Question

The minimum force required to punch a hole of diameter ‘d’ in a plate of thickness ‘t’ when the ultimate shear strength of steel = S is given by

• A. π d s t
• B. π $\bigl(\frac{d}{2}\bigr)^2$ s t
• C. 2π d s t
• D. π $\tfrac{d}{2}$ s t

Answer 1

Answer: (A)

π d s t

Answer 2

When punching a hole, shear occurs along the circumference of the hole.
Shear area = circumference × thickness = π·d·t
Required force, F = shear strength · shear area = S · (π·d·t) = π·d·t·S