Issue 37

J. Vázquez et alii, Frattura ed Integrità Strutturale, 37 (2016) 38-45; DOI: 10.3221/IGF-ESIS.37.06 42 Figure 5 : Scheme for first crack initiation procedure. Figure 6 : Crack paths predicted with the first procedure. It is worthwhile pointing out that in the analysis using the FS parameter, and at the trailing edge, two possible critical planes appear, i.e., two planes producing the same maximum value for the parameter. One critical plane points towards the region beneath the contact zone (path 1) and the other outside (path 2), Fig 6b. The path considering the first critical plane (path 1) rapidly and abruptly rotates and follows a path nearly identical to that pointing towards the region outside the contact zone (path 2). According to this, it is virtually irrelevant whether one or the other initial critical plane is considered. Figure 7 : Contour plots for the FS and SWT parameters. Second Crack Initiation Analysis Procedure This procedure only shows the zones with a higher level of damage and gives a hint of the crack initiation path. Fig. 7 shows, in addition to the paths of Fig. 6 and the experimental cracks, the contours plot obtained using both fatigue parameters. Regarding the FS parameter contour plot, it is clear that the most likely area for crack initiation is that beneath the contact, and the reasoning for this fact is clear, this area presents, in terms of the parameter value, a lower gradient than the region that is not beneath the contact zone. Therefore, beneath the contact any possible crack initiation path presents higher mean values of the FS parameter than a crack path growing outside the region beneath the contact zone.