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Experimental and numerical study to predict crack growth in a thick-walled cylinder under fatigue loading

Experimental and numerical studies were carried out to predict the crack growth rate under fatigue loading in a thick-walled cylinder made of aluminum alloy. Extensive experimental fatigue-crack growth data on middle tension samples was compiled and applied to simulate and predict the crack growth process using detailed two-dimensional parametric finite-element (FE) technique. The fatigue-crack propagation was simulated, based on linear elastic fracture mechanics and stress intensity factor determination. The FE model provided results of crack-growth analysis optimized for stress levels ranging from 40 per cent to 25 per cent of the material yield stress. Fatigue-life analysis of the samples showed that the results obtained from the two techniques were in good agreement up to a stress range of 79 MPa. However, at lower stress ranges, the number of cycles to failure as determined by FE analysis (FEA) was smaller than found experimentally. The experimental results were 13 per cent and 36 per cent higher than FEA results at stress ranges of 63 and 49 MPa, respectively. This disparity was explained in terms of the crack growth rates near the threshold stress intensity factor range.