Targeted creation of residual stresses by forming of local structures in sheet thickness direction via an embossing process to improve component performance

研究项目的总体目标是开发薄壁钣金件残余应力定向产生的成形工艺路线。成形诱导RS旨在提高主要受动载荷的金属薄板结构部件的疲劳强度。在项目范围内，在i和II期间进行了演示。通过结合成型和压印工艺，可以在薄壁金属板部件中产生残余压应力，从而持续提高部件的循环运行强度。本研究项目的特别重点将放在粗相多相材料（双相钢x2crni -23-4）的形成上。特别是，将系统地评估相控微rs的贡献。在此背景下，一方面，材料分析领域发展了局部RS分析的测量和评价策略。另一方面，本文建立了基于机理的RS模型。ⅲ。采用数值上有效的平均场方法，为两相微观结构中RS的双尺度建模提供了可能。这些实验和数值研究的结果最终导致了薄壁结构部件的组合制造工艺的发展，其中压缩RS通过将成形操作与同时压花和随后的重整相结合，以有针对性的方式诱导。这些局部RS抵消了组件在运行时的拉伸载荷应力。第三个资助期的目的是将在前两个资助期获得的关于RS的产生、分析、稳定性和模拟的知识转移到一个循环加载的实际组件上，特别是一个抽象的载体板。这包括刀具概念的整体数值设计及其制造实现。在资助期I和II中制定的测量、评估和模拟策略考虑到在所有尺度（I至III）上最精确地确定载体板中的诱导RS。类)。对于RS在所有尺度上的模拟和实验分析，在即将到来的资助期内，重点将放在晶体结构上。除了考虑跨板厚的织构梯度外，还将通过数值和实验研究变形驱动的织构演化的影响。在项目中开发的RS模拟和分析方法将在所有规模上进行验证，并在跨项目基准中进一步应用。该研究项目作为IFU、斯图加特大学、IAM-WK和卡尔斯鲁厄理工学院（KIT） ITM-KM的联合项目，在2013年优先计划提案征集框架内进行。

The general objective of the research project is to develop a forming process route for the targeted generation of residual stresses (RS) into thin-walled sheet metal components. The forming-induced RS is intended to improve the fatigue strength of structural components made of sheet metal that are predominantly subjected to dynamic loads. Within the scope of the project, it was demonstrated during the I. and II. funding period that by combining a form-ing and embossing process, compressive residual stresses can be generated in a thin-walled sheet metal component, which sustainably increase the cyclic operational strength of the component. A particular focus of this research project will be on the forming of coarse multiphase materi-als (duplex steel X2CrNiN-23-4). In particular, the contribution of phase-specific micro-RS will be systematically evaluated. In this context, on the one hand, measurement and evaluation strategies for local RS analyses are developed in the field of materials analysis. On the other hand, the mechanism-based modeling of RS of the I., II. and III. kind by means of numerically efficient mean-field approaches offers the possibility of two-scale modeling of RS in two-phase microstructures. The findings from these experimental and numerical investigations finally lead to the development of a combined manufacturing process for a thin-walled struc-tural component, into which compression RS are induced in a targeted manner by combining a forming operation with simultaneous embossing and subsequent reforming. These local RS counteract the tensile load stresses that act when the components are in operation.The aim of funding period III is to transfer the knowledge gained in the previous two funding periods with regard to the generation, analysis, stability and simulation of RS onto a cyclically loaded real component, in particular an abstracted carrier plate. This includes the holistic nu-merical design of the tool concept and its manufacturing implementation. The measurement, evaluation and simulation strategies developed in funding periods I and II are considered with regard to the most exact possible determination of the induced RS in the carrier plate on all scales (I. to III. kind). For the simulation and experimental analysis of RS on all scales, the focus in the upcoming funding period will be on crystallographic texture. In addition to consid-ering the texture gradient across sheet thickness, the influence of deformation-driven texture evolution will be investigated numerically and experimentally. The methods for simulation and analysis of RS developed in the project will be validated on all scales and additionally applied within cross-project benchmarks.The research project is carried out as a joint project between the IFU, University of Stuttgart, the IAM-WK and the ITM-KM of the Karlsruhe Institute of Technology (KIT) within the frame-work of the call for proposals of the Priority Program 2013.