product platform and product family design methods and applications（中）

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1、174Chapter9ReartorsionFronttorsionFigure9-13.Automotivebodystructuremodel.Thefiniteelementanalysisoutputsmassandnaturalfrequencies,aswellasdisplacementsandstressresponsesforstaticloadingcasesoffronttorsion,reartorsion,andbending(denoteddfhdrt,anddb,respectively)alongwithc

2、orrespondingsensitivityinformationforallthedesignvariables.Thesearethecross-sectionaldimensionsofthebeams(widthb,heighth,andthickness/)andshellthicknessest.Thereisatotalof66designvariables.WeusedtheSCPIPalgorithmforsolvingtheoptimizationproblems,whichisanimplementationoft

3、hemethodofmovingasymptotes(MMA),tailoredtosolvelarge-scalestructuraloptimizationproblemsefficiently(Zillober,2001).Asmentioned,variantsaregeneratedeitherbyimplementingdimensionalchangesorbyimposingdifferentdesignrequirements.Wewillexaminebothcases.Letusfirstconsiderafamil

4、yoftwovariantsbasedondimensionalchangeshavingthesameobjectivefunctionsandconstraints.AsshowninFigure9-14,asecondvariantisgeneratedbystretchingthewheelbaseandtrunkofthebaselinevehicle.Theenginecompartmentisshortened,andthereforeasmallerengine(andlumpedmassrepresentingtheen

5、gine)isassumed.Themodelswillbereferredtoastheshortandlongwheelbasebodymodels.-JUvariantBvariantBenginetrunkcompartmentexpandedshortenedvariantB-wheelbase(stretched)Figure9-14.Automotivebodystructuredimensionalvariants.CommonalityDecisionsinProductFamilyDesign175Theindivid

6、ualoptimaldesignproblemforbothvariantsisformulatedasmmb,h,tsubjecttocoK>2Hz,co2>24Hz,dft<2.9mm(25)d,,<2.9mm,dh<0.2mm,

7、0022.06co2(Hz)24.8227.00dft(mm)2.1582.170drt(mm)1.9051.909db(mm)0.2000.200TheperformancedeviationvectorIIiscomputedaccordingtoEq.(23)andtheplatformisdeterminedusingathresholdvalueof0.01.59variablesareselectedforsharingandthefamilydesignproblemofEq.(1)issolved.Thefamilypro

8、blemissolvedalsoconsideringa"total"platform-inwhichallvariablesareshared-toassesstheusefulnessof