"S

200 -

160 -

120 -

@
fo}
i)

7"
°

O-+

DECELERATION FORCE IN “

t
o 4 #8 #2 20 24 28 32
DURATION TIME IN MILLISECONDS

INPUT

200 -

160 -

120 -

@o
fo}
1

ff
°
t
vd

Or in '
o 4 8 i2 16 20 24 28 32
DURATION TIME IN MILLISECONDS

OUTPUT

DECELERATION FORCE IN “g"S

Fiaure 12. Hairline fractures of nose-zygomatic connections from a 12-ft/sec impact on molded block on the nose.
Stopping distance—1%% inches.

Appendix

16


fe

n Nn
fo} +
° °
1 t

160

120-

80- a

40-

DECELERATION FORCE IN "g's

O74 1 1
° 4 8 12 16 20 24 28 32 36 40

DURATION TIME IN MILLISECONDS

Ficure 6. Impact of right zygomatic arch. Bruises and concussion.

Appendix 10


9"
- Nn
o od
o o¢o
' !

120

@
fo}

y
fo}

°

DECELERATION FORCE IN

1 1
o 4 8 12 1 20 24 28 32
DURATION TIME IN MILLISECONDS

INPUT

n
7200 -

a
°
\

120 -

[+
°
-

ph
°

°

T |
o 4 8 #12 16 20 24 28 32

DURATION TIME IN MILLISECONDS
OUTPUT

DECELERATION FORCE |

Fieure 16. Typical mandibular condyle fracture from impact on molded block on tip of chin. Velocity—29.23
ft/see, stopping distance—1 inch.

Appendix 20


TOLERANCES OF THE HUMAN FACE TO CRASH IMPACT

I, Introduction

Many accident investigators have reported that
70% to 80% of all deaths and injuries in crash
decelerations are from face and/or head injuries
caused by body flailing and the head striking
surrounding structures with less yield character-
istics than those of the head." ** Design engi-
neers can eliminate a large portion of these in-
juries and deaths by structural redesign if facial
and head tolerances to impact are made available
to them.

Most researchers in the past have reported
on studies designed to determine tolerances of
the human head to impact forces applied to
the top, side, and back of the head against non-
yielding flat steel blocks, flat concrete, steel balls,
or hammer blows. In crashes of aircraft as well
as in other transportation vehicles, the head usu-
ally contacts structures that have some degree
of deformation yielding. This bending increases
the deceleration time history and allows the
structure to contact. more surface area of the
face or forehead, both of which should increase
the tolerance limits of the head. Snyder’s study
of survival in fall cases,® studies of Gurdjian
et al., of cadaver impacts against laminated glass,’
and the early work done at Cornell shooting
plastic skulls at deformable panels* (all against
yielding structures) seem to support this theory,
in a general way. The purpose of the work pre-
sented here is to delineate tolerances of each
portion of the face and forehead to serve as
guidelines for engineers in the design of struc-
tures in our transportation environments that
would produce less injury upon impact.

II. Procedure and Discussion

To obtain impact tolerance data of living hu-
man heads, auto salvage yards were searched to
locate dash panels that had dents made by the
head of the right front seat passenger as he
jacknifed forward during a front-end collision.
These dash panels were purchased from the sal-
vage yard and brought to the laboratory for

study. Since the auto license plate remains with
the car in Oklahoma, it was possible to contact
the injured passenger and obtain his complete
medical history.

Next, entire cowlings from identical cars
(make, model and year) were purchased and
impacted with an instrumented dummy head on a
small catapult (Figure 1. All figures, 1 through
20, are in the Appendix), until the dent made by
the human head was duplicated as to area, depth,
and exact location on the dash. Thus, injuries
sustained in producing the head dent could be
correlated with the “g” time—force parameters
from the dummy-head impacts to determine
forces necessary to produce unconsciousness, facial
fractures, and lacerations.

