Question

2. (80 points) A rod that is used as a rotating component is machined from steel billet, which has an ultimate tensile strength of 1300 MPa. The shaft sits at

a site within the machine such that it operate sat a temperature of 400 degrees Celsius. In this problem, we can assume that failure occurs at the site of the fillet, where the static stress concentration factor is 1.85. The manufacturer has request design such that there is a conservative approach to the boundary of the low cycle fatigue and high cycle fatigue regimes. In line with this conservative approach, the manufacturer requires 90% reliability for this component (a) (65 points) Determine the number of cycles to failure for the described problem. Show all work, including shear and moment diagrams. Justify all steps of the problem either numerically or with words - any unjustified portions will go ungraded. (b) (15 points) If all modification factors are ignored, what is the answer to the above question?Explain, and draw an example S-N diagram to justify your reasoning.

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