UD prepreg, as it integrates unidirectionally-aligned fibres with minimal amounts of resin, enhances the lightness, strength and rust resistance characteristics of carbon fibre. However, when manufacturing complex shapes, its limited formability can generate various defects such as wrinkling, voids and resin-rich areas due to the bridging of fibre at corners.
One way to enhance its formability is to use woven fabric. The disadvantage of woven fabric is that its mechanical properties and surface flatness are inferior to those offered by UD prepreg. Another technique consists in using carbon fibre pellets in injection moulding and Sheet Moulding Compounds. This method is capable of manufacturing complex shapes such as sharp convex and concave forms. However, the fibre volume fraction of parts manufactured using this technique is lower than that of UD prepreg and their mechanical properties are insufficient due to the use of pre-cut fibres.
Concept of Torayca ET40 Prepreg
> Extensible and transformable
> Equivalent modulus and 80% the strength of UD prepreg
> One-shot moulding and quick cure
> Multiple rib formation from flat laminate in compression moulding
> Excellent drapeability similar to woven fabrics used in preforming processes
The extensible and transformable Torayca ET40 prepreg was developed to provide an innovative product that simultaneously combines high mechanical properties and excellent formability. It has the advantages of UD prepreg without the usual trade-off between mechanical properties and formability. Torayca ET40 prepreg is made by introducing slits into a UD prepreg in a controlled manner, creating a type of unidirectional SMC material in which fibre bundles are regularly arrayed in the same direction. This allows for consistent and regular flow of the bundles during the moulding process and therefore results in the ability to be shaped into complex shapes, such as ribs and deep-drawing, while maintaining a homogenous laminate structure due to its extensible and transformable nature.
As a result of specific slitting patterns, ET40 can achieve equivalent surface appearance, modulus and over 80% of the strength of UD prepreg.
ET40 application in bikebody
Industries: Sports, Leisure & Recreation