DERA unveils first plastic tank

DERA unveils first plastic tank

16 March 2000

DERA and Vickers have developed the first Armoured Fighting Vehicle (AFV) with a plastic/glass fibre composite hull rather than the traditional aluminium or steel hull. Advanced Composite Armoured Vehicle Platform (ACAVP) is a materials demonstrator vehicle programme which is funded by the MoD and designed and built jointly by DERA and Vickers.

The vehicle, developed with support from Ciba, Hexcel and Perkins Engines, has stemmed from a need to maintain and improve the survivability of light-weight AFV structures, and according to DERA, represents the most revolutionary change in AFV materials since the introduction of aluminium in the early 1960s.

The ACAVP hull is made from E-glass, a plastic/fibre glass composite manufactured by Vosper Thornycroft. Apart from the weight advantage given by the use of composite materials, this application also eliminates the need for a separate composite spall liner, used to reduce the effect of armour 'splinters' that ricochet around the turret after a hit by an incoming round. An additional advantage is the material's damping capacity, which reduces noise levels both inside and outside the vehicle. This results in lower crew fatigue and a lower acoustic signature for the vehicle.

Weight reduction increases both tactical mobility of the vehicle in terms of vehicle speed and ability to cross rugged terrain, and strategic mobility in terms of being air portable. Stealth features that reduce the radar signature can be built into the vehicle's hull. The composite is also easy to machine, relatively cheap compared to alternatives, and is corrosion resistant wet/salt water conditions.

The ACAVP demonstrator is based on a future scout reconnaissance vehicle with a battle weight of between 18-25 tonnes. DERA scientists are confident that further weight savings are achievable for future vehicles based on their continuing research into new materials and design methods.

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Development for the Advanced Composite Armoured Vehicle Platform (ACAVP)

The aim of the Defence Evaluation and Research Agency's ACAVP programme is to produce Europe's first composite armoured fighting vehicle. This is in response to the changing demands of the military, and the need for lighter weight, air-deployable vehicles. A demonstrator vehicle is intended to test the feasibility of using composite materials thick enough to provide both ballistic protection and to serve as a primary load-bearing structure.


The figure below shows the solid model representation of the prototype ACAVP (courtesy DERA Land Systems, Chertsey). A full description of the project has been published by M. French and M. Lewis in Journal of Defence Science, Vol. 1 (1996), pp. 296-301.




In 1992, ACMC was commissioned to produce a series of test panels for ballistic and mechanical property evaluation. The project involved not only materials characterisation, but also process development, since DRA were keen to consider the feasibility of using RTM for the eventual full scale prototype.


The test panels were quite different from anything previously attempted at ACMC. Although only 1 square metre in area, they were up to 60 mm thick monolithic composite, each containing up to 70 kg of reinforcement at a target fibre content of around 55% by volume. They also required 6 large stainless steel threaded inserts to be bonded in.


At this time, the materials specification was completely open, and the manufacturing schedule included a wide range of reinforcements (E, S2, R and T-glass, plus carbon and aramid fibre). Before concentrating on epoxy resin, trials were also carried out with polyester, vinylester and phenolic resin.




In order to maximise mechanical properties, many of the mouldings used non-crimp fabrics. These fabrics are stitch-bonded, rather than woven. The result is a highly conformable fabric (see right), which achieves good mechanical properties by maintaining the straightness of fibres.

A further important consideration for this work is the availability of non-crimp fabrics in high areal weights - this reduces the lay up time for thick laminates. Work began with 'quadriaxial' fabric (plies at 0, 90 and 45o) of areal weights over 2 kg/m2, and progressed on to a wide range of biaxial materials, with areal weights between 1 and 2 kg/m2.

The pictures below show two examples of glass/epoxy panels produced. The panel on the left has its threaded bolts integrally moulded; the panel on the right is being drilled for subsequent bonding of the inserts.



Several processing problems were encountered during the project. One related to the high loft associated with such a thick reinforcement pack. This made mould closure particularly difficult, and has important implications for tooling and preform design. Resin flow was generally satisfactory, but it was noted that the quadriaxial non-crimp fabric presented a high resistance to flow in the through-thickness direction, occasionally leading to dry areas near the centre of the panels. Impregnation was generally better with the biaxial fabrics.


Manufacture of the prototype vehicle has been in progress at Shorts, Belfast and at Vosper-Thorneycroft, Southampton. For more details on the ACAVP programme, contact Dr. Mark French, DRA Chertsey (E-mail: mafrenchtaz.dra.hmg.gb).

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