Experimental and numerical analysis of forming-induced residual stresses for fatigue strength increase of highly cyclically loaded high-purity copper components

成形引起的残余应力可提高高循环载荷高纯度铜部件的疲劳强度的实验和数值分析

• 批准号: 531874972
• 负责人: Professor Dr.-Ing. Alexander Brosius
• 金额: --
• 依托单位: Professur für Formgebende Fertigungsverfahren
• 依托单位国家: 德国
• 项目类别: Research Grants (Transfer Project)
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/531874972?language=en
• 关键词: Experimental; numerical; analysis; forming; induced

With respect to the transformation of transportation and energy policy and the resulting increased usage of electric traction drives and generators, the question of the fatigue behavior of high-purity copper components, which serve as parts for power transmission in the highly cyclically loaded powertrain of battery electric vehicles, for example, is becoming the focus of current research. The multi-stage forming process of the components results in complex and interacting influences on their fatigue life. In particular, the influence of forming induced residual stresses has not been considered to date and, analogous to the utilization in steel components, could have high potential for component improvements. The objective of the project is the application and the transfer of methodological knowledge developed for steel components in the SPP on the use of forming-induced residual stresses for the improvement of fatigue life to components made of high-purity copper. The focus is on the establishment of generalized process-structure-property linkages taking residual stresses into account. A conductor rail produced by bending is used as an example for the investigation. Its service life is to be improved by inducing compressive residual stresses. For this purpose, an additional process step during manufacturing is planned. In addition to the influence on residual stresses, the overall process causes a change in the local material state. This makes it necessary to consider the influence of residual stresses, local hardening and the process-related microstructure on fatigue life. By implementing a targeted, cyclic material characterization, the investigation of defined material states under the influence of residual stresses is carried out. The forming of the reference component is mapped virtually with the aid of suitable process modeling. Using the process model, the process is optimized with a residual compressive stress distribution at the failure-critical point as the target. Accompanying residual stress measurements are used to validate the model. Subsequently, experimental component characterization of selected process variants is carried out to determine the influence of the process variants on the service life. Based on the compiled virtual and experimental data, a computational fatigue life evaluation is developed considering process-related residual stresses and local material state. At the end of the knowledge transfer project, elaborated process-structure-property linkages are available as a basis of the performed process design for lifetime improvement of high-purity copper components. Through the extensive experiments on residual stress influence for different material states, transferable knowledge is developed, which expands the data base for copper materials.

随着交通和能源政策的转变以及由此导致的电力牵引驱动装置和发电机使用量的增加，高纯度铜部件的疲劳行为问题正在成为当前研究的焦点，例如，高纯度铜部件在电池电动汽车的高循环负载动力系统中用作动力传输部件。零件的多阶段成形过程对其疲劳寿命产生复杂的相互影响。特别是，成形诱导的残余应力的影响迄今尚未被考虑，并且类似于在钢部件中的利用，可能具有部件改进的高潜力。该项目的目标是应用和转让SPP中为钢部件开发的关于使用成形引起的残余应力来提高高纯度铜部件疲劳寿命的方法知识。重点是建立广义的工艺-结构-性能的联系，考虑到残余应力。并以弯曲法生产的导电轨为例进行了分析。通过诱导残余压应力来提高其使用寿命。为此，计划在生产过程中增加一个工艺步骤。除了对残余应力的影响外，整个过程还导致局部材料状态的变化。这使得有必要考虑残余应力、局部硬化和与工艺相关的显微组织对疲劳寿命的影响。通过实施有针对性的循环材料表征，可以在残余应力的影响下对定义的材料状态进行研究。参考部件的形成借助于适当的工艺建模虚拟地映射。利用该工艺模型，以失效临界点处的残余压应力分布为目标进行了工艺优化。伴随的残余应力测量用于验证模型。随后，对选定的工艺变量进行实验部件表征，以确定工艺变量对使用寿命的影响。基于编制的虚拟和实验数据，计算疲劳寿命评估开发考虑工艺相关的残余应力和局部材料状态。在知识转移项目结束时，详细的工艺-结构-性能联系可作为高纯度铜部件寿命改进的工艺设计的基础。通过对不同材料状态下残余应力影响的大量实验，开发了可传递的知识，扩展了铜材料的数据库。