NUMERICAL INVESTIGATION ON THE INFLUENCE OF PUNCH GEOMETRY ON THE BENDING PROPERTIES OF SHEET METAL SUBJECTED TO EMBOSSING AND RESTORATION TECHNIQUE

摘要

Embossing and restoration technique is utilized as a simple method for strengthening sheet metal. Through this technique, sheet metal of thinner gage can be utilized with remarkable increase in mechanical properties such as strength and rigidity resulting to weight reduction of sheet product. In our previous studies, embossing and restoration technique was conducted to sheet metals utilizing a spherical punch. The processed sheets were then subjected to flexural tests at different types of loading. Results showed that this technique is an efficient way to improve the rigidity of thinner sheet metals which can be enhanced by taking into considerations several important parameters such as the number, position and pitch of the emboss or restoration points. Moreover, this technique can be used not only for increasing the rigidity but also for making decorative sheets without any special tools. In the present study, numerical simulations of embossing and restoration process of different sheet metals utilizing different geometry of embossing punches are carried out using LS-DYNA3D. The punch shapes considered are hexagonal, diamond and hemispherical. The effect of punch geometry on the flexural properties of the sheet is then investigated and evaluated by finite element method (FEM).