Delamination

Delamination
Delamination of CFRP under compression load

Delamination is a mode of failure for composite materials.[1] Modes of failure are also known as 'failure mechanisms'. In laminated 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 also occurs in reinforced concrete structures subject to reinforcement corrosion, in which case the oxidized metal of the reinforcement is greater in volume than the original metal. The oxidized metal therefore requires greater space than the original reinforcing bars, which causes a wedge-like stress on the concrete. This force eventually overcomes the relatively weak tensile strength of concrete, resulting in a separation (or delamination) of the concrete above and below the reinforcing bars.

The cause of fiber pull-out (another form of failure mechanism) and delamination is weak bonding.[2] Thus, 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, reinforced concrete sounds solid, whereas delaminated concrete will have a light drum-like sound when exposed to a dragged chain pulled across its surface. Bridge decks in cold climate countries which use de-icing salts and chemicals are commonly subject to delamination and as such are typically scheduled for annual inspection by chain-dragging as well as subsequent patch repairs of the surface. Other nondestructive testing methods are used, including embedding optical fibers coupled with optical time domain reflectometer testing of their state, testing with ultrasound, radiographic imagining, 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.

References

  1. ^ WJ Cantwell, J Morton (1991). "The impact resistance of composite materials -- a review". Composites 22 (5): 347–62. doi:10.1016/0010-4361(91)90549-V. 
  2. ^ Serope Kalpakjian, Steven R Schmid. "Manufacturing Engineering and Technology". International edition. 4th Ed. Prentice Hall, Inc. 2001. ISBN 0-13-017440-8

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Look at other dictionaries:

  • Delamination — De*lam i*na tion, n. (Biol.) Formation and separation of lamin[ae] or layers; one of the methods by which the various blastodermic layers of the ovum are differentiated. [1913 Webster] Note: This process consists of a concentric splitting of the… …   The Collaborative International Dictionary of English

  • délamination — ● délamination nom féminin Séparation des feuillets d un ensemble à structure feuilletée, par exemple chez un embryon animal …   Encyclopédie Universelle

  • Delamination — Delamination, Abblätterung ⇒ Gastrulation …   Deutsch wörterbuch der biologie

  • delamination — 1877, from DE (Cf. de ) + LAMINATION (Cf. lamination) …   Etymology dictionary

  • delamination — [dē lam΄ə nā′shən] n. 1. separation into layers 2. Embryology the formation of endoderm by the splitting of the blastoderm into two layers of cells …   English World dictionary

  • Delamination — vom Rand her delaminierendes Verbund Sicherheitsglas Delamination (Enthaftung) bezeichnet das Ablösen von Schichten in Werkstoffverbunden, zum Beispiel in Faserverbundwerkstoffen oder das Ablösen einer Korrosionsschutzschicht auf einem Stahlteil …   Deutsch Wikipedia

  • Delamination — Schichtablösung; Ablösung von (Laminat ) Schichten * * * Delamination   [lateinisch] die, / en, Form der Gastrulation. * * * De|la|mi|na|ti|on, die; , en [zu lat. de = von weg u. lam(i)na = Blatt] (Biol.): (bei der tierischen Entwicklung)… …   Universal-Lexikon

  • delamination — sluoksniavimasis statusas T sritis chemija apibrėžtis Išsiskirstymas sluoksniais. atitikmenys: angl. delamination; exfoliation; foliation; lamination; settling; splitting; stratification rus. расслаивание; расслоение …   Chemijos terminų aiškinamasis žodynas

  • Delamination (geology) — Sierra Nevada Mountains (formed by delamination) as seen from the International Space Station. In geophysics, delamination refers to the loss and sinking of the portion of the lowermost lithosphere from the tectonic plate to which it was attached …   Wikipedia

  • Délamination cathodique — La délamination cathodique est une forme de dégradation très courante pour les produits métallurgiques peints ou vernis. Il s agit habituellement d une réduction de l oxygène pour former de l hydroxyde, qui a lieu sous le film organique. Les… …   Wikipédia en Français

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