Mechanical properties of vacuum infused CFRP-laminates - dependency of fibres, resins and processing parameters

Carbon fibre reinforced plastic (CFRP) laminates are getting more widely used outside the aerospace industry. For large structures the selected process is often vacuum infusion, due to tool cost and heating/pressure limitations for large components. It has also been shown that such process can give sufficient mechanical properties. In the current EUROPE 103-014 project, supported by the Western Union Armament Group (WEAG), CFRP structures has been investigated for Armoured Fighting Vehicles (AFV). The Norwegian consortium conducted a large testing program on CFRP-laminates and CFRP/sandwich in order to qualify candidate carbon fibres, resins and production process. This paper is focusing on the dependency of the mechanical properties of CFRP laminates and CFRP/sandwich on process parameters in the vacuum infusion process, resin selection, cure system, cure temperature, test method, and fibre sizing. Especially the compression properties are varying much, but it is shown that it is possible to achieve properties close to the theoretical potential. It is shown that relatively small changes in material and process can give substantial difference in mechanical properties. The paper discusses the need for qualification procedures and quality control in order to take this reality into consideration when ply data for structural design are established.