Experimental and Numerical Investigation of the Gurson–Tveergard–Needleman Model Parameters for AISI 1045 Steel

Herein, the determination and verification of the Gurson–Tveergard–Needleman (GTN) damage model parameters are studied. AISI 1045 steel is examined in two conditions, as-received and normalized, showing Luders strain. Experimental and numerical methods are used to obtain and verify the parameters. Instead of using advanced experimental techniques, the experimental part of the parameter identification is employed by utilizing tensile tests and density measurements. Scanning electron microscopy micrographs of the nondeformed material surface and rupture surface of tensile specimens are examined to identify the initial void volume fraction (f₀) and nucleated volume void fraction (f_N) at the rupture. The critical (f_c) and final (f_f) void volume fractions are employed with density measurements of tensile test specimen sections. Thus, all six different GTN parameters are determined experimentally with the usual techniques. Parameter verifications are done by finite element (FE) simulations compared with tensile test results. As a result, GTN model parameters are indicated. The difference between the parameters belonging to the case of having Luders strain and not for the same material is revealed. Furthermore, a series of FE simulations are executed to clarify the effects of the parameters on the deformation characteristics of materials.