AN iWESTEGA?EON 0F VAMOUS MEASURES USED
IN FOOTsALL HELMET EVALEJATiON

Thesis £0! tho Dawn Of Ph. D.
MICHiGAN STATE UNIVERSITY
Richaré Carreé! Neison
1960

EE$1§

This is to certify that the
thesis entitled

An Investigation Of Various Measures Used
In Football Helmet Evaluation

presented by

Richard C. Nelson

has been accepted towards fulfillment
of the requirements for
Health, Physical
Ph.D. degree in Education 8: Recreation

 

 

 

ABSTRACT

AN INVESTIGATION OF VARIOUS MEASURES USED
IN FOOTBALL HELMET EVALUATION

by Richard C. Nelson

The purpose of this study has been to evaluate and
compare certain measures used in the evaluation of football
helmets. This was accomplished by relating the findings
of the medical research on brain injury to the information
secured from the impact test data.

Thirty-nine football helmets were impacted by a
pendulum striker at four velocities (12, 15, 18, and 21
feet/sec.). The helmets, mounted on a wooden head, were
struck at four positions; front, back, side, and top. Two
accelerometers, one placed on the back of the pendulum and
the other inside the wooden head were employed. The output
from the accelerometer circuits was fed into a dual trace
oscilloscope. A Polaroid camera, mounted on the face of
the instrument, was used to record the acceleration-time
curves for both acceleration of the head and deceleration
of the pendulum striker. . f

The photographs were projected and plotted on graph
paper. Pour measures were determined for both acceleration
and deceleration: (1) peak or maximum acceleration, (2)

rate of change of acceleration, (3) time duration of accel-
eration, and (A) kinetic energy.

2
Richard C. Nelson

The interrelationship of these four measures for
acceleration of the head was determined from the plots of
the six combinations or pairs of measures. The acceleration
values were plotted against those for deceleration to deter-
mine to what degree they are related.

It is concluded that, the front and back positions
responded similarly as did the top and side. Peak acceler-
ation, rate of acceleration, and kinetic energy increased
with an increase in impact velocity, while the fourth
measure, time duration of acceleration, decreased. A posi-
tive relationship was noted for peak, rate, and kinetic
energy. These three measures were negatively correlated
with time duration of acceleration. These findings indicate
that the measurement of peak acceleration alone is suffici-
ent under these testing conditions. The acceleration values
were directly related to those for deceleratiOn. This was
especially true of time duration, peak acceleration, and
rate. 0n the basis of these results, it is concluded that
observing the phenomenon of deceleration of the striker at

impact is unnecessary for this type of helmet testing.

AN INVESTIGATION OF VARIOUS MEASURES USED
IN FOOTBALL HELMET EVALUATION

by A

f

V
Richard cc‘weison

A THESIS

Submitted to the School for Advanced Graduate Studies of
Michigan State university of Agriculture and
Applied Science in partial fulfillment of

the requirements for the degree of

DOCTOR OF PHILOSOPHY
Department of Health, Physical Education, and Recreation

1960

845777
4/ 2 0/(44

CHAPTER
I.

II.

III.

TABLE OF CONTENTS

INTRODUCTION AND STATEMENT OF THE PROBLEM.
Introduction . . . . . . . .
Statement of the Problem . . . . .
Justification of the Study. . . . .
Limitations of the Study . . . . .

REVIEW OF RELATED LITERATURE . . . .
Skull Fracture and Brain Concussion.
Protective Headgear Research .

Summary . .g . . . . . . . .

EXPERIMENTAL METHOD . . . . . . . .
Testing Equipment. . . . . . . .
Design of the Experiment . . . . .
Measurements and Calculations. . .

Comparison of Measures for Acceleration
Of tm Head 0 O O 0 O O O O 0

Kinetic Energy vs. Time Duration . .
Kinetic Energy vs. Peak Acceleration.

Kinetic Energy vs. Rate of Acceleration.

Peak Acceleration vs. Time Duration .

Peak Acceleration vs. Rate of
Acceleration . . . . . . . .

Time Duration vs. Rate of Acceleration .

Summary . . . . . . . .

PAGE

##WNI—‘H

15
19
23
23
2h
28

31

31
31
32
32
39

39

39
M6

CHAPTER

Acceleration vs. Deceleration.

Peak . . . .
Rate 0 O O 0
Time Duration .

Kinetic Energy .

Summary of Acceleration vs. Deceleration

V. SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS.

Summary . . . .
Conclusions. . .

Recommendations .

BIBLIOGRAPHY . . . . . .

APPENDICES.

PAGE
a?
1w
#7
47
54
54
58
58
59

62
67

FIGURE
1.
2.

3.

10.

11.

12.

13.

14.

15.

16.

LIST OF FIGURES

Striker . .

and Oscillator .

Front Position .

Back Position

Side Position

pr Position.

Front POSition .

Back Position

Side Position

Top Position.

Front Position .

Kinetic Energy vs. Time

Kinetic Energy vs. Time

Kinetic Energy vs. Time

Kinetic Energy vs. Peak

Kinetic Energy vs. Peak

Kinetic Energy vs. Peak

Kinetic Energy vs. Peak

Kinetic Energy vs. Rate

Three Acceleration-Time Curves. . .

Sample Acceleration-Time Curve. . .

Kinetic Energy vs. Time Duration,

Duration,

Duration,

Duration,

Acceleration,

Acceleration,

Acceleration,

0 O O O O

Acceleration,

Polaroid Camera, Dual Trace Oscilloscope,

Photographic Record Showing Acceleration-
Time Curves for the Head and Pendulum

of Acceleration,

Wooden Head, Helmet, and Pendulum Striker .

Accelerometers Mounted on Insert and Pendulum

Plotting of the Projected Photographic Record.

PAGE
17
22

23

25

26
27
3O

33

33

34

3h

35

35

36

36

37

vii

FIGURE PAGE

17. Kinetic Energy vs. Rate of Acceleration,
_ Back Position . . . . . . . . . . 37
18. Kinetic Energy vs. Rate of Acceleration,

Side Poaition e e e e e e e e s e 38
19. Kinetic Energy vs. Rate of Acceleration,

pr Position . . . . . . . . . 38
20. Peak Acceleration vs. Time Duration,

Front Position. . . . . 40
21. Peak Acceleration vs. Time Duration,

Back Position . . . . . . . . no
22. Peak Acceleration vs. Time Duration,

Side Position . . . . . . . Al
23. Peak Acceleration vs. Time Duration,

pr Position . . . . . . . . . #1
2A. Peak Acceleration vs. Rate of Acceleration,

Front Position. . . . . . . . . A2
25. Peak Acceleration vs. Rate of Acceleration,

Back Position . . . . . . . . . 42
26. Peak Acceleration vs. Rate of Acceleration,

Side Position . . . . . . . . #3
27. Peak Acceleration vs. Rate of Acceleration,

Top Position . . . . . . . . . . A3

28. Time Duration vs. Rate of Acceleration,
Front Position. . . . . . . . . . 4A

29. Time Duration vs. Rate of Acceleration,
Back Position . . . . . . . . . . AA

30. Time Duration vs. Rate of Acceleration,
Side Position . . . A. . . . . . . A5

31. Time Duration vs. Rate of Acceleration,
pr Position . . . . . . . . . . A5

32. Peak Acceleration vs. Peak Deceleration,
Front Position. . . . . . . . . . 48

33. Peak Acceleration vs. Peak Deceleration,
Back Position . . . . . . . . . . “8

FIGURE
314.

35.

36.

37.

38.

39.

no.

Al.

42.

43.

an.

45.

1&6.

47.

Peak Acceleration vs. Peak Deceleration,
Side Position . . . . . . .

Peak Acceleration vs. Peak Deceleration,
Top Position . . . . . . .

