晶粒尺度下变形铝镁合金低周疲劳损伤的机理研究

项目名称： 晶粒尺度下变形铝镁合金低周疲劳损伤的机理研究

项目编号： No.51465002

项目类型： 地区科学基金项目

立项/批准年度： 2015

项目学科： 机械、仪表工业

项目作者： 郑战光

作者单位： 广西大学

项目金额： 48万元

中文摘要： 综合性能优异的变形铝镁合金应用广泛，但变形铝镁合金低周疲劳寿命较短，一旦遭受循环重载荷的作用，材料局部或整体的应力承载能力会在瞬间迅速丧失，引发灾难性事故。本项目针对这一问题，在晶体塑性理论与损伤力学的框架内，考虑循环塑性与疲劳损伤的相互作用，结合变形铝镁合金低周疲劳的实验数据建立耦合疲劳损伤的弹塑性晶体循环本构模型，采用显式向前梯度法并结合切线刚度法的积分方案开展晶体循环塑性的有限元数值模拟，描述变形铝镁合金低周疲劳的行为过程，探明材料微观变形破坏机制与材料微观结构及微观破坏准则相关参数之间的关系，揭示变形铝镁合金低周疲劳的损伤机理，进而建立起一种科学实验与数值模拟相结合的理论分析方法。该项目的完成将使晶体塑性理论得到进一步完善和补充，为材料与构件的可靠性设计及寿命分析提供新的理论依据。

中文关键词： 疲劳损伤；本构模型；损伤力学；有限元分析

英文摘要： Ultrafine-grained Al-Mg alloy with good mechanical properties has been widely applied. However, low cycle fatigue life of ultrafine-grained Al-Mg alloy is very short. Once subjected to cyclic heavy loading effects, materials in part or as a whole are quickly lost bearing capacity of stress in instantaneous,and catastrophe will also be happen. To solve this question, the interaction of cyclic plasticity and fatigue damage is considered within the framework of crystal plasticity theory and continuum damage mechanics, and a fatigue damage coupled elastic-plastic crystal cyclic constitutive model is proposed on the basis of low cycle fatigue test data of ultrafine grain Al-Mg alloy. Besides, a integration scheme combined with explicit forward gradient method and tangent stiffness method is used, and numerical simulation of the constitutive model is carried out. Therefore, low cycle fatigue behaviors of ultrafine grain Al-Mg alloy can be reasonably described, and the relations between the microscopic failure mechanisms of material and the parameters of microstructure and failure criterion can be ascertained, and low cycle fatigue damage mechanism of ultrafine grain Al-Mg alloy can also be revealed. Lastly, a theory analysing method incorporating with test and numerical simulation is developed. After the project is completed, crystal plasticity theory will be further improved, and a new theory will be built to help reliability design and fatigue life prediction of materials and component.

英文关键词： fatigue damage;constitutive model;damage mechanics;finite element analysis