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都会发生变化，因此，该提案的目标是首先。模型链的时间开发表达了制造过程对循环负载下部件性能的影响。这种新开发的模型链可以用于或反对过程链方向，因此，可以实现该模型的总体目标。该项目的第一阶段（资金为现在要求）是在考虑所有制造工艺引起的材料机械性能变化的情况下，找到最适合指定部件疲劳性能的工艺参数。在项目的未来阶段，所需的部件性能将转化为所需的性能。原始材料在进入制造过程之前提供的微观结构配置基于这样的研究假设：给定部件的疲劳强度及其整体完整性由其关键点的实际微观结构决定。从制造前组件的初始状态实际上，用于在微观和宏观尺度上模拟制造工艺和组件性能的模型已经存在，这些方法将得到进一步开发，以便针对选定的演示示例进行定制。通过包括固体正向挤压（块状金属成形）和深轧（渐进成形）在内的工艺链形成。在项目过程中，WZL 将了解工艺参数与部件最终微观结构之间的相互依赖性。基于实验和计划中的工件材料在成形前以及工艺链各个步骤中的初始状态的综合表征将为微观机械建模和疲劳性能验证提供信息。通过微观建模和模拟的微观结构特征和部件疲劳特性将应用于整个制造过程的各个步骤，这些步骤是通过宏观模拟产生的边界条件来识别的。特别是，WZL 的数值定义载荷曲线的模拟将建立成型后残余应力的数据，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发展的信息。沿着流程链。