SAFETY HELMET-HEAD INTERACTION STUDY

SAFETY HELMET-HEAD INTERACTION STUDY

USING HIGH-SPEED CINERADIOGRAPHY

Prepared f o r :

N a t i o n a l I n s t i t u t e s o f Occupat iona l S a f e t y and H e a l t h 944 Chestnut Ridge Road Morgantown , West V i r g i n i a 26505

Prepared by:

R ichard L. S t a l naker , Ph. D. Max Bender John W . Me lv in , Ph.D.

Highway S a f e t y Research I n s t i t u t e The U n i v e r s i t y o f Mich igan Ann Arbor , Mich igan 48109

F i n a l Repor t f o r P e r i o d

August 29, 1977 through October 30, 1977

October 31, 1977

Tuhaicd R q a d D # u t e ( i & n Pug.

1. R u f me. 2. Act.ssion No.

8 . P u b m i y [email protected] R.)wc No. 7. k ~ l )

S t a l n a k e r , R. L . , Bender, M., and M e l v i n , J. W . I UM-HSRI-77-48

3. Rocipmt'r Cat+ Ma.

UM-HSRI-77-48 4. Title d Subtitlo

S a f e t y Helmet-Head I n t e r a c t i o n Study Us ing H i gh-Speed C i n e r a d i ography

I 9. Pu-ng 0vqai;ai.n N w m d Ad&ass ( lo. - ~ o ~ - U ~ i ! No. (TRAIS)

1

'. 7 r 5 p I j 7 6. Puforrinq Or- rmtion coir

I H i shwar S a f e t y Research I n s t i t u t e

N a t i o n a l I n s t i t u t e s o f Occupat iona l S a f e t y & 944 Chestnut Ridge Road H e a l t h Morgantown , West V i r g i n i a 26505

/ he u n i v e r s i G o f Mich igan Ann Arbor , Mich igan 48109

12. *.ring A q m q N a a d A*..

S i x specimen i n d u s t r i a l s a f e t y helmets s u p p l i e d by NIOSH were sub- j e c t e d t o impact f o r c e by an 8 I b. s p h e r i c a l mass, dropped f rom a v e r t i - c a l h e i g h t o f 5 ft., w h i l e worn on t h e head o f a seated HSRI dummy. The purpose o f these t e s t s was t o e v a l u a t e helmet-head dynamic performance by means o f i n f o r m a t i o n o b t a i n e d f rom 1000-frame-per-second x - r a y c ine - matography, and impac to r and dummy head a c c e l e r a t i o n i n s t r u m e n t a t i o n . Peak and average f o r c e s , f o r c e d u r a t i o n s , component and average r e s u l t a n t head a c c e l e r a t i o n s a r e r e p o r t e d f o r each he lmet type. A n a l y s i s and d i s - c u s s i o n i n c l u d e a d e f i n e d helmet-head s t i f f n e s s parameter, and cons idera- t i o n o f t h e da ta on t h e b a s i s o f t h e Mean S t r a i n C r i t e r i o n Head I n j u r y Model. A l l s i x specimen helmets were found t o f u n c t i o n p r o p e r l y under t h e t e s t cond i t i o n s .

1 1. b n u c or GI& No.

77-1 21 22 13. TW of Roped a d Pwiod 6 r w d

F i n a l

17. X q lord.

S a f e t y Helmet, Crash T e s t Device Impact ,

Id. Dislribrcion Stn-t

Unl i m i t e d

19. Srorriq Cluuf. (of this -1

U n c l a s s i f i e d

H i gh-Speed C i nerad iography I

4

R - e r 04 - 1 4 pope M k r i x o d

a. h c u i i y Classif. (of a s w)

U n c l a s s i f i e d

21. NO. o i Paqo.

4 2

22. Pncm

TABLE OF CONTENTS

Tab le o f Contents

L i s t o f F igu res

L i s t o f Tables

Acknowledgments

1.0 I n t r o d u c t i o n

1 .I Background

1 . 2 Purpose

2.0 T e s t Methodology

2.1 Mount ing o f Specimen Helmets

2 .2 Tes t Procedure

2.3 H i gh-Speed C i nerad iography

3.0 Resu l t s

3.1 Dynamics Data f r o m I n s t r u m e n t a t i o n

3 .2 Helmet-Head System Mot ion f rom C i nerad iography

4 .0 D iscuss ion

5.0 Conclusions

6.0 References

APPENDIX A: Dynamic Data

Page

i i i

i v

v

v i

1

1

1

3

3

3

11

15

15

15

19

2 3

2 5

A- 1

LIST OF FIGURES

Figure 1 .

