损伤演化细观机制的宏观研究

Macroscopic Study on Mesoscopic Mechanism of Damage Evolution

摘要: 损伤力学通过损伤度表征损伤，以损伤演化方程描述材料损伤演化进程，形成了完整的力学分析体系，但目前对材质损伤机制的认识尚存在较大不足。为探讨材料损伤演化规律，更准确的描述材料损伤本质，本文通过含孔洞大板的有限元模型在不同应力状态下的仿真计算，探究了材料细观损伤机制，通过探讨拉/压载荷以及损伤驱动力中偏斜应力与体积应力对损伤造成的不同影响，提出了一种新的损伤驱动力形式，揭示了“拉应力造成损伤，压应力造成较小损伤”的细观机制，并结合疲劳实验的结果证明了其合理性，建立了“偏斜应力累积损伤，体积应力较少累积损伤”的理论认识。上述研究为损伤机制认识和工程应用中的损伤分析打下了良好的理论基础，同时提供了适用性的损伤力学分析方法，为工程设计和疲劳寿命预估提供了理论指导。

Abstract: Damage mechanics characterizes damage through damage degree, and describes the process of material damage evolution by damage evolution equation, forming a complete mechanical analysis system. However, there is still a big gap in the understanding of material damage mechanism. In order to explore the evolution law of material damage and describe the nature of material damage more accurately, this paper explores the meso-damage mechanism of materials through the simulation calculation of finite element model of large slab with different stress states, and discusses the tensile/compressive load and damage. In the driving force, the different effects of skew stress and volume stress on the damage are proposed, and a new form of damage driving force is proposed, which reveals the mesoscopic mechanism of “damage caused by tensile stress and small damage caused by compressive stress”, combined with fatigue. The experimental results prove its rationality, and establish a theoretical understanding of “accumulated stress of skew stress and less cumulative damage of volume stress”. The above research lays a good theoretical foundation for the damage mechanism understanding and damage analysis in engineering appli-cation, and provides the applicability of damage mechanics analysis method, which provides theo-retical guidance for engineering design and fatigue life prediction.