Rate of Acceleration vs. Rate of Deceleration,
Front Position. . . . . . . . .

Rate of Acceleration vs. Rate of Deceleration,
Back Position . . . . . . . . .

Rate of Acceleration vs. Rate of Deceleration,
Side Position . . . . . . . . .

Rate of Acceleration vs. Rate of Deceleration,
Top Position . . . . . . . . .

Time Duration of Acceleration vs. Time
Duration of Deceleration, Front Position .

Time Duration of Acceleration vs. Time
Duration of Deceleration, Back Position

Time Duration of Acceleration vs. Time
Duration of Deceleration, Side Position .

Time Duration of Acceleration vs. Time
Duration of Deceleration, pr Position.

Kinetic Energy Acceleration vs. Kinetic
Energy Deceleration, Front Position. .

Kinetic Energy Acceleration vs. Kinetic
Energy Deceleration, Back Position . . .

Kinetic Energy Acceleration vs. Kinetic
Energy Deceleration, Side Position .

Kinetic Energy Acceleration vs. Kinetic
Energy Deceleration, Top Position

viii
PAGE

’49

49

50

50

51

51

52

52

53

53

55

55

56

56

DEDICATION

This dissertation is dedicated to my wife,
Inez, and to our two children, Holly and David,

who Joined us during the past three years.

ACKNOWLEDGMENTS

The writer wishes to express his appreciation and
gratitude to the following persons who have made the com-
pletion of this study possible. These include Dr. Henry
J. Montoye and Dr. Wayne D. vanHuss, who were responsible
for securing the helmets and the necessary electronic
equipment. In addition, their assistance in the design
of the experiment and encouragement throughout the study
have been greatly appreciated. Dr. George Mass of the
Department of Applied Mechanics has been most generous of
his time in serving as a consultant. His suggestions
concerning the problems of mechanics and interpretation

of the data have been most helpful.

CHAPTER I
INTRODUCTION AND STATEMENT OF THE PROBLEM

Introduction

The percentage of football fatalities due to head and
spine injuries has risen steadily from 66% in 19h? to 80% in
.1959.(3) As a result, concern has been shown by the medical
profession and other groups directly associated with the
game of football. These facts have, in turn, stimulated
investigation in the area of football headgear, but unfor-
tunately, an insufficient amount of work has been done to
date. Much of this work has been hampered by the absence
of explicit criteria upon which to base the comparison and
evaluation of football helmets.

Statement of the Problem

The purposes of this study were to:. (l) attempt to
relate the medical research evidence to the impact test
data; (2) to determine what relationships exist, if any,
between the four measures of acceleration of the head
(peak acceleration, rate of acceleration, time duration of
acceleration, and kinetic energy absorbed by the head); and
(3) to examine the relationship of the acceleration and

deceleration values.

The impact test data were obtained by the use of a .
free swinging pendulum to deliver blows of varying magni-
tudes to different positions of the helmet.

Justification of the Study

The over-all problem of protecting the head and brain
from injury is extremely complex. Despite extensive inves-
tigation by members of the medical profession the exact
mechanism of concussion is still not fully understood.
There is sufficient evidence, however, that acceleration
(or deceleration) of the head at impact is one of the most
important factors in brain injury. Other factors that
appear to be related are the duration of acceleration,
kinetic energy absorbed by the head, rate of application
of the energy, the rise or fluctuation in intracranial v
pressure at impact and the time duration of this pressure. /

On the basis of these findings investigators have
developed various impact testing apparatuses to determine
these measures. Most of these have employed some type of
pendulum arrangement to impart the force to the helmet and
head form. A linear accelerometer is usually mounted~x
either within the head (to measure acceleration of the head),
on the pendulum (to determine deceleration of the striker),
or placed in both positions for simultaneous measurement.
The following measures are obtainable under these testing
conditions: peak acceleration, rate of change of acceler-

ation, time duration of acceleration, and kinetic energy.

There is at present no information available as to

the existing relationships between these measures. Although

assumptions have been made concerning the direct relation-

ship between acceleration and deceleration at impact (A1)

no data have been reported to substantiate this assumption.

Knowing how these measures are related would enhance the

understanding of the phenomenon occurring at impact. In

addition this information could lead to the simplification

of future helmet testing techniques.

Limitations of the Study

1.

The results of this study are, of course, limited
to football headgear.

The helmets were impacted at four distinct
positions. It is possible that a different
response would have been observed had other areas
of the helmet been hit.

The results are further limited to test apparatuses
having a helmet-head mass to pendulum mass ratio
of approximately 2.6 to 1 (.38 slug to .15 slug),
and a flat surface striker moving at the four
velocities specified.

The fact that the data have been collected under
laboratory conditions is a further limitation.
Whether these conditions simulate those found in
the normal football environment is open to

question.

CHAPTER II
REVIEW OF RELATED LITERATURE

The problems of skull fracture and brain concussion
have challenged medical research workers for many centuries.
Much of the earlier work in this area was primarily of a
theoretical nature, since adequate research tools had not
been developed. The recent improvement in laboratory tech-
niques and instruments has opened the way to more fruitful
investigation. The review of the medical literature
relating to brain injury will be discussed in the first
‘section.

Protective headgear research has expanded considerably
during the past 25 years. Much of this work has come about
as a result of improved laboratory instrumentation and the
application of sound principles of mechanics. Although
only a limited amount of research has been done on football
helmets, extensive work has been conducted on aircraft,
motorcycle, and racing headgear. The second portion of
this review contains the material relating to these inves-
tigations.

Skull Fracture and Brain Concussion

 

The lack of relationship between skull fracture and
brain concussion has been well established.(h5,37,26)

Lissner, gt 21., stated, "There is no direct correlation

5
between severity of cerebral damage and linear skull frac—
ture.” (37,p.68) Fatalities due to concussion frequently
occur with no fracture of the skull present. Likewise,
skull fracture may occur with no concussive effect experi-
enced. The fact that a small amount of energy is dissipated
by fracturing the skull may account for the absence of
concussion.(23)

A review of the case histories on football fatalities
indicates that skull fracture rarely occurs in this sport.
During the last fourteen seasons 125 football fatalities
have resulted from head injuries. Of this total, eleven
skull fractures were reported. Six of these occurred in
sandlot games in which the player was not wearing a helmet.
Three of the remaining five were victims of fracture in the
basal region of the sku11.(3) Gay (15) in his report on
fifteen football head injuries observed no fractures, and
only one death resulting from the injury incurred.

Lewin and Kennedy (36), in their report on nine motor-
cycle deaths, observed that in two cases in which the
victim had worn a crash helmet, no signs of scalp marks or
skull fracture were present. Of the seven deaths in which
helmets had not been worn, six showed skull fracture and
all seven suffered surface bleeding.

Further evidence that minimal protection is needed to
prevent skull fracture was reported by Cole, MacNamee, and
Herget.(2) In their experimental work on Rhesus monkeys,

concussion was induced by firing a shell against a steel
plate placed against the animal's head. It was noted that
a layer of sponge rubber one centimeter thick inserted
between the plate and head was sufficient to prevent frac-
ture of the skull.

These findings substantiate Gross's (19) contention
that most protective helmets currently in use provide
reasonable protection from scalp laceration and skull
fracture. He suggests (18) that the primary function of
the helmet is to provide protection from brain concussion
in case of impact.

Brain concussion is defined as a state of post-
traumatic unconsciousness associated with palor and shock-
like state. It may be of varying intensity from a completely
recoverable state to that of continued coma and death. (32,
p.128) Research workers in the field of medicine, with
assistance from technicians from other fields, have exten-
sively investigated the mechanism of brain concussion.
Despite this intensified effort, the phenomenon is still
not fully understood.

