Issue 36

Lj. L. Vulićević et alii, Frattura ed Integrità Strutturale, 36 (2016) 46-54; DOI: 10.3221/IGF-ESIS.36.05 48 The initial crack length used in the analysis was 2 mm. The growing crack was incremented at steps of 0.16 mm (chosen by the software) and 28 steps were performed. The first step in 3D analysis using XFEM was crack “opening” (Fig. 2). In this step stresses in the specimen are obtained, as well as stress intensity factors (SIFs) at the crack tip. Based on that, Morfeo/Crack for Abaqus, computes the SIFs for mode I, II and III, for every step of the crack propagation, and the corresponding crack growth. Fig. 2 shows crack at beginning (1 st step- crack opening), Fig. 3, after 8 th step, while Fig. 4 shows the crack after the 27 th step. Figure 2 : Step one - crack opening and Von Mises stresses at crack tip. Figure 3 : Crack length after 8 th step. Figure 4 : Crack length after 27 th step. The SIF values at the crack tip determine the appropriate crack growth increment. This procedure was performed in 28 steps in order to simulate incremental crack growth. Values obtained in Abaqus for the 16 th crack growth step are shown in Tab. 1, indicating SIF values K eq , K I , K II , and K III ) in the last four columns. As expected, crack growth was characterized by K I , since values of K II and K III are negligible. Therefore, data for all crack growth steps is given only for