip deformation behavior and the energy dissipation evolution law. The multi-scale fatigue crack growth behavior and the residual life assessment method will be studied. Research results will enrich the fatigue fracture theory of magnesium alloy components, and have large scientific significance and application value for the reliability analysis of their use.

英文关键词： magnesium alloy;welding joints;fatigue crack;multi-scale analysis;energy dissipation