It is generally agreed that brain concussion is
usually produced in one of two ways: acceleration (or
deceleration) of the head, and compression of the intra-
cranial contents caused by inbending or crushing of the
skull. (7, 8, 26, 28, 29, 30, 31, 35) "Acceleration con-

cussion" refers to cases in which the head is either

 

accelerated or decelerated. It is associated with an
increase in intracranial pressure at the point of impact
and a decrease (negative) on the opposite side of the head.
(16, 22, 28) Compression concussion occurs with the head
more or less fixed while the increase in pressure is uni-
form throughout the cranial cavity.(16, 22, 28)

Denny—Brown and Russell (6, 8) in their work on cats
and monkeys observed that in using a light pendulum to
strike the animal concussion did not occur when the head
was fixed. However, if the head was allowed to move as
little as 3 mm. concussion was produced. They concluded
that compression concussion required much greater force
than acceleration concussion to produce the same effect.

More recent investigations have failed to substantiate
this conclusion. Gurdjian and co-workers, in their experi-
ments on dogs (25, 26, 29) reported that, for a given blow,
the degree of injury decreased as the freedom of motion of
the head increased. Groat, g_t_ 3;. (17,p.125) in their work
with cats reported that, "A blow that caused concussion in
the movable head demolished the fixed head."

Other theories have been advanced to explain the
mechanism of brain injury. Eden (12) suggests that there
are two ways in which the brain may be injured by a blow
to the head: (1) a generalized effect in which the force
is transmitted throughout the skull to the brain as a whole,
and (2) a localized bruising effect characterized by signs

of focal damage or contusion to the brain. In addition,
the important factor determining the presence or absence of
concussion (assuming adequate momentum) is the area of the
skull struck. f

Holbourn (35) as a result of his work with cats
theorized that, in addition to compression, concussion was
caused by rotational acceleration. He further suggested
that linear acceleration was of little importance, since it
brought about no appreciable relative movement between parts
of the brain. The limitation in his work lies in the fact
that he did not observe the movement of the brain when
the head was impacted nor did he attempt to differentiate
between rotational and linear acceleration. No measures
of either of these factors were reported. Further he
related the mechanical factors to shear-strains (tearing)
of the brain and not to concussive symtoms or effects.

In their work with Rhesus monkeys, Cole and fellow
investigators (2) used a different approach to the problem.
A lipiodal injection was administered to the brain of the
animal. This substance formed globs which were recorded
radiographically. During impact, changes in the shape of
these globs were observed indicating a disbursing of the
brain matter away from the point of impact. Autopsies later
revealed that the site of injury was at this point. This
phenomenon occurred in a time before much, if any, movement

(acceleration) had taken place. They concluded that, "Brain

9
injury, without skull fracture during an intense local blow,
is caused by a local circulation of brain substance resulting
from stresses transferred through the skull to the brain."(2,
9.32)

A more recent theory, based on hydrodynamic principles,
has been advanced by Gross.(20) He photographed closed test
tubes which were accelerated by a sharp blow. Whenever the
tensile force of the blow exceeded the tensil strength of
the liquid, gaseous cavities were formed. This process,
which he called "cavitation,” may occur at the point of im-
pact (coup cavitation), or on the opposite side (contrecoup).
He proposed that the violent collapsing of these cavities
is the principle cause of brain damage when the human head
is accelerated.

Regardless of which type of concussion is produced
(acceleration or compression) the physiological changes;
namely, a sudden rise in blood pressure, loss of the corneal
reflexes, reduction in respiration, and unconsciousness, are
the same. Gurdjian and Webster (26) found, for blows caused
by a pendulum, there was no essential difference of response
phenomena between the fixed and the movable head. This
observation applied even when the skulls were actually pene-
trated by bullets.(25) Other studies have shown that accel-
eration and compression invoke similar physiological
responses. (17, 55) The findings do not, however, suggest
that acceleration concussion is necessarily identical with

the effects of brief compression.

10

Although the relative importance of these two mechan-
isms of concussion has not been firmly established, it
appears that acceleration concussion occurs more frequently
in accidents as well as in football. Courville (50,p.hO-h1)
states,

It has now come to be recognized that compression con-
cussion resulting from pressure or a blow to the head,
which is more or less fixed in position, is relatively
mild or may be absent altogether. 0n the other hand,
concussion produced by acceleration or deceleration of
the head (acceleration concussion) is of a more serious
degree.
Other investigators (56,h6,1h,6) concluded that acceleration
concussion is the type that occurs most frequently in falls
and other accidents. Gurdjian and Webster stated, however,
that pure compression or acceleration concussion are rare
(26), and that they usually coexist.(27) They further insist
that it is impossible to have acceleration injury without
some compression effect due to inertia of the head or the
object struck.(28) Foltz (1h), however, contends that accel-
eration concussion differs fundamentally from the various
types of compression concussion. '

Pudenz and Sheldon, in their classic experiment on
monkeys (#3), added further evidence of the movement of the
brain at impact. In their study, the tops of the monkeys'
skulls were removed and replaced by a transparent lucite
dome. After the animals recovered from the surgery, the

investigators took high speed movies of the brain as the
head was subjected to varying blows. They concluded that

11

(1) when the head was free to move at impact the cortex
rotated mainly in the sagittal and horizontal planes; (2)

if the head was fixed, little or no motion took place;

(3) for all blows inflicted, the parietal and occipital parts
of the brain moved farther than the frontal and temporal
parts, and (A) brain movement is much greater following blows
in the parietal and temporal than in the frontal and occipital
regions.

Evidence of the importance of rotational acceleration
in the contre— coup injury is offered by Goggio.(l6) He stated
that the fronto-temporal area is most frequently involved in
contra-coup injury because this is the roughest surface of
the inside of the skull. Rotation rather than linear force
frequently accompanies the blow. On the other hand, Russell
(A6) contends that contre-coup injury is due simply to the
tearing away of the brain from its meninges by its own
momentum.

Courville (h), in a more thorough study of the coup-
contra-coup mechanism observed that this type of injury
occurred only when the moving head strikes a stationary or
relatively stationary object. The coup injury is manifest
at the point under impact, and centre-coup in the area dia-
metrically opposite. The frontal area appeared to be the
most vulnerable to injury. If the blow is struck in the
frontal region, coup injury develops. However, if impact

occurs in the occipital region, contra-coup injury occurs

12
(injury in the frontal area).‘ This was explained by the
fact that the tips of the fronto-temporal lobes lay enclosed
in a bony pocket having irregular walls.

The use of electronic equipment in recent investi-
gations has made possible the measurement of the following
factors in impact: acceleration of the head, time duration
of acceleration, intracranial pressure and its time duration,
the kinetic energy absorbed. In most of these animal studies,
an attempt was made to associate one or more of these factors
either with concussive effect or actual brain damage.

Lissner and co-workers (37) suggest that the total
injurious effect is due to the absorption of energy by the
head, with the magnitude of the energy and its rate of
absorption being the important factors. They further state,
that if the accidental input of energy into the human head
can be kept below A00 inch pounds, a considerable reduction
in fatalities and serious injuries will result. In a closely
related study by Gurdjian and Webster (26,27), it was con-
cluded that the quantity of energy absorbed by the head in
an optimum period of time determined the intensity of the
physiologic response. This was found to be true whether the
head was fixed or free to move. In the experimental animal
(dog), 200 inch pounds absorbed by the head in .001 to .002
seconds or less caused profound patho-physiologic effects,
usually resulting in death. Lombard, 33 21. (#0), pointed
out that the effect of the absorption of a given amount of

13
energy is dependent upon the accompanying maximum acceler-
ation of the head.

