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.

通常在冷锻过程的模拟中不考虑鲍辛格效应，不考虑初始屈服应力的显着降低，以及由于作用应力符号的变化而引起的冷锻材料的永久软化效应。忽略这些影响会导致对局部产品特性、残余应力以及加工力进行有风味的数值预测，这是首次可以系统地捕获冷锻材料的循环塑性行为。锻造这些条件包括传统材料测试方法无法达到的大应变，通过对预应变样本进行拉伸和压缩测试，可以覆盖相关应变的完整区域，从而获得对材料行为的新见解。迄今为止仅用于金属板材成形模拟领域的本构模型的使用，在该领域中，该模型改进了大块材料成形操作中经历循环变形的回弹预测。包辛格效应变为当模拟多阶段成形操作时，包辛格效应的考虑将变得更加重要，预计模拟结果将得到显着改善，这已经针对选定的材料得到了证明。改进的局部产品特性、残余应力和加工力的数值预测可以缩短部件测试的时间和成本，可以更彻底地开发轻量化设计的潜力，并可以延长刀具寿命。