フレッティング疲労向上対策法と、疲労寿命予測法

抄録

Fretting fatigue process have many features such as early stage crack initiation at contact edge, very slow crack propagation and fatigue failure after very long life operation. In previous paper we present fretting fatigue model which was considering the wear process, and this model can explain these fretting fatigue features reasonably. But, the estimation of fretting wear process requires a large amount of labor, so this precise wear estimation method is not suitable for actual design site. In this paper we try to present simple fretting fatigue limit and life estimation method using critical distance stress theory. In this method the critical distance rc for fatigue limit estimation can be derived using fatigue limit of smooth specimen and threshold stress intensity factor range ΔK_th. And the critical distance r’_c for fatigue life estimation can be derived using tensile strength of smooth specimen and fracture toughness K_IC. And we apply this simple fatigue limit and life estimation method for the fatigue strength evaluation of fretting fatigue strength improved models such as grooving at contact edge. And finally we confirm the validity of this simple fatigue life estimation method and fretting fatigue improvement by providing groove at contact edge by fretting fatigue tests.