A Proposed Model for Biaxial Fatigue Analysis Using the Triaxiality Factor Concept

Abstract

A biaxial fatigue model for axial-torsion strain cycling is proposed which includes elastic and plastic strain life regimes at elevated temperatures. The biaxial fatigue model is based on the concept that the transition from the plastic strain region to the elastic strain region on the bilinear fatigue life curve occurs at a cycle at which the elastic and plastic strain components of the total applied strain are equal. This transition corresponds to the intersection of the elastic and plastic strain lifelines of either a uniaxial or a torsional strain cycling condition. The transition point can combine the fatigue strength and fracture ductility coefficients of the material. The von Mises yield criterion was modified by using the Davis and Connelly triaxiality factor (TF) to account for the effects of the stress state and strain rate on the fracture ductility at elevated temperatures, which decreases as TF increases. Experimental data by the authors as well other available data were analyzed on the basis of the proposed model.

On thermal stress and fatigue life evaluation in work rolls of hot rolling mill

“…Also the elastic line has to be shifted horizontally to preserve the cyclic axial stressstrain curve under different states of multiaxial stress, as explained in Manson and Halford. 39 Zamrik's criterion 43 This approach assumes that stress multiaxiality can alter the transition region in both axial and torsional strain-fatigue life lines; the following Z-parameter is then introduced…”

Toward consistent fatigue crack initiation criteria for 304L austenitic stainless steel under multi-axial loads

“…In this paper, Z is taken as 1.42 for the 304L stainless steel [29]. Within the framework proposed in this paper, Zamrick's criterion appears to have the best consistency when K is taken as 0.5 for the limited evaluations performed in this study.…”

Implementation of a plastically dissipated energy criterion for three dimensional modeling of fatigue crack growth

“…The crack front is subjected to a multi-axial state of stress that varies along the crack front, influencing the size and shape of the plastic zone. It is well known that a multi-axial state of stress significantly alters the ductility, fracture and fatigue properties of materials [43]. Under the application of a very high pure hydro static tension, ductile materials become brittle and under a very high pure hydrostatic pressure, even brittle materials become duc tile [43].…”

“…It is well known that a multi-axial state of stress significantly alters the ductility, fracture and fatigue properties of materials [43]. Under the application of a very high pure hydro static tension, ductile materials become brittle and under a very high pure hydrostatic pressure, even brittle materials become duc tile [43]. The effect of stress state on ductility under monotonic loading has been quantified through the use of triaxiality factor introduced by Davis and Connelly [44].…”