Question 4 A steel alloy has a tensile strength of 620 MPa, and a fatigue limit of 275 MPa at 106 cycles. Find the Basquin exponent. (A) 0.0588 B -0.0588 10 Points -0.0521 0.0321 Question 5 Given the SN curve: (i) What is the fatigue limit and (ii) the allowable stress amplitude for a life of 105 cycles Stress amplitude (MN/m) 500 1045 steel 400 Fatigue limit 300 200 100 0 10 10 10 10 107 10% 10 Number of cycles, N (A) (i) 300 MPa (ii) 400 MPa (B) (i) 500 MPa (ii) Infinite allowable stress (i) No fatigue limit (ii) 400 MPa (i) 300 MPa (ii) 500 MPa 10 Points Question 7 10 Points A metal has an allowable stress amplitude of 550 MPa at 1000 cycles. Its Basquin exponent is -0.1021. Find allowable stress amplitude at life of 80,000 cycles. (A) 495 MPa B) 860 MPa 352 MPa 336 MPa Question 8 10 Points At mean stress of 0, the endurance limit is 550 MPa at 106 cycles. Find the equivalent endurance limit when the mean stress is 200 MPa using Goodman equation. The tensile strength is 1100 MPa. A 350 MPa B 400 MPa 450 MPa 750 MPa