Question

A rectangular plate of length 2h = 20 mm, width 2b = 50 mm and thickness 5 mm, containing a central crack of length 2a, is subjected to a uniform tensile stress of 40 MPa in the direction of its length as shown in the figure. Determine the maximum permissible crack dimension to avoid its further propagation choosing a factor of safety of 1.6. The plate material is BS 816M40.

Answer 1

maximum permissible load $F = \sigma \times A =40 \times 10\times 25=100$ kN

After taking FOS 1.6

Safe load = 260 kN

Area A = $\frac{260\times10^3}{40}=6500$

as we know , $b = 2h$

$b\times h = 6500$

$2h\times h = 6500$

$h =57$mm and $b = 114$ mm