Definition
The measured force required to separate two surfaces that have been joined by an adhesive, weld, solder, or other bonding process. It indicates how well the bonded joint resists being pulled apart, peeled, or sheared under load.
Plain English
How strongly two pieces stick together once they have been glued, welded, or otherwise joined. The higher the bond strength, the harder it is to pull them apart.
Context Anchor
Seen in aircraft maintenance, repair, and inspection discussions involving adhesives, bonded panels, fabric, sealants, or composite parts.
Derivation
From bond, meaning a tie or link that holds things together, and strength, meaning the force something can withstand. Together: the holding power of a joined connection.
Why Pilots Care
Bonded joints appear throughout modern aircraft, especially in composite skins, control surfaces, and honeycomb structures. If bond strength is reduced by age, moisture, or poor repair, the joint can fail in flight under loads it was designed to handle.
Analogy
Think of two pieces of wood glued together. Bond strength is not the strength of the wood itself; it is how hard it is to make the glued joint come apart.
Intuition Check
Do not read bond strength as a general statement that something is “strong.” Here it means the holding ability of the joined area between two surfaces.
Example Sentence 1
The repair manual specified a cure time of 24 hours to ensure the adhesive reached full bond strength before the panel was returned to service.
Example Sentence 2
The repair was rejected because the bond strength fell below the minimum value specified in the maintenance manual.