A NUMERICAL AND EXPERIMENTAL ANALYSIS ON FORMING LIMIT OF AA 3105 IN RADIAL EXTRUSION PROCESS

초록

In metal forming, formability is the criteria of certain forming process without producing any defects and it is generally determined in high strain value due to the initiation of ductile fracture [1]. This standard formula of ductile fracture is represented by integral form of stress and strain. Ductile fracture is assumed to be initiated if integral value becomes greater than critical damage value [2]. Ductile fracture can be divided into internal and surface fracture according to the location of fracture. Flange forming in radial extrusion, the non-flow phenomenon is presented in the central part of contact between die and work-piece due to high compression stress. Internal shear stress also occurs by flow difference with the surface. Shear stress may cause fracture of flange internally. However, this kind of fracture occurs during forward extrusion process and is not a critical factor in radial extrusion process [3]. This study focuses on circumferential strain of certain surface element by simulation according to compressive deformation.