Reading

Ch$.6$: $6-11$ to $6-14,6-16$

Graphical. The "master fatigue diagram" on the right describes the material response to variable loading of AISI $4340$ steel $(S_{\frac{J}{\text{I}}}=158k,S_y=147k).$ Use this plot to help solve the following problems. $[$value $=4]$

a$.$ Using the above master fatigue diagram, what is the alternating and midrange tensile stress if you want a part to last $100,000$ cycles, and your ratio of ${}_{\text{m}\text{i}\text{n}}$ to ${}_{\text{m}\text{a}\text{x}}$ is $0\mathrm{.}4?$

b$.$ For this material, create a fluctuating$-$stress diagram $($figure $6-34$ in ${11}^{th}$ ed$.)$ with fatigue boundary lines and yield boundary lines and

place the point from part $($a$)$ in this plot.

Please help with parts a and b