Surface modelling cuts development time at Bentley

“We save a considerable amount of time at the concept development stage through the software’s ‘Scan Modelling’ and ‘Quick Surfacing’ tools,” explained Jim Shaw, head of concept design at car manufacturer Bentley Motors. He continued: “It enables us to produce a better, higher quality design in less time and through the ability to share design information, to reduce the number of design changes required. In turn, this gives us more confidence in our suppliers’ ability to deliver what we need, when we need it.” Shaw works at Bentley’s UK headquarters in Crewe where he was responsible for interpreting the original design brief for Bentley’s new, six litre, 500bhp, Continental GT car into a feasible design. He is in charge of the company’s concept engineering department which is responsible for developing the overall vehicle packaging, style and feasibility, both from an engineering viewpoint and in terms of satisfying the original design specification, marketing requirements and the product plan. You could say that Shaw and his team are right at the front-end of vehicle design and development, before the decision is even made to proceed with a proposed new vehicle. Once the decision to proceed has been made, it is then the responsibility of Shaw and his team to develop the wishes of the vehicle’s exterior and interior stylists and designers into a viable design from an engineering and manufacturing standpoint, and to deliver to the engineering department the engineering data that describes the car’s interior and exterior surfaces. The process starts with a full scale clay model. The software Bentley uses for this is ICEM’s Surf suite of 3D surface modelling, analysis and visualisation software. Bentley also uses ICEM’s ‘Scan Modelling’, ‘Quick Surfacing’, ‘Realtime rendering’ and ‘Global Modelling’ add-on modules. With the scan modelling software, dense ordered or random ‘point cloud’ data generated by automatic laser and photogrammetric 3D digitisers can be read into, manipulated and visualised in Surf. Quick Surfacing then automatically creates a surface model of the complete vehicle body shape from the scan data. Although the model will undergo a lot of refinement before the final version is reached, the surface model created this way is good enough to be passed to other applications, such as CFD and tooling design for early feasibility studies. As Shaw explained to Eureka, “The design is still very fluid at this stage in the vehicle’s development, so what we need is a surface model that people can cut and visualise in order to check its form and clearance with other components.” Once the initial surface model has been created, Shaw and his team then work in parallel with two sets groups, the designers and clay modellers, and also with the detailed design engineers and suppliers to ensure that the project moves forward smoothly. The clay and digital models also move forward in parallel. Any modifications or design refinements are made to the clay model, then scanned and imported to the digital model in Surf. Changes to the digital, virtual model, for example, an engineering concern, are verified in the clay model or with a physical prototype machined from resin. As a result of this ‘closed loop’ process, the clay and virtual models alternate at being in front. One advantage of being able to track changes to the clay model, as they are made, is that the concept team no longer has to wait for what in the past could have been anything up to a few weeks to be notified of design changes. Changes are now reflected in the virtual model within hours, saving a great deal of development time. It also means the team can undertake feasibility studies with suppliers and with Bentley’s engineering and manufacturing groups, as the design develops so that any potential problems can be detected at a stage in the development when the design can more easily be changed. According to Shaw, it also ensures that everyone involved is always working with the most up-to-date design information. Sharing design data is also helping Bentley. Shaw explained: “The detailed engineering design of the rest of the car is carried out using Catia CAD/CAM software. Surf enables an image of the Catia CAD model to be imported and displayed in Surf where it is used as a reference model for ensuring that the surface model fits to and doesn’t foul any of the ‘hard points’ defined in the engineering CAD model.” This is where ICEM’s Global Modelling module comes into play. This software allows Shaw’s team to manipulate and stretch the surface model over the engineering hard points without, crucially, losing the character of the surface or the original design intent.