Community Research and Development Information Service - CORDIS

Embroidered reinforcements for structural composites

From engineering to medicine, textile technology research has uncovered greater scope for application. A novel innovation takes advantage of the embroidery stitching technology for creating cost-effective fibrous composites for engineering structures and surgical implants.
Embroidered reinforcements for structural composites
Fibre-composites based upon matrices are increasingly used in many industrial and medical applications. Medically speaking, the present advancement in embroidery technology has facilitated medical implants that do not suffer the detrimental limitations of current embroidery stitching such as size limitations, structural instability and incompatible uniformity. The technology allows for greater manipulation of implants. For example, in the case of abdominal aortic aneurisms, the lumen can be looped or twisted without suffering from structural collapse or closure. Additionally, the stitching process now allows for implants to be customized according to patient specific needs and offers, high specific stiffness and excellent fatigue resistance.

These embroidery techniques allow multi-angle fibres that are highly impact resistant. They can also integrate fixation meshes in multiple orientations for suture purposes. The reinforced patterns may incorporate bioactive materials, including drug releasers, growth promoters and antibiotics to name a few. By exploiting a wide range of conventional biocompatible materials that are introduced to the implants without human intervention, they are widely accepted by the surgeons' society.

Aided by current CAD-CAM techniques, embroidery enables the optimal fibre architecture for flexible, structural excellence. Such flexible patterns can improve local strength and stiffness, while at the same time minimising the costs associated with current embroidery techniques and waste of raw material. A current test project, MASCET identified two embroidery techniques, Cornely and Schiffli, and found that under this technological advancement, the results were comparable to commercially available reinforcement fabrics.

As an alternative to conventional fibrous technologies, the experimental study proved that the new embroidery techniques are suitable in assembling high modulus reinforcement fibres in near net-shape pre-forms, doing so at low costs. The study encompassed the materials used for embroidery, as well as the process variables and the architecture of the reinforcement for both pre-form elements (patches) and near net-shape pre-forms. As a result, a number of embroidered textile pre-forms for composite materials were fabricated that are comparable to conventional fabrics.

Another aspect of the embroidering technology is through thickness stitching technique, which is a method to minimise the separation of the layers, that are the constituent parts of many textile reinforced composites. If the finished part is subjected to a heavy impact, there is a danger that the layers may split apart, resulting in the composite failure. “Through stitching” is a fast, flexible and economical, three-dimensional method to improve impact resistance for both thermoset and thermoplastic matrices. It is also worth mentioning that it can be applied to many liquid moulding techniques, such as resin injection.
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