Influence of cold working and interference fit on fatigue life of 7475-T7351 aluminium alloy fastener hole

摘要

The influence of cold working (CW), interference fit fastener (IF) and a combination of both processes (CW + IF) on the fatigue life of a 7475-T7351 aluminium plate containing a countersunk filled hole is studied. One degree of cold working (4%) and one level of interference fit (1.2%) have been considered in this work. During fatigue loading, using a video-camera, the fatigue crack initiation site was detected, then the crack length was monitored in order to evaluate the effectiveness of each process in the fatigue life improvement. Also, an analysis was performed, using 3-D finite element method to establish the stress and strain distributions resulting from the application of the processes and from the fatigue loading. The results obtained from the finite element analysis were used in conjunction with the Coffin-Manson method for calculating the initiation life, then with the weight function technique for determining the propagation life. The relevance of the fatigue life estimation procedure for both initiation and propagation phases is discussed in relation with experimental values.