We at MULE attended a crash course in Composite manufacturing hosted by a few fine fellows at the City of Bristol College, to look into the potential use of carbon/glass fibre resin composites.
This composite mat comprises 4 layers of glass fibre matting layered between 2 layers of carbon fibre matting. The tensile strength of this material can potentially withstand many tons of force. Its flexural strength however is nowhere near as impressive.
So what have we learnt about composite materials?
- Carbon fibre has amazing tensile and good compressive strength, but poor shear strength. The fibres are incredibly difficult to break whilst straight, but simply tying a knot into a fibre renders it extremely weak when pulled.Interesting fact: Each of the woven cords that you can see in the make up of the mat in the picture is actually made up of 3000 strands of carbon fibre. No, I didn’t count them, but I don’t think they were pulling our legs.
- Carbon fibre is brittle. This means that on its own it would be no good for our false floors as they are sure to suffer more than the odd impact in their lifetime.To counter carbon fibres’ poor flexural strength and brittle nature, carbon fibre is often sandwiched with fibre-glass to give both resilience to impact, and improved flexural strength. For increased flexural strength the layers of carbon fibre can be distanced from each other by the insertion of a bonded honeycomb core material with a high sheer strength. In this configuration the carbon fibre is only really subjected to compressive and tensile forces that it can handle easily. This filler is known as a composite sandwich core.
- Composites can be incredibly light when compared to other materials of similar strength.
Will MULE be using composites in the future?
We would certainly like to take advantage of the weight reduction possibilities available with composites, but at present we feel it would be prohibitively expensive for us. Volume of manufacture will however dictate to us when it is an appropriate time for us to revisit this possibility. In the mean time we will be experimenting with different composite materials to find the best combination for us.