REFINED CALCULATION AND SIMULATION SYSTEM OF LOCAL LARGE DEFORMATION FOR ACCIDENT VEHICLE

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1 REFINED CALCULATION AND SIMULATION SYSTEM OF LOCAL LARGE DEFORMATION FOR ACCIDENT VEHICLE WagFag Yua Lctur of Autoobl Egrg, School of Autoobl, Chag a Uvrsty, X a, Cha, -al: autoyuaz@63.co Lag W Profssor of Autoobl Egrg, School of Autoobl, Chag a Uvrsty, X a, Cha, -al: qch_@chd.du.c ChuJu Yu Rsarchr, Traffc Maagt Rsarch Isttut of th Mstry of Publc Scurty, Wux, Cha, -al: Yucj23@yahoo.c Tao Ch Assocat Profssor of Autoobl Egrg, School of Autoobl, Chag a Uvrsty, X a, Cha, -al: chtao@chd.du.c. Subttd to th 3 rd Itratoal Cofrc o Road Safty ad Sulato, Sptbr 4-6, 20, Idaapols, USA ABSTRACT Dtrg th collso spd s th ky to rcostruct vhcl crash accdt ad aalyz th accdt org. Th prst papr as to dtfy th procss of vhcl crash ad th local larg dforato for accdt vhcl. Basd o th collctd typcal accdt cass of th vhcl crash, w dvd local larg dforato to sh usg hxahdral sh grato algorth ad t od curvd dg ttrahdral lt. Basd o th sh chart of collso dforato rgy of ft lt thory, th rlatoshp btw vhcl collso spd ad body dforato was aalyzd quattatvly. Cobd wth th corrlato btw collso spd ad rsdual body dforato, th quvalt spd loss was obtad. Th odl of th pact forc ad stataous spd for ach shg cll was cratd usg vhcl dyacs odl, lastc chacs. Accordg to th aalyss for vhcl crash accdt, th accurat valus of spd ad drcto of th vhcl bfor th accdt occurs hav b calculatd. Ths study provdd a thortcal foudato for accdt aalyss ad dtfcato. Accordg to th calculato odl of th pact forc ad stataous spd, w buld th aalyss ad rcostructo syst of vhcl-fxty crash accdts o VC++ platfor.th rfd calculato ad sulato syst has b appld to aalyz th actual vhcl-fxty crash accdt o

2 Xag Wstr Road X a. Ths syst s a portat copot aalyss ad rcostructo syst of traffc accdts, whch ca rch th aalyss of traffc accdts. Kywords: ft lt thod, local larg dforato, rfd calculato. INTRODUCTION I rct yars, th accdt rcostructos tchology provdd advacd as for accdt aalyss. Through th coparso btw th dforato photo of actual accdt ad databas photo, th stat spd bfor crash ca b obtad. It s th ky to dtr th stat spd for accdt rcostructo ad th aalyss of accdt causs. Th coo thods ar thortcal calculato (ktc rgy, otu thor, tc) ad xprcal judgt usg tools. If th rgy absorbd by vhcl dforato was gott, t wll b hlpful for th calculato of spd. Th stadard of th Mstry of Publc Scurty GA/T provd th rlatoshp btw spd ad dforato dpth. I th 970s ad 80s, th atoal hghway traffc safty adstrato approvd that thr s a lar rlatoshp btw crash spd ad rsdual dforato fro 80 ts of vhcl crash tst. Th aalyss of spd bfor accdt s achvd through vrtual frotal crash tst of ft lt odl Shagha Jao Tog Uvrsty. Th odl of th spd bfor crash ad dforato dpth was stablshd through 30 ts of sulato aalyss ad calculato Dala Uvrsty of Tchology. Most studsaalyzd th spd usg rgdty coffct. Ths rsarch rsults ar cofd to a fw collso fors ad practcal accdt whch s slar to tst. Bcaus th vhcl typs ad collso ways of accdt ar vard, ths study dvds local larg dforato to sh usg ft lt thod. Cobd wth th coo pot of varous dforatos, ths study bulds rfd calculato odl of th stataous spd ad pact ara usg vhcl dyacs odl, ktc rgy thor, otu thor ad lastc chacs, wh collso occurs. Th ft lt thod ca cosdr lastcoplastc dforato of th vhcl ad collso objcts, so that hac th accuracy of accdt rcostructo. I th procss of th aalyss for vhcl crash accdt, ths study got th spd valu ad drcto of th vhcl bfor th accdt occurs basd o paralll coputg of ft lt thod, whch hav hghr coputatoal accuracy. Thrfor, ths study ca provd sctfc thortcal foudato for accdt aalyss ad dtfcato. Basd o collctg th typcal accdt cass rlatd to th vhcl crash, ths study buld rfd calculato ad sulato syst of local larg dforato for accdt vhcl usg vhcl dyacs odl, lastc chacs ad ft lt thod. STRUCTURE AND CHARACTERISTIC OF VEHICLE DEFORMATION Accordg to rsarch stuato at ho ad abroad, ths study rsarch o th structur charactrstc of collso posto bfor accdt happd ad th dforato charactrstc aftr crash at frst. Through collctg th accdt cass, w collct th structur ad charactrstc of th a accdt typs, whch clud frot profl rar posto, structur charactrstc ad atral of ay typs(cars, buss, ad trucks). Through usg hadhld postog 3d lasr scar EXASCAN, w ca sca th dforato charactrstc of th vhcl, th xtract rlvat forato whch clud th dforato posto axu 2