Gurdjian and co-workers attempted to relate degree of
concussive effect with acceleration of the head and increase
in intracranial pressure. (28, 30, 31, 33) They attached
a linear accelerometer to the side of the dog's head opposite
the point of impact, and mounted a pressure gauge on each
side of the head. The animal was then struck with a hammer
and the acceleration-time curve and pressure changes were
recorded by use of electronic oscilloscopes. Their results
indicated there is little relationship between magnitude of
acceleration and physiological response evoked at the time
of impact. However, the time duration of the acceleration
did appear to be related to the degree of clinical effects.
The greater the time duration, the more serious the concus-
sive effect. Also, the magnitude of the pressure alone did
not determine the concussive effect obtained, but time dura-
tion of pressure was also significant. In other words, the
same affect was obtained with high pressure over a short
period of time as with lower pressure over a longer time.

It should be noted that because of the type of blow
inflicted, compression concussion was primarily being pro-
duced. The authors found that skull deformation was so great
that the pressure due to this deformation was of primary
significance and positive pressures were generally measured

opposite the point of the blow as well as on the same side

14
of the blow (of the 23 dogs tested only three developed
negative pressure on the side opposite the point of impact).
The fact that peak acceleration was not related to concus-
sive effect is not surprising since the greater the crushing
of the skull, the lower the resulting acceleration would be,
and the greater the compression of the brain.

As a result of this work, these investigators con-
cluded that acceleration and deceleration of the head pro-
duced clinical effects by causing an increase in pressure
of the intracranial contents and this pressure increase in
turn causes the injurious effect.(3l) This may hold true
only for compression concussion since other studies (8, 1h,
58, 6) have shown that acceleration concussion is not accom-
panied by an increase in intracranial pressure. Gurdjian
and fellow investigators further examined the importance of
the elevation of intracranial pressure and its time duration.
(29) To do this, they applied pressure directly to the
dural sac through an opening in the skull. Again, the time
duration as well as the maximum pressure appeared to be
related to the concussive effect. Walker, Kollross, and
Case (55), while using a similar technique found that the
rapid changes in pressure constituted the most important
factor in causing the resultant concussion. Whether this
type of stimulus is present in acceleration concussion,
however, is open to question. Foltz (1A) in his work with
cats and monkeysreported that experimental variation of

15
compression concussion can be devised in which the intra-
cranial contents are directly compressed through an opening
in the skull in a variety of ways, but this technique does
not simulate acceleration concussion. The fact that mech-
anically increasing the pressure produces the same results
as inflicting a blow to the fixed head (compression concus-
sion) (A7), casts further doubt as to the applicability of

these results to acceleration concussion.,

Protective Headgear Research

Recent improvement in helmet testing techniques has
resulted in extensive research on many types of protective
headgear._ Most of these investigations have utilized a
pendulum arrangement to administer blows to the helmet which
is mounted either on a wooden or metal head. Linear accel-
erometers are mounted either on the pendulum or attached
to, or secured within, the head form. An electronic oscil-
loscope is generally used to portray either maximum acceler-
ation or the whole acceleration-time curve, while motion or
still pictures are taken at the time of impact. From these
records the following measurements are obtained: peak
acceleration, rate of change of acceleration, time duration
of acceleration, and the change in velocity (area under the
acceleration-time curve). The relative importance of these
measures for use in comparing and evaluating helmets is yet

to be determined.

16

The Cornel Aeronautical Laboratory (9), under the
direction of Edward Dye, measured two components of the blow:
magnitude of energy and concentration of pressure on the
head. The report stated that blows, in terms of kinetic
energy, was believed to be the important factor. In a later
report, however, Dye (11) suggested that several component
effects of the blow received through the helmet by the head must
be considered collectively to make an accurate evaluation
of the helmet. These were: (1) linear accelerationcaf the
head, (2) rate of change of linear acceleration, (3) distri-
bution of force received by the head, (4) angular acceler-
ation of the head, (5) rate of angular acceleration, and
(6) intensity of negative pressure within the brain fluid.
Under the existing test apparatus only the first five of
these can be determined.

Since no explicit criteria for head protection are
available, Strand (54) made the assumption that the following
characteristics were desirable: (1) minimum peak acceler-
ation, (2) maximum energy absorption by the helmet, (3)
minimum tendency to "bottom-out" against the head, and
(A) uniform protection over the entire head. He concludes
by stating that other factors,such as rate of change of
acceleration and duration of the peak acceleration, must
be considered in a final determination of adequacy of the

helmet protection at a particular point.

17

The importance of maximum acceleration has been em-
phasized by Lombard, gt_al.(38, A0) and Snively.(h9) The
latter investigator believes that along with acceleration
of a low order, the energy should be dissipated over a
broad base in terms of time. Mindlin, (A2) in his report on
the "Dynamics of Package Cushioning," concluded that if the
outer container is adequate, the survival of a packaged item
in a drop test depends upon the form of the acceleration-
time curve and the magnitude of the maximum acceleration that
cushioning permits the packaged item to reach. In his work
on aviation protection helmets, Hendler (34) implies the
importance of rate of change of acceleration. For even
though the three curves in Figure l have the same area,
magnitude,and total duration of acceleration, the dynamic
effect would be quite different. The curve with the steepest
upward slope (rate of change of acceleration) would elicit
the greatest dynamic effect.

Acceleration

 

 

Time

Fig. 1. Acceleration vs Time

18

The only data available on human tolerance to acceler-
ation of the head has been reported by Lombard and co-
investigators.(h1) In this experiment they measured deceler-
ation and rate of deceleration of the pendulum striker at
impact. The subjects wore various types of protective head-
gear, and were hit from the front, back, side, and top. The
velocity of the pendulum was steadily increased until the
subject voluntarily quit. Pendulums of 13 and 9.“ pounds
(approximating the weight of the human head) were used. The
highest deceleration tolerated for each position were:
Top-~3ua, Front-~38G, Side--25G, and Back-~35G. The limi-
tation of this study lies in the assumption that deceleration
of the pendulum can be considered equal to acceleration of
the head (which was not measured). The authors implied the
forces are equal and opposite. However, when two objects
collide, it is the momentum, not the force, which is con-
served. Because of this, the G values reported are of
limited value.

Although Stapp's (52) investigation of human tolerance
to deceleration involved the whole body, his work is worth
noting. The subjects were mounted on a movable sled which
was propelled at high speed and then suddenly stopped. The
author determined that A00 at a rate of 12,000 G per second
rate of application for .12 seconds could be endured without
irreversible damage if the body is adequately restrained.

Attempts to establish tolerance limits in terms of

peak acceleration, rate of acceleration and pressure have

19
been made by various investigators.(11, 39, 50) The limits
proposed apply only to the given test apparatus, however,
and thus are of limited use. Further, since no concussion
data are available on the human the technique of extrapol-
ation from animal data has necessarily been used. As a
result, the tolerance limits established for helmets to date
are of little value when applied to football players or
other helmet test situations.

The only research located concerning the relationship
of acceleration of the head and deceleration of the pendulum
striker was conducted by Edwards.(13) In this study rank
order correlations were reported for a pendulum velocity of
21 feet per second at four positions. The coefficients of
correlation were: Front -.016, Back .10, Top .932, and
Side .90. The two measures were not secured simultaneously,

however, but rather in two separate testing sessions.

Summary
It is apparent that skull fracture rarely occurs in

football, especially if helmets are worn. This fact indi-

cates that brain injury in football is primarily caused by

acceleration rather than compression concussion. Because

of the absence of concussion data on humans it has been

necessary to apply the results of animal experimentation.
The investigations relating to acceleration concussion

conclude that the magnitude (peak) of the acceleration

20
appears to be related to the clinical effects produced.
Other factors that are apparently important include the
.kinetic energy and its rate of absorption as well as the
changes in pressure within the cranial cavity during the
time the head is accelerated. The evidence concerning the
importance of time duration of acceleration is of limited
value since compression of the brain was occurring during
impact. No attempts have been made as yet to relate the
rate of acceleration to concussive effect.

