Thermal Expansion Calculator

Unrestrained thermal expansion is a geometric effect — the material simply grows in proportion to its length, coefficient of expansion, and temperature change, regardless of how thick or stiff the cross-section is. Area and elastic modulus only come into play when expansion is prevented, determining how much stress and force build up in a restrained member instead of how far it would have moved if free.

Free expansion is what happens when a member is allowed to change length unopposed, producing physical movement with no internal stress from the temperature change alone. Restrained thermal stress occurs when something prevents that movement entirely, converting the expansion that would have happened into internal stress and force instead, which can be severe enough to yield or fracture the material.

Aluminum's coefficient of thermal expansion is roughly double that of steel, so for the same length and temperature swing, an aluminum member moves about twice as far. Expansion joints, sliding supports, and clearances designed for steel are typically undersized if the same structure or assembly is built from aluminum instead.

Yes — if a member is fully restrained and the temperature swing is large enough, the resulting thermal stress can exceed the material's yield strength, causing permanent deformation, or exceed its ultimate strength and cause fracture. This is why expansion joints, sliding bearings, and flexible couplings are standard practice anywhere a rigid, fully restrained run of pipe, rail, or structural member would otherwise fight against thermal movement.