Study of crack closure under single and intermediate tensile overload cycles for 6061-T6 Al-alloy

Abstract

Crack closure experiments were performed on 6061-T6 Al-alloy using a COD gauge for various overload ratios and constant stress ratio (R = 0). On the basis of these experiments, some relations are developed. These relations are, amongst others, U min, OLR, N D, ΔU, etc. The delay period after application of the single overload cycle is also increased as the magnitude of overload cycle is increased. The crack closure load is stabilized before overload. It is sharply increased after overload in 10 cycles and remains constant for a certain number of cycles. Then it decreases to attain the CAL value of crack closure. 15