Analysis of the preforming behaviour of the braided and woven flax/polyamide fabrics

Abstract

Natural flax fibres have been extensively recognized by automotive industries to reduce the weight of vehicles and obtain recyclable composite parts. Most of composite parts are produced by using resin transfer moulding or thermoforming processes. As the first step of these two composite manufacturing processes, the preforming is quite important. Braided and woven fabrics are widely used as textile reinforcements to manufacture the advanced composite parts. But few research works concern the preforming of the reinforcements based on natural fibres and also there is no analysis of dry braided fabrics forming. In the present work, the studies of formability behaviour of braided and woven fabrics made of the same flax/polyamide 12 commingled yarns are performed. Furthermore, an experimental comparison between the preforming behaviour of braided and woven flax/polyamide fabrics is investigated under identical preforming conditions. The different formability behaviour and the defects developed during preforming stage are analysed. First results obtained on hemispherical shape show a higher deformability for the braided reinforcements, which can generate some forming defects, in particular buckles.

Specific features of flax fibres used to manufacture composite materials

“…The braid angle is defined as the angle between axial direction and bias tow and is in the range 5° to 85°. From flax/PA12 commingled yarns the production of biaxial braids with a braiding angle of 35° was presented by Jacquot et al [169] ( Figure 11). The formability behaviour was analysed and compared to woven fabrics made with the same yarns.…”

Intra-ply yarn sliding defect in hemisphere preforming of a woven preform

“…Fig. 1 shows the experimental preforming machine developed at the GEMTEX laboratory [16,31]. The machine is composed of three basic parts: a punch and two square-shaped plates.…”

“…For the first configuration, corresponding to the machine design employed for the analysis and the experiments conducted previously in this study, the lower plate is fixed while the upper plate is mobile. The blank holder force is applied on the upper plate so it is in the opposite direction of the punch translation [24,31], Fig. 1.…”

A novel route for volume manufacturing of hollow braided composite beam structures

“…Among the available hybrid yarns, commingled thermoplastic yarns are more suitable for braiding because of their easy handleability [13,14] and relatively superior drapeability. Previous literature shows several instances of incorporation of commingled thermoplastic yarns in a braiding process [15][16][17][18][19].…”