Q1-A hot-rolled 7-mm-diameter steel rod is axially loaded at room Temp under a fully reversed cyclic loading. under the rotating beam test, the endurance limit for this steel is 470 MPA, under static loading the ultimate strenght is 1200 MPA. What is the endurance limit for this rod ?
Q2- a zirconia bar, loaded in tension, fractures at applied stress of 275 MPA. the toughness of the zirconia 4.7 MPA*m^(0.5) . what is the lenght of the critical exterior flaw (largest flaw) in the bar? (assume y=1.1).