“Carbon fibre curved boards with tips • Geometry as per 3D Model of 07/06/16; HB60_DSS_2016_3105_stp.stp • Structure based on 2D structural drawing • Material – Carbon Fibre prepreg Uni direction T800, T800 Nano, M40J and T700n woven • Process - half moulded using Autoclave/vac, CMC machined lower face • Finish - delta surface film for the entire length of the shaft on both sides. Unfinished from start of elbow to end of tip. • Delivery8th August 2016 .” • Geometry as per 3D Model of 07/06/16; HB60_DSS_2016_3105_stp.stp • Structure based on 2D structural drawing • Material – Carbon Fibre prepreg Uni direction T800, T800 Nano, M40J and T700n woven • Process - half moulded using Autoclave/vac, CMC machined lower face • Finish - delta surface film for the entire length of the shaft on both sides. Unfinished from start of elbow to end of tip. • Delivery8th August 2016 .”
“4.2.3 A laminate is composed of fibres and matrix. We could start by thinking of the fibres as being like a ponytail and the matrix as a strong hairgel. 4.2.4 If we want to carry a load in tension, say lifting a bucket out of a well, we could cut off the ponytail, attach our load to each end then pull. The load we could carry would be proportional to the number of hairs, and aside from the difficulty of attaching the load to the ends of the hairs, we wouldn’t really need a matrix to contribute to the tensile strength - each hair would take its share of the tensile load. 4.2.5 If on the other we want to carry a load in compression, as in the case of a table leg, the bundle of hairs would be no use at all as individual strands would buckle and collapse. Gluing the hairs together with gel (like a punk spike hairstyle), would resist the tendency of the individual hairs to buckle and increase the capacity of a given bundle to resist compressive loads. If the matrix properly bonds to each strand and there are sufficient hairs in the bundle we could make a table leg capable of supporting the top and whatever is on it. The matrix is therefore important for compressive strength.”
“if there is too much resin then the fibre may be able to buckle within the matrix itself since the resin is roughly 100 times less stiff than the fibre. Or if there is a void, i.e. air, where there should be matrix, then the fibre will be even more poorly supported and prone to buckling. And once again it is also important the fibre to resin bond is good so that the fibres can adequately share the load and transmit it to one another.”
“On our third run the foil angle of attack was changed from 2.8˚ to 3.8˚ and boat was sailing at around 26 knots downwind when there was a huge bang and the boat heeled violently. The helmsman reacted very quickly and turned the boat downwind and the boat slowed. When deployed the foil curves out from the side of the boat. Looking over the side of the boat we could immediately see the foil had broken. It was not completely separated but it was hinging up and down at the break point. We managed to get a halyard on the end of the foil to support it clear of the water and returned to port. The load cell was averaging 11.5 tons and reached its maximum reading of 13 tonnes when the foil broke.”
“The load pins that were measuring the load in the foil were working and recording what I believe to be accurate loads. The pins were supposed to be setup to read up to 16 tons, however there was a mistake and the limit during the testing was set at 13 tons. This meant that any load over 13 tons appeared as 13 tons. When we reinstalled the V1 foils the pins were set up to 16 tons. The data recorded during the 2016-2107 Vendée Globe shows that in only a few instances did the foil loads exceed the maximum reading of 16 tons. That was over the full length of the race during which all conditions were experienced from light to storm force winds and wave heights over 6m. Boat speeds in excess of 30 knots were experienced on numerous occasions.”
“It is not possible to identify a single cause of failure; it seems to be a combination of various effects. Testing indicates that the materials were weaker than could have been expected, and visual inspections of the failed components reveal a number of less-than-ideal build features in the areas which can be seen.”
“It is not possible to identify a single cause of failure: it seems to be a combination of various effects. Also, critical information like the component structural report and failure load, is not available which does not allow a complete analysis.”