Issue 47

S. Akbari et alii, Frattura ed Integrità Strutturale, 47 (2019) 39-53; DOI: 10.3221/IGF-ESIS.47.04 51 Figure 6 : Variation of SIFs vs. c/B for the deepest point of the crack under the real pin loading for different a/c ratios. E VALUATING THE EFFECT OF BUSH AND INTERFERENCE FITTING ne of the cases for the contact between the lug and the pin is when the diameter of the pin is a little larger than the lug hole, which is called interference loading. Another approach is when a bush exists between the pin and lug hole (in this case the bush would have interference contact with the hole of lug) and the contact between the pin and the bush is neat. In this paper the amount of interferences for both cases is considered 0.1 mm and the consequence effects are studied for different values of a /c, c/B and fixed value of R o /R i =2.25. The thickness of bush is 1 mm and it is made of the same material as the lug. The analysis was performed for 100 kN force of pin. The results are compared with the those obtained from neat loading condition without any interferences and bush in Tab. 15. It is obvious that the values of SIFs for neat contact between the pin and the lug are more than the case of interference contact and the bush existence. That is the reason why these two cases are used in fatigue conditions for increasing the life time. By comparing the results between the interference contact of the pin and the lug and the case that the bush exists, it can be understood that in the presence of bush, the values of SIFs are lower than the other. This is a study for this case of loading and for choosing an appropriate value for the interference to have a benefit effect on the fatigue life of the lug, the extracted WF could be used to avoid the time consumer modelling and analysing. a /c c/B Point location K I   MPa mm Neat loading Interference With bush 0.2 0.2 surface 426.972 378.88 370.98 deepest 218.556 192.959 188.99 0.4 surface 576.559 517.312 506.279 deepest 323.459 287.412 277.315 0.6 surface 693.524 628.975 615.364 deepest 412.142 364.62 351.471 0.8 surface 794.21 728.448 712.531 deepest 487.162 432.112 417.291 1 0.2 surface 654.173 610.42 607.183 deepest 718.31 638.72 625.38 0.4 surface 854.616 826.41 824.37 deepest 1012.92 914.711 895.211 0.6 surface 1030.5 1008.37 987.51 deepest 1283.41 1173.69 1148.81 0.8 surface 1248.31 1121.21 1106.14 deepest 1591.54 1196.32 1138.26 Table 15 : SIFs (MPa(mm) 0.5 ) for crack under the pin loading in three conditions. O