Under the guiding principle that damage is not a failure, a fundamental understanding of the damage mechanisms involved in the forming process and their effects on product properties is investigated within TRR 188. The interdisciplinary scientific consortium consisting of forming technology, materials science, material testing technology, and mechanics aims for two paradigm shifts: The goal in forming technology is to shift from "formability" to "usability" of the products. When designing the products, the use of the actual product properties after forming should be taken into account rather than the nominal ones. In the long term, the TRR 188 aims to quantify the degree of damage of a component, control it, and specifically adjust it along the process chain. This lays the foundation for the development of a new generation of tailor-made, high-performance lightweight products that are reliable during use. Forming processes induce damage in manufactured metallic components due to their extensive plastic deformations and stress states. At the same time, quantifying and controlling this damage formation is of paramount importance to ensure component performance over their service life. To support this, TRR 188 has developed numerical models to quantify damage a priori. This enables informed manufacturing process decisions; moreover, local output responses such as stress triaxiality η, Lode angle ϑ, and damage D can be calculated. The calculation of such responses entails solving highly complex non-linear finite element analyses. Based on the calculated output responses, it is possible to make decisions; that is, selecting parameters of the forming process such that, e.g., damage remains below an acceptable threshold. However, in practice it is difficult to identify precise values for these aforementioned input quantities due to both inherent part-to-part variations as well as potential lack of knowledge on the exact to-be modeled quantities. As parameters governing the forming process become uncertain, studying the effects of uncertainty on forming processes for decision-making becomes vital. Thus, the process of selecting optimal metal forming parameters, material properties, and part design becomes inevitably more involved.

The CRE participates in the TRR 188 within Project C06, Damage Optimization of Bulk Metal Forming Processes under Uncertainty, which aims to optimize the mechanical performance of metal-formed parts through the robust design optimization of the manufacturing process to control and minimize damage and its variability. To this end, state-of-the-art methods to quantify, propagate and optimize under uncertainty will be developed, implemented, and validated. Specific focus is placed on uncertainties in constitutive mechanical model parameters, geometrical parameters, and manufacturing condition parameters. Accordingly, the research is structured into three key elements: (1) uncertainty characterization, (2) uncertainty propagation and (3) decision-making.

Link to the TRR 188 website