Question

A high strength steel band-saw of 90 mm width and 0.5 mm thickness runs over a pulley of 500 mm diameter. Assuming E = 200 GPa, the maximum flexural stress developed would be

• A. 100 MPa
• B. 200 MPa
• C. 400 MPa
• D. 500 MPa

Answer 1

The correct option is B 200 MPa

For pure bending,

$\frac{M}{I}=\frac{E}{R}=\frac{f}{y}$

$y=\frac{0.5}{2}=0.25mm$

$R=\frac{500}{2}=250mm$

$\therefore f=\frac{200\times 0.25\times {10}^3}{250}=200MPa$