Microstructure-sensitive fatigue lifetime assessment considering forming history effects

考虑成形历史影响的微观结构敏感疲劳寿命评估

• 批准号: 432053466
• 负责人: Professor Dr.-Ing. Thomas Bergs
• 金额: --
• 依托单位: Werkzeugmaschinenlabor - WZL
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/432053466?language=en
• 关键词: Microstructure; sensitive; fatigue; lifetime; assessment

The accurate modelling of fatigue mechanisms is a key factor for the safe design of components under cyclic loading conditions. However, the fatigue resistance of a material is altered in the course of most manufacturing processes. Therefore, the aim of the proposal is a first-time development of a chain of models which expresses the influence of manufacturing processes on the performance of a component under cyclic loads. This newly-developed model chain can be used in and against the process chain direction. As a consequence, the overarching objective of the first phase of the project (for which the funding is now requested) is to find the best suited process parameters for a defined component fatigue performance under consideration of all manufacturing process-induced changes of the material’s mechanical properties. In the future phase of the project, the desired component performance will be translated into a required microstructural configuration to be provided by the virgin material before it enters the manufacturing process. The research proposal is based on the research hypothesis that the fatigue strength of a given component and its overall integrity is governed by the actual microstructure at its critical points. The actual microstructure results from the initial state of the component before manufacturing and evolves during manufacturing and operation stages. Actually, models are already existing for the simulation of manufacturing processes and component performance on the micro and the macro scales. These approaches will be further developed in order to tailor them for the selected demonstrator example, which will be formed by means of a process chain including solid forward extrusion (bulk metal forming) and deep rolling (incremental forming). In the course of the project, WZL will gain knowledge on the interdependencies between the process parameters and the resulting microstructure of the component based on experiments and corresponding macro-modelling. The planned comprehensive characterization of the workpiece material in initial state before forming as well as during the individual steps of the process chain will give the information for micromechanical modelling and fatigue properties validation. The contribution of IEHK will focus on bridging between the microstructural features and component fatigue properties by means of micro-modelling and simulations. Microstructure-sensitive fatigue modelling approaches will be applied throughout the individual steps of the manufacturing process, which are identified by boundary conditions resulting from macro-simulations performed by WZL. In particular, the simulations with the numerically defined loading profiles of WZL will establish the data on residual stresses after forming. The microstructure-sensitive fatigue simulations under cyclic tension-compression conditions will give the information on how the fatigue strength of the component develops along the process chain.

疲劳机制的精确建模是循环载荷条件下部件安全设计的关键因素。然而，材料的抗疲劳性在大多数制造过程中会发生变化。因此，该提案的目的是首次开发一系列模型，这些模型表达了制造工艺对循环载荷下组件性能的影响。这种新开发的模型链可以在流程链方向上使用，也可以在流程链方向上使用。因此，该项目第一阶段的首要目标（现已申请供资）是在考虑到所有制造工艺引起的材料机械性能变化的情况下，为确定的部件疲劳性能找到最合适的工艺参数。在项目的未来阶段，所需的组件性能将转化为所需的微观结构配置，由原始材料在进入制造过程之前提供。该研究提案基于这样的研究假设，即给定部件的疲劳强度及其整体完整性由其临界点处的实际微观结构决定。实际微观结构产生于制造前的部件初始状态，并在制造和操作阶段演变。实际上，模型已经存在于微观和宏观尺度上的制造过程和部件性能的模拟中。这些方法将进一步发展，以适应选定的示范例子，这将是通过一个过程链，包括固体前向挤压（块体金属成形）和深轧制（增量成形）形成。在项目过程中，WZL将根据实验和相应的宏观建模，获得有关工艺参数与部件微观结构之间相互依赖性的知识。在成形前的初始状态以及工艺链的各个步骤中，工件材料的计划综合表征将为微观力学建模和疲劳性能验证提供信息。IEHK的贡献将侧重于通过微观建模和模拟在微观结构特征和部件疲劳性能之间建立桥梁。微观结构敏感疲劳建模方法将应用于整个制造过程的各个步骤，这些步骤通过WZL进行的宏观模拟产生的边界条件进行识别。特别是，WZL的数值定义的加载曲线的模拟将建立成形后的残余应力的数据。循环拉伸-压缩条件下的微观结构敏感疲劳模拟将提供有关部件疲劳强度如何沿工艺链沿着发展的信息。