Despite the identification of these factors as being
related to brain injury, their applicability to conditions
involving the human head is questionable. There are no
tolerance limits available for humans on any of the above

mentioned factors.

Tlll‘ I-‘Illl.tl[ (l..lt‘_.'l I‘ I! I“ 'I‘!lli| .‘ai‘ Til-T Ill-‘1 i! T

CHAPTER III
EXPERIMENTAL METHOD

TestinggEquipment

The helmets were mounted on a size 7-1/h wooden head
weighing 12.2 lbs. which was suspended upside down from the
ceiling by two steel cables. A cast iron striker weighing
n.58 lbs. was suspended in a pendulum arrangement (Figure 2).
Tb insure a consistent pendulum impact velocity, an adjustable
electro-magnetic release was utilized. This unit, with pen-
dulum attached, was elevated to the preassigned heights so
that upon release the desired impact velocities of 12, 15,
18, and 21 ft./sec. could be achieved.

Tb measure deceleration of the pendulum and acceler-
ation of the head at impact two Schaevitz type‘V6-750 linear
accelerometers were used. One was mounted on the back of
the pendulum and the second attached to an insert that was
secured within the wooden head (Figure 3).

A Hewlitt Packard oscillator, model 200 cd, was
utilized to establish a signal frequency of 3,000 c.p.s. at
approximately 7 volts in the accelerometer circuits. These
signals were fed into a Hewlitt Packard model 150 A dual
trace oscilloscope. The impulse from the pendulum acceler-
ometer was portrayed on the lower trace and the head

acceleration on the upper trace. A Beattie-Varitron Polaroid

s
3
(1
i
E

Fig. 2. Wooden Head, Helmet, and Pendulum Striker

 

$4
0)
:s
'I-\
$4
4.)
U)
E
5
H
:5
'0
5:
(1)
04
'U
Q
(d
4.3
$4
(1)
U)
C.
H
C
O
"O
(D
E
O
E
0')
$4
Q)
.p
(D
E
O
it
<1)
:—I
(1)
O
0
<2

3.

Fig.

 

24

Camera (Figure 4) was mounted on the face of the oscilloscope
to secure a time exposure of the oscilloscope tracings at

the time of impact. This photograph provided a record of the
time-acceleration curves on both traces (Figure 5) from which
the desired measures were later secured. Tb increase the
accuracy of the measurements the photographs were placed in
a Beseler van Lyfe II projector and displayed four times as
large on graph paper (20 squares to the inch). The outline
of the acceleration-time curves was plotted (Figure 6) and
later drawn in completely with a French curve.

A calibration record was taken each test period using
the following technique. The accelerometer was first
positioned so that its main axis was parallel to the force
of gravity. In this position the force of gravity tends to
pull the core of the accelerometer toward the null position.
It was then swung down through the neutral position to a
point where the gravitational force was again directed
parallel to the main axis. In this position, the force
tended to pull the core away from the null position. A
photographic record (time exposure) was taken at the most
sensitive setting as each accelerometer was positioned and
moved as described. The deflection recorded represented

twice the force of gravity, or two G's.

Design of the Experiment
Three replicates of each of thirteen different helmet
models were subjected to the impact tests. Impact blows at

mommaaaomo mum .oQOOmOHHHomo momma Hmsa .meoemo ofioeMHom .: .me

 

26

 

Photographic Record Showing Acceleration-
Time Curves for the Head and Pendulum

Fig. 5.

(Upper Trace - Acceleration; Lower Trace - Deceleration)

cacoom oanamewOponm oopoonomm map wo wcappon .w .wam

 

28
four velocities (12, 15, 18, 21 ft./sec.) were inflicted to
the front, side, back, and top positions. Each replicate
received the blows in the same sequence for a given position.
In order to minimize the fatigue effect of repeated impacts,
the order of pendulum velocities was randomized for each
replicate at each position. The brand names and model num-
bers as well as the weights of the helmets appear in Appen-
dix A.

Both acceleration of the head and deceleration of the
pendulum were recorded simultaneously at impact. The
photograph in Figure 5 shows the curves for the head and
pendulum. A sample of 104 was drawn from the total 624
blows recorded. For each helmet model at each position two
velocities were randomly selected. The records of the three
replicates for each velocity chosen were examined and the one
displaying the most complete acceleration-time curve was

selected for the study.

Measurements and Calcuations
Four measures were deemed important to examine in this

study. They were: peak acceleration, rate of change of
acceleration, time duration of acceleration, and the area
under the acceleration-time curve (representing the change
in velocity).(34) Since the maximum difference in weight
of the helmets was only 4% of the head and insert weight,
the head and helmet mass was considered to be the same for

all helmets. The calculation of kinetic energy is dependent

29
upon the mass and the square of the velocity. However,
since the mass was considered to be constant for all helmets
the square of the area under the curve was used for compara—
tive purposes to represent kinetic energy. In the case of
acceleration of the head the kinetic energy absorbed was
represented in this way while for deceleration the kinetic
energy 1993. Throughout this dissertation the square of
the area under the curve is referred to as kinetic energy.

Peak acceleration was determined by measuring with a
sliding vernier caliper the maximum deflection (Distance A
in Figure 7), subtracting the baseline width (Distance B)
and dividing by two. This value was in turn multiplied by
the calibration factor for the given test period and sensi-
tivity setting to obtain the G value.

The average rate of acceleration was computed by
dividing the peak acceleration by the time required to reach
the peak. The time value was calculated by measuring the
time line (Distance D) and multiplying it by a calibration
factor for the given sweep time.

The time duration of acceleration was obtained by
measuring Distance 0 (Figure 7) and converting it to time,
using the computed factor for the appropriate sweep time.

The area under the curve was secured by the use of an
Ott Compensating Polar Planimeter. Five tracings were made
around the total area and the mean determined. Next the

area of the baseline was subtracted from the total area.

30
This result was divided by two to give the average area
above the baseline. Since the area is dependent upon sweep
time and sensitivity all values for area had to be converted
to a common sweep time and sensitivity setting. Factors
were determined for each combination of the two and multi-
plied by the value obtained for area from the plot. In
addition, slight corrections were made to compensate for
variations from day to day in calibration factors. These
were all converted to a common calibration value and compen-
sating factors computed. The previously adjusted area values
were next corrected for calibration variation by multiplying
these values by the appropriate factor. The measures for

deceleration were obtained in the same manner.

 

}s —A

 

 

 

 

 

U-

l
C

Fig. 7. Sample Acceleration-Time Curve
The data determined for all four measures from the

'Bample selected appear in Appendix.B.

CHAPTER IV
RESULTS

The results are presented in two sections. The first
considers the relationships of the various measures for
acceleration of the head, and the second the relationship
of the measures for acceleration and deceleration. Each
pair of values has been plotted and presented in graphic
form.

These data are based on the use of four impact veloci-
ties. Because of this, the calculation of correlation co—
efficients was deemed unnecessary since they could be
erroneously high or low, and, therefore, obscure the true
relationship. An example would be the case in which no
relationship exists within each impact velocity. If both
measures tend to increase, however, as the impact velocity
does then combining of the data adds linearity to the rela-
tionship. Consequently, the correlation coefficient would
indicate a stronger relationship than actually exists. In
each of the plots the velocity of the pendulum at impact
is identified by its appropriate symbol.

