A Study On Critical Thinning In Thin-walled Tube Bending Of Al-Alloy 5052O Via Coupled Ductile Fracture Criteria

Abstract

Thin‐walled tube bending(TWTB) method of Al‐alloy tube has attracted wide applications in aerospace, aviation and automobile,etc. While, under in‐plane double tensile stress states at the extrados of bending tube, the over‐thinning induced ductile fracture is one dominant defect in Al‐alloy tube bending. The main objective of this study is to predict the critical wall‐thinning of Al‐alloy tube bending by coupling two ductile fracture criteria(DFCs) into FE simulation. The DFCs include Continuum Damage Mechanics(CDM)‐based model and GTN porous model. Through the uniaxial tensile test of the curved specimen, the basic material properties of the Al‐alloy 5052O tube is obtained; via the inverse problem solution, the damage parameters of both the two fracture criteria are interatively determined. Thus the application study of the above DFCs in the TWTB is performed, and the more reasonable one is selected to obtain the critical thinning of Al‐alloy tube in bending. The virtual damage initiation and evolution (when and where the ductile fracture occurs) in TWTB are investigated, and the fracture mechanisms of the voided Al‐alloy tube in tube bending are consequently discussed.