= 20 mm A punch for making holes in steel plates is shown in Fig. 1-29a. Assume that a punch having diameter d is used to punch a hole in an 8-mm plate, as shown in the cross-sectional view (Fig. 1-29b). If a force P= 110 kN is required to create the hole, what is the average shear stress in the plate and the average compressive stress in the punch? P = 110 kN d = 20 mm (a) (b) 7=8.0 mm