I. Comparison of Measures for Acceleration
‘6? the Head

 

Kinetic Energy vs. Time Duration
Examination of the plots for the front and back

32
positions indicates that both show a negative relationship.
That is, the longer time duration is associated with a lower
kinetic energy. It is also apparent that the higher
impact velocities have shorter time durations and higher
kinetic energy values. This does not hold true for the top
and side positions, however. For each impact velocity a
strong positive relationship exists. When all velocities
are considered together, this dependence is considerably

weakened. (Figures 8, 9, 10, and 11)

Kinetic Energy vs. Peak Acceleration

 

The front and back positions both show a very strong
positive association between these two measures. This
appears to hold for all four impact velocities. Over-all
the top and side positions show little or no dependence.
For the two higher impact velocities, a negative tendency

is present. (Figures 12, 13, 14, and 15)

Kinetic Energy vs. Rate of Acceleration

 

The front position plot indicates a strong positive
correlation exists which is consistent across all impact
velocities. This is not as pronounced for the back position
except for the two higher blows. The top and side values
suggest no composite relationship but the lower blows
reflect a slight negative slope, and the higher blows a
more definite one. (Figures 16, 17, 18, and 19)

L?

C) Fig. 8. Kinetic Energy vs. Time
Duration, Front Position

.4
r

 

Time Duration of Acceleration (secs.x 10’2)

 

 

 

.0
«1%-
A A ‘
A. a ‘ ' o
00 a 1
NC- ‘
' O
} 1 l J t i i
.4 .8 1.2 1.6 2.
,2 Kinetic Energy--Sq. of Area Uh er Acceleration
S 03(- 0 Curve [(sq.in) ]
R C><D
3 o
3.? A A
8 “Jr Fig. 9. Kinetic Energy vs. Time
I; A Duration, Back Position
‘3 A
a j
0
H
8
2 "i-
“ 43
° 0
9 «i. A a
1% ' [M3 “
A AA . ‘ .
e 4A .A
5 $ 0
5..
l l , i - L a J— 7
6 1.2 1.8 2.4

Kinetic Energy--Square of Area Under Acceleration
Curve [(sq.in)2].

Code for Impact Velocities (ft./sec.) 12--0 15-- a
18--o 21-- a

 

C?“
Elxo- (3 34
3 C)
33. O C a
5 cu ‘A (I
,L
as A
a A. .A
e
H 00
o L A 0
° a
‘3 coL ‘.
t3 1. Fig. 10 Kinetic Energy vs.
Time Duration,
‘3 A Side Position
1. A.
16
.3 :p- 4‘ A»
a 0
e
E A

 

‘L'V‘r a _12.O # J— 1 i

- .0 .40 .0
Kinetic Energy--Sq3are of Area under Aegeleration

 

 

 

(J‘.e- Curve [(sq.in)2]

u .r

O H .

'* AA

"5 4 O O A .

g 0 0A

i; “Ur (3 Fig. 11. Kinetic Energy
0 H vs. Tillie DuratiOn,
I; A Top Position
a C) .A

S o o

H A A

o

o 0—-

o a)

< ’ A

E O ‘ a

‘3 O

‘3 .A

4::e_

5 ° ‘

A
5;
- J i 1 1 i 4
.1 2 .3 4

Kinetic Energy—-Square of Areaeunder Acceleration
Curve [(sq.in) ]

Code for Impact Velocities (ft./sec.) 12-- O 15--A
18-- . 2l--a

 

 

 

 

 

o-
8'.
g A
L A 35
O?
o A
J
‘2’ 9
.a
:3 ‘A.‘
c:
" Ch Fig. 12. Kinetic Energy vs.
(3 :2" Peak Acceleration,
«H A 0 Front Position
4.: O A
2 4 0 AA
e
H
3 o
0 8% A
<:.4
as A0
+
E Q 0
‘> O
I; , 1: e :4 i 1 1 i
.4 .8 1.2 1.6
Kenetic Energy--Square of Area under Acceleration
Curve [(sq.inJe]
A
1.
c:
C)b A ‘
mi 1
A.
C)
g}.
1; Fig. 13. Kinetic Energy
- . vs. Peak
3 8.. A ‘ Acceleration,
r: 0‘ A ‘ Back Position
0
H
0*
‘5. a '
A»).
.a .A
o A A
2 8+
:5 H A
.A
g 0 A00
W, O O
C)
I l I l 1 l r '1 j J
.6 1.2 1.8 2.14 3.0

Kinetic Energy-~Square of Area Uhder Acceleration
Curve [(sq.in.)2]
Code for Impact Velocities (ft. /sec.) 12--o 15-- A
18». 21-- A

36

Fig. 1h. Kinetic Energy vs.

120
T‘“""——1—‘
O
P
b

 

 

‘_ Peak Acceleration,

0 A Side Position
AON
m
8
g A
00
H0"
4.)
as
h
3 A CA . A
0
30. A0 A ‘A0

L—
<m3 Q Q .
as j 0 c
o C) C) C)
"‘ 1,

,_i i i 1 - L_ , i
.20 .30 .ho .50

Kinetic Energy--Square of Area under Acceleration
Curve [(sq.in.)2]

 

 

 

m-
m i A
"" A Fig. 15. Kinetic Energy vs.
Peak Acceleration,
0 Top Position
A J».
o S g
3 A
g is
v1U\_
+>b~
m
p
.94, ’ ‘
8
23:— A ,
:3. s
9‘ ?
“g ‘30 (A .A CD ‘.
“'3- o 053%
5;: O c) C>C>C>
O
i 4. A ! a. ! leen~1-~.-~~
.10 .20 .30 .40

Kinetic Energy—-Square of Area gnder Acceleration
Curve [(sq.in.) ]

Code for Impact Velocities (ft./sec.) 12--O 15--A
18". 21--A

Rate of Acceleration (G's/sec. x 103)

Rate or Acceleration (G's/sec. x 103)

Q A
1' 37
i.
A
.53.L . e
H
‘A Fig. 16. Kinetic Energy vs.
A. Rate of Acceleration,
g1. . ‘ ‘ Front Position
A
‘A .A
c> C) .A
O?-
'* i.
A .00 A
8+
.A
C)

 

 

. O
i A“ E - 4 J A J
.3 1.2 1.6 2.0

Kinetic Energy-~Square of Area gnder Acceleration
Curve [(sq.in.) ]

 

 

 

1 U

Fig. 1?. Kinetic Energy vs.
Rate of Acceleration, A
q Back Position
<3
8-:- ‘ '
O
A
A
A
E . A
§q~ A AA ‘
. 0A A‘ O
AotggO+ J . AL —

l
6 1 1k 1 £8 £4
Kinetic Energy-~Square of Area nder Acceleration
Curve [(sq.in.)

Code for Impact Velocities (ft./sec.) 12-—O 15-- A
18--. 21--A

x 103)

Rate of Acceleration (G's/sec.

Rate of Acceleration (G's/bec. x 103)

“O

30

20

10

e ‘ 38

Fig. 18. Kinetic Energy vs.
Rate of Acceleration,

 

 

f A. Side Position
F A

A AA

.1
F OA‘C) A: A» . A
a? d? (3 A C' ‘.

