Question

A circular shaft of diameter 120mm is welded to a rigid plate by a fillet weld of size 6mm. If a torque of 8 kN-m is applied to the shaft, then the maximum stress induced in the weld is

• A. $84N/m{m}^2$
• B. $90N/m{m}^2$
• C. $108N/m{m}^2$
• D. $120N/m{m}^2$

Answer 1

The correct option is A $84N/m{m}^2$


$\text{Strength of weld per mm length}=0.7\times 6\times \sigma$
$=4.2\sigma$
$\text{Weld length}=\pi d$
$=\pi \left(120\right)mm$
$\therefore \text{Maximum twisting moment,}T=\left(4.2\sigma \right)120\pi \left(\frac{120}{2}\right)$
$\Rightarrow 8\times {10}^6=\left(4.2\sigma \right)120\pi \left(60\right)$
$\Rightarrow \sigma =84.21\simeq 84N/m{m}^2$