Figure 2 .

Figure 3.

Figure 4.

Figure 5.

Figure 6 .

Figure 7 .

Figure 8.

Figure 9 .

Helmet Test Apparatus Configuration Page

4

Helmet type ESE, she1 1 and suspension 5

Helmet type SUR, she1 1 and suspension 6

Helmet type E R E , shell and suspension 7

Helmet type FBM Superlectr ic, shell and suspen- 8 sion

Helmet type FBM Tuf- i te , shell and suspension 9

Helmet type SG, shell and suspension 10

High-speed x-ray cinematographic system 13

Example o f t e s t sequence obtained with x-ray 1 7 sys tern

L IST OF TABLES

T a b l e 1 Summary o f Da ta

T a b l e 2 Summary o f Helmet-Head Geometry

T a b l e 3 Summary o f A n a l y s i s

Page

1 6

1 8

2 0

ACKNOWLEDGMENTS

T h i s research program was c a r r i e d o u t by t h e s t a f f o f t h e B iosc iences

D i v i s i o n o f The Highway S a f e t y Research I n s t i t u t e , t h e U n i v e r s i t y o f

Mich igan. The au tho rs would l i k e t o thank Mr. W . I. Cook o f NIOSH

f o r h i s c o o p e r a t i o n and s u p p o r t .

1.0 INTRODUCTION

1 .1 Background

I n d u s t r i a l p r o t e c t i v e helmets a r e designed f o r t h e p r o t e c t i o n o f

heads o f o c c u p a t i o n a l workers f rom impact and p e n e t r a t i o n f rom f a 1 1 i ng

and f l y i n g o b j e c t s under average c o n d i t i o n s . There a r e a number o f d i f -

f e r e n t approaches t o head p r o t e c t i o n i n v a r i o u s p r o t e c t i ve he lmet des igns , b u t , i n genera l , a1 1 o f them c o n s i s t o f two p r i n c i p a l components: 1 ) a s h e l l , wh ich i s a hard , r e s i l i e n t , dome-shaped seamless cover ing ,

wh ich c o n t a i n s 2 ) a suspens ion system, o r i n t e r n a l c r a d l e o f t h e he lmet ,

wh ich ho lds i t i n p l a c e on t h e head and i s made up o f a headband and

crown s t r a p s capable o f b e i n g f i t t e d t o t h e head. The comb ina t ion o f

she1 1 and suspension d i s s i p a t e s , d i s t r i b u t e s , and a t t e n u a t e s impac t

1 oads . 1.2 Purpose

The purpose o f t h i s i n v e s t i g a t i o n was t o observe and compare d i f f e r e n c e s

i n performance o f s i x he lmet t ypes , s u p p l i e d by N a t i o n a l I n s t i t u t e s o f

Occupat iona l S a f e t y and H e a l t h , by means o f 1 ) d i r e c t o b s e r v a t i o n o f

impac t events w i t h a h igh-speed x - ray c inematograph ic system developed

by H S R I ; 2 ) a n a l y s i s o f h igh-speed c i n e r a d i o g r a p h i c f i l m s ob ta ined , and

3 ) a n a l y s i s o f f o r c e and a c c e l e r a t i o n d a t a r e s u l t i n g f rom impac t o f an

8 - l b . s p h e r i c a l mass dropped f r o m a v e r t i c a l h e i g h t o f 5 - f t . , a s s p e c i f i e d

by American N a t i o n a l Standard A N S I 289.1-1969, (1); o n t o t h e helmets

as worn by an anthropomorphic dummy, a l s o developed by HSRI . One 9 - f t .

d rop on one he lmet t y p e and one 5 - f t d rop w i t h no he lmet were a l s o conducted.

T h i s r e p o r t c o n s i s t s o f a d e s c r i p t i o n o f t h e t e s t methodology, r e s u l t s

ob ta ined , and an accompanyi ng 16-mm m o t i o n - p i c t u r e f i l m d e p i c t i n g x - r a y

rad iog raphy o f each he lmet impac t e v e n t and a s s o c i a t e d helmet- head

b e h a v i o r .

