Carbon Fibre Monocoque Chassis Feasibility and Manufacturability for FSAE 2015-01-0078
The Curtin Motorsport Team (CMT) currently utilise a 4130 alloy steel space frame chassis for their entry into the Formula SAE-A competition (FSAE). According to SolidWorks models, the current chassis has a weight of 32kg with a torsional stiffness of 744Nm/degree. Although this is an adequate system proven to be cost effective, relatively easy to manufacture and is torsionally stiff enough for a chassis in FSAE, CMT wish to investigate the feasibility of a carbon fibre monocoque chassis. The main goals of this paper are to benchmark the current space frame chassis design, and investigate feasibility of a carbon fibre monocoque, while reducing the chassis' weight, and increasing its torsional stiffness without increasing manufacture time. Preliminary modelling indicates that a transition to a half monocoque will yield a weight drop of 18kg, and a full monocoque will yield a drop of 23kg. The monocoque can also provide a torsional stiffness of approximately 4000-10000Nm/degree. This wide range of values is due to the vastly different chassis geometries, composite fabric weights, resin types, and layup methods.
Physical testing of the 2013 chassis revealed that it has a torsional stiffness value of 813Nm/degree (which correlates with preliminary FEAs). For CMT it would seem that based upon the 2013 car's performance, torsional stiffness is not particularly important in this particular case study.
Flat panel testing was conducted, however the panels were not as successful as the author had calculated they would be. All carbon fibre laminates passed the skin shear test, however only the aluminium honeycomb panels passed the three point bend test for the side impact structure.