Certain facts became apparent early in this
study. The facial structure is, roughly, a convex
portion of a sphere, whereas the automobile dash
panel is a portion of a cylinder lying on its side
and convex toward the passenger. The initial
contact point of these two surfaces during impact
is necessarily small in area. If the dash panel is
weaker than the portion of the face making con-
tact, it deforms, contours to the face, and in-
creases ‘the contact area and distribution of the
impact load. Thus, in a number of cases studied,
there was a progressive failure of facial structure,
and it was impossible to separate the fracture
forces for separate facial bones. More was learned
from the nonfracture cases, and, although more
than one facial bone made contact, it was possible
to tell accurately from lacerations and bruises
the area of the face taking the impact load. Some
of the most interesting cases are presented in
Figures 2 through 9, and the total data are sum-
marized in Figures 19 and 20.

To verify the data obtained in the accident
study and to determine the fracture points of
each facial structure separately, 45 impacts were
made on cadaver heads using the small catapult.
Blocks containing accelerometers (to record input
forces) were molded to fit the individual facial
bones and placed against the face. The face was



nN

fo}

fe}
!

160 -

120 -

@
°

7"
3°

°

= t 1
Oo 4 8 12 tt 20 24 28 32

DURATION TIME IN MILLISECONDS

DECELERATION FORCE IN “g"S

INPUT

200 -

160 -

120 -

@
°
i)

b
°
1

a

°

|
o 4 #8 2 16 20 24 28 32

DURATION TIME IN MILLISECONDS
OUTPUT

DECELERATION FORCE IN "g"S

Figure 13. Crushing nose fracture. Velocity—14.81 ft/sec, stopping distance—% inch.

Appendix 1





9"

nN

fe}

°
i)

Zz —
=, f AR i
r 160 + f
a
120
2
2
g 80 ; H
=
= 40
4 ACY
fs} 0 1 ' ! !
w 0 4 8 2 6 20 24 28 32

DURATION TIME IN MILLISECONDS
INPUT

nN

°

°
1

tot
o 4 #8 l2 16 20 24 2 32

DURATION TIME IN MILLISECONDS
OUTPUT

DECELERATION FORCE IN "g"S

Ficure 15, Fractures produced by 8.6-sq. in. block molded to fit teeth and maxilla. Fractures of maxilla and
compound fracture of mandible. Velocity—35.97 ft/sec, stopping distance—1-3/16 in

Appendix 19



wn
*o 200 -

z

= 160 -

ui

©

_§ 1205 pig finn

S 80

=

= 40

Ww

a

8 O-f * towo4
uw 0 4 8 2 6 20 24 28 32

DURATION TIME IN MILLISECONDS
INPUT

200 -
160 -

120 -

a
fo}

ey
°

°

toro
o 4 8 2 16 20 24 28 32

DURATION TIME IN MILLISECONDS
OUTPUT

DECELERATION FORCE IN "g"S_.

Fieure 10. Cadaver-head impact against 1-inch-square block on forehead against deformable metal. Velocity of
impact—20.88 ft/sec, stopping distance—2% inches. Hairline fracture.

Appendix 14


240-
” =
*o
=" 200- a
z
en ha

® 160- =a
a
fo}
ire
= 120-
3
Ee
= 80-
Ww
Pr a
H 40-
Ww
Qa

oe

Oo 4 #8 12 16 20 24 28 32 36 40

DURATION TIME IN MILLISECONDS
Figure 2. Forehead impact producing lacerations and concussion.

Appendix 6





wv

3

a

REFERENCES

. DeHaven, H. The Site, Frequency and Dangerousness

of Injury Sustained by 800 Survivors of Light Plane
Accidents. Department of Public Health and Pre-
ventive Medicine, Cornell University Medical College,
New York, N.Y. July 1952,

Gurdjian, E. S, et al. Intracranial Pressure and
‘Acceleration Accompanying Head Impacts in Human
Cadavers. Surgery, Gynecology and Obstetrics. 113:
185-190, August 1961.

