Production Principles and Technological Development of Novel Woven Spacer Preforms and Integrated Stiffener Structures
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Production Principles and Technological Development of Novel Woven Spacer Preforms and Integrated Stiffener Structures Ahmet R. Torun & Adil Mountasir & Gerald Hoffmann & Chokri Cherif
Received: 17 May 2012 / Accepted: 21 June 2012 / Published online: 5 July 2012 # Springer Science+Business Media B.V. 2012
Abstract 3D textile preforms offer a high potential to increase mechanical properties of composites and/or decrease manufacturing costs. Within the scope of this study, production principles were developed for complex spacer preforms and integrated stiffeners. These principles were applied through technological further development of the well-known faceto-face and terry weaving techniques. Various woven preforms were produced with Glass fibre/Polypropylene (GF/PP) Commingled yarns, however, the technology is suitable for any type of reinforcement yarns. U-shaped woven spacer preform was consolidated into a sandwich composite component for lightweight applications. Keywords 3D preforms . Spacer fabrics . Stiffener . Manufacturing
1 Introduction Spacer preforms are characterized by two outer fabric surfaces connected with pile yarns. Warp knitting, Weft knitting and Weaving technologies are conventionally utilized for producing this kind of 3D structures. Woven spacer fabrics are produced with the so called face-to-face weaving technique [1]. This technique is mainly applied for producing velvet and carpets with high productivity. Two surfaces of outer woven layers are connected with pile yarns and a cutting mechanism separates these two layers in the middle of pile yarns. If the cutting system is omitted, woven spacer fabrics are produced with connecting piles. Along the width of the spacer fabric, pile yarns have a right angle, however, along the length pile yarns are binding the two layers with angle. After consolidation, pile connections have an angle distortion and they have limited capacity to withstand high pressure and shear stresses. Conventional woven spacer fabrics are mainly used as reinforcements especially for pressure tanks, transportation and marine industry [2] (Fig. 1). A. R. Torun (*) : A. Mountasir : G. Hoffmann : C. Cherif Institute of Textile Machinery and High Performance Material Technology, Technische Universität Dresden, 01062 Dresden, Germany e-mail: [email protected]
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Appl Compos Mater (2013) 20:275–285
Fig. 1 Woven spacer fabric [2]
For flexural stiff Thermoplastic composites, spacer fabrics with fabric cross-links are necessary. The conventional pile connection is not suitable for hot pressing of Thermoplastic composites. Spacer fabrics with fabric cross-links have already been described in two early patents [3, 4]. The technological modification of flat Knitting and Weaving technologies were described in the literature [5–8]. These two technologies are suitable for the development of this special kind of spacer fabrics which has the advantages of continuous reinforcement along the connecting points of base fabrics and cross-links. Similar structures of integrated stif
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