Delamination

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This article is about composite materials. For delamination in embryology, see Embryogenesis. For delamination in geology, see Delamination (geology)

'Delamination' is a mode of failure of laminated composite materials. Repeated cyclic stresses, impact, and so on can cause layers to separate, forming a mica-like structure of separate layers, with significant loss of mechanical toughness. Delamination is an insidious kind of failure as it develops inside of the material, without being obvious on the surface, much like metal fatigue.

Delamination failure may be detected in the material by its sound; solid composite has bright sound, while delaminated part sounds dull. Other nondestructive testing methods involve embedding optical fibers coupled with optical time domain reflectometer testing of their state, testing with ultrasound, and infrared imaging.

Some manufacturers of carbon composite bike frames suggest to dispose of the expensive frame after a particularly bad crash, because the impact could develop defects inside the material.

Due to increasing use of composite materials in aviation, delamination is increasingly an air safety concern, especially in the tail sections of the airplanes.

Delamination risk is as old as composite material. Even in 1940s, several Yak-9s experienced delamination of plywood in their construction.

Delamination can also occur in large steel I beams too. Due to Welding or heat on the exterior of the beam, which cause the beam web, or flange lose its shape.