* Numbers i n parentheses r e f e r t o re fe rences i n S e c t i o n 6.0

2. TEST METHODOLOGY

Tes t apparatus c o n s i s t e d o f t h e f o l l o w i n g elements : 1 ) a dummy head,

which was an i n t e g r a l p a r t o f t h e HSRI dummy, d e s c r i b e d i n r e f e r e n c e 2;

t h e dummy was a d j u s t e d i n a seated p o s i t i o n ; 2 ) a hemispher i ca l s t e e l

mass weigh ing 8-1 b, mounted on a v e r t i c a l column and coupled t o t h e column

by Thompson 1 i n e a r bear ings; 3 ) a S e t r a 11 1 u n i a x i a l acce lerometer

mounted i n t h e i m p a c t i n g mass, f rom which f o r c e was d e r i v e d , and a

S e t r a 113 t r i a x pack mounted a t t h e c.g. o f t h e dummy head, f rom which

r e s u l t a n t a c c e l e r a t i o n was d e r i v e d ; and 4 ) t h e HSRI high-speed c i ne rad io -

g raph ic system, desc r ibed i n r e f e r e n c e 3.

The t e s t c o n f i g u r a t i o n showing t h e seated dummy p o s i t i o n e d under

t h e impac to r , and a d j a c e n t t o t h e i n p u t screen o f t h e high-speed c i n e -

r a d i o g r a p h i c d e t e c t o r , i s shown i n F i g u r e 1 .

2.1 Mount ing o f Specimen Helmets

Suspensions o f each o f t h e s i x specimen helmets were removed;

headbands were a d j u s t e d t o f i t t h e dummy head. Helmet s h e l l s were then

rep laced. The c e n t e r o f t h e crown o f each specimen was cen te red as n e a r l y

as p o s s i b l e w i t h t h e v e r t i c a l a x i s o f mot ion, w i t h t h e impac to r a t r e s t

on t h e crown. Each specimen was mounted w i t h t h e back toward t h e

v e r t i c a l drop c o l umn. Specimen she l 1s and t h e i r suspensions a r e shown

i n f i g u r e s 2, 3, 4, 5, 6 and 7. ,

2.2 Tes t Procedure

The impac to r mass was dropped v e r t i c a l l y on t h e he lmet crown f rom

a h e i g h t o f 60 inches , measured f rom t h e bot tom o f t h e b a l l t o t h e t o p

o f t h e she l 1 . Accelerometer o u t p u t s were r e c e i v e d by S e t r a s i g n a l c o n d i t i o n e r s

and then s t o r e d on magnet ic tape by a Honeywell 7600 tape r e c o r d e r .

I n p u t r e c o r d i n g r a t e was 30 inches p e r second. Recorded acce lerometer

data were then f i l t e r e d by Class 1000 f i l t e r s t o 1650 Hz, a t 16:1 reduc-

t i o n a t a p layback r a t e o f 1-718 inches p e r second.

R e s u l t a n t d e c e l e r a t i o n s were ob ta ined f rom analog computat ion by

a Model 1710 Thomas I n s t r u m e n t a t i o n Impact Computer, which r e c e i v e d com-

ponent d e c e l e r a t i o n s i n x , y , and z, a f t e r s i g n a l c o n d i t i o n i n g and f i l -

t r a t i o n . Impact f o r c e da ta were o b t a i n e d f rom t h e p r o d u c t o f a s c a l e

f a c t o r co r respond ing t o t h e mass o f t h e impac to r and d e c e l e r a t i o n da ta

from the Setra 111 uniaxial accelerometer located in the impactor. Impactor velocity data were derived from time of impactor passage between two magnetic pi ck-up transducers spaced one inch apar t , 1 ocated 20 inches above the crown of the helmet. This height above the helmet was necessary for x-ray system timing requirements. Velocity data were corrected for th i s d i f fe ren t ia l above the point of impact.

2 .3 Hi gh-Speed C i neradiography

Specimen helmets positioned on the dummy head were radiographed during impact, l a t e r a l l y from l e f t to r i gh t , a t approximately 1000 frames per second. X-ray contrast of boundaries between the inner and outer surfaces of helmet she l l s , and the midsaggi t a l plane of the dummy head, was enhanced by taping 0.040 inch diameter lead wire on these surfaces.

