Advances in chas­sis de­sign improve safety, ride com­fort

Auto components India - - COVER STORY - Story by: Ramya Srini­vasan

The chas­sis man­u­fac­tur­ing sec­tor is de­fined by the short­ened de­vel­op­ment times, in­creas­ing use of com­puter-aided en­gi­neer­ing and de­vel­op­ment tools, in­te­gra­tion of new elec­tronic chas­sis con­trol sys­tems, and the in­creas­ing pres­sure to sim­plify and stan­dard­ise the chas­sis and sus­pen­sion sys­tems. De­vel­op­ment times are re­duced with ev­ery suc­ces­sive ve­hi­cle model, de­spite the ever-in­creas­ing com­plex­ity of chas­sis tech­nol­ogy. De­vel­op­ment times can be re­duced by con­tin­u­ing to cut down the num­ber of phys­i­cal pro­to­types and ex­per­i­ments. The de­vel­op­ment of mod­ern chas­sis and sus­pen­sion is pos­si­ble only with the help of com­puter-aided en­gi­neer­ing (CAE) tools. Over the years, the use of CAE tools showed a dras­tic im­prove­ment in the qual­ity of chas­sis and sus­pen­sion sys­tems. These advances have led to con­sid­er­able im­prove­ments in ve­hi­cle safety and ride com­fort.

The lat­est soft­ware pack­ages are ca­pa­ble of in­te­grat­ing the ex­pert knowl­edge base of a cor­po­ra­tion into a su­per­or­di­nate de­vel­op­ment en­vi­ron­ment. It is un­likely that any com­pletely new sus­pen­sion sys­tems will be de­vel­oped in the com­ing years. In­stead, le­gal reg­u­la­tions (low emis­sion lim­its and low weight chas­sis), pack­age re­stric­tions, and the in­te­gra­tion of new chas­sis sys­tems such as air springs, roll sta­bilis­ers, ac­tive body con­trol and elec­tric ve­hi­cles force chas­sis and sus­pen­sion en­gi­neers to de­velop new sys­tems and so­lu­tions.

Big OEMs will con­tinue to use stan­dard­ised chas­sis and sus­pen­sion sys­tems to re­duce en­gi­neer­ing costs and de­vel­op­ment time. With re­gard to chas­sis and sus­pen­sion tech­nol­ogy, the main chal­lenges be­ing faced by the OEMs are the ac­cu­rate and re­li­able pre­dic­tion, de­ter­mi­na­tion of re­quire­ments and spec­i­fi­ca­tions for new ve­hi­cle gen­er­a­tions and sub­se­quent de­vel­op­ment of cost-ef­fec­tive and weight-op­ti­mised chas­sis and sus­pen­sion so­lu­tions which ful­fill these re­quire­ments.

Chas­sis man­u­fac­tur­ing in In­dia

Com­pa­nies like KLT Au­to­mo­tive and Tubu­lar Prod­ucts, ALF En­gi­neer­ing, DuPont, GS Auto, and Me­tal­man Auto are the key man­u­fac­tur­ers of dif­fer­ent types of chas­sis sys­tems in In­dia.

Among these, KLT man­u­fac­tures au­to­mo­tive prod­ucts, pre­ci­sion tubes, chas­sis frames, chas­sis com­po­nents and body com­po­nents and as­sem­blies. The com­pany spe­cialises in hy­dro­formed chas­sis. Hy­dro­form­ing is a process to ex­pand metal tubes through high wa­ter pres­sure from in­side in a closed form­ing die. Hol­low parts can be formed with a com­plex outer shape and spe­cial char­ac­ter­is­tics through hy­dro­form­ing process. The hy­dro­form­ing process can be em­ployed for sheet form­ing com­po­nents as well as tube form­ing com­po­nents.

KLT set up man­u­fac­tur­ing fa­cil­i­ties for hy­dro­form­ing com­po­nents and ag­gre­gates for au­to­mo­tive ap­pli­ca­tion in 2006. The fa­cil­i­ties in­clude 5000tonne ca­pac­ity hy­dro­form­ing press with pres­sure in­ten­si­fier and other rel­e­vant aux­il­iary sys­tems, pro­cured from Schuler

Hy­dro­form­ing, Ger­many, the pi­o­neer in Hy­dro­form­ing tech­nol­ogy and Hy­dro­form­ing press and tool­ing. KLT has also ac­quired CNC tube bend­ing ma­chine from Chiy­oda, Ja­pan, for the bend­ing of tube prior to hy­dro­form­ing op­er­a­tions.

KLT in­tends to aug­ment the man­u­fac­tur­ing fa­cil­i­ties by adding more hy­dro­form­ing presses (for pre-form­ing as well as fi­nal form­ing) to meet the in­creas­ing de­mand from do­mes­tic and global mar­kets. The com­pany has in­cor­po­rated ro­botic load­ing and un­load­ing fa­cil­i­ties on hy­dro­form­ing press to improve pro­duc­tiv­ity and safety as­pects.

