A Numerical and Experimental Study on Fatigue Crack Growth of Ti-6Al-4V specimens in Presence of Residual Stress

Fatigue Crack Growth is an important physical phenomenon and one of the damage mechanisms in engineering materials. This damage mechanism is intensified in the presence of tensile residual stresses. In contrast, compressive residual stresses delay the fatigue crack growth process. In this study, The effects of tensile residual stresses are studied on fatigue crack growth in the titanium alloy Ti-6Al-4V specimens. Mechanical residual stresses are induced in the samples using the 4-point bending method and measured using the hole drilling technique. Fatigue crack growth tests are conducted on SEN(b) specimens according to the ASTM-E647 standard, using samples with and without residual stresses. The commercial finite element software ABAQUS was used to study the distribution of residual stresses, the plastic zone sizes at the crack front and fracture mechanics parameters. The finite element results were in good agreement with the experimental results. The results reveal that the presence of tensile residual stress may accelerate the fatigue crack growth rate in the specimens. This increase in fatigue crack growth rate can reduce the fatigue life of samples up to 50%.