Issue34

F. Curà et alii, Frattura ed Integrità Strutturale, 34 (2015) 447-455; DOI: 10.3221/IGF-ESIS.34.50 451 The aim of this second analysis is to study the combinations of the two loads that produces the maximum allowable stress (in this case the material yield stress is considered as maximum stress) in order to verify how the position of the maximum allowable stress may shift by changing these two parameters. The yield stress of the material considered in this work is 1034 MPa. Figure 4 : Interaction between bending and centrifugal load on the crack propagation direction: a) F + rotation; b) 2F + rotation; c) 5F + rotation; d) 8F + rotation. Firstly, the value of the bending force (applied at the highest point of the single tooth contact HPSTC) that alone (without centrifugal load), may produce yield stress has been obtained and the relative element, where the stress has been reached, has been identified. Consequently, the speed value that, alone (without bending force applied), produces the yield stress, and the corresponding element has been determined. Fig. 5 shows the two elements where the yield stress has been reached: the green one is the most stressed one subjected only to the bending force and the red one is the most stressed with only the centrifugal field. In the model considered in this work, between these two limit elements there are 15 elements, so a range of about 1.5 mm, on a root fillet with radius equal to 3mm, represents the 33% of the fillet length. Figure 5 : Elements where the yield stress is reached (green: only bending force applied, red: only centrifugal load applied). Any combination of these two loads gives the maximum stress element between these extremes, the tensors of tensions has been evaluated in all these elements for both these limit conditions. For each element between these two extremities elements, two data have been collected:  b (stress tensor evaluated in condition of maximum force) and  c (stress tensor evaluated in condition of maximum speed). Once this result has been reached, other different combinations have been considered. To take into account all possible combinations of these two loads, a Matlab script has been employed. Considering the combination of these stresses as linear, the implemented formula is: yeld c b B A   (1)