Stress Intensity Factors, Crack Profiles, and Fatigue Crack Growth Rates in Residual Stress Fields

Abstract

A linear elastic fracture mechanics approach to crack growth rate prediction implies the need to calculate accurate, effective stress intensity (K) factors, and hence effective R-values, (Kmin/Kmax), for components containing residual stress. To this end the weight function and associated superposition techniques are described, with emphasis on stress intensity and crack shape prediction for residual stress problems. Stress intensity factors are presented for various geometries with residual stress fields. The nonlinear, crack surface ‘overlapping’ effect is noted, and the case of cracks emanating from notches in residual stress fields is shown to be an associated problem. The application of such results in crack growth rate prediction is addressed. The characteristic crack growth rate features of several different loading systems are predicted, and shown to agree with available experimental data. Finally, the qualitative changes in the form of standard S-N curves for welded details are predicted, and shown to conform with limited available S-N curve experimental data.

The effects of process variations on residual stress in laser peened 7049 T73 aluminum alloy

“…This contribution is most often quantified using the weight function [25], which shows that the contribution is linearly affected by the residual stress magnitude and non-linearly affected by the shape of the residual stress profile. While a weight-function analysis is beyond the scope of the present work, it can be stated unequivocally that residual stresses resulting from LP with higher fluence and larger layer overlap would have a larger contribution to the stress intensity factor because they have higher levels of compressive stress ( Figure 5 The effects of the LP variations on total fatigue life may depend on the level of loading.…”

Effect of high-pressure rolling followed by laser processing on mechanical properties, microstructure and residual stress distribution in multi-pass welds of 304L stainless steel

“…This fatigue and stress corrosion cracking are surfacesensitive phenomena [4], and often initiation of such crack depends on surface residual stress state. In large thickness, multi-pass welding process is normally employed which causes a variable distribution of residual stress field.…”

Retardation of fatigue crack growth in aircraft aluminium alloys via laser heating – Numerical prediction of fatigue crack growth

“…Hence, because precise predictions of fatigue crack growth are required for damage tolerant design, several recent studies have addressed the prediction of fatigue crack growth in integral aircraft aluminium structures including residual stress effects [4][5][6]. The approach that has found common acceptance consists of the following steps [4,6,[9][10][11][12][13][14][15][16][17][18][19]:…”

“…For cracks growing through compressive residual stress fields, nonlinear contact corrections are needed to prevent a physically unsound overlapping of the crack faces during the calculations [9]. Hence, the application of the superposition law is no longer valid.…”