Experimental Study on the Response and Failure of Round-hole Tubes with a Redundant Hole under Cyclic Bending

Abstract

This paper experimentally studies the behavior and failure of 6061-T6 round-hole tubes with redundant hole under cyclic bending and the redundant hole have the same diameter and the same cross-section as the round holes of the round hole tube This paper considers five different circular holes with diameters of 2 4 6 8 and 10 mm and the five different angles of redundant circular holes are 45o 67 5o 90o 135o and 180o During the symmetrical cycling bending the moment-curvature relationship is found that the curve forms a stable loop from the first cycle and the diameter of the hole and the direction of the hole have almost no effect on the curve From the ovalization-curvature relationship it is found that with the increase of the number of cycles the curve shows an increasing trend of asymmetry ratchet and butterfly-shape and the larger the diameter of the hole the faster the ovalization increases It is shown from the experimental controlled curvature-number of bending cycles required to produce failure relationships on a log-log scale that five different diameters of the round hole correspond to five parallel straight lines As for the critical ovalization -control curvature relationship it can be found that The larger the control curvature the larger the critical ovalization Finally this paper proposes a theory to describe the relationship between the control curvature of the 6061-T6 round hole tube with redundant round holes under controlled curvature and the number of bending cycles required to produce failure By comparing the theoretical analysis with the experimental data it is shown that the theoretical formulation can properly simulate the experimental results Key words: Cyclic Bending Moment Curvature Ovalization Number of Bending Cycles Required to Produce Failure redundant hole Tubes

Date of Award	2020
Original language	English
Supervisor	Wen-Fung Pan (Supervisor)