- •1 Introduction
- •1.1 Luego Sports Cars Ltd
- •1.2 Aims of Project
- •2 Definition of a Chassis and Required Properties
- •2.1 Definition of a Chassis
- •4 Calculation of the Global Torsional Stiffness
- •5 Description of Prototype Chassis
- •6 Physical Testing of the Chassis
- •Fe Modelling Description and Validation of Baseline Model
- •7.1 Fe Model
- •7.2 Patran/Nastran
- •7.2.1 Bar element
- •7.2.2 Shell element
- •7.3 Model correction
- •7 .4 Final Validation of Baseline Model
- •Design Improvement Study
- •8.1 Stage 1 – Discussed Modifications
- •8.1.3 Cross bracing of engine bay tubes
- •8.1.4 Addition of rear firewall
- •8.1.5 Addition of bar across dash area
- •8.1.6 Panelled dash bar and footwell tops
- •8.1.7 Addition of aluminium side panels to passenger compartment
- •8.1.8 Conversion of dash panel, transmission panels and rear wall to Aluminium
- •Addition of Aluminium panels to engine bay sides
- •Stage 2 - Application of structures theory to bare chassis
- •8 .2.1 Conversion of X-brace to w-brace on engine bay
- •8 .2.2 Addition of X-brace to front of engine bay
- •8.2.3 Addition of triangulation from top of footwell bulkhead to lower main rails
- •8.2.4 Addition of ‘Ring Beam’ to engine bay
- •8.2.5 Addition of ‘Ring Beam’ to lower engine bay
- •8.2.6 Addition of lower triangulation to the suspension box
- •8.2.11 Conversion of 8mm flat bar to 2” X 1” rhs
- •8.3 Stage 3-Identical Modifications to Fully Panelled Chassis
- •8.4 Stage 4-Optimisation Study
- •8.4.1 Conversion of 5mm thick bar to 2” X 1” rhs
- •8.4.2 Conversion of mild steel floor to aluminium
- •8 .4.3 Conversion of mild steel transmission tunnel panels to aluminium
- •Conversion of Transmission Tunnel Entrance Beams to 1” X 1” rhs
- •Conversion of Aluminium panels from 1.6mm to 1mm Thickness
- •8.5 Rollcage Study
- •9 Conclusions
- •9.1 Physical Testing
- •9.2 Creation of fe baseline model
- •9.3 Design Improvement Study
- •Discussed Modifications
- •9.3.2 Applications of Structures Theory to Bare Chassis
- •9.3.3 Inclusion of Design Improvements to Fully Panelled Chassis
- •Optimisation Study
- •References
Optimisation Study
With the torsional stiffness increased sufficiently the optimisation study aimed to keep the stiffness over 6000Nm/deg whilst minimising mass and maximising efficiency. An optimum combination will be a compromise as are most areas of design of a sports car. The optimum was reached in model 8.4.4 with a torsional stiffness of 6474.9Nm/deg, an increase of 378% over the baseline model. A mass of 135.9Kg for the fully panelled chassis was achieved with an efficiency of 20.99g/Nm/deg, an increase of 323% over the baseline model.
References
Forbes, Aird. (1997). Race Car Chassis, Design and Construction. MBI Publishing Company, Wisconsin, USA.
Brown, J.C. (2002). Structural Design for Motorsport. Lecture Notes, Cranfield University.
Pawlowski, J. (1969). Vehicle Body Engineering. Business Books, London.
Brown, J.C., Robertson, A.J. and Serpents, S.J. (2002). Motor Vehicle Structures: Concepts and Fundamentals. Butterworth-Heinemann, Oxford.
Champion, Ron. (2000). Build Your Own Sports Car for as Little as £250-and Race It!, 2nd ed. Haynes Publishing, Somerset.
MSC/NASTRAN Quick Reference Guide. (1998). MacNeal-Schwendler Corporation.
www.daxcars.co.uk. Company Information Website. Accessed 24th July 2002.
www.caterhamcars.co.uk. Company Information Website. Accessed 2nd August 2002.
www.westfield.co.uk. Company Information Website. Accessed 2nd August 2002.
www.quantumcars.co.uk. . Company Information Website. Accessed 4th August 2002.
www.robinhoodengineering.co.uk. Company Information Website. Accessed 7th August 2002.