Experimental and Finite Element Investigation on the Behavior of Local Sharp-Notched Circular Tubes Under Cyclic Bending

In this paper, the mechanical behavior of local sharp-notched circulartubes under cyclic bending was experimentally and theoretically investigated.The material of the tubes was SUS304 stainless steel. The local sharpnotcheddepths included: 0.2, 0.4, 0.6, 0.8 and 1.0 mm, and the local sharpnotcheddirections included: 0, 15, 30, 45, 60, 75 and 90. Accordingto the experimental result, the moment-curvature curve exhibits cyclic hardeningand becomes stable after a few cycles. The notch depth and direction havealmost no influence on the moment-curvature relationship. The ovalizationcurvaturecurve shows an increasing and ratcheting manner with the numberof cycles. The notch depth increases, the unsymmetrical phenomenon ofthe ovalization-curvature relationship becomes more obvious and the ovalizationincreases faster. In addition, the ovalization- curvature relationshipbecomes more symmetrical and the ovalization increases slower when thenotch direction increases. Finally, finite element software ANSYS was usedto simulate the moment-curvature and ovalization-curvature relationships.Although the experimental and theoretical results had some differences, butboth trends were similar.