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.

疲劳机制的准确建模是在循环加载条件下安全设计的关键因素。但是，在大多数制造过程的过程中，材料的疲劳抗性发生了改变。因此，该提案的目的是首次开发一系列模型，该链表达了制造过程对循环负载下组件性能的影响。这个新开发的模型链可用于过程链方向。结果，项目的第一阶段的总体目标（现在要求资金）是为了考虑所有制造过程引起的机械性能变化的定义组件疲劳性能的最佳合适过程参数。在项目的未来阶段，所需的组件性能将被转化为所需的微观结构配置，并在进入制造过程之前由维珍材料提供。该研究提案基于研究假设，即给定组件的疲劳强度及其整体完整性受其关键点的实际微观结构的控制。实际的微观结构是由在制造和运营阶段制造和进化之前的组件的初始状态产生的。实际上，模型已经存在用于模拟微型和宏观尺度上的制造过程和组件性能。这些方法将进一步开发，以便为选定的演示者示例定制它们，该示例将通过过程链形成，包括固体正向扩展（散装金属形成）和深滚动（增量形成）。在项目的过程中，WZL将根据实验和相应的宏观模型获得过程参数与所得的组件的相互依赖性知识。在成型之前和过程链的各个步骤中，计划的工作场所材料的计划综合表征将提供微机械建模和疲劳性能验证的信息。 IEHK的贡献将集中在微观结构特征和组件疲劳性能之间通过微模型和模拟进行桥接。在制造过程的整个各个步骤中，将采用对微观结构敏感的疲劳建模方法，这是由WZL执行的宏观模拟引起的边界条件确定的。特别是，使用数值定义的WZL加载曲线的仿真将在形成后建立有关残余应力的数据。在循环张力压缩条件下，对微结构敏感的疲劳模拟将提供有关如何沿过程链的组件发展的疲劳强度的信息。