The dummy head and specimen helmets were positioned so tha t the t e s t configuration f i l l e d a 12-inch diameter x-ray-to-1 i g h t conversion screen. The midsaggi ta l plane of the dummy head was located 4 .5 inches from, and paral lel t o , the input screen. A 2-inch lead wire was placed on the screen fo r dimensional reference. X-ray tube focal spot t o screen distance was 31 . 5 inches. Radiographic factors f o r each t e s t were as follows: 125 k i lovol ts , peak, f i l t e r e d through 0.080-inch s t e e l , a t 50-mi 11 i amperes, and 0 . 2 sec. x-ray on-time t o cover impactor entrance in to field-of-view, impact event, and subsequent motion of helmet, head, and impactor. High-speed radiographic images were filmed with a Photosonics 1 - B high-speed, 16-mm motion picture camera using Eastman 7222 (Double-X) black and white film; these films were developed with Accufine developer a t 69' F for 5 minutes.

Each x-ray motion-picture t e s t sequence contains an image of a 2-inch lead wire marker v is ib le on the motion-picture frames, for the purpose of dimensional scaling on a Vanguard motion-picture analyzer. X-ray magnification of the helmet-head system, due to the geometry of the x-ray focal spot-to-screen distance and the dummy head midsaggi ta l plane distance to screen distance was taken in to account i n the derivation of the scale fac tor .

An overall view of the x-ray system showing the x-ray source and

detector geometry i s shown i n Figure 8; a larger i n p u t field was used for these tests t h a n i s shown.

F i g u r e 8 . H i g h - s p e e d x-ray c i n e m a t o g r a p h i c sys tem.

13

3.0 RESULTS

Primary t e s t data were obtained in two formats: 1 ) f i l t e r e d dynamics instrumentation outputs were recorded o n a Gould Brush recorder, and 2 ) cineradiography was recorded on 16-mm, black and white, motion- picture film. Dynamics instrumentation outputs are given in the appendix, and each helmet type i s ident i f ied with i t s corresponding impact force as a function of time, posterior-anteri or head accelerat ion, 1 a tera l , or 1 e f t - r i gh t , head accelerat ion, super ior- infer ior head accelerat ion, and resul tant head accelera t ion, a l l as a function of time. Appropriate scale factors fo r each output are also given.

3.1 Dynamics Data from Instrumentation

Dynamics instrumentation data are summarized in Tab1 e 1 , in English and metric system un i t s , which gives average impact veloci ty , peak impact force , impact duration, average force , peak resul tant head accelerat ion, and average resul t an t head acceleration fo r each helmet type. Average force and average resul tant head acceleration were determined from the r a t i o of integrated force-time, and resul tant acceleration-time, outputs to impact duration time interval , respectively.

3.2 Helmet-Head System Motion from Ci neradiography

Motion o f the helmet-head system during impact for each helmet type may be observed by projection of a 16-mm motion picture f i lm, which accompanies t h i s report , and comprises part of the primary data, An example of a t e s t sequence obtained with the x-ray system i s shown in Figure 9 , which was reproduced from the motion-picture film.

Analysis of t e s t sequences on a Vanguard analyzer yielded three quant i t ies : 1 ) i ni t i a1 helmet-head clearance before impact; 2 ) f inal helmet-head clearance, taken a t the frame where the energy absorption process appeared t o be completed; and 3) deformation of the shell during impact. I n each case, the inside surface of the she1 1 was considered with respect t o the l ine demarcating the crown of the dummy's head.

Table 2 contains a summary of these da ta , as we1 1 as maximum helmet def lec t ion, together with some brief comments obtained from ob-

serving the impact sequences.

Z W a a w - e o w e >on ak-

Z 0 H

I- I- za

w a e a + w a d d CT=>w-

M O ~ 01 a a d- o v,

h h h h h h h h h h h h h h h h

w c n u a > W O aea

z 0 u

I- + z a a e V, C W - J J C I

Y Z W a m u W W O Led:

Frame 8

Frame 2

Frame 3

Figure 9. Example o f t e s t sequence o b t a i n e d w i t h x - r a y sys tem.

