Question 1: A steel rotating-beam test specimen has an ultimate strength of 1600 MPa. If tested at a completely reversed stress amplitude of 900 Mpa, estimate the specimen's life. Use a value of fas 0.77. Answer: N 168,700 to 190,000 cycles Solve questions 2 by referring to and understanding the examples given in lecture slides (Fatigue). Question 2: A steel shaft in bending has an ultimate tensile strength of 710 MPa and a shoulder with a fillet radius of 3 mm connecting a 32 mm diameter with a 38 mm diameter. Estimate the fatigue stress concentration factor, Kf. Answer: Kf= 1.51 Solve question 3 by referring to and understanding the examples in lecture slides (Ceramics). Question 3: The modulus of elasticity for spinel (MgAl204) having 5 vol% porosity is 240 GPa. (a) Compute the modulus of elasticity for the nonporous material. (b) Compute the modulus of elasticity for 15 vol% porosity. Answer: a) 265 GPa b) 195 GPa Solve question 4 by referring to and understanding the examples in lecture slides (vibrations). Question 4: What is the torsional stiffness of an annular steel shaft (G = 80 x 10 N/m2) with a length of 2.5 m, inner radius of 10 cm, and outer radius of 15 cm? Answer: K = 2 x 107 Nm/rad