Prediction of crack growth in damage-tolerant design - a basic parametric study

Abstract

A study has been undertaken to obtain some experience of the difficulties likely to arise in predicting crack behaviour when implementing the damage-tolerant design philosophy and to obtain an indication of the influence of some of the design parameters involved on life to failure. The study was centred on the growth of a corner-crack from a hole in an infinite plate, remotely loaded. The parameters considered included hole diameter, initial crack length and the severity of the spectrum of applied loads. Predictions of life were made for five different aluminium alloys. The study highlighted difficulties associated both with the analytical method and with shortcomings in available materials data. The results of the life predictions showed that, as would be expected, the predominant parameter was spectrum severity. However, variation of the other parameters within a reasonable range also resulted in significant changes in life (typically in the region of 5:1), the influence of change of material being only slightly greater.