DISCUSSION

The principal mechanical function of a helmet i s to d iss ipate impact energy so t ha t an im?acting object w i l l not come in to contact

the head. Observation of the high-speed x-ray motion pictures suggested t ha t a convenient way to characterize helmet performance was by defining

a helmet-head average s t i f f ne s s parameter, o r sprinq constant. I t i s recoq- nized tha t a shell-suspension combination represents a ra ther complex mechanical system, and t h i s , together with the neck, represents a to ta l sys tem that i s not ye t well understood. Hence, within the scope of these t e s t s and data available from x-ray motion pictures and dynamics instrumentation, an average helmet-head s t i f f ne s s was defined as the r a t i o of the av'erage force t o the maximum deflection distance of the inside surface of the helmet shell with respect t o the t o p of the dummy head. The average force , rather than peak, was taken because i t more closely represents the integrated force described in the ANSI Z 89.1 standard.

Table 3 l i s t s t h i s derived parameter fo r each helmet type, together w i t h minimum percent helmet-head clearance and re1 a t i ve energy absorption of the helmet head system. Percent clearance was determined from analyzer measurements of distance of c loses t approach of the shell t o

the head and i n i t i a l shell position with respect t o the head; fo r example, i f the she1 1 did not def lec t a t a l l , percent clearance would be 100%. Range of t h i s quantity for the specimen helmets i s seen t o vary from 62% t o 31%, in Table 3 .

Re1 a t ive energy absorption by the helmet-head system was determined from the difference between i n i t i a l impact kinetic energy and impactor rebound kinet ic energy. The ari thmetic mean of the values 1 i s ted in Table 3 i s 92%; range i s between 97% and 87%.

Another important function of a helmet i s to prevent o r minimize occurrence of closed brain injury. I t i s possible t o evaluate the helmets tested for th i s property on the basis of comparison of resul tant

head accelerations obtained w i t h the Mean Strain Criterion (MSC) , ( 4 ) .

Although several other head injury c r i t e r i a models e x i s t , MSC was selected because i t was developed for various directions and average resul tant accelerat ions. Also, the MSC average resul t an t accelerations as a function of impact pulse duration are known fo r various Abbreviated

TABLE 3. SUMMARY OF ANALYSIS

FINAL HELMET-HEAD CLEARANCES

%

38

6 2

3 7

3 1

45

4 8

28

-

TEST NO.

77H001

77H003

77H004

77H006

77H007

77H008

77H009

77H010

RELATIVE ENERGY ABSORPTION OF HELMET-HEAD SYSTEM

%

9 0

9 2

96

9 5

87

9 7

88

-

HELMET TYPE

ESE

SUR

ERB

FBM Super1 e c t r i c

FBM T u f - I t e

SG

SG

No Helmet

HELMET-HEAD SYSTEM

. ST1 FFNESS I b l i n

135

234

117

118

173

205

220

-

~ / c m

236

411

205

208

302

359

385

-

Injury Scale (AIS) levels ( 5 ) . I t was found in these t e s t s t ha t the

larges t average resul tant head acceleration was 10.4 g ' s . This i s substant ia l ly l e ss than the approximately 30 g ' s required fo r a closed brain injury AIS level of one, the l e a s t injury. Therefore, under the conditions of these t e s t s , the probabil i ty of closed head injury t o a wearer of these helmets tested i s minimal ; whereas f o r no he1 met worn, the probability of an AIS injury level of approximately three would be qui te large , providing the load were dis t r ibuted over the head so tha t sku1 1 f rac ture would not occur f i r s t . Average tolerance load fo r

skull f rac ture i s 1240 I b (5518 Newtons), ( 6 ) . I n the no helmet case in these t e s t s , a maximum force of 1340 I b (5961 N ) was obtained.

Since a l l of the head accelerations are low, helmets with the greates t s t i f f ne s s are considered preferable over those with l esse r s t i f f n e s s .

CONCLUSIONS

On the basis of data obtained from high-speed x-ray cinematography and dynamics instrumentation and analysis of these data, i t is concluded that:

1 ) high-speed x-ray cinematography gave good contrast and resolution image sequences during impact events, and yielded analysis of helmet- head motion;

2 ) a comparative basis for helmet performance was found through definition of a helmet-head s t i f fness parameter, and consideration of the Mean Strain Criterion for head injury;

3 ) under the t e s t conditions, a l l of the helmets functioned properly with respect t o head clearance, load distribution, and dissipation of impact ki neti c energy;

4 ) no evaluation of potential neck injury could be made i n this study due t o lack of knowledge about the head-neck interaction;

5 ) the higher the s t i f fness parameter for a given helmet, the better the head protection, provided tolerable g levels are not ex- ceeded, and i t should be noted that potential neck injury i s n o t yet cons i dered .

