Definition
A measurement of the force required to peel a flexible bonded material away from the surface it is adhered to, expressed as force per unit width (typically pounds per inch). It indicates how well an adhesive resists being lifted or stripped from one edge.
Plain English
How hard you have to pull to peel something glued down off its surface, starting from one edge.
Context Anchor
Seen in aircraft maintenance when checking fabric covering, bonded repairs, protective coatings, tapes, or glue joints.
Derivation
From 'peel' (to strip away a thin outer layer) and 'strength' (resistance to force). The name describes the test itself: pulling one edge of a bonded material upward and measuring how much force the bond resists before separating.
Why Pilots Care
Ensures bonded repairs on composite structures hold under flight loads and environmental stress.
Analogy
Think of pulling tape off a surface. The tape may hold well when pulled straight along the surface, but once an edge lifts, it can peel away much more easily.
Intuition Check
Peel strength does not mean the overall strength of the part. It means how well an attached layer resists being pulled off from an edge.
Example Sentence 1
The technician checked the manufacturer's specification for peel strength before approving the bonded doubler repair.
Example Sentence 2
The inspector noted reduced peel strength along the seam after exposure to moisture.