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## Homework Statement

A drive shaft tube for a rear wheel drive high-performance sedan requires a lighter weight unit than one made from conventional steel. The requirements are that the applied torque be 814 N-m (600 ft-lbs) the factor of safety be 2 or more and the maximum angular displacement at full torque be no more than 3 degrees.

The shaft is 36 inches long (0.9144m) and has a fixed outer diameter of 67mm (2.637 in.).

Determine the material indices for

this application and calculate the inner diameter, weight and cost for tubes made from the candidate materials.

## Homework Equations

(tau)f/N=2M/(pi)r^3

m=L(rho)(pi)r^2

minimize (rho)/(tau)f^2/3

## The Attempt at a Solution

I can derive the term to be minimized using the above equations, just need to do it with the variables given in the problem. (especially with the inner diameter not given)