This paper presents some of the recent research work taking place in the development of complex shape preforms using weft-knitting and braiding technologies for technical applications, especially for composite materials reinforcement. A FEA model has been used for the prediction of the deformation behaviour and related mechanical properties of weft knitted fabrics and corresponding composite material. A plain weft knitted fabric, based on the simple loop structure, is simplified and represented by a 2D hexagonal structure constructed by the non-linear truss elements. The characteristics of the truss elements for FEA simulation are obtained from experimental results through an analytical method when a loop is converted to a FEA model. The elongation deformation is simulated in one, two and multi directions. The model can also be used to calculate a plain weft-knitted fabric to be deformed to fit a 3D mould with a spherical form.