Question

Calculate the force 'F' needed to punch a 1.46 cm diameter hole in a steel plate 1.27cm thick. The ultimate shear strength of steel is $345MN/m^2$ (Appox) .

• A. 300 KN
• B. 400 KN
• C. 200 KN
• D. 100 KN

Answer 1

Answer: (C)

As in punching, shear elasticity' is involved, the hole will be punched it
$\left(\frac{F_{11}}{A}\right)>$ ultimate shear stress
$F_{11}>(shearstress)\times Area$
$F_{11}$ min > $(3.45\times 10^8)(2\pi rL)[A=2\pi rL]$
= $(3.45\times 10^8)(2\times 3.14)\times 0.73\times 10^{-2}\times 1.27\times 10^{-2}$ = 200 KN