EXPECTED BELT-SPEC I F I C I NJURY PATTERNS DEPENDENT ON THE ANGLE OF I MPACT

D . Adomei t , H . Goegl er* , V . Vu Han Inst i tute of Automotive Engi neer ing Techni sche Un ivers i tät Berl i n , Germany *Surgica l Department Kl i n i kum Charl ottenburg Fre ie Universi tät Ber l in , Germany

ABSTRACT

Resu l ts of dummy cra s h test series have been stud i ed to derive from these predi ctions of i nj ury patterns rel a ted to three-point-bel t usage i n real road acci dents . For head-on col l i s i ons correl at ions between i njury patterns and dummy behav iour i n cra s h tests can obv ious ly be stated .

The a i m of thi s paper i s to d i scuss the infl uence of the ang le of impact . I n our dummy tests the ang l es varied between 20° and 56° . Two speeds of impact (v 1 = 38 , 5 km/h and v2 = 47 km/ h } were u sed . Up to 40° of i mpact- there were no s i gn if i cant d i fferences i n dummy-behav iour as in head-on col l i s i ons . The same can be pred icted for the bel t ­spec if ic i nj ury patterns .

INTRODUCTION

Ana l yses of bel ted pas sengers i n road acc i dents s how typica l inj ury patterns . These injuries may be due to : 1 . the bel t i tse l f ( bel t-spec i f i c i n j ur ie s ) and 2 . the contact with parts of the compartment in sp ite of bel t u sage . I n thi s study, primar i ly bel t - spec i f i c injur ies s hou l d be eva l uated .

From dummy cra s h tests , three types of motion sequences are known : ( see F i g . 1 - 3 ) 1 . stS ( st iff seati n g ) 2 . soS ( soft seat ing ) 3 . Sub ( s u bmar i n i n g ) Each of these types has i ts spec if ic l oad i ng a rea s o n the pas senger ' s body. Type Sub i s the c l a s s i ca l " su bmar i n i ng" . l t i s rel a ted to the type soS , in which the l ap bel t does not move up over the i l iac crests as i t _ i s in the case of " su bmari n i ng" . But the bi omechan ical un­favourabl e a l l -over l oading pattern is s imi l ar ( 1 ) . The moti on sequences

type Sub and soS can sti l l s i gn i f icantly be ana lysed from the i nj ury patterns in real road acc i dents due to unfavourab l e current seat desi gn ( too soft seati ng ) and poor bel t geometry ( too l ow l ap bel t ang l es and/or too l ong buckl e parts ) ( 2 , 6 , 8 ) .

F i g . 4 s hows h i gh l oada b l e body areas wi th favourab l e ranges of ang les of l oad appl i cat ion . Thi s i s rel a ted to ba s i c anatomical and mechan i ca l knowl edges and exp l a i ns why the mot i on sequence of type stS s hou l d be the biomechanica l most favourabl e under acc ident cond itions ( 3 , 7 ) .

METHODE

Di fferent crash cond i t i ons were u sed for studying the dummy behaviour dependent on the angl e and speed of impact . To get s imi l ar cond i tions as i n Sub or soS-type acc idents , the dummy was seated on a commerc ia l soft sea t . The three-po i nt bel t wa s mounted a s i n a two-door car i n co-driver pos i tion ( off-pos i tion o f the impact ) . The bel t forces on the dummy were measured at the anchor-points A , B and C . A rearwa rd accel erating pneumat ic catapu l t s imu l ated a head-on cra s h . The dummy was of the ALDERSON-type V I P 1 03 0 . The motion sequences of the dummy were reg i stered by a high-speed fi l m (250 frames per second ) . In F i g . 5 the test-rig under an ang l e of i mpact 0( i s shown . The speeds of impact were v 1 = 38 ,5 km/h and v2 = 47 km/ h . The ang les of i mpact var ied between 20° and 56° .

The a im was to find out at what ang l e the dummy s l i pped out of the upper be l t port i on ; in other word s : when the bel t force at anchor­po int A decreased to zero .

RESULTS AND D ISCUSS IONS

On F i g . 6 , 7 and 8 the mot i on sequences with an ang l e of impact from 2 0 , 30 and 40° a re. s hown . There i s a c l ear $ im i l ari ty to the motion sequences occuring i n soS-type accidents .