C>

W\/ l A Jr J
.20 .30 .40 .50

Kinetic Energy--Square of Area Ender Acceleration
Curve [(sq.in.) ]

 

.A
Fig. 19. Kinetic Energy vs.
Rate of Acceleration,
Top Position
.pA
.A
“ A.
.A
C) as A A
(3 A .A <0
0 o A
O () CDC> A15 ‘0
"‘—“"1‘"""‘T““ “ "“‘“‘[““"' 1"" ’1 i

_ r inf” 1-, ,H Ti
.05 .1 .15 .20 .25 .30 .35 .AO
Kinetic Energy-~Square of Area gnder Acceleration
Curve [(sq.in.) ]

Code for Impact Velocities (ft./Sec.). 12--C> 15-~A

18“. 21—-A

39
Peak Acceleration vs. Time Duration
All four positions show a marked negative correlation
which is apparent at each pendulum velocity. With the
exception of the side position, the slopes are slightly
curvilinear. In all positions the higher impact velocity
results in a higher peak acceleration and a lower time

duration. (Figures 20, 21, 22, and 23)

Peak Acceleration vs. Rate of Acceleration

A very strong positive relationship is apparent
especially for the back and front positions. In this case,
the higher blows are associated with high peak acceleration
and also high rate of acceleration. (Figures 2“, 25, 26,
and 27)

Time Duration vs. Rate of Acceleration

All four plots denote a definite curvilinear negative
association. The slopes for back and front depict a "break-
off" point at approximately 750 per second for rate, and
.0035 seconds time duration. This is also present in the
plots for side and back but it occurs at a lower rate and
longer time duration point. (Figures 28, 29, 30, and 31)

These results suggest that two basic acceleration-time
curves exist under the present test situation. The one is
characterized by a high rate of acceleration (high peak,
also) and relatively short time duration. The second basic

curve has a low peak and rate of acceleration but a

 

 

 

 

 

m P"
C) .A 40
0 Fig. 20. Peak Acceleration vs.
Time Duration,
‘5 *" Front Position
c .
O
H
‘3
to" Q .
.33] cm)-
:9. - A
A
3 x 0 AA A ‘
‘8 a o 0 £0
8 3 0: <- A
av . A
‘3
3
G V
a T. . .
_..._.--- - . l- . .. 1....” -..... . . A ._ A A,
E 100 140 180 220 260
Peak Acceleration (G's)
<3? 0
.3. 00
' °° 0 Fig. 21. Peak Acceleration vs.
3 ' A A Time Duration,
8 3 Back Position
V 3
S A
3
4: 0 A
s - ;
a .
Q, .
H
3
:2 E A
:r O
‘5 i” o
s j ‘
4.9:2 ; A A A
A A
s A 0 AA A .
g (‘5 A A
g Q
E i i ii- - i _ ii. in.-.“ 1
100 200 300 “00

Peak Acceleration (G's)

Code for Impact Velocities (ft./sec.) 12-—O 15-- A
18". 21-- A

 

 

T O in
(b Fig. 22. Peak Acceleration vs.
Time Duration,
Side Position
H
c O
O O .
*‘ C)
Ear A A
.36 m .i O 0 AA .
3" - A A
o N
“ . A
‘5 3
o A
‘33 A
z: “2 ~
as ‘ A
E: v .
Q) L41 ; ,L W L :4
g 20 no 60 80 100

Peak Acceleration (6'3)

“3% 0 Fig. 23. Peak Acceleration vs.
'* A Time Duration,
g (9% . Top Position
«H O A
” o
a:
3.0 (‘1 lb’ 0
8H H
‘3»: E; nus
‘33 AA
0 . 0
came:
r .v-
a A
5 ° . .
D ‘A .
é .

 

 

 

 

dir—
“L
iv ' ‘
-.-L. .L a i _..-_ a A.
25 50 75 100 125

Peak Acceleration (G's)

Code for Impact Velocities (ft/sec.) 12--O 15--A
18". 21--A

.2

 

 

 

 

 

 

 

A
O
1&2

O A
J: 8" ‘
3 A
N ‘
3' a A
n H " O
} O A A
3?, A

A

5 o: O A A I
.4 04*- Fig. 214. Peak Acceleration vs.
*3 H Q Rate of Acceleration,
p
o O A A. . Front Position
H
o O
O
2 O A

in
t 00
3 L 41 a. L .- “1-.-“--- J
g 100 150 200 250

Peak Acceleration (G's)
' A
m
3
A O

o C
8
\
'3 A
3 o

o «-
t: (v
«S A A
4’ e
as
3 Fig. 25. Peak Acceleration vs.
'3 Rate of Acceleration,
8 8‘- A AA A Back Position
4:
'8 A ‘ O
3 000,0? A
cg J - A ......... x i

100 200 ‘ 300 400
Peak Acceleration (G's)

Code for Impact Velocities (ft/see.) 12--O 15-- A

18--. 21-- A

Rate of Acceleration (G's/sec. 103)

Rate of Acceleration (G's/bee. x 103)

 

 

 

 

 

 

 

43
Fig. 26. Peak Acceleration vs.
g; L Rate of Acceleration, A
, Side Position ‘
i
l
i
c?» '..
‘ A
A A
m A
H 1"
A A
o A '
(A A A
‘3;
CK}?
000
_._,I\,L J .-.__,-._--W-i--._--- . _ .-__.J--.-..-_.~...-i--.- -. ”WWI
30 60 90
Peak Acceleration (0'3)
53 ”a
Fig. 27. Peak Acceleration vs.
Rate of Acceleration,
pr Position
8 4~ 3
.' . ‘
3 .A
3 _§
J
a _. 5% ‘ ‘
‘A .A
0 0A 0A A
A A.’
A
LOWL J 1 t l 1
25 50 75 100 125 150
Peak Acceleration (G's)
Code for Impact Velocities (ft/sec.) 12-— O 15-- A
13-- O 21-- A

Rate of Acceleration (G's/sec. x 103)

Rate of Acceleration (G's/sec. x 103)

200

150

100

50

 

 

 

O ‘ A 4“
4. 1.
A.
A Fig. 28. Time Duration vs.
.A Rate of Acceleration,
Front Position
“ '0
!k .A
A
AA
0 A
‘g ‘I
0 O
C) C)
L A
%_{\V' C)
l A1 A J. ..._.,..W.... 1 “WWW i
.3 4 5 6

Time Duration of Acceleration (secs. x 10’2)

 

 

 

 

‘ Fig. 29. Time Duration vs.
Rate of Acceleration,
8 A. Back Position
“‘ i.
A
8 «~
cu .A
‘A
.A
<3 .A
3 “F AA ‘
o . A ‘ A
A A
_/\'L_ 1 A -..-._ i - 0904 O 1
.3 .6 .9 1.2

Time Duration of Acceleration (secs. x 10'2)

Code for Impact velocities (ft./sec.) 12--(3 15-—z&

18-- Q 21--A

III! I If 1' II lull! .11" 1‘ lull I. I'lll i III III II I
. i .I 1!! l [I l I.
.1, (III 1"...

 

 

 

 

 

A ’45
mo ob- Fig. 30. Time Duration vs. .
H m A Rate or Acceleration,
K Side Position
:5
A
< o A
a 01"
8
C ‘.
.2 ‘ A
a o
g H“ OA .
m A A ‘
'3 O Q
g o . A 00 0
<1: 0 O
9H
O .ngh L— ; l l
g .6 1.0 1.14 1.8 2
6'2 Time Duration of Acceleration (secs. 3: 10" )
A
MA Fig. 31. Time Duration vs.
3 Rate of Acceleration,
K Top Position
8 *L
o’ A o
o
{ A
0
8
c: S *r
o
«H
J)
as
p
3
a) o A ‘
0 mm
2
‘34 A A A A
0 O 0‘ O
a) A 0 <2) 0
.u 0 fiéA
$2 4 1, ‘1 g
.4 .8 1.2 1.6
_ Time Duration of Acceleration (secs. x 10’?)
Code for Impact Velocities (ft./sec.) 12--O 15--A

18--. ~21--A

46

relatively long time duration. The first is more triangular

in shape while the latter tends to be flat and spread out

along the time axis. This contention was substantiated by

a re-examination of the basic photographic records.

Summary

The results presented in this section may be sum-

marized:

1.

The front and back respond similarly. This was
also true for the side and top.

The strongest positive relationship considering
all four positions was peak acceleration vs. rate
of acceleration. '

The strongest negative correlations for all blows
occurred with peak acceleration vs. time duration
and rate of acceleration vs. time duration.

The back and front positions showed a strong
correlation between kinetic energy and rate of
acceleration and also kinetic energy vs. peak
acceleration.

The back and front positions showed no clear
relationship between kinetic energy and time
duration.

