Com­puter de­sign

Ev­ery­thing you al­ways wanted to know about ve­hi­cles but were afraid to ask

Townsville Bulletin - - Cars Guide -

MOD­ERN car de­sign has been trans­formed by the use of com­put­ers. The ef­fect of this can be seen not only in how a car looks but also in how it per­forms in a crash and its ride and han­dling. The process de­sign­ers now use to en­sure that a car per­forms to its op­ti­mum is called fi­nite el­e­ment anal­y­sis (FEA). Twenty years ago a new car started life as sketches on pa­per from which scale mod­els and then full­size mock-ups were cre­ated us­ing clay and other ma­te­ri­als. To­day the sketches are done on-screen and the mod­els cre­ated by com­puter-con­trolled ma­chines that carve the re­quired shapes from polystyrene or clay. How­ever, the real ad­van­tage of us­ing com­put­ers is that they en­able de­sign­ers to work out ac­cu­rately how com­po­nents and ma­te­ri­als will re­act when the car is driven. How a car re­sponds used to be worked out us­ing a mix of in­tu­ition, math­e­mat­ics and re­peated test­ing. To­day the use of FEA means that the pre­cise be­hav­iour of ev­ery nut, bolt and piece of metal can be cal­cu­lated ex­actly be­fore it is even made. The prin­ci­ple is sim­ple. Al­though de­sign­ers can­not pre­dict how com­plex shapes be­have when sub­jected to dif­fer­ent forces or tem­per­a­ture changes, they do know ex­actly what sim­ple ones will do. Us­ing FEA, com­pli­cated car com­po­nents are di­vided into tiny squares on screen this looks as though a net has been stretched over the car. Then a the­o­ret­i­cal force is ap­plied at a given point and its ef­fect on the squares it touches is cal­cu­lated. This process con­tin­ues through the struc­ture of the car. None of the cal­cu­la­tions is es­pe­cially dif­fi­cult, but the sheer num­ber of them had pre­vi­ously been be­yond de­sign­ers. To­day com­puter-aided de­sign is so ac­cu­rate that com­po­nents such as en­gine blocks have vari­able wall thick­nesses to en­sure the stresses in them are per­fectly even, and a car can be crashed count­less times to as­sess its strengths with­out it ever hav­ing been built.

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