Paper -Technical and economic advantages of continuous length +α -β Spread Tow Fabrics

A new reinforcement fabric called +α/-β Spread Tow Fabric (+α/-β STF) has been developed recently. It incorporates Spread Tow Tapes of carbon fibers in angular orientations relative to the fabric’s length direction. The +α/-β STF is producible in continuous length. It has been developed to enable direct production of multi-directional reinforcement by plying. Through use of +α/-β STF the production of composite materials can be simplified and quickened, besides improving their performance and quality. The technical and economic advantages of +α/-β STF, which is considered to be a uniquely optimized material solution for enabling automated composite material manufacture, introduced in this Paper.

Plying of woven fabrics has been practiced for long to obtain multidirectional orientation of fibers in the final composite material products. However, the following drawbacks of this approach are well known: 
(a) The relative relationship between warp and weft remains 90º no matter how the woven fabric is oriented. 
(b) The plying can be achieved using only fabric patches of limited area as they are cut from larger woven fabrics. 
(c) Cutting and plying involves labor, which in turn causes inconsistency in quality and increases production costs, material wastage and contamination risks. 
(d) Discontinuity of fibers and misalignment of fiber orientations due to use of fabric patches adversely affect the composite material performance.
(e) Uneven material thickness arising from overlapping of fabric patches.
(f) Difficulty in realizing process continuity or automated production.

The recent development of +α/-β Spread Tow Fabric (+α/-β STF) overcomes all the drawbacks indicated above directly and accords other advantages as well. The +α/-β STF is a continuous length fabric comprising Spread Tow Tapes in oblique orientations with respect to the length direction of the fabric.


This paper, written by Fredrik Ohlsson, Product Manager Materials, and Dr. Nandan Khokar, R&D Manager, was presented at the SAMPE TECH in October 2011 by Fredrik Ohlsson.