Z-Axis Stitching

Ellis Developments Limited

Nottinghamshire, United Kingdom

Through-Thickness Reinforcement of Composites for Improved Impact Resistance and Delamination Resistance

Through Stitching)

The Mascet project studied the potential for the use of embroidery in the manufacture of structural composites (reinforced plastics) and was completed in 1997. Since then Ellis Developments have examined the use of stitching technologies to hold together different layers of textiles, similarly for use in structural composites.

Through thickness stitching has the potential to reduce the splitting apart of the layers which are used to form many textile reinforced composites. If the finished part is subjected to a heavy impact, there is a danger that the layers may delaminate, and the composite will fail in its task. Through stitching has been found to improve impact resistance, and may have particular application in aircraft which are subject to bird strikes.

The ZARC Project was an initial study part funded by the European Community’s Framework research fund, and was run in collaboration with Teritex and the University of Nottingham, Department of Mechanical Engineering. The results of the literature study indicated that there is considerable confusion about what can be achieved: we believe we can bring some considerable clarity to the subject through our knowledge of the subject.

Our work on through stitching is continuing at Ellis Developments in conjunction with QinetiQ at Farnborough, England, Airbus UK and others. Through stitching is proving to be a rapid, flexible and inexpensive method of achieving the desired results.

The reinforcement of corners is usually possible, and we have successfully through-stitched prepregs (fabrics pre-impregnated with resin), and have developed this and can provide a service to customers. The through stitching demonstrates significantly improved impact resistance characteristics.

Through Stitching

We are currently carrying out work on through stitching pre-impregnated carbon fibre for composites. This has long been considered almost impossible, but we are achieving exciting results on 6 mm thick lay-ups, and usually use PBO as a through stitching material, which has better moisture relations than Kevlar, although are currently examining other materials. We have also been successful with Kevlar and glass. For further details contact us, but clicking here will provide more information on through-thickness stitching,