Technology

CompoTech places equal importance on every aspect of its technical capability, from the initial design and engineering through to materials selection and production process. Much research has been carried out into all of these areas to ensure customers receive a structural composite tube that will perform to the highest standards, whatever the application.

Zero degree axial fibre laying process

CompoTech has developed its own fibre laying process for structural composite tubes, which is particularly suitable for components which require high bending stiffness, stability & significantly improved Dynamic properties

This process offers:

• Maximum bending stiffness and strength
• Excellent dynamic properties
• Predictable and controllable high fibre content
• Consistent and repeatable thin or thick walled tubes and sections

This is due to the optimisation of the axial fibre placement, fibre fraction fraction and low porosity, all of which contribute to the impressive stiffness, strength and dynamic performance.

The laying of fibres in filament winding is carried out at a small ‘helical' angle of 5° or 7°, which is often called ‘near zero'. Although many people believe the strength and stiffness characteristics to be the same as zero degree (unidirectional) axial filament laying, CompoTech's research has shown that there is a clear improvement of about 15% in stiffness and about 40% in strength of zero degree axial fibre laying over ‘near zero' degree.

CompoTech collaborated with the Czech Technical University in Prague to test over 300 tubes with different winding angles. Each tube was made out of the same number of carbon fibre tows per layer. Two groups of tubes were made – one using a helical ‘near zero' degree winding technique and one using CompoTech's zero degree axial fibre laying technique. All tubes were tested for axial stiffness and strength.

Figure 1

In Figure 1, above, it is clear to see that fibre tow cross overs, as found in helical ‘near zero' winding, decrease both the strength and the stiffness of a layer. A composite tube made with the zero degree axial fibre laying process can achieve greater stiffness than one made with helical winding, yet retain the same weight and radial characteristics. Alternatively, a tube can be made with the zero degree axial fibre laying process to have the same stiffness as a helical wound tube, but with significant weight and cost saving.