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 $345 M N/m^2$ (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
$F_{11} > (shear \, stress) \times Area$
$F_{11}$ min > $( 3.45 \times 10^8 )(2 \pi r L) \, [A = 2 \pi r L ]$
= $(3.45 \times 10^8)(2 \times 3.14 ) \times 0.73 \times 10^{-2} \times 1.27 \times 10^{-2} $ = 200 KN