Development of fibrous preforms for FRP pipe connections

This paper describes the experimental work carried on at the University of Minho concerning the design of weft-knitted fleecy fabrics for application in pipe connections produced with composite materials reinforced by 3D weft-knitted fabric preforms. The specifications of a T tube composite connexion have been established according to the information of the composites producer company involved in the project. The weft-knitted fleecy fabric has been optimized to perform a better mechanical performance, i.e., to increase the stiffness due to the use of straight fleece yarns. Special knitting techniques, developed by the authors, have been applied to produce 3D shaped performs to be impregnated by using RTM techniques. A special mould has been produced according to the required geometry. The results of the mechanical tests made on the final produced samples are presented, discussed and compared with those imposed in the initial specifications.