Cyclic Bending Failure of Local Sharp-dented 6061-T6 Aluminum Alloy Tubes

Kuo-Long Lee, Wen-Fung Pan

This study presents an experiment for examining the degradation and failure of local sharp-dented 6061-T6 aluminum alloy tubes submitted to cyclic bending. The dent depths of circular tubes were considered from very trivial to approximately 0.6 times the tube’s wall thickness. The moment-curvature response revealed an almost stable and closed hysteresis loop. The dent depths had almost no influence on the loop configuration. The ovalization-curvature behaviour demonstrated an asymmetrical and ratcheting trend along with the number of bending cycles. Furthermore, the deeper dent depths led to larger ovalizations. The relationship between the controlled curvature and the number of bending cycles required to ignite failure on a log-log scale displayed five nonparallel straight lines for five different dent depths. Finally, an empirical formula was introduced to simulate the relationship between the controlled curvature and the number of bending cycles required to produce failure. As a result, the experimental and analytical data were found to agree well.