Table of Contents
What Is Thermal Stress?
Thermal stress occurs when constrained materials cannot freely expand or contract with temperature changes. A fixed steel beam heated by 100K develops 240 MPa of compressive stress - significant compared to steel's yield strength of 250-400 MPa. This causes buckling in rails, cracking in concrete, and fatigue in engine parts.
Engineers manage thermal stress through expansion joints, sliding supports, flexible connections, and material selection. Low-expansion alloys like Invar minimize thermal stress in precision applications.
Formula
σ = E × α × ΔT
F = σ × A
Thermal Stress (ΔT = 100K)
| Material | Stress (MPa) |
|---|---|
| Steel (E=200, α=12) | 240 |
| Aluminum (70, 23) | 161 |
| Copper (120, 17) | 204 |
| Invar (140, 1.2) | 17 |
FAQ
When do thermal stresses matter?
When structures are rigidly constrained, temperature changes are large, or materials are brittle. Primary cause of fatigue failure in thermally cycled components like exhaust manifolds and turbine blades.