6.0 R E F E R E N C E S

1 . Arneri can National Standard: "Safety Requi rements fo r Industri a1 Head Protection," ANSI 289.1-1 969, American National Standards In s t i t u t e , Inc . , New York , 1969.

2 . J . H . McElhaney, e t a l . , "A New Crash Test Device -- Repeatable Pete," Proceedings of the 17th Stapp Car Crash Conference, Society of Automotive Engineers, Warrendale; Pa. , 19 /3 .

3. M. Bender, J . Melvin, and R . L. Stalnaker, "A High-Speed Cineradiographic Technique fo r Biomechanics Research," Proceedings of the 20th Stapp Car Crash Conference, Society of Automotive Engineers, Inc. , Warren- da le , Pa., 1976.

4 . J . H . McElhaney, R . 1. Stalnaker, and V . L . Roberts, "Biomechanical Aspects of Head Injury," Human Impact Response - Measurement and Simulation, Ed. W . F. King and H . J . Mertz, Plenum Press, New York, 1973.

5 . Jo in t Committee on Injury Scaling; The Abbreviated Injury Scale (AIS), 1976 Revised Ed., American Association for Automotive Medicine , Morton Grove, I1 1 i noi s , 1976.

6. V . R. Hodgson, J . Brinn, 1. M . Thomas and S . W . Greenberg, "Fracture Behavior of the Sku1 1 Frontal Bone Against Cylindrical Surfaces," Proceedings of the 14th Stapp Car Crash Conference, Society of Automotive Engineers, Warrendale, Pa . , 1970.

APPENDIX A

DYNAMICS DATA

NIOSH HELMET-HEAD ! NTERACTION

DATA SUMMARY

TEST IUMBER K- 041 HELMET TYPE ES E IMPACT VELOCITY 16.5 f p s

Compensated F o r c e 1 0 0 l b s . / D i v i s i o n F i 1 t e r e d 1650 Hz

P o s t e r i o r - Head A c c e l

5 G ' --- F i 1 t e r e d

. A n t e r i o r e r a t i o n s / D i v i s i o n 1650 Hz

L e f t - R i g h t Head A c c e l e r a t i o n

I n f e r i o r - S u p e r i o r Head A c c e l e r a t i o n 5 G ' s I D i v i s i o n

F i l t e r e d F650 Hz

R e s u l t a n t Head A c c e l e r a t i o n 5s ' s /D i v i s i on ii 1 t e r e d 1650 Hz

NIOSH HELMET-HEAD INTERACTION

3ATA SUMMARY

TEST NUMBER 1-003 HELMET T Y P E S U R IMPACT VELOCITY 16.9 f p s

compensated Force 100 1 b s . j D i v i s i o n F i l t e r e d 1650 Hz

Pos t e r i o r - A n t e r i o r Head A c c e l e r a t i o n

5 G ' s j D i v i s i o n F i l t e r e d 1650 Hz


f G 1 s / D i v i s i o n F i t e r e d 1650 Hz

I n f e r i o r - S u p e r i o r Head A c c e l e r a t i o n 5 G ' s j D i v i s i o n --

F i 1 t e r e d 1650 Hz

Resultant Head A c c e l e r a t i o n = ~ ' s / ~ i v i s i o n F i l t e r e d 1650 Hz

1 . 5 6 msec 4 k


DATA SUMWRY

TEST NUMBER //-()oy

Compensated Force 1 0 0 1 b s . l D i v i s i o n F i ? t e r e d 1650 Hz

P o s t e r i o r - A n t e r i o r Head A c c e l e r a t i o n

5 G 1 s / D i v i s i o n -- F i l t e r e d 1650 Hz

L e f t - R i a h t Head ~ c c e l e r a t i o n 5 G C s / D i v i s i o n

F i 1 t e r e d 1650 Hz

Head A c c e l e r a t i o n 5 G 1 s / D i v i s i o n --

F i l t e r e d 1650 Hz

R e s u l t a n t Head Accel e r a t i on ~ G t s / D i v i s i o n ii 1 t e r e d 1650 Hz


