Experimental determination of critical void volume fraction fF for the Gurson Tvergaard Needleman (GTN) model

Abstract The goal of the present study is the experimental determination of critical void volume fraction at the moment of failure (f F ) in the GTN model. The experiment involved static tensile tests of notched specimens. The notch geometry allowed to obtain low stress state triaxiality ratio in the notch center, equal to 0.516. Fracture surfaces of the specimens used in tensile tests were then observed with the use of scanning electron microscope (SEM). Photographs obtained by SEM were subjected to image analysis procedure in order to extract areas representing voids in the picture and calculate their surface fraction as the fragment of the whole picture. Therefore, the void surface fraction in the picture was identified with the f F parameter. The procedure described above allowed to obtain f F = 0.598. The GTN model and the obtained f F parameter were used for the numerical simulation of static tensile test, providing good convergence with the experimental data.