Question

A double riveted double strap butt joint is made with 12 mm thick plates and 18 mm diameter rivets. The pitch of the joint is 80 mm. Allowable stresses are : ${\sigma }_t$ = 115 MPa, $\tau$ = 80 MPa, and ${\sigma }_c$ = 160 MPa.
The efficiency of the joint is

Answer 1

d = 18 mm, t = 12 mm, p = 80 mm

${\sigma }_t=115\text{MPa},{\sigma }_c=160\text{MPa},\tau =80\text{MPa}$

Tearing Resistance

$P_t=(p-d)\times t\times {\sigma }_t=(80-18)\times 12\times 115=85560N$

Shearing resistance

$P_s=2\times 2\times \frac{\pi }{4}{d}^2\times \tau =2\times 2\times \frac{\pi }{4}\left({18}^2\right)\times 80=81430.08N$

Crusting resistance

$P_c=N\times d\times t\times {\sigma }_c=2\times 18\times 12\times 160=69120N$

Strength of unriveted joint

$P=p\times t\times {\sigma }_t=80\times 12\times 115=110400N\eta =\frac{\text{least of}{P}_{t1}{P}_s\text{and}{P}_s}{P}$

$=\frac{69120}{110400}\text{= 62.6 \%}$