Fatigue damage and cyclic plasticity assessment of engineering materials under various uniaxial and biaxial loading conditions

众所周知，疲劳是许多工程部件和结构失效的主要原因。由于构件和结构的复杂几何形状以及它们在服务载荷条件下经历的严重载荷，每年报告的工程结构中的过早灾难性失效的成本超过1500亿美元。与工程材料失效相关的安全问题和费用，需要通过开发可靠的疲劳损伤方法来实施针对材料失效的高度可靠性分析。 该研究建议提供了一个损伤耦合循环塑性模型，能够评估疲劳损伤和预测寿命的工程材料受到各种单轴和双轴载荷条件。所提出的模型将解决早期开发的损伤模型的缺点，包括负载比例，循环塑性，应变硬化和棘轮变形的影响，在疲劳应力循环与非零平均应力，这是最有影响力的因素，造成过早和灾难性的故障。 该研究的最终目标是建立一个准确可靠的疲劳损伤模型，用于预测工程构件和结构在恒幅和变幅单轴和双轴载荷条件下的疲劳寿命。该研究旨在发展基于疲劳损伤和变形物理学的模型，以现实地预测工程构件的疲劳寿命。申请人的长期研究计划将是进一步扩大材料在各种载荷谱、恶劣环境和高温下的损伤评估，在这些条件下，文献缺乏可靠的数据库，无法设计承受复杂载荷的工程部件和结构。申请人认为，本研究提案的结果将有助于制定该领域安全领先专业人员的设计指南和规范，以实现更安全、更可靠的承重部件和结构设计。这有利于加拿大工业和社会的安全和可靠的制造组件。

Fatigue is known to be the principal cause of failure in many engineering components and structures. The reported cost of premature catastrophic failure in engineering structures annually is in excess of $150 billion due to the complex geometry of components and structures and the sever loads they experience under service loading conditions. The safety issues and the expenses associated with failure of engineering materials, necessitate implementing a high degree of reliability analysis against failure of materials by developing a reliable fatigue damage approach. The research proposal offers a damage-coupled cyclic plasticity model capable of assessing fatigue damage and predicting life of engineering materials subjected to various uniaxial and biaxial loading conditions. The proposed model will address shortcomings of earlier developed damage models by involving the effects of load proportionality, cyclic plasticity, strain hardening, and ratcheting deformation over fatigue stress cycles with non-zero mean stresses which are most influential factors causing premature and catastrophic failures. The ultimate objective of the proposed research is to develop an accurate and reliable fatigue damage model to predict the fatigue life of engineering components and structures under constant and variable amplitude uniaxial and biaxial loading conditions. The proposed research is geared to developing the model based on physics of fatigue damage and deformation to predict fatigue lives of engineering components realistically. The applicant's long-term research plan will be to further expand the damage assessment of materials at various loading spectra, hostile environments and elevated temperatures at which the literature lacks reliable database for design of engineering components and structures subjected to complex loading. The applicant believes that the outcomes of this research proposal will contribute in developing design guidelines and codes of safety leading professionals in the field toward a safer and more reliable design of load-bearing components and structures. This benefits both Canadian industry and society with safe and reliable manufactured components.