Use the graphs provided in the handout to answer the following question. (Select the option that is closest to your answer).

For full marks show all calculation handwritten work in your answer booklet. 

Handout: Figure 4  

Given data: 

Material: 1045 Steel 

Ultimate tensile strength = 625 MPa

Stress range for rotating part: Min stress = -120 MPa, Max stress = 460 MPa

Rotation: 4 Hz ( 1 Hz = 1 cycle per second)

• How many hours would the part be expected to

  survive before failing due to fatigue

  ?