Fatigue crack growth behaviour in half-hard aluminium sheet was investigated at stress ratios of 0.1, 0.2 and 0.3. Tests were conducted on center-cracked tension specimens, having a notch in perpendicular and parallel to the rolling direction. Crack length was measured by using traveling microscope and linear elastic fracture mechanics was used to analyse the growth behaviour.Crack growth was sensitive to the orientation but not sensitive to the stress ratio. Fracture surfaces were studied in scanning electron microscope to under stand crack growth mechanism in the sheet material.
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