Topic: Strength of Materials
A solid bar 50 mm in diameter and 2000 mm long consists of a steel and aluminum part joined together. When axial force P is applied to the system, a strain gauge attached to the aluminum indicates an axial strain of 800 mu m/m. What is the corresponding axial strain on the Steel? Assume Est = 200 GPa and EAl = 70 Gpa.
- A. 28 mu m/m
- B. 140 mu m/m
- C. 280 mu m/m
- D. 14 mu m/m
Answer: C. 280 mu m/m
Explanation: The parts are in series, so the stress is identical in both. Stress = Strain_Al * E_Al = 800 * 10^-6 * 70 GPa = 56 MPa. Strain in steel = Stress / E_st = 56 MPa / 200 GPa = 280 * 10^-6 = 280 microstrain (mu m/m).