DATA SUMMARY

TEST NUMBER //-OOb HELMET TYPE FBV - SUPERLECTRIC

IMPACT VELOCITY 16.7 fps

compensated Force 1 0 0 l b s . / D i v i s i o n F i l t e r e d 1650 Hz

Pos t e r i o r - A n t e r i o r Head A c c e l e r a t i o n

5 G ' s I D i v i s i o n --- F i l t e r e d 1650 Hz

L e f t - R i g n t Head A c c e l e r a t i o n

5 G 1 s / D i v i s i o n F i l t e r e d 1650 Hz

R e s u l t a n t Head A c c e l e r a t i o n X y G 1 s / D i v i s i o n F i 1 t e r e d 1650 Hz


DATA SUMMARY

TEST NUMBER /A407 iiELMET TYPE FBM TuF- ITE

INPACT VELOCITY I d - 2 f p s

Compensated Force 100 l b s . / D i v i s i o n F i l t e r e d 1650 Hz

Pos t e r i o r - A n t e r i o r Head A c c e l e r a t i o n l ; L L G 1 s / D i v i s i o n - F i l t e r e d 1650 Hz

L e f t - R i a h t Head A c c e l e r a t i o n /,Z. f G 1 s / D i v i s i o n F i 1 t e r e d 1650 Hz

I n f e r i o r - S u p e r i o r Head A c c e l e r a t i o n !_2;L S ' s / D i v i s i o n


R e s u l t a n t Head A c c e l e r a t i o n d ~ ' s / ~ i v i s i o n F i 1 t e r e d 1650 Hz

NIOSH HELMET-4EAD INTERACTION

DATA SUMMARY

TEST NUMBE2 ff-008 HELMET TYPE SG

IMPACT VELOCITY 17. 0 f p s

Compensated Force 100 l b s . / D i v i s i o n F i l t e r e d 1650 Hz


5 G ' s / D i v i s i o n --- F i l t e r e d 1650 Hz


5 G 4 s / D i v i s i o n F i 1 t e r e d 1650 Hz

I n f e r i o r - S u p e r i o r Head A c c e l e r a t i o n

5 G ' s I D i v i s i o n -- F i l t e r e a 1650 Hz

- I 1 - - - - -

_ I / - . -

R e s u l t a n t - -

I -

Head A c c e l e r a t i o n - -

Cq G i s / D i v i s i o n I -

ill t e r e d 1650 H z

TEST NUMBER M' 00 9

Compensated Force 100 l b s . / D i v i s i o n F i l t e r e d 1650 h z


HELMET-hEAD INTERACTION

DATA SUMMARY

- HELMET TYPE SG IMPACT VELOCITY 2 2 . 4 f p s

5 G 1 s / D i v i s i o n F i 1 t e r e d 1650 H z

L e f t - R i q h t Head ~ c c e l e r a t i o n

5 G 1 s / D i v i s i o n F i 1 t e r e d 1650 Hz

I n f e r i o r - S u p e r i o r Head A c c e l e r a t i o n

, G 1 s / D i v i s i o n F i 1 t e r e d 1650 H z

R e s u l t a n t Head A c c e l e r a t i o n ~ G 1 s / D i v i s i o n F i l t e r e d 1650 Hz

1.56 msec 4


DATA SljMMARY

TEST NUMBER #- 610 HELMET TYPE NO h ' E L k F f

IMPACT VELOCITY 16.3 fps

Compensated Force Y O 0 l b s . / D i v i s i o n


Pos t e r i o r - A n t e r i o r Head A c c e l e r a t i o n 2 L G ' s / D i v i s i o n -

F i 1 t e r e d 1650 Hz


_aL G 1 s / D i v i s i o n F i 1 t e r e d 1650 Hz

I n f e r i o r - S u p e r i o r Head A c c e l e r a t i o n 25 G 1 s / D i v i s i o n --

F i l t e r e d 1650 H z

R e s u l t a n t Head A c c e l e r a t i o n

J L L ( e G 1 s / D i v i s i o n F i 1 t e r e d 1650 Hz

1 . 5 6 msec -4 t

SAFETY HELMET-HEAD INTERACTION STUDY

Documents

Transcript of SAFETY HELMET-HEAD INTERACTION STUDY