How to Calculate Thermal Stress
What is Thermal Stress?
Thermal stress develops when temperature changes constrain material expansion. Critical in composite structures and multi-material assemblies.
Formula
Calculate: σ_th = E × α × ΔT where α is expansion coefficient
- E
- E value — Variable used in the calculation
Step-by-Step Guide
- 1Calculate: σ_th = E × α × ΔT where α is expansion coefficient
- 2If constrained (cannot expand freely), stress develops
- 3Account for different materials with different expansions
Worked Examples
Input
Steel bar L=1m, ΔT=50K, α=12×10⁻⁶, E=200GPa, fully constrained
Result
σ ≈ 120 MPa tensile stress
Significant stress
Common Mistakes to Avoid
- ✕Neglecting thermal stress in composite structures
- ✕Assuming small temperature changes are negligible
Frequently Asked Questions
Why do bridges have expansion joints?
To allow free expansion/contraction from temperature; otherwise excessive stress develops.
How do mismatched material expansions cause problems?
Different αbetween materials creates internal stress at interfaces that can cause cracking.
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