3 dforato dpth ad dforato wdth. Thrfor, ths study bult th coputato od of local larg dforato for accdt vhcl basd o ft lt. MESH GENERATION OF VEHICLE DEFORMATION AREA Ft-lt Aalyss Procss of Dforato Ara Th basc da of ft lt thod s that dsprs cotuous ara to assbly of th uts whch s ltd ad coctd togthr. Bcaus th ut ca b cobd by dffrt ways, ad th shaps of th uts ar dffrt, th coplcatd solvg doa of gotry shap ca b odld. Furthror, wh th ut s sall ough, ad th sh s clos ough, th approxato rror wll b gradually covrgc as shs ar rfg, so that calculato accuracy ca also b fully guaratd. Th soluto of statc olar probl ca b gott by showg ad calculatg stady-stat codto. Ths thod s appld to th cott of ft dffrc, whch s ad dyac rlas of statc olar probl. Th dforato of vhcl crash s a larg thr-dsoal probl, ad th soluto s gott by usg a dyac sch. Th showg progra provds th vald soluto of crash probl. Th stps of th thod ar as follows (usg approxato prcpl): Stp : Dvdg th o-dvdual body to ft lt usg agary ls ad facs. Stp 2: Suppos that ths ut ar coctd by dscrt pots whch l boudary ad r. Stp 3: Df th dsplact stat th r ad boudary of ft ut by slctg th fucto basd o od dsplact. Stp 4: Accordg to dsplact fucto of od dsplact, ths study dtrs th strss stat th r of ut, ths stra ad th rlatoshp of prary stra ad atral. Stp 5: Dtr varous forcs clud forc whch focus o od, ufor boudary strss ad dscrtoary dstrbutg load. Th grato algorth of hxahdro sh Accordg to th shap ad physcal charactrstc of th odl, w cut th solvd ara to so trlkag uts ad aalyz th strss ad dforato of th ut, ad th solv for algbra quato. Sc th surfacs of vhcl body ar curvd orally, w dvd th ara to sh bfor ad aftr dforg. Ths study covrts ttrahdro ut of t ods to hxahdro sh (Fgur ). Th stps of th shg algorth ar as follows: Stp : Covrt th aalyss fld to ttrahdro ut of t ods (TET 0 for short). Ths study xtracts charactrstc pot fro vhcl dforato ara usg lasr scar, th th ttrahdro shs ar gratd. Stp 2: Judg that th bordr of vry TEN0 ut s curvg or ot. It d to judg that th ddl coordat (M) of th l AB ad th ddl coordat (E) of ut bordr ar qual or ot (Fgur 2). If th coordats ar qual, AB s a straght bordr. Othrws, AB s a curv. 3

