A Test Method for Mode Ii Fatigue Crack Growth Relating to a Model for Rolling Contact Fatigue

Abstract

From fractographic observations of specimens that have failed due to rolling contact fatigue, it has been concluded that the first stage of damage is the formation of mode 11 fatigue cracks parallel to the contact surface due to the cyclic shear stress component of the contact stress. Although these initial subsurface cracks, in both metals and ceramics, are produced in a direction parallel to the cyclic shear stress, cracks eventually grow in a direction close to the plane of the maximum tensile stress if we apply a simple mode I1 loading to them. The difference between crack growth in simple mode I1 loading and crack growth due to rolling contact fatigue is, we suppose, whether or not there is a superimposed compressive stress. Based on this hypothesis, we developed an apparatus to obtain the intrinsic characteristics of mode I1 fatigue crack growth, and developed a simplified model of subsurface crack growth due to rolling contact fatigue.Some results in terms of da/dN versus AKII relations have been obtained using this apparatus on specimens of steel and aluminum alloys. Fractographs of the mode I1 fatigue fracture surfaces of the various materials are also provided.

Failure mode and fatigue mechanism of laser-remelted plasma-sprayed Ni alloy coatings in rolling contact

“…By comparing the depth of maximum shear stress and that of the subsurface branched cracks, it may be concluded that the shear stress may be the dominate factor that governs the initiation of the subsurface branched cracks. A similar result was obtained by Otsuka et al [27]. Hence, for the laser-remelted coatings in the rolling contact, the joining of the ring-type cracks and subsurface branched cracks to form the denser crack network may directly lead to the spall formation.…”

Life prediction of titanium and aluminum alloys under fretting fatigue conditions using various crack propagation criteria. Part 1. Experimental and calculation techniques

“…FCP section by K II type followed by crack deviation. This well correlates with data of Otsuka [48] and attributed to FCP instability by K II type in this material, which suggests application of the modified test scheme [50]. On the other hand, considering the analogue model [36] not only from the SIF calculation standpoint, but for interpretation of experimental data as well, it is evident that if crack propagation K II type is observed during implementation of the contact scheme (Fig.…”

“…As a basic loading scheme, we have used the four-point bending one (Fig. 16a), widely used in [45][46][47][48]. The above scheme has been adapted for testing of specimens of the same edge-notched configuration as those tested by K I type, and for transmission of reversal loads and realization of load 696 Fig.15.…”

Fatigue crack growth rates under sequential mixed‐mode I and II loading cycles

“…On the contrary, Bold 8 showed that coplanar long cracks were able to be produced in laboratory tests where cyclic mode I and mode II loads were applied sequentially. Similarly Otsuka et al 9 demonstrated that a compressive mean stress applied across potential branches but parallel to the shear mode crack suppresses branch growth while permitting stable shear mode growth under pure mode II cycling.…”