OS14-3-3 Fretting Fatigue Life Estimations Based on Critical Distance Theory

Abstract

Generally fretting fatigue S-N curve have two regions, one is high cycle (low stress) region and second is low cycle (high stress) region. In previous paper we introduced the fretting fatigue life estimation methods in high cycle region by considering the wear process. And in this estimation method the fretting fatigue limit can be estimated as the crack initiation limit at contact edge. In this paper we introduce the low cycle fretting fatigue life estimation method using the critical distance theory. Generally this critical distance theory was applied for the fatigue limit estimation using fatigue limit of smooth specimen σw0, and threshold stress intensity factor range ΔKth. In this paper we estimated the low cycle fretting fatigue life based on new critical distance theory, which is modified for high stress region using ultimate tensile strength σB, and fracture toughness KIC. The critical distance for estimating low cycle fretting fatigue strength was calculated by interpolation of critical distance on fretting fatigue limit (estimated from σw0 and ΔKth ) with critical distance on static strength (estimated from σB and KIC ). By unifying these low cycle fretting fatigue life estimation method with high cycle fretting fatigue life estimation method which was presented previous paper we can estimate the total fretting life easily. And to confirm the availability of this estimation method we perform the fretting fatigue test using Ni-Mo-V steel.