CAM Size Optimization Based on a Fatigue Life Model

Abstract

The cam fatigue life of the translating roller-follower system is studied for polynomial and cycloidal displacement functions. The stress distribution in the contact zone between the cam and the roller-follower is determined by using a computer program. The “volume under risk” where the stress field is higher than the endurance limit is determined. Ioannides-Harris (IH) theory is used on the ‘volume under risk’ and the expected fatigue life is calculated. The effects of cam base circle radius, follower offset, follower total lift and cam angular velocity on the fatigue life are studied. The primary design parameter governing the cam fatigue life is found to be the base circle radius. The fatigue life curve shows an improvement in the life up to a critical base circle radius value. Any further increase in the base circle radius appears as a decrease in the fatigue life.

A modified model of Lundberg-Palmgren rolling contact fatigue formula considering the effects of surface treatments

“…As a common statistical fatigue life model, the L-P fatigue model is constantly modified. Ioannides and Harris [5] introduced the fatigue-limiting shear stress to the original L-P fatigue model and put it forward in an integral form, which could be applied with the finite element method [6][7][8]. After that, Zaretsky [9] suggested that the Weibull distribution slope and the shear stress-life exponent should be taken into account independently.…”