Formability prediction for AHSS materials using damage models

6th International Conference on Fracture Fatigue and Wear

Amaral, R.^1 ; Santos, Abel D.^2 ; José, César De Sá^2 ; Miranda, Sara^1

Institute of Science and Innovation in Mechanical and Industrial Engineering, Rua Dr. Roberto Frias, Porto

4200-465, Portugal^1

Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias 400, Porto

4200-465, Portugal^2

关键词: Advanced high strength steel;    Comparative analysis;    Damage mechanics approach;    Ductile damage models;    Forming limit diagrams;    Greenhouse gases emissions;    Numerical predictions;    Phenomenological models;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/843/1/012018/pdf
DOI  :  10.1088/1742-6596/843/1/012018

来源: IOP

【 摘 要 】

Advanced high strength steels (AHSS) are seeing an increased use, mostly due to lightweight design in automobile industry and strict regulations on safety and greenhouse gases emissions. However, the use of these materials, characterized by a high strength to weight ratio, stiffness and high work hardening at early stages of plastic deformation, have imposed many challenges in sheet metal industry, mainly their low formability and different behaviour, when compared to traditional steels, which may represent a defying task, both to obtain a successful component and also when using numerical simulation to predict material behaviour and its fracture limits. Although numerical prediction of critical strains in sheet metal forming processes is still very often based on the classic forming limit diagrams, alternative approaches can use damage models, which are based on stress states to predict failure during the forming process and they can be classified as empirical, physics based and phenomenological models. In the present paper a comparative analysis of different ductile damage models is carried out, in order numerically evaluate two isotropic coupled damage models proposed by Johnson-Cook and Gurson-Tvergaard-Needleman (GTN), each of them corresponding to the first two previous group classification. Finite element analysis is used considering these damage mechanics approaches and the obtained results are compared with experimental Nakajima tests, thus being possible to evaluate and validate the ability to predict damage and formability limits for previous defined approaches.