The tubes re­quired for hy­dro­form­ing ap­pli­ca­tions have also been de­vel­oped by KLT and man­u­fac­tured in its par­ent tube plant which has rolling, an­neal­ing and test­ing fa­cil­i­ties. Hy­dro­form­ing is a rel­a­tively new process. It is a boon to the au­to­mo­bile in­dus­try as now au­to­mo­biles can be made much lighter by us­ing hy­dro­formed com­po­nents made up of steel. Struc­tural strength and stiff­ness can be im­proved. The tool­ing cost is re­duced as sev­eral com­po­nents can be con­sol­i­dated into 1 hy­dro­formed part.

DuPont Au­to­mo­tive of­fers the ma­te­ri­als, de­sign tech­nol­ogy, pre­dic­tive en­gi­neer­ing and pro­cess­ing ca­pa­bil­i­ties re­quired for innovative au­to­mo­tive chas­sis de­sign. The com­pany has iden­ti­fied lightweight­ing op­por­tu­ni­ties in au­to­mo­tive chas­sis, sus­pen­sion and steer­ing sys­tems. Its highly en­gi­neered ma­te­ri­als re­tain their strength and stiff­ness de­spite heat and chem­i­cal ex­po­sure and shed pounds in ex­haust sys­tems and other au­to­mo­tive chas­sis com­po­nents. To help au­tomak­ers gain 1% to 4% im­prove­ment in fuel ef­fi­ciency, DuPont ma­te­ri­als help improve rolling re­sis­tance in tyres by 10%. The com­pany is en­hanc­ing its bench­mark ma­te­ri­als to ad­dress stricter re­quire­ments and improve per­for­mance while reducing weight and cost.

ALF En­gi­neer­ing has 11 plants across In­dia and man­u­fac­tures wide range of chas­sis and sup­plies to M&M, Ashok Leyland, Tata Mo­tors, Daim­ler In­dia Com­mer­cial Ve­hi­cles and Pi­ag­gio. The com­pany man­u­fac­tures chas­sis frame, sus­pen­sion as­sem­blies and hy­dro­formed com­po­nents for SUV’s, MUV’, LCV’s. It is work­ing on new op­por­tu­ni­ties in the heav­ier seg­ment. ALF has in­dige­nously de­signed and de­vel­oped hy­dro­formed com­po­nents for the au­to­mo­tive ma­jors. It has in­vested in 7 hy­dro­form­ing presses (1000 - 5000 tonne) and has a cen­tralised hy­dro­form­ing fa­cil­ity at Nasik. It has also in­vested in Au­tophoretic paint shops for chas­sis at Nasik, Chakan and Hosur of­fer­ing the lat­est in cost- ef­fec­tive paint­ing tech­nol­ogy.

ALF, the chas­sis man­u­fac­turer for M&M, Ashok Leyland and Tata Mo­tors, has bagged or­der from Isuzu Mo­tors and has de­vel­oped chas­sis for its Pickup and SUV range.

New par­a­digm

At present the new par­a­digm is the ‘skate­board’ ap­proach, in which the mo­tor, bat­tery, sus­pen­sion, brakes, and other com­po­nents nec­es­sary to make the car go, stop, and steer are com­bined into one uni­fied struc­ture. Then man­u­fac­tur­ers can take that struc­ture and mount on it any style of body and interior. It could be a sports car or a cross­over. The bat­ter­ies are con­tained in folded alu­minium boxes which also han­dle the ve­hi­cle load. This is the key to a simple, light and very easy to con­struct car. It pro­vides a high level of strength and stiff­ness from a very simple and light struc­ture. The chas­sis is one of the few items that has to be fab­ri­cated. As a ma­jor­ity of items are sourced and at­tached to the chas­sis.

Sus­pen­sion com­po­nents are made from car­bon fiber re­in­forced com­po­nents that are 40% lighter than con­ven­tional alu­minum pieces and made with a pro­pri­etary zero waste process. The ad­di­tional weight of the bat­ter­ies will cause com­pres­sion of the springs which in most ve­hi­cles will change the sus­pen­sion ge­om­e­try. This will also re­duce the space avail­able for sus­pen­sion travel. Such com­pres­sion might be rarely en­coun­tered in an ICE ve­hi­cle as

it cor­re­sponds to the max­i­mum load.

Elec­tric ve­hi­cle

In an elec­tric ve­hi­cle this load will be present at all times, so the sus­pen­sion travel and ge­om­e­try should be re­stored by var­i­ous mod­i­fi­ca­tions. When the spring rate is in­creased, then the damp­ing rate ap­plied by the shock ab­sorbers should also be in­creased. If the sus­pen­sion mod­i­fi­ca­tions are by use of coilover or air ad­justable shocks then the ap­pro­pri­ate damp­ing may be ob­tained by proper equip­ment se­lec­tion.

