Short-Crack Growth Behaviour in an Aluminum Alloy - An AGARD Cooperative Test Programme

An AGARD test programme on the growth of short fatigue cracks was conducted to define the significance of the short-crack effect, to compare test results from various laboratories and to evaluate and existing analytical model to predict the growth of such cracks. The first phase of this programme, the Core Programme, was aimed at test procedure and specimen standardisation and calibration of the various laboratories. A detailed working document has been prepared and is included in this report. It describes the testing fundamentals and procedures and includes the analysis procedures used for handling the test data. The results from the test programme showed good agreement among the participants on short-crack growth rates, on fatigue life to various crack sizes and breakthrough surface- or corner-crack became a through crack, and on crack shapes. A crack-growth model, incorporating crack-closure effects was used to analyse the growth of short cracks from small inclusion defects in the material along the notch surface.