4 A M B Fgur Ttrahdro ut of t ods Fgur 2 Judgg that bordrs ar curvg Stp 3: Calculat th ctr of th four tragls vry TET 0 ut, th ctrs ar P ABC, P ABD, P BCD, P ACD. Stp 4: Judg that vry surfac of TEN0 uts hav curvg bordr or ot. If curvg bordr xsts, th surfac s curvg fac. Ths study appd th ctr of th four tragls th ut surfac to th curvg fac usg shap fucto of tragl whch has ad 6 ods ad curvg bordr. Th appd thod s as follows: = N x + N x + N x + N x + N x N x () xw A 2 B 3 D 4 E 5 I + 6 H yw N ya + N2 yb + N3yD + N4 ye + N5yI + N6 yh zw N z A + N 2zB + N3zD + N 4zE + N5zI + N 6zH = (2) = (3) Th dfto th shap fucto N ( =,,6) s: N L ( 2L ), =,2,3 (4) = 4 4L L2 N = (5) N 5 = 4L2L3 (6) N 6 = 4L L3 (7) Stp 5: Calculat th ctr of ttrahdro ut whch has straght bordr, th O pot s gott. Stp 6: Judg that vry surfac of TEN0 uts hav curvg bordr or ot. If curvg bordr xsts, ths study appd th pot O to a w posto usg shap fucto of ttrahdro ut of t ods whch has curvg bordr. Th appg thod s slar to th appg of curvg fac, bcaus th warpg of hxahdro ut s sallst through coctg th appg pot to othr rlvat pot. Stp 7: Dvd vry TEN0 ut to four hxahdro uts through coctg pot O to othr rlvat pot. Stp 8: Elat rpatd ods ad ubr th uts ad ods rwdly. CALCULATION MODEL OF IMPACT FORCE AND INSTANTANEOUS SPEED Calculato Modl of Ipact Forc Accordg to th basc thory of ft lt thod, th procss of ft lt aalyss whch dals wth th cotuu s as follows: ()Dvd th cotuu to ft uts, whch ca b dscrbd by ft varabls. 4

5 (2)Accordg to th rul of stadard dscrt syst, ths uts ar cobd, th th soluto of th whol syst ca b achvd. Suppos that th ubrs of th ods s th typcal ut. Accordg to th od dsplact, dstrbutg loads ad prary stra, w ca gt th forc whch brgs prssur to bar o th od uquly. Suppos that th bhavor of ut s lar lastcty, th forc s quato (8) whr f p s th od forc whch balacs th dstrbutg loads, f ε s th od forc whch 0 a balacs th prary stra, u a = a2, a = ar od dsplact. K s rgdty atrx. a v 3 q = K a + f p + f ε 0 (8) I ordr to gt a whol soluto, t ust b satsfd wth th haroy of th dsplact ad th balac of forc, so th forc whch brgs prssur to bar o od s quato (9). r = = q = = = ( K ) a + ( K ) a +... f (9) 2 Equato (9) oly as at th od whch s cojot to od. If w cob all th quatos, th syst quato ca b gott, such as quato (0), whr K ad f ar quato ().. Ka = r f (0) K j = K j = () f = f = Accordg to th procss of ft lt aalyss of cotuu, ths study calculats th pact forc bfor body dforg of accdt vhcl rlyg o th charactrstc data of dforato. Calculato Modl of Istataous Spd Basd o th sh chart of collso dforato rgy of th ft lt thory, ths study quattatvly aalyzs th rlatoshp btw vhcl collso spd ad body dforato. Th sh chart of collso dforato rgy dvds th body to ay aras, ad th absorbd rgy valu of vry dforato ara s calculatd aftr th crash. Wh coparg th actual dforato of a crash vhcl wth th valus th sh chart, th valu of th ara btw th dforato curv ad vhcl cotour l s th absorbd rgy bcaus of vhcl crushg shrkag. Itally, hypothss ar as follows:.th dforato dgrs of all aras ar sa th tr wdth vrtcal drcto; 2.Th frcto btw cars ad groud s glctd th procss of collso; 3.Th lastcty rstor s glctd aftr crashg. Th calculato forula of cocluso dforato s quato (2) whr f s collso forc of body wdth, c s dforato dpth, w s th body wdth, E s th absorbd rgy. Ths 2 = 5

