Final answer:
The fatigue factor of safety can be estimated for a steel bar under fluctuating tensile load using the Modified Goodman criteria. The yielding factor of safety and estimation of cycles to failure for finite life are also determined based on the material's mechanical properties and geometrical factors such as the stress-concentration factor.
Step-by-step explanation:
A 1.5-in-diameter bar has been machined from an AISI 1050 cold-drawn steel bar to withstand a fluctuating tensile load from 0 to 62 kip. Given a fatigue stress-concentration factor (Kf) of 1.85 for a life of 106 cycles or more, the fatigue factor of safety for infinite life can be calculated using the Modified Goodman criteria. The calculation requires the material's ultimate tensile strength and yield strength, which can be found in material property databases or textbooks.
For an analysis of the safe tensile load variation a steel rod can withstand, it's important to determine the yielding factor of safety. This involves calculating the actual stress from the given load and comparing it to the yield strength of the material, taking into account stress concentrations.
If the criteria predict a finite life (i.e., not achieving infinite life), the number of cycles to failure can be estimated using the Modified Goodman criteria, which will involve additional material properties like fatigue strength and endurance limit.
In addition to the bar under cyclic loading, other questions of interest in the field may involve determining the normal stress in a steel rod due to its own weight, the stress caused by temperature changes in a steel beam, or the stretch of a steel pipe supporting its own weight plus additional loads.