Mating flanges of two rotating discs with dissimilar materials were stress analysed by 3D Finite Elements using a contact algorithm to simulate the relative motion between the flanges. All the hardware associated with the flanges (bolts, nuts, bushings and washers) were also modelled. The difference in radial growths of the two flanges, hereby called “slip”, produces high cyclic stresses in the bolt holes leading to Low Cycle Fatigue (LCF) and premature cracking. Design changes were studied where the slip was minimised by changing the thermal and centrifugal response of the mating flanges. In order to substantiate the LCF life of a rotating part, spin pit testing is carried out. In the spin pits available for testing the temperature remains constant while the speed is cycled. So in order to simulate the engine duty cycle which includes thermal stresses, the spin pit test conditions are modified. The procedure adopted in this case is explained in the paper.

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