Problem 1.5-2 A bar of length 2.0 m is made of a structural stoel having the stres-strain dingram shown in the figure. The yield stresa of the steel is 250 MPa and the slope of the initial lincar part of the stress-strain curve (modulus of elasticity) is 200 GP. The bar is loaded axially until it eklongates 6.5 mm, and then the load is removod. How does the final length of the bar compare with its orig- inal length? Hint: Ue the concepts illustrated in Fig. 1-36h) MP 300 200 100 0.002 0.004 0.006

A steel component is subjected to alternate cyclical loading. The steel follows Basquin's law for high cycle fatigue, o, x N = C, (where the stress amplitude is in MPa). Ignore the geometric detail and assume that Marin's modifying factors are all equal to 1. You are given the minimum stress ain = -213 MPa, the maximum stress omax = 213 MPa. The material data are Tensile strength oUTS = 539 MPa, Basquin's constant c, = 875 MPa, Basquin's exponent a = 0.085. a) Calculate the stress ratio R, the stress amplitude o, in MPa and the mean stress am in MPa. The answers are acceptable with a tolerance of 0.01 for R and of 1 MPa the stresses. R: MPa MPа b) Calculate the corresponding life, in 10° cycles, (tolerance of 0.1 106 cycles) N :