Investigation of the formability of ductile sheet materials under non-proportional loading with consideration of the anisotropic damage behaviour

考虑各向异性损伤行为的非比例载荷下延性板材的可成形性研究

• 批准号: 455960756
• 负责人: Professor Dr.-Ing. Michael Brünig
• 金额: --
• 依托单位: Institut für Mechanik und Statik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2021
• 资助国家: 德国
• 起止时间: 2020-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/455960756?language=en
• 关键词: Investigation; formability; ductile; sheet; materials

The determination of the formability of sheet materials is an important step in the design of sheet metal components. Since complex components have a non-linear deformation history, a description by means of a linear limit shape change curve is not sufficient because the remaining formability as well as the failure mode significantly depend on the deformation history. Within the framework of this research project, it should be possible to predict the deformability after non-proportional loading paths with a change in the loading direction. For this purpose, two materials, AA6xxx and DP600, are systematically investigated in order to obtain their forming capability and the failure mode after a complex deformation history. With the help of numerical simulations, a damage model is created, which isintended to map the deformation and failure behavior of these materials and thus enables a numerical analysis of the materialbehavior. The main goals of the research project include: • Identification of the influence of the forming history, the loading direction as well as the stress state on the formability and themechanical parameters of the selected materials. • Systematic differentiation and detection method for distinguishing between ductile failure and shear failure with adaptation of the time-dependent evaluation method. • Deriving a critical ratio between the pre-strain and a load direction change, from which on a shear failure occurs instead of necking which leads to a consequent loss of formability. • Determining the influence of a relieving step and the associated relaxation of the material between the forming operations on thefailure pattern.• The non-linear texture development has a significant influence on the formation of micropores. This effect, which has not yet been investigated, is to be examined in more detail within the scope of this project.

板料成形性的确定是板料零件设计中的一个重要步骤。由于复杂的部件具有非线性的变形历史，通过线性极限形状变化曲线的描述是不够的，因为剩余的可成形性以及失效模式显著地依赖于变形历史。在这个研究项目的框架内，它应该是可以预测的变形后，非比例加载路径与加载方向的变化。为此，两种材料，AA6xxx和DP600，进行了系统的研究，以获得其成形能力和一个复杂的变形历史后的失效模式。在数值模拟的帮助下，建立了损伤模型，该模型旨在映射这些材料的变形和破坏行为，从而能够对材料行为进行数值分析。该研究项目的主要目标包括：·确定成形历史、加载方向以及应力状态对所选材料的成形性和力学参数的影响。·用于区分延性破坏和剪切破坏的系统化区分和检测方法，并采用时间相关评估方法。·推导出预应变和载荷方向变化之间的临界比率，由此发生剪切破坏而不是颈缩，颈缩导致随后的可成形性损失。·确定卸荷步骤和成形操作之间材料的相关松弛对失效模式的影响。·非线性织构发展对微孔的形成有重要影响。这一影响尚未得到调查，将在本项目范围内进行更详细的研究。