Automotive
BLiSS - Butted Lightweight Steel Structures
The BLiSS project delivered the worlds first double-butted automotive spaceframe
The UK low volume/niche vehicle industry and the bicycle industry have been a particular interest of ours and in this project, we transfer technology from one to the other and evaluated the use of butted (variable wall thickness) tubing for lightweight automotive spaceframes.
Project Partners
Working closely with project partners Reynolds Technology and Caterham Cars Ltd, the project was part funded by the UK Niche Vehicle Network (NVN) and their Proof of Concept Competition. Reynolds are well known for inventing the tube butting process in 1898 and their lightweight, high strength tubing is used predominantly in the bicycle industry. Caterham Cars make the iconic Super 7 sportscar and as power to weight ratio is a key performance measure in their market, there was a strong interest from our niche automotive partner who we knew well having a long history with the development of the Caterham 7 - in particularly safety and crash test development.
Simpact was responsible for creating a simulation driven process using FEA tools that incorporated up-to-date CAD information from Caterham and KPI's derived by Simpact
Design Target Specifications
The project would investigate the weight saving potential based on a benchmark Caterham Series 3 chassis.
Senior engineers at Caterham were very clear from the start that they were only interested in maintaining the torsional stiffness of the 7. There is a clear logic here as the stiffness of the car was known and the suspension tuned for compatibility.
Equally of importance was to ensure that the existing chassis production was not effected. So that included all of the jigs for spaceframe manufacturing. Vehicle packaging should also be kept unchanged.
By creating a virtual (FEA) model of the Caterham 7 and correlating the model to torsional test of the baseline S3 chassis, the model can then be used as a tool to determine which tubes should be replaced with Reynolds tubing. Reynolds identified all options on materials, typical yield strength, tube sizes and dimensions possible.
It should be noted that the perfect spaceframe will not benefit from butted tubing.
Concept Design - Beam Element Model
A simple beam element model is well suited for the modelling of a thin walled tubular spaceframe like this. Especially during the early concept design phase of the project where quick run times and investigations are required. The beam element formulation represents the prismatic cross section perfectly by the and the model can be constructed quickly from the Caterham CAD model.
The front and rear suspension including rear de-Dion tube are added to the model so that the torsion load case can be applied in precisely the same way in which the car is loaded from the road.
Torsion Rig Design
A torsion test rig was designed and manufactured.
Get in touch
We would love to hear about your project, get in touch and let’s explore how the expert team at Simpact can take it from design target specification through to verification.