Project in the Field of Research
Numerical Modeling and Process Design
SFB TRR 188: Influencing the damage evolution in deep drawing - Project A06
The production of three-dimensional parts by means of deep drawing uses flat metal sheets, which are cut out of continuous coil bands. Due to the production of these coil, local materials inhomogeneities as anisotropy, micropores, etc. appear. These material properties, especially micropores and lattice defects, affect the parts properties evolving in the following forming process (in this case deep drawing) causing damage in form of a growing of micropores or an anisotrope elongation. Depending on the process variation varying process loads are applied, which lead to a different damage evaluation. The damage in a specific material location depends on the process loads and can be determined by means of damage criteria and models. The results of theses models are still uncertain in favor of the localization and value of the maximum damage. Furthermore, the interactions between the pre-damage evolved in an earlier forming process and damage induced by the deep drawing process are unknown.
The aim of this project is the quantitative description and prediction of the interaction between the pre-damage evolved in an earlier forming process and the process parameters of deep drawing as well as the control of a further damage evolution by a tailored process route. The hypotheses of the research project is, that by means of a multiple staged process route in deep drawing, different load paths can be set. Whilst the principal geometry and end geometry are not changed, and a damage controlled blanking process is applied. The course of action is based on three design steps: In the first step, the influence of conventional deep drawing parameters (e.g. drawing ratio, punch velocity, blank holder force, friction, drawing radius,…) on the load path are analyzed. Specimens for material characterization are extracted from the lower and middle frame, the flange area, and the transition area from flange to frame and frame to base. These areas are known as critical locations where damage occurs and should be interpreted as interaction points of a pre-damage and further damage evolution. In the second step, a process extension by means of multiple staged deep drawing as well as deep drawing with counter pressure and the influence of this process extension on the stress variation of the load path and the different workpiece areas is investigated. The third step includes the observation of the forming history and the influence on the load path. The experimental investigations are supported by numerical analysis to distinguish and evaluate the load path more detailed.
The findings of this research project enable a damage reduction in automotive parts in dependency of the load paths. The damage reduction can be used as a safety reserve as well as for a reduction of the part’s mass, which also favors the trend to lightweight parts.
The project partners thank the German Research Foundation (DFG) for supporting the presented research project Influencing the damage evolution in deep drawing.
Do you have questions concerning this project?
Matthias Nick, M.Sc. RWTH
Cluster Produktionstechnik 3A 332
Tel.: +49 241 80-24978
Fax: +49 241 80-628213