Round Tube

Carbon Fiber Tube Characteristics

Carbon fiber tubes are typically produced in circular, square, or rectangular shapes, but they can be fabricated into almost any shape, including oval or elliptical, octagonal, hexagonal, or custom shapes. Roll-wrapped prepreg carbon fiber tubes consists of multiple wraps of twill and/or unidirectional carbon fiber fabric. Roll-wrapped tubes work well for applications that need high bending stiffness combined with low weight.

Alternatively, braided carbon fiber tubes are made up of a combination of carbon fiber braid and unidirectional carbon fiber fabric. Braided tubes offer excellent torsional characteristics and crush strength, and they are well-suited for high-torque applications. Large diameter carbon fiber tubes are typically constructed using rolled bi-directional woven carbon fiber. By combining the right fiber, fiber orientation, and fabrication process, carbon fiber tubes can be created with the proper characteristics for any application.

Other characteristics that can be varied by application include:
Materials—Tubes can be fabricated from standard, intermediate, high, or ultra-high modulus carbon fiber.

Diameter—Carbon fiber tubes can be made from very small to large diameters. Custom ID and OD specifications can be met for particular needs. They can be made in fractional and metric sizes.

Tapering—Carbon fiber tubes can be tapered for progressive stiffness along the length.

Wall thickness—Prepreg carbon fiber tubes can be fabricated to virtually any wall thickness by combining layers of various prepreg thicknesses.

Length—Roll-wrapped carbon fiber tubes come in several standard lengths or can be built to a custom length. If a requested tube length is longer than recommended, multiple tubes can be joined with internal splices to create a longer tube.

Exterior and sometimes interior finish—Prepreg carbon fiber tubes typically have a cello-wrapped gloss finish, but a smooth, sanded finish is available, too. Braided carbon fiber tubes typically come with a wet-looking, shiny finish. They can also be cello-wrapped for a glossier finish, or a peel-ply texture can be added for better bonding. Large diameter carbon fiber tubes are textured on both the interior and exterior to allow for bonding or painting of both surfaces.

Exterior materials—Using prepreg carbon fiber tubes allows for the option of selecting different exterior layers. In some cases, this can also allow the customer to select the exterior color.

Types of Carbon Fiber Tubes

Applications of Carbon Fiber Tubes

Advantages of Carbon Fiber Tube

How To Care For Your Carbon Fibre Products?

In order to get the maximum life from your carbon fibre composite tubing we recommend the following care and precautions:

Do not allow the tubing to become excessively hot. High performance epoxy resins, together with oven post curing, are employed in our tubes, however at temperatures above approximately 75oC the epoxy can soften which dramatically reduces strength or otherwise can cause the tube to bow or warp. Note that black objects are the best absorbers of IR radiation (heat) and we have recorded a surface temperature of 65oC from a tube lying flat on the ground in the summer sun on a windless day.

Epoxy resins are UV light degraded. Excessive UV light has the effect of turning the exposed epoxy resin into a chalky layer which can then easily fall off, resulting in exposure of the fibres to the weather. Moisture can then enter the exposed fibres and cause wicking to the inside of the laminate which further reduces the laminate’s strength and integrity.

3)Whilst these two effects can be either avoided, or are relatively long term (many dinghy sailors have chosen to leave their masts naturally black), we recommend painting the composite tubing with a UV resistant polyurethane based paint or clear coating. Correct application of paint will effectively eliminate degradation due to these effects and allow the other long life properties (ie. excellent corrosion and fatigue resistance) of composite tubing to be realised.

Carbon fibres are good conductors of electricity. In a similar way that aluminium masts need lighting strike protection so do carbon fibre composite masts.

Because carbon fibres are good conductors there is potential for corrosion with dissimilar metals. The major metal to avoid here is aluminium. which is anodic to carbon, and hence corrodes in time. The use of plastic fittings, SS fittings or aluminium fittings with isolation barriers is good practise. Some SS metals may still corrode but generally higher grades of SS possess sufficient surface passivity protection to avoid corrosion. All said and done, many people still use aluminium fittings in direct contact with carbon fibre composites (ie spinnaker pole end fittings) and the corrosion effect is no greater than the general aging that occurs to the fitting due to wear and tear.

Carbon fibre composites are very directional in regard to mechanical properties. This is generally seen as an advantage because fibre direction can be optimised by aligning in the same direction as load paths. Most composite tubing used for masts, booms, poles, etc. are optimised for axial strength and stiffness. The strength and stiffness in the other ‘hoop’ direction is correspondingly much less. As a result, carbon fibre composite spars are produced with thicker walls than aluminium spars, however they can still be weaker in this hoop direction. Care should be taken to avoid excessive hoop loads for tubes designed for axial loads. An example of this kind of load is dropping a spinnaker pole onto the forestay whilst under spinnaker load. Localised sleeving of the pole (ie SS inner tube, Carbon inner tube) is good practise to strengthen the pole at this point.

Carbon fibre composites do not yield (plastically deform) prior to failure. Often little warning is given that the tube is likely to fail. Care should be taken in regard to heavily loaded tubes to avoid personal and product injury.