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perspective of the vehicle and its orthographic projections is shown in Figs. 3 and 4, respectively.

Two models at a scale of 1:10 were machined from polyurethane _UreolW. material to analyse the vehicle’s Fig. 3. aesthetics and volumetric dimensions, which were then optimised based on the pilot’s ergonomic profile _Fig. 5.. A model at a scale of 1:5 model was also manufactured for the aerodynamics study. The ergonomic study was done considering the pilot’s inherent physical char- acteristics, mainly its height _1.65 m., and the non-ergonomic driving position. The optimal final geometry was achieved based on studies concerning the pilot’s ampli-tude field view _visibility., driving posture and accessi-bility to the driving commands _hands and feet.. For these studies, the pilot’s anthropometrical profile wascomputer generated, as shown in Fig. 2 and Fig. 5, which allowed to minimise, as much as possible, the volumetric dimensions of the vehicle and therefore reduce the vehicle’s weight. The pilot’s visibility area was determined based on the direct visibility control through an arc from ahead to 908 on either side of the vehicle.

Fig. 3. Image rendering of Icarus.

Fig. 4. Orthographic projections of the vehicle.

Fig. 5.Scaled 1:10 models of the vehicle and pilot’s driving position. The models also allowed to correct the pilot’s legposition and feet, as well as to define the location ofthe feet and hand commands.

Toimprove the driving comfort,，acustomised ergonomicseat was manufactured. For this purpose, thesurface geometry of the seat was obtained in situ byplacing the pilot inside the cockpit of the vehicle in thedriving posture. The seat was hand modelled with liquidpolyurethane that was then coated with an epoxyand covered with a flexible foam and tissue

3. Prototype vehicle manufacturing

Materials play an important key role in the materializationof an idea or concept, and are important in thedesign process. Nowadays, the choice of materials isalmost unlimited, which is simultaneously bad and goodnews to designers. It is good news because one can findthe suitable, even optimal, compromise of designparameters for a specific product; it is bad news becausethe less effort to choose materials for a certainapplication has vanished. The selection of materials isan important aspect of the design process and shouldbe, as much as possible, a quantified process. Thenecessity of selecting materials can be provoked by thedesign of a new product, by the necessity to introducebetter characteristics of existing products or even toredesign a product that has failed in service by somereason. The selection is done preceded

by

the

product’sfunction_s.

definition

and

is

carried-out

interactivelyconsidering the potential manufacturing processes to transform the raw material into the final form of theproduct.

The organic shape of the vehicle limited our choicesto a few conventional and advanced composite materials.In fact, the materials were an important choiceparameter to correctly achieve the desired shape. Thedesign process, as shown in Fig. 1, consisted on theconcept definition, three-dimensional CAD modelling, ergonomic study, manufacturing of scale models, designand manufacturing of the chassis, bodyworkcockpit., transmission driven train, braking system andsteering system, engine modifications and adaptations,aerodynamics testing, electronics and telemetry implementation.The chassis, an important structural elementof the vehicle, could be manufactured eitherusing composite materials or by a conventional weldedtubular structure system. However, due to the geometryshape of the vehicle, composite technology was usedto manufacture the vehicle.

The chassis and the cockpit structure were manufacturedas an integrated structure using

advancedcompositematerials

moulded

with

CADrCAM

technology.Differentiated structural parts of vehicle were consideredbased on its structural importance, and thereforedifferent moulds of these considered parts of thevehicle were manufactured. The strategy consisted onthe fabrication of mould-modular parts machined fromlow-density 100 kgrm3. polyurethane foam material.The parts of the vehicle considered for the manufacturingof the moulds are shown in Fig. 6. Four mouldswere manufactured, namely those for the chassis, cockpitbodywork, front and rear covers. The surface of thepilot’s visibility area was moulded in an acrylic mate-rial. Due to the numerical controlled machine _MikronVCE 500 with Fanuc controller. limitations, the mouldswere manufactured in several modular parts whichwhere bonded to form the complete mould. The computermodelling data of the vehicle were converted andmanipulated to generate the NC machining strategiesusing PowershaperPowermill CADrCAM softwareDelcam plc., Birmingham. and moulds machined.These were then covered with an epoxy resin rein forced withwoven glass fabrics and coated with gel-coatfor surface polishing. Fig. 7 shows the mould used tomanufacture the rear cover of the vehicle. The chassis-cockpit was manufactured as an integralcomponent using an advanced sandwich composite materialto improved structural integrity. A sandwichstructure consisting of a foam core material combinedwith high strength skins was the solution encounteredto manufacture the bodywork of the vehicle. The sandwichstructure was built with load bearing compositeskins bonded to a core of very lightweight foam. Twodifferent sandwich structures were manufactured forthe cockpit and for the chassis. For the cockpit, thecomposite sandwich was composed of two skins of twoplies of woven carbon fabric _195 grm2 . bonded to acommercial PVC foam material _HerexW C70.75,Alusuisse Airex AG Speciality Foams. of 6-mm thickness.For the chassis, the sandwich structure was identical,with the exception to the core which had a 15-mmthickness and the skins were manufactured with unidirectionalcarbon fabric added between the woven carbonfabrics to higher the flexural rigidity. The foamused is a crossed-linked foam with rigid closed cellstructure with high stiffness and strength to weightratio and good compression strength and vibration resistancew7x. Table 1 shows the typical properties of the foam used _manufacturer’s data.. These foam materialsare commercialised in scrim-cloth panels, therefore areeasily adaptable to manufacture complex geometry surfaces. The

chassis-bodywork _cockpit., constructed asan integrated sandwich structure is shown in Fig. 8. Forthe front and rear covers, a composite material ofepoxy resin reinforced with woven carbon fabrics wasmanufactured to give the necessary stiffness. The twolateral wings of the vehicle were manufactured bondingwoven carbon fibre to a machined core which had thegeometry of the wing. Table 2 shows the differentcomposite sandwich structures manufactured for thechassis-cockpit, rear and front covers of the vehicle.The roll-bar of the cockpit had to withstand a staticload of 700 N imposed by regulations w8x, and so an insitu roll-bar was made of unidirectional carbon fibre.Some ribs were also added to both sides of the cockpitto withstand possible lateral shocks. Fig. 9 shows theIcarus vehicle in competition at the Paul Ricard circuit 4. Conclusions

Icarus was born in the computer laboratory of th School of Arts and Design of Matosinhos, where theconceptual design was transformed into computer models based on performed ergonomic studies. At theworkshop of the Department of Mechanical Engineeringof the University of Aveiro the virtual model wastransformed into a prototype vehicle. The designprocess was developed considering the function andaesthetics of the vehicle, as well as the integration ofselected materials with manufacturing capabilities. Thesandwich structures manufactured showed to be anexcellent material to manufacture resistant lightweightcomplex surface structures. As a pedagogic point of view, the project presentedan extra-added teaching value because it allowed thestudents involved in the project a more practical learningengineering basis, which sometimes is not possibleto be given within the curricula of the engineeringcourses. To successfully materialise the objectives ofthe project, it was necessary to integrate different designareas of knowledge, which was well interpreted bythe students. Projects with these characteristics mustbe supported and, even more, stimulated in educationalracademicenvironments; if so, the students willcertainly benefit from them in their step-by-step formationas engineersrdesigners. Finally, Icarus wasawarded with the first Design prize and with an InternationalCommunication prize at the 1998 Shell EcoMarathon competition. Acknowledgements

The author would like to thank all students, designersand teachers involved in the Icarus project. Specialacknowledgements to the Rector of the University ofAveiro and sponsors who gave logistic and financialsupport.