2.4 (18 pts) Assume a metal workpiece is perfectly rigid plastically deformed under the action of a rigid flat punch (see Fig. 2). The workpiece surface apart from the portion covered by the punch is free. The punch is 2b in width with a length (perpendicular to the paper plane) much larger than the width. The deformation of the workpiece can be treated as a plane strain deformation approximately. It is assumed that Tresca yield criterion , -0,=2K is satisfied here, in which K is the shear yield strength of the material. Do the following calculations using Prandt's slip line field: (1) Supplement the missing slip line field shown in Fig. 2. (2) Draw the hodograph of a typical slip line. (3) Calculate the average flow pressure of the flat punch p using the slip line method. Fig. 2 Prandtl's slip line field of a workpiece under the action of a flat punch. 2.4 (18 pts) Assume a metal workpiece is perfectly rigid plastically deformed under the action of a rigid flat punch (see Fig. 2). The workpiece surface apart from the portion covered by the punch is free. The punch is 2b in width with a length (perpendicular to the paper plane) much larger than the width. The deformation of the workpiece can be treated as a plane strain deformation approximately. It is assumed that Tresca yield criterion , -0,=2K is satisfied here, in which K is the shear yield strength of the material. Do the following calculations using Prandt's slip line field: (1) Supplement the missing slip line field shown in Fig. 2. (2) Draw the hodograph of a typical slip line. (3) Calculate the average flow pressure of the flat punch p using the slip line method. Fig. 2 Prandtl's slip line field of a workpiece under the action of a flat punch