Hasbrook, A. H. “Crash-Safe” Design Can Make Many
Accidents Survivable. Space Aeronautics, September
1960. 79-80, 87.

. Haynes, A. L., and Lissner, H. R. Experimental Head

Impact Studies, Proceedings of Fifth Stapp Automo-
tive Crash and Field Demonstration Conference, Min-

neapolis, Univ. of Minnesota, 1962. pp. 158-170.

. Huelke, D. F., Gikas,- P. W., and Hendrix, R. C.

Patterns of Injury in Fatal Automobile Accidents.

Proceedings of the Sixth Stapp Car Crash and Field
Demonstration Conference, Holloman Air Force Base,
New Mexico. November 1962. pp 44-58.

. Morrow, D. J. Analysis of Injuries of 1942 Persons

in 1422’ Light Plane Accidents. CAA Medical Service
Records, Washington, D.C. Unpublished data. 1949.

. Moore, J. O., Tourin, B., and Garrett, J. W. A Study

of Crash Injury Patterns as Related to Two Periods
of Vehicular Design. Department of Public Health
and Preventive Medicine, Cornell University Medical
College, New York, N.Y. March 1955.

Snyder, R. G. Human Survivability of Extreme Im-
pacts in Free Fall. Federal Aviation Agency, Civil
Aeromedical Research Institute Report 63-15. August
1963.

. Wahl, N. E., et al. Head Impact Investigation. Final

Report. Cornell Aeronautical Laboratory, Inc. De-
cember 1948.



then impacted with increments of force until
fracture occurred. The areas studied in this man-
ner along with fracture tolerances are shown
in Figures 19 and 20. A second accelerometer
was rigidly attached to the back of the skull
(using dental acrylic) to record the magnitude
and duration of the input loads transmitted
through the head. Figures 10 through 16 show
typical fractures with flesh removed and the
shapes of input and output loads.

In order to determine whether the forces re-
quired to fracture individual bones of the face
would be additive if the forces were applied to
the entire face simultaneously, a final test was
made. In this test, a cadaver head was impacted
against a block molded to fit the entire surface
of the face (Figure 17). A force of over 300 g,
the highest attainable with our catapult, caused
no lacerations or injuries. Response during im-
pact of facial tissue of cadaver heads would
necessarily be different than for living tissue. The
heads used in this study, however, were in an
excellent state of preservation with facial tissues
pliable and moist, and the author feels the effects
of tissue differences on facial tolerances were
negligible.

The cadaver heads tested in this study were
from persons whose age ranged from 28 to 74
years of age with a mean age of 51. Before test-
ing, the cranial cavity left by shrinkage of brain
tissue was filled with a gelatin material (same
specific gravity as brain) through the foramen
magnum. After adding the gelatin, head weights
varied from 8.50 to 11.82 pounds, with a mean
of 10.39 pounds.

Although individuals vary in tolerances to
fracture forces, there was no correlation between
tolerance and age. The frontal bone of one 66-
year-old head fractured with a force of 330 g on
the 214-sq. in. block, while the frontal bone of a
younger (38-year-old) head fractured at 190 g
on the same area block.

III. Conclusions.

There is a shameful and needless loss of life
and facial destruction in crash impacts with
transportation vehicles. Man, in a vehicle, is
surrounded by rigid tubes, angles, knobs, heavy
door posts, sharp instruments, and heavy metal

of small radius of curvature (to name a few)
all designed to impact the face and head on very
small areas.

This study has shown that if this environment
were changed to a medium-weight deformable
metal (without heavy structure directly behind
it) with a radius of curvature of 6 to 10 inches
for energy attenuation and padded with 1 to 2
inches of slow return material to contour to the
bones of the face and distribute the impact load
over the available area of the face, it would be
impossible to produce facial and forehead frac-
tures in crash impacts. The limit of human
tolerance would then be the forces necessary to
produce brain lacerations without fracture.

