Fatigue crack closure: From LCF to small scale yielding

Modelling combined HCF-LCF fatigue crack growth under the influence of LCF overload

Fatigue crack growth (FCG) rates have previously been reported in forged Ti6Al-4V aero-engine disk material under the conjoint action of LCF and HCF cycles at room temperature. It is found that systematic increases in LCF overload, applied prior to the commencement of the HCF cycles, reduce the contribution of the HCF cycles to crack growth rates. The application of overload also enhances the s...

Limitations to the Small Scale Yielding Approximation for Crack Tip Plasticity

Recent finite-element results by S. Cl. Larsson and A. J. Carlsson suggest a limited range of validity to the ‘small scale yielding approximation’, whereby small crack tip plastic zones are correlated in terms of the elastic stress intensity factor, It is shown with the help of a model for plane strain yielding that their results may be explained by considering the non-singular stress, acting p...

Fatigue Crack Shielding and Deflection in Plain Bearings under Large Scale Yielding

Multi-layered bearing systems used in the automotive industry show shielding and antishielding effects that reduce or amplify the crack driving force under large scale yielding conditions. Using finite element analysis, it is shown that shielding in such systems results in path deflection and bifurcation despite the absence of mixed-mode loading. As the crack approaches a stiff layer, the tange...

Small Scale Yielding Near a Crack in Plane Strain: A Finite Element Analysis

A B S TR AC T This paper presents an incremental elastic-plastic finite element solution to the problem of small scale yieldmg near a crack in plane strain for a non-hardening material. Emphasis is placed on the design of finite elements which allow accurate reproduction, m a numerical solution, of the detailed structure of the near crack tip stress and strain fields, as understood from previou...

A Finite Element Analysis of Small - Scale Yielding near a Stationary Crack under Plane Stress