Final answer:
The endurance strength of a 1.5-in-diameter rod of AISI 1040 steel can be estimated to be approximately 55 ksi, based on the assumption that it is approximately 50% of the tensile strength.
Step-by-step explanation:
To estimate the endurance strength of the 1.5-in-diameter rod of AISI 1040 steel, we need to use the S-N curve for the material. The endurance strength is the stress level below which the material can withstand an infinite number of cycles without failure. Unfortunately, the S-N curve for AISI 1040 steel is not provided, so we cannot give a specific value for the endurance strength.
However, we can make an estimate using the tensile strength of the material. Typically, the endurance strength is approximately 50% of the tensile strength. Therefore, we can estimate the endurance strength to be approximately 55 ksi (110 ksi * 0.5).
Keep in mind that this is just an estimate, and the actual endurance strength may vary depending on factors such as surface finish and quality of heat treatment.