As might be suspected, the weakest part of
the face is the nose, which has a fracture point
varying between 35 and 80 g. Impact force on a
single zygomatic prominence of 50 to 80 g will
produce compound fractures of the arches.
Condyles of the mandible will be fractured by
forces of between 70 and 110 g applied on the
tip of the chin. The teeth and maxilla can with-
stand forces of more than 150 g if applied to a
contoured area of about 4 sq. in. The anterior
surface of the cranium (forehead) is more
rugged, requiring forces ranging between 120 and
180 g (applied to 1 sq. in.) to produce fracture.
Utilizing 3 to 4 inches of the forehead area as the
impact point raised the tolerance to as high as
300 g in some tests. Automobile accident injuries
studied here established that blows to the face
in excess of 30 g produce unconsciousness (15
minutes to 2 hours) with or without fractures.
Variations were noted between the fracture toler-
ances of different heads, but. these variations did
not correlate with age.

Airline-seat and aircraft manufacturers should
design all structures surrounding the passengers
to deform with head impacts of 40 ft/sec and
not exceed this 30-g figure. In addition, satis-
factory padding should be provided to distribute
the impact load over as much facial area as
possible.

Designers of other transportation vehicles
should strive not to exceed 40 g since temporary
unconsciousness is not such a major concern in
escape.

_——_


9"
Nn
fo}
fo}
i]

120

@
°

$
fo}

i .

°

DECELERATION FORCE IN

'
o 4 8 #2 6 20 24 28 32
DURATION TIME IN MILLISECONDS
INPUT

Nn

°

fo}
'

160

120

80 - T v

40- f

°

toot
o 4 8 12 16 20 24 28 32

DURATION TIME IN MILLISECONDS
OUTPUT

DECELERATION FORCE IN “g"S

Froure 11, “Crushing fracture with 1-inch-square block. Velocity—35.19 ft/sec, stopping distance—1% inches,

Appendix 15



APPENDIX

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21

Appendix



AM 65-20

TOLERANCES OF THE HUMAN
FACE TO CRASH IMPACT

John J. Swearingen, M.S.

Approved by Released by

Stemter A YeehL Y/ f Wade

Srantey R. Mouter, M.D. M.S. Wurre, M.D.
Drrecror, CARI Feperat Air SurGEON

July 1965

FEDERAL AVIATION AGENCY
Office of Aviation Medicine
Civil Aeromedical Research Institute
Oklahoma City, Oklahoma



TTT
240-—- +
Tt 7 i
SEE einees
200-1 et ;
160-4 "iiaa
120

@
°o

$s
fo}

DECELERATION FORCE IN “g's

or — t 1
° 4 8 12 16 20 24 28 32 36 40

DURATION TIME IN MILLISECONDS

Ficure 4. Nose and mouth impact of a 7-year-old girl. Laceration of mouth and nose, no fractures.

Appendix 8


iv
240 =
2” lat ao 4 o-
‘o Lis
=" 900
z 4
8 160-
a
oO
irs
= 120-+f
2°
Ee
< 80- |
Ww
a
w 40-
WwW
a
° om

{e] 4 8 12 16 20 24 28 32 36 40

DURATION TIME IN MILLISECONDS

Frcure 3. Forehead impact against a sharp rigid edge. Fatal skull fracture of frontan bone.

Appendix 7





~ 160 —
3
a iv
120
2
S 80 A
E
< 4
& 40 Ly
a re) L L
(s} T v 1 t
8 Oo 4 8 2 16 20 24 28 32

DURATION TIME IN MILLISECONDS
INPUT

80 im

h
°

°

! '
oO 4 8 #2 16 20 24 28 32
DURATION TIME IN MILLISECONDS
OUTPUT

Faure 14. Both zygomatic arches crushed inward. Velocity—25.8 ft/sec, stopping distance—1 inch.

