Building the Stretched Ferrari F1 360
A Technical Report By
Chris Wright, Carbonyte UK Ltd
Overview of task
To determine the optimum stretch length of the conversion, and to account for a further six passengers whilst retaining minimum deflection of the body structure.
The stiffness and overall weight increase of the conversion will determine how the vehicle performs under acceleration, braking and cornering.
It is recognised due to the increase in wheelbase the vehicle dynamic cornering ability will be affected.
Stage 1 The Chassis
The existing chassis is an AA6063T6 extruded alloy with an AA6022T6 floor which has undergone a Cataphoresis process to prevent corrosion.
The new chassis will replicate the sections of the extruded alloy, but will be made from 12k carbon fibre reinforcement with a high modulus epoxy resin.
The laminate is engineered to give maximum stiffness to the existing sections with minimal weight gain. For example longitudinal unidirectional carbon fibres are placed on top of the beam sections to give stiffness through the length of the chassis, so it will not bend under the extra load of six passengers.
The beams are connected with quasisotropic carbon fibres (+/-45° and 0/90°) for tortional stiffness, this will prevent the vehicle from twisting during high speed turns and retain the ‘feel’ of the car when driven hard.
The chassis will be manufactured by Carbonyte’s HotFusion® process and will be post cured in an Aerospace Autoclave that is capable of curing components at high temperature without inducing stresses into the chassis. The finished chassis will then have maximum properties in terms of TG (the temperature at which the material softens again) and the maximum mechanical properties.
The chassis will then be adhesively bonded into the existing extruded aluminium sections with a structural epoxy adhesive
The adhesive selected for this task exhibits excellent high strength, fatigue resistance and outstanding impact resistance.
A retained sample of the chassis will be used to bond samples to aluminium with the selected adhesive and these samples will be placed through mechanical testing in the laboratory to confirm at what load the material fails, and the mode of failure, i.e.: through thickness of material or through the aluminium or carbon composite or at the interfaces.
The test results will be compared to the anticipated loads calculated and the adhesive selected as fit for use.
The bonded interface will have isolating layers contained within to prevent galvanic corrosion caused by dissimilar materials.
Stage 2 The Safety Device
Although the vehicle will be long and low, the possibility of a roll over scenario has to be considered and the protection of the additional occupants.
Two roll hoops will be manufactured from carbon composite, primarily from unidirectional fibres. These roll hoops will be bonded to the chassis sections and the centre roof box section. These sections will contribute to the overall tortional stiffness of the vehicle.
The roof box section will be built to hinge the gull wing doors from and to transmit loads through the existing A and B pillars of the vehicle.
Stage 3 The Body Structure
The body will be built from non-structural monolithic carbon fibre panels bonded to the existing structure and the new chassis sections.
Panels will be manufactured by Carbonyte’s HotFusion® process which has been developed for the best composite body structure on the market, capable of withstanding the extreme in temperature the vehicle may experience in hotter countries
The Carbon fibre body will be adhesively bonded to the chassis and structural elements of the vehicle.
Conclusion
The anticipated weight increase of the 2700mm structure is 150kg which will be equivalent to two passengers, and the overall stiffness of the original vehicle will be maintained through correct engineering principles and correct manufacturing placement of the carbon fibre reinforcement.
Chris Wright Managing Director Carbonyte UK Ltd
