A fully restrained steel member is heated 60 degrees C. With E=200 GPa and thermal expansion coefficient 12e-6 per degree C, compressive thermal stress magnitude is most nearly:
- (A)144 MPa
- (B)240 MPa
- (C)288 MPa
- (D)720 MPa
Show worked solution
Answer: (A)
Full restraint converts free thermal strain alpha delta T into stress E alpha delta T=144 MPa compression.
The member's prevented free strain is alpha times temperature change.
Elastic stress balances that restrained strain.
FE Reference Handbook — Materials Science: Thermal Stress
Why the other choices appear
- (B)Using only one-sixth of the temperature rise understates stress.
- (C)Multiplying modulus and expansion coefficient but omitting part of temperature rise gives an unrelated result.
- (D)Using half the elastic modulus gives half the restrained stress.