Influence of the multi-axial Bauschinger effet in cold forging

多轴鲍辛格效应对冷锻的影响

• 批准号: 418815343
• 负责人: Professor Dr.-Ing. A. Erman Tekkaya
• 金额: --
• 依托单位: Institut für Umformtechnik und Leichtbau (IUL)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/418815343?language=en
• 关键词: Influence; multi; axial; Bauschinger; effet

Usually the Bauschinger effect is not considered in the simulation of cold forging processes. Consequently, the significant reduction of the initial yield stress, as well as the permanent softening effect of cold forged materials caused by a change of sign of the acting stresses are not taken into account. Neglecting these effects leads to a flawed numerical prediction of local product properties, residual stresses as well as process forces. Preliminary studies show, that – for the first time – the cyclic plastic behaviour of cold forged materials can be captured systematically under cold forging conditions. Such conditions include large strains, which cannot be reached by means of conventional material testing methods. By the application of tensile and compressive tests on prestrained specimens, the complete region of relevant strains can be covered. The new insights into the material behaviour allow for a use of constitutive models that are so far only used in the field of sheet metal forming simulation. In this field, the models lead to an improvement of spring-back prediction. In bulk forming operations large regions of material undergo cyclic deformation, by which the Bauschinger effect becomes active. The consideration of the Bauschinger effect becomes even more important, when multi-staged forming operations are simulated. By use of combined hardening models a drastic improvement of simulation results can be expected, which could already be proven for selected materials.Ultimately, the improved numerical prediction of local product properties, residual stresses and process forces lead to a cut of time and cost-consuming component tests, potentials for lightweight design can be exploited more thoroughly and tool life can be prolonged.

通常，在模拟冷宽恕过程中不考虑鲍申格效应。因此，没有考虑到由作用应力的变化引起的最初屈服应力的显着减少以及冷遗忘材料的永久软化作用。忽略这些效果会导致局部产品特性，残余应力和过程力的数值预测有缺陷。初步研究表明，第一次可以在冷原谅的条件下系统地捕获冷遗忘材料的循环塑料行为。这种情况包括大型菌株，这些菌株无法通过常规的材料测试方法来达到。通过在预校试样上应用拉伸和压缩测试，可以涵盖相关菌株的完整区域。对材料行为的新见解允许使用迄今仅在金属形成模拟领域中使用的本构模型。在该领域，这些模型会改善弹簧预测。在散装作业中，大的材料区域会经历循环变形，鲍申格效应变得活跃。当模拟多阶段的形成操作时，对Bauschinger效应的考虑变得更加重要。通过使用组合硬化模型，可以预期仿真结果的急剧改善，这已经可以证明对选定的材料进行证明。截然，改善了当地产品属性的数值预测，残余压力和过程力量会导致时间和成本累积的组件测试，可以更彻底地探索轻量级设计的潜力，并且可以更彻底地探索工具寿命。