Multi-Discipline gauge Optimization of Automobile BIW Brahmendra S Dasaka Senior Engineer: CAE - Body & Ex teriors General Motors Technical Center- India 2nd Floor, Creator building, International Tech Park Ltd, Bangalore – 5! !brahmendra"dasaka#gm"com $othilingam Chennia%%an Group Leader: CAE - Body & Exte riors General Motors Technical Center- India 2nd Floor, Creator building, International Tech Park Ltd, Bangalore – 5! !&othilingam"chennia%%an#gm"com 'bbre(iations) *D+ – *ulti disci%line o%timi ation, BI-. Bod/ in -hite" 0e/1ords) *ulti disci%line o%timiat ion, auge o%timiation, Discrete o%timi ation, Torsional sti33nes s, *odal %er3ormance Astract:The need 3or more 3uel e33icient and cost e33ecti(e cars has gro1n ra%idl/ in the %resent da/ automoti(e market" This has intern ga(e rise to more e33ecti(e use o3 materials 3or the automoti(e %arts 1hich can reduce the mass o3 the (ehicle at the same time enhance the %er3ormance" This %a%er e4%lains the use o3 the o%timiation techniues 3or multi.disci%line gauge o%timiation o3 %assenger car BI- 6Bod/ in -hite7" *ost mass contribu ting and load bearing %anels 1ere considered 3or the gauge o%timiation" The thickn esses o3 these %anels 1ere conside red as the design (ariable s and the sti33ness and 3reuen c/ %er3ormances o3 BI- 1ere considered as the design constraints" The %ractical thicknesses 3or the gauges 1ere gi(en as discrete (alues 1hich can be readil/ a(ailable" This stud/ 1as carried out in +%tistruct 1ith its o%timiation ca%abilities and the results 1ere com%ared 1ith that o3 8astran" The sco%e o3 this anal/sis is limited to the load cases mentioned earlier" 9999999999999 9!"# M$% Int rod uction:*ult i disc i%li ne o%timiati on can be de3i ned as :+%t imal design o3 com%l e4 engineering s/stems 1hich reuires anal/sis that accounts 3or interactions amongst the disci%lines 6or %arts o3 the s/stem7 and 1hich seeks to s/nergistica ll/ e4%loit these interactions;" The gener al o%timiation %roblem can be modeled mathematica ll/ as, Find ' That, *ini mie s ()* 6<7 Sub&ect to g)* + #' h)* , # 'nd, l+ + u-here(is an ob&ecti(e, is a (ectoro3 design (ari ables, gis a (ector o3 ineualit/ constraints, his a (ecto r o3 eualit / constrai nts, and land uare (ectors o3 lo1er and u%%er bounds on the design (ariables" 'n/ engineering s/stem needs to satis3/ the reuirements o3 one or more disci%lines" For e4am%le, an engine air intake mani3old design has to satis3/ thermo.mechanical anal/sis, modal anal/sis, acoustic anal/sis and also other reuirements like cost, %rocess, CFD, etc" =ach indi(idual disci%line gi(es an o%timiation solution 1hich ma/ or ma/ not be o%timal o(erall" It reuires a lot o3 iterations to com%lete the o(erall o%timiation i3 a decou%led o%timiation is carried out" >ence it calls 3or a robust cou%led o%timiation scheme 1here in the constraints o3 all the disci%lines are taken together at the same time 1hic h gi(e s a uniu e %areto o%ti mali t/ 3ron tier " >enc e, a mult i disci %lina r/ o%ti mia tion includes constraints o3 t1o or more disci%lines" Such kind o3 multi disci%linar/ o%timiation %roblems can be sol(ed b/ e(olutionar/ algorithms, gradient methods, 8e1ton methods and res%onse sur3ace methods, etc" The %resent stud/ is carried out in +%tistruct using gradient methods to sol(e the linear multi disci%linar/
