On the impact of pre-deformation on the fatigue performance of metallic laminates

预变形对金属层合板疲劳性能的影响

• 批准号: 461734789
• 负责人: Professor Dr.-Ing. Thomas Niendorf
• 金额: --
• 依托单位: Fachgebiet Metallische Werkstoffe
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/461734789?language=en
• 关键词: impact; pre; deformation; fatigue; performance

Due to their ability to combine opposing material properties, modern metallic multi-layer materials are able to outperform their monolithic counterparts. As a result, these metallic laminates are used in a variety of applications and have been in focus of various research studies for many years. Current progress in processing now allows to use hot-rolled metallic laminates in the automotive industry. The cost-effective sheet materials suitable for mass production with specifically adjustable, graded properties are very promising for numerous applications in this field. In order to ensure a reliable use of such materials, a profound understanding of their fatigue properties is needed. As components made from hot-rolled laminates are produced by forming and, thus, are subjected to pre-deformations during processing, the influence of pre-deformation is of particular importance in this context. However, analysis of the current state-of-the-art reveals that no systematic investigations on the fatigue properties of layered composites are available and that the influence of monotonic pre-deformations on the fatigue performance has not been addressed so far. Well-known factors significantly influencing the fatigue behavior are defect density and the residual stress state of a component. Regarding formation of residual stresses in roll-laminated composite materials and their evolution upon pre-deformation and under cyclic loading no comprehensive data can be found in open literature. In light of this lack of data the present project was designed. The fatigue behavior of a two-layer composite produced by hot rolling will be thoroughly investigated. The role of the individual layers of the composite as well as the boundary layer will be in focus. With respect to the envisaged fields of application of the two-layer composite material, the effects of pre-deformation on the microstructure development, defect density and distribution, the residual stress state and the fatigue behavior of the material will be investigated and an adequate model allowing to capture relevant relationships will be proposed. The analysis methods used in the project will allow for the evaluation of the influence of the surface and boundary layer on the fatigue behavior of the two-layer laminate material. In addition, the influence of targeted pre-deformations is investigated and modelled, thus, providing insights into whether the resulting residual stress states, defect densities and microstructural changes lead to superior or inferior fatigue performance.

由于它们能够联合收割机结合相反的材料特性，现代金属多层材料能够胜过它们的单片对应物。因此，这些金属层压板用于各种应用中，并且多年来一直是各种研究的焦点。目前的工艺进展允许在汽车工业中使用热轧金属层压板。适合大规模生产的具有特定可调分级性能的成本效益板材在该领域的众多应用中非常有前途。为了确保这些材料的可靠使用，需要对其疲劳特性有深刻的了解。由于由热轧层压板制成的部件通过成形来生产，并且因此在加工过程中经受预变形，因此预变形的影响在这种情况下特别重要。然而，目前的最先进的分析表明，没有系统的研究层状复合材料的疲劳性能是可用的，单调的预变形对疲劳性能的影响还没有得到解决。众所周知，显著影响疲劳行为的因素是缺陷密度和构件的残余应力状态。关于辊压复合材料中残余应力的形成及其在预变形和循环载荷下的演变，在公开文献中找不到全面的数据。鉴于缺乏数据，设计了本项目。将深入研究热轧生产的两层复合材料的疲劳行为。复合材料的各个层以及边界层的作用将是重点。关于两层复合材料的应用领域，将研究预变形对材料的微观结构发展、缺陷密度和分布、残余应力状态和疲劳行为的影响，并提出一个能够捕捉相关关系的适当模型。该项目中使用的分析方法将允许评估表面层和边界层对两层层压材料的疲劳行为的影响。此外，有针对性的预变形的影响进行调查和建模，从而提供洞察所产生的残余应力状态，缺陷密度和微观结构的变化是否导致上级或劣质的疲劳性能。