Composite Materials

· A two-ply laminate that is in a planar stress-free condition at room temperature will distort as shown if its temperature is changed.

· Many polymeric-matrix composites are cured at temperatures of about 200 C and will be stress free in the as-cured state. When these samples are removed from the autoclave and cooled to room temperature they will also distort in the manner shown.
· This behavior must be taken into consideration when designing components for airfoils, etc.. Symmetric laminate construction reduces these effects.

From: Hull,
"Introduction to Composite Materials,"
Cambridge (1992)