6 quato shows th rgy wh th dforato wdth s fro w to dpth s fro c to c. E w c w c w, ad th dforato = fdcdw( =,2...) (2) Cobd wth th lar rlatoshp btw collso spd ad rsdual body dforato, th quvalt spd loss s obtad wh th apltud of body dforato s fro w ad c to w ad c, whr a ad b ar rgdty coffcts. 2 w w 2 2 v = [ ac + b] [ ac + b] ( =,2...) (3) w Through quato (2) ad quato (3), th calculato odl of stat dsplacts ca b stablshd. Cobd wth vhcl dyacs odl whch cluds tr odl thory, ths study costructs th rfd calculato ad sulato rcostructo of th vhcl-fxty crash accdt. Ths study bulds th databass of accdt vhcl dforato usg th thod of xtractg ad aalyzg th data. Through cobg wth th rfd calculato ad sulato rcostructo of th vhcl-fxty crash accdt, ths study dvlops th aalyss ad rcostructo syst of vhcl-fxty crash accdts o th Vsual C++6.0 dvlopt platfor. APPLICATION CASE OF THE SYSTEM If w would us aalyss ad rcostructo syst of vhcl-fxty crash accdts, so paratrs should b gott fro accdt spot, such as th spcs ad shaps of fxty collso posto ad fal stop collso collso trac posto groud brak prtg ad a structural paratrs. Th, th collso spd groud coordat syst th spd bfor accdts happ ad ovt codto th procss of accdt ca b calculatd. I xaato of a vhcl-fxty crash accdt that occurrd o Xag Wstr Road X a, ths study aalyss th actual cas usg th aalyss ad rcostructo syst of vhclfxty crash accdts. I ths accdt, a Jtta FV760CIX/CNG car colldd wth lapposts ad trs. Accordgly, ths accdt s a typcal vhcl-fxty crash accdt. Usg th syst, th rlvat data ad accdt procss bfor ad aftr th crash ca b obtad through aalyss, th rsults of whch wll dtfy th raso for ad procss of th vhcl-fxty crash. Th data gathrd th spot was put to th aalyss ad rcostructo syst of vhclfxty crash accdts. Th data clud th spcs ad shaps of fxty, collso posto ad fal stop collso, collso trac posto, groud brak prtg ad th a structural paratrs. As dsplayd Fgur 3, th spd bfor th vhcl-fxty crash ad th spd wh th drvr bgs to brak wr rad. Th, th brf troducto of accdt procss(fgur 4) ca b gott. 6

7 Fgur 3 Calculato procss ad rsult Fgur 4 Brf troducto of accdt procss Accordg to th spot dagra ad databas, th raso, procss ad rsult of th accdt ca b dscrbd, so that th accdt ca b accuratly dtfd. A slar accdt ca b calculatd ad rcostructd usg th aalyss ad rcostructo syst of vhcl-fxty crash accdts. CONCLUSIONS At frst, ths study rsarchd o th xtractg thod of structur charactrstc of collso posto bfor accdt happd ad th dforato charactrstc aftr crash.through th ft-lt aalyss procss of dforato ara, ths study shd th dforato ara, usg th grato algorth of hxahdro sh. Accordg to th basc thory of ft lt thod, ths study bult calculato odl of pact forc ad stataous spd. Thrfor, ths study costructd th rfd calculato ad sulato rcostructo of th 7

8 vhcl-fxty crash accdt. Ths study dvlopd th aalyss ad rcostructo syst of vhcl-fxty crash accdts o th Vsual C++6.0 dvlopt platfor. Through aalyss of th actual cas, ths study obtas data ad th spot dagra of th accdt, achvg a succssful applcato of th syst ACKNOWLEDGEMENTS Th projct s supportd by atoal scc ad tchology supportg progra of Cha (NO. 2009BAG3A07). REFERENCES Clff, Wlla E., ad Motgory, Drcy T. (996). Valdato of PC-Crash Motu-basd Accdt Rcostructo. Accdt Rcostructo Tchology ad Aato VI, 50, 0. H, Hogyu, Fg, Hao. (2009). Spd aalyss th accdt of vhcl barrr crash. Chs Joural of Forsc Sccs, 5, W, Lag. (999). A aalyss of vhcl dyac sulatg tr odl usd collsos accdts. Joural of X a Hghway Uvrsty, 9 (), W, Lag, Ch, Ygsa, t al. (2000). A study o sulato odl for car-to-car crash ad thr scod pact traffc accdts. Autootv Egrg, 22(), W, Lag, Ch, Tao, Yu, Qag. (2003). Thr-dsoal vhcl dyacs odl for road traffc accdt sulato ad rcostructo. Joural of Traffc ad Trasportato Egrg, 3(3), Zhag Xaoyu, J Xalog, Zhag Shu. (2004). Applcato prspctv of ft lt thod to traffc accdt rcostructo. Trasacto of th Chs socty for Agrcultural Machry, 35(6), Zhag Xaoyu, J Xalog, Q Wguo, t al. (2008). Vhcl crash accdt rcostructo basd o th aalyss 3D dforato of th auto-body. Advacs grg softwar, 39(6), L. Artxabalta, J. Aurrkotxa, G. Castllo, M. Matos, I. Urrutbascoa.(2008). Iso-stra rat atral bhavour curvs appld to th ft lt pact sulato. Proprty odlg, 27(), Byug-Jug Park, Doqu Lord. (2009). Applcato of ft xtur odls for vhcl crash data aalyss. Accdt Aalyss ad Prvto, 4(4), Cha-Yug J, Yuh-Shou Ta. (200). Dforato bhavor of a stffd pal subjctd to udrwatr shock loadg usg th o-lar ft lt thod. Matrals & Dsg, 3(),