Software helps Lotus produce fewer prototypes

ICEM's surface modelling software has enabled Lotus to go from a digital model straight to tooling for the Elise II - eliminating the model stack process.

ICEM's surface modelling software has enabled Lotus to go from a digital model straight to tooling for the Elise II - eliminating the model stack process.

The design development and manufacture of the Lotus Elise II could well be considered to be a textbook example of how the use of today's advanced 3D surface modelling, analysis and visualisation software can cut time and costs from the vehicle development process.

It certainly represented a 'first' for the team responsible for the vehicle's body design at Lotus Engineering.

Lotus is no stranger to advanced, computer-based technology in the design engineering and manufacturing process.

For example, in addition to using high-end CAD/CAM software for the detailed engineering design process, it has used the ICEM Surf surface modelling, analysis and visualisation software suite for most of its vehicle body and interior design projects for several years now.

However, the Elise II project was to be the first time that they would rely on this software to the extent of going straight to tooling development from the final digital surface model of the car, without first going through the usual physical stacking model verification process.

The result: a valuable saving in man-hours, far fewer physical prototypes and a consequent reduction in development costs.

The key to this major step forward by the Elise II design team lies in the confidence that the surface modelling, analysis and visualisation capabilities of ICEM Surf gave them in the quality and accuracy of the final surface model.

The software also enabled a concurrent engineering approach to be adopted, with the design development of the car's 'customer-visible' surfaces and the detailed engineering design of the vehicle structure proceeding in parallel.

ICEM Surf provides a set of software tools that enables the user to create complex, free-form surfaces and to dynamically modify, analyse and refine them in order to arrive at the optimum surface shape, while maintaining the design intent.

It also provides sophisticated real-time rendering and visualisation tools for use in the design review process, as well as a range of dynamic surface model analysis tools, such as curvature, gap, levelling, flatness, continuity and highlights analysis, among others, to enable the development of the final Class A and associated Class B surface data required for the vehicle manufacturing process.

"In the concept development phase, one of the real values of ICEM Surf's dynamic modelling and visualisation facilities is that it enables you to make subtle changes and to quickly try out different ways of arriving at a desired result, or to adopt a 'what-if' approach to the design and see the results immediately", said Russell Carr, Chief Designer, Lotus Design.

"This enables you to quickly arrive at a point that everyone can relate to and agree on, at the computer, so that the design can move forward smoothly".

Phil Hayden, Surface Development Manager, Lotus Engineering, agrees: "With ICEM Surf, what you see on the computer screen is what you will get in reality".

"That is because it is an engineering tool as well as a concept development tool".

"With the Elise II, that gave us the confidence that once we had completed all the fine tuning of the model from a design development standpoint and had analysed all the surfaces to ensure optimum quality from an engineering standpoint, the resulting digital model would be correct".

With the Elise II, the design development process started with a 'first pass' digital surface model being generated automatically by ICEM Surf, using 'point cloud' scan data of a 1:3 scale clay model of the car.

Two design information streams - one between the clay modellers and the surface development team and a second between the surface development team and the design engineers responsible for the vehicle structure - then ensured that the project moved forward smoothly.

Modifications to the digital model as the design was refined were reflected and verified in the clay or in a few cases, with resin prototypes machined from the surface data, while changes to the clay were scanned and imported back into ICEM Surf where the digital model was updated and analysed for quality.

At the same time, data from the engineering CAD model were imported into the surface modelling environment where they were used as a reference in ensuring that all 'hard points' defined in the engineering CAD model were met as the surface model developed.

With this two-way flow of information and the ability of ICEM Surf to accurately model surfaces within fractions of a millimetre, only two prototype levels were considered necessary - and then only for the major body components - throughout the whole Elise II development process.

Then it was straight from final surface model to tooling design - marking a 'first' for Lotus and a vote of confidence in today's design development software.

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