Interference fit effect on improving fatigue life of a holed single plate

This paper deals with the influence of interference fit coupling on the fatigue strength of holed plates. The effect was investigated both experimentally and numerically. Axial fatigue tests have been carried out on holed specimens made of high performance steel (35KB2, 1075MPa of Ultimate strength and 990MPa of Yield strength) with or without a pin, made of the same material, press fitted into their central hole. Three different conditions have been investigated: the open hole specimens, specimens with 0.6% of nominal specific interference and specimens with 2% of nominal specific interference. The experimental stress-life (S–N) curves pointed out an increased fatigue life of the interference fit specimens compared with the open hole ones. The numerical investigation was performed in order to analyse the stress field by applying an elastic plastic 2D simulation with commercial Finite Element software. The stress history and distribution around the interference fitted hole, indicates a significant reduction of the stress amplitude produced by the external loading (remote stress) since a residual and compressive stress field is generated by the pin insertion.