CARBON VS. ALUMINIUM

Carbon fibre is an anisotropic material, this means it is extremely efficient when working in the designed direction, but relatively poor in any other direction. Aluminium alloy is isotropic (average in all directions). To optimise a carbon mast we have to ‘lay’ the fibres in a cleverly designed ‘laminate’ to produce a tube that can give us all the characteristics the spar will require (i.e. longitudinal, torsional, hoop strength and stiffness).Seldén have researched the optimum fibre angles to generate the resultant stiffness for ultimate stiffness and performance. In filament winding we can laminate any angle from 5° to 90° (angle to zero axis), and add 0° fibres manually when necessary. However our competitors will claim that our masts are not as good as theirs because our fibres are not laid at 0°. This is not true. Their claimed performance is theoretical, which is rarely achieved in the final laminated product for the following reasons:

Resin and void content

Factors such as resin and void content have a dramatic effect on the strength of the laminate. The resin content in pre-preg tow is far more accurately controlled than in wet lay up or infusion processes so the laminate strength is maximised.The resin cure cycle is also very important in maximising the strength of the final structure. An autoclave has a very sophisticated ramp cycle and pressured cure, which virtually eliminates voids from the laminate. Voids are effectively holes and a high void content will dramatically reduce the laminate strength. (Autoclave cure is essential on profiled laminates).
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