# Homework Help: Shear stress, what is a flat tie bar ?

1. Nov 8, 2007

### scotthands

shear stress, what is a flat tie bar....?

1. The problem statement, all variables and given/known data
two lengths of flat tie bar are connected together by a lap riveted joint with three rivets each 10mm in diameter. Calculate the maximum pull that can be applied to the tie-bars if the shear stress in the rivets is not to exceed 60MN/m^2

3. The attempt at a solution

i can't attempt this because i don't know that a flat tie bar is or what it would look like if they were connected together by a lap riveted joint with three rivets...
does anyone know what it is?

2. Nov 8, 2007

### Math Jeans

This is a tie bar. http://en.wikipedia.org/wiki/Image:Tieslide.jpg

3. Nov 8, 2007

### Astronuc

Staff Emeritus
Well a flat tie bar is flat strip of metal, usually uniform thickness with a rectangular cross-section - basically looks like a ruler, but thicker. The two bars are overlapped and held together by 3 rivets. However that is irrelevant to this problem.

What is relevant is the fact that there are three rivets, each of 10 mm dia, which will bear the load P to be determined such that the shear force does not exceed 60 MN/m2.

State assumptions, e.g. not credit given to the friction in the lap joint of the lapped tie bars, i.e. one assumes the rivets bear the full load. What else?

4. Nov 8, 2007

### scotthands

so have i just to work out P? as in: P=T(tau) * Area
?

if so then i'm not really sure about the area, do i take the 10mm diameter and work out the area that the rivets go through?(or is it the perimeter of the 10mm diameter the hole that the rivets go through?)

thanks for the help.

5. Nov 8, 2007

### Astronuc

Staff Emeritus
The cross-sectional area of the three rivets will bear the shear stress.

The stress is just the load divided by the area bearing that load (force).

Remember stress, which has the units of pressure (lbf/in2, or MPa), is simply force divided by area, whether it's a tensile, compressive or shear force.