Up to 40° the s houl der bel t wa s a l ways i n the c l av i c u l a area . Thi s i s surpri s ing but may be exp l a i ned by the forward movement of the dummy arms . An increased tors ion on the vert ical ax i s of the dummy was observed which l ead to an i ncrease of forward d i splacement of that torso s i de . There was a l so a remarkab l e antefl exion of the cerv ica l sp ine wi th l a teral movements wh ich are biomechan ica l l y unfavoura b l e ( 5 ) .

F i g . 9 s hows the be l t -forces on the anchor-poi nts A , B and C versus angle . of i mpact for the two speeds u sed . lt can be stated that an ang l e of 20° does not d i ffer from a head -on cra s h . Up to 40° the forces on the bel ts decrea se a t 20 - 30 percent due to the increa s i ng

1 1 . „� . 1 ,

rotation of the dummy torso .

On ly at the ang l e of 56° (wi th v 1 = 27 km/h ) the dunvny torso sl edged out of the s hou l der bel t . But even then , l ow restra int forces at po int A cou l d be measured because the l ower arm got hooked i n the upper bel t l oop . But i n thi s case an excess ive forward d i spl a cement of the upper torso and head occured . There i s no further effect of the upper portion of the restra i nt system.

CONCLUSIONS

From these tests the fol l owing concl us ions can be drawn :

1 . For the co-driver - s l i pp i ng out the s houl der bel t : a ) Up to an angl e. of impact of 40° s imi l a r motion sequences a s

i n a head-on cra s h may be expected . b ) The pas senger l oad ings by the be l t- system are s im i lar and

decrease at 40° on ly at 20 - 30%. c ) Up to 40° bel t-specif ic injury patterns depend more on the

mot i on sequence type stS , soS or Sub than on the ang l e of impact .

d ) There i s no infl uence of the speed of impact on the type of mot i on sequence .

2 . For the driver - fal l i ng aga i n st the s houl der bel t : a ) Addi tional neck injuries due to contact to the stretched

webbi ng may be e xpected . b ) Injuries due to contact wi th parts of the compartment may

incre�se because of l es s space for d i splacement ava i l a b l e .

Genera l l y , i t can be pred icted that u p to a n ang le of ± 40° of impact bel t-speci f i c injury patterns wi l l not d i ffer from such of head ­o n cra s he s but add i t i ona l i njur ies due to contact with i nner parts of the compartment must be expected .

REFERENCES

( 1 ) D. Adome i t , A . Heger Mot i on sequence cri teria and des i gn proposa l s for restra int dev ices i n order to avoid unfavourabl e biomechan i c condi t ions and submari n i ng SAE Paper 7 5 1 1 4 6 , 1 9th Stapp Car Crash Conference , 1 975

( 2 ) D . Adome i t B le i bende Veränderungen am Si cherhe i tsgurt-Si tz-System und Fahrzeug­innenraum zur Bewertung der Bel a stungsart des gurtgesi cherten In­sassen beim Unfa l l Der Verkehrsunfa l l Heft 4 / 1 976

( 3 ) Eval uat ion Methods for the Biomechan i cal Qual i ty of Restra i nt Systems Dur i ng Fronta l Impact in press , 2 1 st Stapp Car Crash Conference , 1 977

( 4 ) W. Appel , D . Adome it et a l Verl etzungen durch ei nen 3-Pun kt-Automati kgurt Monatszeitschrift für Unfa l l he i l kunde 78/ 1 975

( 5 ) H. Gögl er , D. Adome i t , S . Athanas i a d i s Fatal cerv i ca l l uxation re l a ted to safety-bel t-wear i ng in pre s s , Journal of Trauma , 1 977

( 6 ) L . M. Patr ick Three-Po int-Harness acci dent and l aboratory data compari son 18th Stapp Car Crash Conference

( 7 ) J . D. Sta tes Trauma eva l uat ion needs G . M. Sympos i um Ed i t . Pl enum Press N . Y . 1 973

( 8 ) R. T i l ch Untersuchung von Ursachen gurtspez ifi scher Verl etzungen unter Verwendung der Theor ie des Bewegungs-Bel a stungs­Abl aufs des gurtges icherten Insassen und im Versuch D i p l omarbe i t August 1 97 5 , I n sti tut für Landverkehrs­mi ttel, TUB

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