Fretting fatigue behavior of 316L stainless steel under combined loading conditions

Fretting fatigue occurs in engineering applications where two interacting surfaces are subjected to fluctuating forces. The fluctuating forces occasionally act as a combined loading condition. The present paper investigates fretting fatigue behaviour of 316L stainless steel under such combined (i.e. tensile and bending) loading conditions. A new fixture was developed in order to apply bending and tensile loads simultaneously. Using this fixture, the effect of different bending-to-tension ratios was investigated. The results showed that increasing the contribution of bending load improves fretting fatigue life. On the other hand, increasing grain size decreases fretting fatigue life. Furthermore, sensitivity analysis based on Taguchi method revealed that fretting fatigue life is more sensitive to the increment of bending force contribution. The cyclic behavior of the specimens was assessed and finite element simulation was utilized to study the main contact parameters, including contact pressure, shear stress, and relative slip. Whilst confirming the experimental results, the simulation further showed that increasing the contribution of bending force reduces the concentration behavior at the contact edges.