PSI - Issue 42

Vítor M. G. Gomes et al. / Procedia Structural Integrity 42 (2022) 1552–1559 V.M.G. Gomes et al. / Structural Integrity Procedia 00 (2019) 000–000

1558

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= 75.0 mm, = 0.0 mm)

= 90.0 mm, = 20.0 mm)

Central Geometrical Notch (z ≈ 0.0 mm) Middle Zone (100.0 < z < 350.0 mm) End Zone (z > 350.0 mm) Fig. 4. A - The surface profile of the maximum variance of the resolved shear stress for two loading scenario in analysis along the length of top surface of master leaf spring; B - fatigue Fracture surfaces’ characteristic for di ff erent potential regions to fatigue failure. highest maximum variance are those located in the geometric notches zone. At this location, the maximum variance surface profile tends to have a symmetrical behaviour across the width. In the case of scenario 2, the low randomness of the vertical and lateral displacements gives rise to a surface profile where it is visible that the critical points are perfectly associated with the most extreme nodes in the middle area of the leaf, a position whose the fibers are more subjected to the e ff ects of lateral bending. The length coordinate value range is also between 100 to 350 mm. After 350 mm, the maximum variance surface profile tends to be symmetrical in width. Evaluating the overlapping zone by the spring buckle, the more extreme lateral zones tend to have a higher value of the maximum variance of the resolved shear stress, still noting the e ff ect of the geometric notch, although not very evident. By comparatively analysing the surface profiles of the maximum variance of the resolved shear stress of scenarios 1 and 2, it is possible to establish that in the spring buckle overlap zone in z = 0.0 mm, greater loading variability induces greater potential to fail in the spring buckle zone ( z = 0.0 mm), central geometric notch, contrary to scenario 2 where the nodes with the highest variance occur at the width end. For nodes in length coordinates in the range 0.0mm > z > 100.0 mm, similar behaviour is verified in both scenarios. For the middle zone, (100.0 mm > z > 350.0 mm), there is an increase in the maximum variance of the resolved shear stress in both scenarios. However, in scenario 1 the value is almost symmetrical, while in scenario 2 there is a greater variation in the lateral areas, x = 60 mm. The peak values in this region are situated practically at the beginning and end of the region, 100.0 and 350.0 mm, respectively. After the coordinate of z = 350 mm, a similar variation of the maximum variance is verified in both scenarios, with practically symmetrical behaviour in the width. Comparing both scenarios with the fatigue fracture surfaces for the three regions in analysis presented in figure 4, apparently there is a good agreement with the prediction of crack initiation given by the MVM approach. 5.2. Comparision between Scenarios in Analysis

6. Conclusions

The research work presented in this paper aimed to investigate the determination of the spots with the greatest potential for fatigue crack initiation in parabolic leaf springs under random loading conditions. The determination