(Solved): Question 4 Fatigue tests are conducted on metallic cylindrical specimens at zero mean stress. The ...

Question 4 Fatigue tests are conducted on metallic cylindrical specimens at zero mean stress. The test results are given in the table below: Stress Amplitude (MPa) 424 459 410 352 315 270 241 Cycles to Failure (N?) 257 1,494 6,749 19,090 36,930 321,500 2,451,000 (a) Plot the S-N curve obtained from the fatigue tests above. (b) If the above S-N curve can be represented in the form of power law ?a = = A(Nƒ)³, propose a method to determine the constants A and B. (c) Obtain the value of constants A and B using your proposed method. (d) If during the service this material is subjected to stress amplitude of 250 MPa at the frequency of 0.1 Hz, examine the expected number of operating hours to failure? (15 Marks)