Some high-end shock ab­sorbers al­low the damp­ing rate to be ad­justed stat­i­cally. The sim­u­la­tion of the orig­i­nal ve­hi­cle with Macpher­son front sus­pen­sion and leaf spring rear sus­pen­sion was built us­ing mo­tion view. It was as­sem­bled with an en­gine as the power sys­tem and sim­u­lated first us­ing a step steer anal­y­sis.

An­other sim­u­la­tion model of elec­tric ve­hi­cle was built by re­plac­ing en­gine sys­tem with mo­tor or bat­tery sys­tem. Elec­tric ve­hi­cles typ­i­cally mount the bat­tery pack - the car’s heav­i­est com­po­nent - as low as pos­si­ble in the chas­sis so all that weight has the least ef­fect on han­dling and driv­ing dy­nam­ics. Elec­tric mo­tors and the con­trollers are smaller than in­ter­nal com­bus­tion en­gines and can be mounted any­where there is space. As a re­sult, new elec­tric cars are re­vert­ing to a form of ‘body on frame’ con­struc­tion that was typ­i­cal in the in­dus­try prior to the ar­rival of uni-body con­struc­tion. Most trucks still use this ap­proach. The de­vel­op­ment sources will be shifted from me­chan­i­cally-ori­ented chas­sis and sus­pen­sion sys­tems to chas­sis and sus­pen­sion sys­tems that are fo­cused on mecha­tron­ics.

Ad­vanced tech­nolo­gies

The au­to­mo­bile in­dus­try is see­ing extensive use of ad­vanced tech­nolo­gies to re­duce emis­sion lev­els, in­crease fuel ef­fi­ciency, and improve the driv­ing dy­nam­ics of the ve­hi­cle. Alu­minum al­loys are used for au­to­mo­biles that weigh half that of reg­u­lar steel ve­hi­cles and ab­sorb twice the im­pact of en­ergy dur­ing ac­ci­dents. Fac­tors such as the ris­ing ven­dor con­sol­i­da­tion, faster re­place­ment mar­ket growth, in­creas­ing lo­cal­i­sa­tion, ex­por­to­ri­ented growth, and grow­ing elec­tronic con­tent per ve­hi­cle have in­duced the In­dian auto com­po­nent seg­ment to con­tinue to grow much faster than the OEM seg­ment. Ac­cord­ing to the So­ci­ety of In­dian Au­to­mo­tive Man­u­fac­tur­ers (SIAM), In­dian au­to­mo­tive sec­tor to­day is a $74 bil­lion in­dus­try and by 2026, the in­dus­try is ex­pected to achieve a turnover of $300 bil­lion- clock­ing a CAGR of 15%.

Global mar­ket

The global au­to­mo­tive chas­sis mar­ket is ex­pected to grow at a sig­nif­i­cant rate ow­ing to the in­creased sales of au­to­mo­biles across the world dur­ing the fore­cast pe­riod. With the grow­ing econ­omy of emerg­ing mar­kets such as China, In­dia, and Mex­ico, these coun­tries are also ex­pected to lead in ve­hi­cle pro­duc­tion and sales. The de­mand for pas­sen­ger cars is ris­ing, par­tic­u­larly in emerg­ing economies like Brazil, China, and In­dia, due to a rise in the purchasing power of con­sumers and the sig­nif­i­cant eco­nomic growth in these coun­tries. China’s mas­sive fis­cal stim­u­lus pack­ages in re­cent years made it the leader in emerg­ing mar­kets. Over the past few years, China has main­tained its po­si­tion as the world’s largest au­to­mo­tive mar­ket.

In Europe and North America, the use of au­to­mo­tive light­weight ma­te­ri­als has in­creased and has high pen­e­tra­tion rates. The adop­tion rate of alu­minum ma­te­rial is ex­pected to be higher in the au­to­mo­bile in­dus­tries in China, Ger­many, Ja­pan, and the US.

The auto com­po­nent mar­ket in In­dia will grow steadily at a mod­er­ate CAGR of around 19% by 2020. Pro­duc­tion ca­pac­ity ex­pan­sion out­pac­ing do­mes­tic con­sump­tion will drive ex­por­to­ri­ented growth in the com­ing years and will be one of the ma­jor fac­tors that will have a pos­i­tive im­pact on the growth of the au­to­mo­bile com­po­nent mar­ket in the fu­ture. Cost-ef­fi­cient op­er­a­tions and ac­cept­able qual­ity have in­creased ex­port vol­umes for the auto com­po­nents to global OEMs. More­over, re­cent reg­u­la­tions that fa­cil­i­tate 100% for­eign direct investment in the au­to­mo­bile in­dus­try will at­tract more joint ven­tures and whol­ly­owned sub­sidiaries. This will aug­ment ex­port growth to OEMs in global mar­kets.

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