Shock Behaviour of 3D Carbon-Carbon Composite

Abstract

. The compressive response of a 3D carbon-carbon composite under shock wave was studied in a plateimpact configuration. Two directions of in~pact were achieved until a nominal value of longitudinal stress of 2.5 GPa. The measured wave profiles are consistent with previous results on 3D composites and confirm the behavim of such materials under impact. It is shown that the initial loading is decomposed in two waves. The first one is transmitted by the longil~rdinal fibres, the second one correspouds to the propagation of a shock wave in the 'matrix'. Macroscopic characteristics of this nlaterial arc provided.RCsumC . On presente la reporise sous choc d'un conlposite 3DCC i partir d'essai d'impact de plaques. Deux directions d'anisotropie ont tte etudiis jusqu'h une contrainte maximum de 2.5 GPa. La rorrne des diagrammes de vitesse est coherente avec les resultats deja obtenus sur les conlposites 3D et confirme leur co~nportement sous choc. On montre que la sollicitatio~~ initiale se decompose en deus ondes. La prernitre est transport& par les fibres longitudinales, la seconde par la matrice. On presente des caracteristiques macroscopiques calculks sur ce composite 3DCC.

The effect of orientation on the shock response of a carbon fibre–epoxy composite

“…1.0 GPa, followed by a much steeper rise to the final stress amplitude. This is qualitatively similar to the traces observed by Bordzilovsky et al [18] and Hereil et al [19] who proposed either an elastic precursor or a high velocity wave front transmitted along the fibres respectively.…”

“…This was interpreted as an elastic wave. Hereil et al [19] observed similar behaviour in a three dimensional carbon -carbon composite, with a low amplitude ramp preceding a much more quickly rising shock front. However, their interpretation suggested that this precursor was due to a high velocity wave transmitted along the fibres orientated in the shock axis, whilst the main shock was transmitted through the "matrix", in this case the fibres and binder orientated orthogonally, in agreement with previous studies [16,17].…”

“…1.0 GPa, before the signal rises more rapidly. This latter behaviour has been observed in a number of other materials, including a unidirectional composite [18], and a three dimensional carboncarbon composite, where by definition, one of the fibre directions lay along the loading axis [19]. A number of mechanisms have been proposed to explain this behaviour.…”

“…In contrast, Hereil et al [19] suggested that the first part of the wave be transmitted along the fibres, with the rest transmitted through the matrix, which they defined as a mixture of fibres orientated normally to the loading axis, and the binder. We also observed that the form of these traces was near identical to similar traces taken from the open structured borosilicate glass [23].…”

“…We note with interest that Hereil et al [19] observed that their material contained a quantity of cracks and voids after the final maufacturing step in their material. Ahrens and Johnson [25] have also quoted the density for monolithic graphite and carbon fibres as 2.21 and 1.52 g cm -3 respectively, suggesting that the carbon fibres themselves contain significant porosity.…”