Wednesday 5th July 2017

Carbon Fibre Compression Tunability

The Carbon Composite Bellows™ Spring (CCBS) is a system of stacked carbon fibre elements, similar in design to a Belleville washer, that combine to work as a high performance, extremely light weight flexible compression spring. Using carbon composites takes advantage of the materials unique high tensile properties in bending.

Offering a new solution to old challenges, the Carbon fibre composite material offers significant advantages compared to conventional metallic alloys when used as a compressive spring material. By using a moulding technique allows for complicated and intricate designs to be formed in a single operation and permits design features not possible with a machined or stamped metallic part. By orientating several individual carbon fibre elements, paired in sets and joining them to make a stack forms the carbon fibre compression spring. The spring rate of the stack is determined by the number of elements, the base spring rate of each element, and their series or parallel orientation in the stack.

 

The laminate construction also permits steeper pitch angles of each disc to be utilised with the design which allows more deflection per element without over-stressing. In fact, recent data has shown that pitch angles of each element between 7° and 10° are possible, which would allow a great degree of deflection and spring rate at desired loads. By then mixing predetermined spring rate spring sets within the same stack can provide a variable and predicted reaction force across the compression range. Or as we like to say a “compressive tunability”.

The unique product delivers excellent reduction in hysteresis during operation. By reducing hysteresis ensures that the deflection value is equal during compression and extension, which translates directly into more predictable, controllable spring rates, which react faster and more precisely.

For a given rate and deflection, a CCBS stack weighs significantly less than its metallic brother often achieving up to a 60-70% weight saving!  In addition, the spring rate of each element is determined by its finished thickness. This means new or custom rates can be built quickly and do not require the use of different raw material sizes or special tooling.  As Carbon fibre is non-magnetic and impervious to many liquids, industries requiring a precise spring rate, a reduction in weight and zero corrosion are ideal for this product. The product is a solution looking for a problem.

For further information contact our sales department on 01386 421005