# Homework Help: Half of the join to have the same number of rivets

1. Feb 23, 2010

### dixonmayte

1. The problem statement, all variables and given/known data

i am given a picture called fig1 which is just a normal 2 lap joint.

the question is assuming each half of the join to have the same number of rivets, determine how many 6mm diameter rivets would be needed in the joint if the maximum allowable shear stress in the rivet material is 8Mn/m2 and the shear force applied is 2.25KN

2. Relevant equations

T(tau)= F(force) divided by A(area)

3. The attempt at a solution

A=F
T

A=2.25x103
8x106

=2.8125x10-4 x2
=5.625x10-4

A=II(pie) x D2(diemeter squared)
4

which transposes to
D2= Ax4
II(pie)

D2= 5.625x10-4m2 x4
II(pie)

D2=7.161972439x10-4

square root that answer to get D=26.76186174x10-3m
D=26.8mm
6
=4.46 which would round up to 5 rivets. but it ant b a odd number so you add 1rivet to make 6 rivets 3 on each side.

I have been told this answer is wrong and really need help solving the problem

2. Feb 23, 2010

### pongo38

Re: stress

Why have you worked out D = 26.8, when D is given as 6 mm?