Characterization and evaluation of yield loci and subsequent yield loci considering isotropic-kinematic hardening
Third party funded individual grant
Start date : 01.01.2007
End date : 10.02.2015
Project details
Short description
The goal of this fundamental research project PAK250 funded by the German Research Foundation (DFG) is the determination and description of material behavior and the identification of the analytical models and the contained parameters to enhance the existing prospects of the process analysis and the planning methods with the help of a finite element analysis (FEA). The research work of the second period builds on the fundamental investigations of the first phase of the project. The focus of this second phase is based on the description of the isotropic-kinematic hardening behavior, especially on the characterization of the Bauschinger effect and the impact of pre-straining on the beginning of plastic yielding. The core intention of this research work is a significant increase of the result quality of numerically designed, complex forming processes by means of improved modeling.
Scientific Abstract
Übersetzungsergebnisse
When using the numerical analysis of forming processes, the influence of the material model used is of fundamental importance. In terms of accuracy, both the selected yield law and its development as a function of the degree of deformation play an important role in the calculation. Especially in the case of non-linear strain paths, the kinematic hardening becomes more important with regard to the shape of the subsequent yield locus. Within the scope of this project, the isotropic-kinematic hardening behavior should be the focus of the experimental and analytical investigations and various approaches to hardening models should be scientifically analyzed and evaluated. By extending and expanding the test rig to determine the start of yielding, tensile tests with cruciform specimen are carried out in order to be able to set defined non-linear load paths for the determination of subsequent yield loci. In addition, the Bauschinger coefficient, which is crucial for modeling of the kinematic hardening behavior, is determined through tests with alternating loads. These experimentally determined data are evaluated and qualified with the implemented isotropic-kinematic hardening models. As a result, a test methodology is developed that enables the best possible modeling with minimal experimental effort at the same time.