PSI - Issue 2_B

Jaime Planas et al. / Procedia Structural Integrity 2 (2016) 3676–3683 J. Planas et al. / Structural Integrity Procedia 00 (2016) 000–000

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Fig. 6. Evolution of crack pattern at the bottom line of the beam, for the finer mesh (left) and for the coarser mesh (right).

Figure 6 summarizes the evolution of the crack pattern along the pre-peak and near post-peak region. Vertical and horizontal rulers are provided to facilitate the estimation of crack lengths and of their position. On the left, a series of overlapping images of the the bottom-center of the specimen are displayed for the finer mesh. The series shows that noticeable cracking appears at step 10 in a shallow, roughly parabolic area that deepens and widens progressively up to step 14 while the cracks become simultaneously sparser. In step 15, a crack is singled out while the others still remain but with an opening much less than the singular crack. In step 16 a second dominant crack appears on the left, which gains dominance in the following steps up to step 24, in the post-peak region, where all the remaining preexisting cracks have very small openings compared to the main crack, which continues to grow in solitary. Note that, at each step, the dark red color marks the element(s) with the widest crack opening, and the elements with no crack or zero crack opening are drawn in dark blue. The central inset in the figure shows the position of each step on the load displacement curve. On the right, a similar set of images is shown for the coarser mesh. The resolution is, obviously, much less, but the sequence of cracking follows closely the same pattern and indicates that the crack pattern is also free of spurious mesh sensitivity.