Papers by Author: Hung Hsiou Hsu

Abstract: Friction stir processes (FSP) are important for enhancing mechanical properties of metal sheets, such as the tensile strength, the elongation, etc. The stress distribution of the tool pin is affected by the thermo-mechanical characteristics of the workpiece in FSP. Recently, magnesium alloy AZ31 is widely used in machine industries due to the light-weight material property. In this paper, a thermo-mechanical model for FSP using three dimensional FEM analyses is proposed for exploring temperature distributions, strain distributions and stress distributions of the workpiece. The heat generated from the plastic deformation and the friction between the head tool and workpiece is considered as the heat source in the simulation of the FSP process. A commercial finite element code – DEFORM 3D is used to carry out the simulation of the plastic deformation of AZ31 sheets during the FSP. The analytical results of temperature, strain and stress distributions of the workpiece and head tool can provide useful knowledge for tool pin design in FSP

Abstract: In this paper, an upper bound approach of rotating compression forming of ring is established. Using the upper bound approach, the effects of friction factor, reduction, aspect ratio etc upon compression force, radius of neutral surface, internal radius, spiral lead etc are investigated systematically. The experiment of rotating compression forming of ring made of aluminum alloy A6061 was carried out. Comparisons between the analytical results and the experiment are used to verify the validity of present upper bound approach. The analytical results are in good agreement with the experiment.