Since the last installment, Chassis Team has worked around tests and exam study to build this year’s monocoque. After getting the cured fibreglass reinforced gel coat from Rivers Carbon, the new moulds were separated from the MDF plugs. The team was delighted with the near perfect finish of the gel coat, requiring a very small amount of bog before the carbon fibre layup.
However, before the layup could commence, a handful of processes were needed to be completed. The first of these tasks were to mark out critical points using the FARO arm at the University of Auckland Bioengineering Institute. This ensured a high level of accuracy for the holes that needed to be drilled. Following this, several MDF plants were made. These were fixed to the mould for the carbon fibre to be laid over and around, creating holes and shapes in the final monocoque. The last week of semester meant projects, tests and study but the team pulled through with rostered shifts both day and night to get the outer carbon fibre skin to very high quality. Thanks to River Carbon and Accentia Group for the carbon fibre - the team were very happy to be using 3k twill for the outermost carbon layers this year.
Two layers of pre-impregnated 3k twill were used, followed by uni-directional patching layers put in the places where a computer model suggested areas of high stresses. The moulds, with their carbon fibre layers, were then prepared for autoclave cooking at Rivers Carbon on Sunday morning. This involved covering the carbon fibre with a peel ply layer to give the carbon a textured finish; and a perforated plastic layer and breather to soak up excess resin from the carbon fibre. Once at Rivers Carbon, team members bagged the two moulds in an overall smooth process. Thanks to Brent from Rivers Carbon for his help with the process.
The following morning we retrieved the cured parts and set about unwrapping them and inspect the results. At the end of each process the team checks the weight of the moulds. After weighing the current moulds we were very pleased to find we were still very much on track for the target mass of 18kg. With the Chassis Team brains deciding on a three stage cook process this year, the next stage required the honeycomb core to be fitted to the moulds. This uses a combination of Nomex core for the flat sections and aluminium flex-core for the rounded sections. The honeycomb structure provides a high rigidity solution with low mass. This core must cover the entire inside surface of the moulds and therefore takes accuracy, time and patience.The team were aiming to get to Rivers Carbon on the first Sunday morning of the exam period, however the decision to achieve quality over time taken was made and the core is planned to be cooked mid week. Despite this minor setback, the team is still on track to complete the monocoque in the time planned.
by Matt Marinovich