Question 2.27:  Repeat Prob. 2–26, except that the design situation is fail...

For stiffness, k=A E / l \quad \Rightarrow A=k l / E For mass, m=A l \rho=(k 1 / E) l \rho=k l^{2} \rho / E

Thus, f_{3}(M)=\rho / E, and maximize E / \rho \quad(\beta=1)

In Fig. (2-16), draw lines parallel to E / \rho

From the list of materials given, tungsten carbide (WC) is best, closely followed by aluminum alloys, and then followed by high carbon heat-treated steel. They are close enough that other factors, like cost or availability, would likely dictate the best choice. Polycarbonate polymer is clearly not a good choice compared to the other candidate materials.  .