Drapability of dry textile fabrics for stampable thermoplastic preforms

Sandwiches based on stampable foam core and face sheets offer potential for cost-effective applications. Since the formability of such sandwich struct ures mainly depends on the drapability of the face sheets, the deformation behaviour of several types of textile preforms was evaluated. Glass fibre f abric preforms in the form of plain weave, twill, crowfoot and eight-harnes s satin as well as warp and weft-knitted architectures were studied. The te nsile properties of the dry fabrics at various orientations and the locking angle of woven fabrics in the bias direction were determined. An analytica l model is proposed to relate the fabric parameters to the locking angle. D rapability tests were performed on several woven and knitted fabrics in ord er to relate the forming energy to the preform architecture. Due to their h igh drapability and low forming energy, warp-knitted structures were select ed as textile reinforcement for the sandwich face sheets. (C) 2000 Elsevier Science Ltd. All rights reserved.