Evaluation of shear mechanisms and influence of the calibration point on the numerical results of the GTN model

• Type: Article in International Scientific Journal
• Date: 2013

Authors

malcher, l (Author) Other; reis, fjp (Author) Other; pires, fma (Author) Other; de sa, jmac (Author) FEUP

Journal

Title: International Journal of Mechanical Sciences

Vol. 75

Pages: 407-422

ISSN: 0020-7403

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 9 Citations

Scopus - 14 Citations

Other information

Authenticus ID: P-006-JVK

DOI: 10.1016/j.ijmecsci.2013.08.008

Abstract (EN): In this contribution, a numerical comparative study is undertaken based on Gurson-Tvergaard-Needleman (GTN) original model and two recent enhancements that include shear mechanisms, employing two different strategies to calibrate the material parameters. The assessment is motivated by the fact that the accuracy of the numerical results obtained with coupled damage models are strongly dependent on the calibration point. Hence, the numerical results obtained with these models are more realistic and in agreement with the experimental evidence when the external loading conditions are close to the calibration point. Two distinct shear mechanisms, proposed by Xue and Nahshon and Hutchison, were selected and added into damage variable of GTN model, in order to allow the prediction of crack formation when predominant shear loading conditions are present. In the first part of this study, mathematical formulations for shear mechanisms are presented as well as the GTN original model. In addition, the numerical strategy followed in this work is described, based on an implicit quasi-static finite element framework. In the following, a specimen under high and other under low stress triaxiality are used as calibration points and by using an inverse method, the material parameters are identified. Regarding the performance of the numerical results and its dependence with the calibration point, numerical tests are carried out for a set of loading conditions, such as: pure shear, combinations of shear/tensile and pure tensile conditions. These simulations were conducted assuming first, the material parameters obtained by the first calibration point and then, using the properties which resulted from the second calibration point. Both numerical results are compared with experimental data, regarding the ability to predict the correct fracture location and the determination of the correct displacement at fracture.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 16