Appendix 18


320

300

280

260

240

220

f

“g" UNITS
Nn
ce}
°°

o
°

IN

a
°

3
°

x
°

ACCELERATION

roy
i)

fl

TIME DURATION

IN MILLISECONDS

Ficure 20. Graphic summary of human and cadaver facial tolerances to impact. Numbers correspond to figure

numbers in this report.

Appendix 24

66-3171


ACKNOWLEDGMENTS

The author acknowledges the diligent assistance of Joseph W. Young and
Don E. Rowlan in the preparation and handling of the cadaver heads and
of William Reed, William M. Tylzynski, and Jimmie Turner in conducting
the many head-impact tests. The author also thanks the Oklahoma and
California Highway Patrols for their assistance in accident investigations.

Qualified requestors may obtain Aviation Medical Reports from Defense Documentation
Center. The general public may purchase from Clearinghouse for Federal Scientific
and Technical Information, U.S. Dept. of Commerce, Springfield, Va. 22151


4 TT TTT TTT TTI ~
240-Frtssbdca L
x rri [|
= 200
>
= a
S 160
ro} cal
mw .
2 '20
2°
Ee
= 80
Ww
d +t jt
8 40-4 -
i) bal
Ce) : HOE 1
0 4 #8 12 #16 20 2 28 32 36 40

DURATION TIME IN MILLISECONDS

Fieure 7. Zygomatic arch and nose impact. Both fractured.

Appendix WW



§ TI
ET

240
”
oO
= 200
z
w y
2 160 y,
°o x ci
ire
z '20 =
8 - nae
Ee
a 80
wu
a
o& 40
ww
a a -

t°) -

° 4 8 12 6 20 24 28 32 36 40

DURATION TIME IN MILLISECONDS

Fravre 9. Impact of nose, both zygomatics, and upper teeth, No fractures, received bruises under eyes and concussion,

Appendix 13



AM 65-20

TOLERANCES OF THE HUMAN
FACE TO CRASH IMPACT

John J. Swearingen, M.S.

Approved by Released by

Stenlery & Mryohbe Y fd jt

Srantey R. Mounier, M.D. M.S. Wurre, M.D.
Drrecror, CARI Frperau Arr Surcron

July 1965

FEDERAL AVIATION AGENCY
Office of Aviation Medicine
Civil Aeromedical Research Institute
Oklahoma City, Oklahoma



Ficure 18. Group of impact blocks used in this study.

Appendix 22


ACKNOWLEDGMENTS

The author acknowledges the diligent assistance of Joseph W. Young and
Don E. Rowlan in the preparation and handling of the cadaver heads and
of William Reed, William M. Tylzynski, and Jimmie Turner in conducting
the many head-impact tests. The author also thanks the Oklahoma and
California Highway Patrols for their assistance in accident investigations.

Qualified requestors may obtain Aviation Medical Reports from Defense Documentation
Center. The general public may purchase from Clearinghouse for Federal Scientific
and Technical Information, U.S. Dept. of Commerce, Springfield, Va. 22151




>| im TTT
240- ie CY
” +f : )
o t
=” 200-1 “a
z y,
~ 1 ic
3 160 x
oO
w
= '20
ce}
=
= 80
irr} 4
a - L imi
40 Wo
ir Sf
o&

0 4 8 12 16 20 24 28 32 36 40

DURATION TIME IN MILLISECONDS

Fiaure 5. Nose impact. Severe lacerations and fracture.

Appendix 9



240+]

200

160

120

o
°

b
°
at
K
A

i
°
|

* DECELERATION FORCE IN "g's

- 5 Sanaa I
16 20 24 28 32 36 40 44 48 52 56

°
>
o4
0

DURATION TIME IN MILLISECONDS

Ficure 8. Impact of chin, teeth, and maxilla (note teeth marks). All received crushing fractures.

Appendix 12