The top and side showed a strong positive associa-
tion for each impact velocity for kinetic energy

vs. time duration but no clear connection between

47
kinetic energy and peak acceleration or kinetic
energy and rate of acceleration.

7. Peak acceleration, rate of acceleration and
kinetic energy all increased with an increase in
pendulum velocity.

8. Time duration decreased with an increase in

impact velocity.

II. Acceleration vs. Deceleration

 

Peak

 

A strong positive relationship was apparent for all
positions and at all impact speeds especially for the back
and front. The highest impact velocity for the top and
side was the most variable. (Figures 32, 33, 3h, and 35)

3222

The response for rate of acceleration was similar
to that for peak acceleration. The top and side position
plots indicate an even less strong association when each
impact speed is considered separately. (Figures 36, 37,
38, and 39)

Time Duration

 

The comparison of time duration of acceleration and
deceleration reveals that a strong positive correlation
exists. This was true for all positions and pendulum

impacts. (Figures #0, 41, #2, and #3)

 

 

 

 

1&8
4.
c:
a” A
0“ A
.A
.‘P 3* A. A
53 C) ¢. A.
c .A .A
a 8_ o
as m 0 . Fig. 32. Peak Acceleration vs.
:1 A Peak Deceleration,
'; 4A Front Position
8 8-
c: 01 C) ‘A
.x
8
n. , c)
i (‘1 L L .1 J L
80 120 160 200 240
Peak Acceleration (G's)
Fig. 33. Peak Acceleration vs.
Peak Deceleration,
Back Position
§i A A‘
2 i '
re 0’
u 1.
- . .A
3 § ‘ ‘
1.
:34 §_ A
.p A
E!
2 .3»?
8 A
:3 Egr ‘5 A A'
a N A
C)
d) O 00
a at 00
4‘ L l i
100 200 300 350
Peak Acceleration (G's)
Code for Impact Velocities (ft./sec.) 12--o 15--A
18“. 21--A

Peak Deceleration (G's)

Peak Deceleration (G's)

 

 

 

 

 

 

 

A
c>_ “ ”9
4'
N
Fig. 3h. Peak Acceleration vs.
Peak Deceleration, ‘
Side Position
<3
m,_
H A
git G. .A
H
1
AA
A.‘ A
s r g 0
OLL . I _L 3 L_ i g
20 140 60 80 100
Peak Acceleration (G's)
Fig. 35. Peak Acceleration vs.
Peak Deceleration
0 Top Position
8 ‘P A
8 ..
ux ‘. .A
C)
o 4-
:r
Ea!
r
«3 .AAA
§ _ A
15 4A
8 7 AA 0
vi CMyA
8 O
L_/\AL i l l ! !
25 50 75 100 125 150

Peak Acceleration (G's)

Code for Impact Velocities (ft./sec.) l2--C) 15--l5
- 18--. Elm-A

Rate of Deceleration (G's/sec. x 103)

Rate of Deceleration (G's/sec. x 103)

 

 

 

 

 

 

 

0
8F-
0
‘O
8..
o A A
8' A .
8 A
arr A0 ‘
o A . A
3* ‘ ‘. Fig. 36. Rate of Acceleration
V8.
8e 00 . A Rate of Deceleration,
cu . Front Position
AA
8- O A
"' o
L l I 1 --..,.-...-.......,L_...~...-.. i
’ ‘ 50 100 150 200 2 0

Rate of Acceleration - (G's/sec. x lO )

0

g.
§J

r

. A
8_
In 0
A A

8 A
3 Fig. 37. Rate of Acceleration

A ‘ V8.
8— A A Rate of Deceleration,
m A A Back Position

AA

8-
N
8 C

e A
"‘ gé‘é‘

J l n l

 

100 200 300 #00
Rate of Acceleration (G's/sec. x 103)

Code for Impact Velocities (ft./sec.) 12--o 15-- A

18". 21-- A

Rate of Deceleration (G's/sec. x 103)

Rate of Deceleration (G's/sec.x 103)

 

 

 

 

 

 

A O
0
2F 51
i A
f Fig. 38. Rate of Acceleration
8’ vs.
"r Rate of Deceleration,
; . Side Position
1
l
o L
°‘ 0
A
A
‘ A
8 r—
‘A 0
A A
O __ O A0
AAA
. O o ‘
L 1 l l 4.__._.i.._- l l i
10 20 3O 40 50 60 70
Rate of Acceleration (G's/sec. x 103)
A
A
c:
8
F13. 39. Rate of Acceleration
vs.
. Rate of Deceleration,
8 Top Position
H " A ‘
Ci
8 .
H O A
O'.A
O
o C>0 A
in—AO
A
A .A
83 A
A O
l l J l
20 40 6O 80

Rate or Acceleration (G's/sec. x 103)

Code for Impact Velocities (ft./sec.) 12-- O 15--L\.
18-- Q 21-- A

 

 

 

. O
" r-
0:0 52
H O A
u: o
a "2-
3 A
~v (A
‘3 A0 .
13' 29.. A‘ A
3 ° A0 Fig. no. Time Duration of
3 .AA Acceleration vs.
3 . A Time Duration of
o o L . Deceleration,
9 W Front Position
'3 0‘
8 .A‘
H in ..
4.; F:
§
2 % i 1 l -L.-- J
a .2 .3 .4 .5 .6

Time Duration of Acceleration (Secs. x 10‘2)

 

 

‘t‘ o
o
32
. °°. ‘
O
3
v 0
g 0
I; W A A O
8 ’“
o
H
8
A
8 0
a4 3 A Fig. 41. Time Duration Of
0 . - O Acceleration vs.
: ‘ Time Duration of
3 A A Deceleration,
J; ‘ 386k Position
AA
g A‘A
m . .5 A
l t
5
E f 1* A! A. J J 1 I
’3 05 07 09 1.1

Time Duration of Acceleration (sec. 1: 10'2)

Code for Impact velocities (rt./sec.)

12-- O 15-- A
18". 21-- A

Time Duration of Deceleration (sec. 1: 10-2)

Time Duration of Deceleration (sec. 1: 10'2)

 

 

 

 

o o 53
(V
- O
43
.3.
0
A23 C)
.O
“2 .A
.A
‘ O
‘ Fig. 142. Time Duration of Acceleration
vs.
.3 ‘ Time Duration of Deceleration,
' Side Position
“’A.
.L..._........--.. . . I-. J L L L
.u .8 1.2 1.6 2.0
Time Duration of Acceleration (sec. 1: 10‘2)
\o
'* (3
‘5A. «0
0: O A
C)
O
A.
A“ CIA ‘3 A
a) A. C) (3
° Fig. 143. Time Duration of Acceleration
A vs.
. A Time Duration of Deceleration,
Top Position
=5 ‘ A
.A
i i 1 L 1 i.
.4 8 1.2 1.5 2.0

Time Duration of Acceleration (secs. x 10'?)

Code for Impact Velocities (ft./sec.) 12--O 15--A

18--. 21-- A

54
Kinetic Energy

Although the two lowest velocities for all positions
showed a slight association, the values for the two highest
pendulum speeds were completely dispersed. (Figures an, us,
A6, and it?)

In his study comparing peak acceleration vs. peak
deceleration at 21 feet per second, Edwards (13) found a
strong relationship for top and side positions but none
for the other two positions. The results of this study
show that for the back and front the 21 feet per second
values are widely dispersed while for the top and side a
strong dependence is present. This essentially agrees with
this previous work. It is apparent, though, that rank
order correlation coefficients for the back and front on
the lower velocities would be considerably higher than.
that which was reported at 21 feet per second.

Summary of Acceleration vs. Deceleration

 

1. The strongest positive relationship was for time
duration followed by peak acceleration and then
rate of acceleration.

2. Kinetic energy showed very low dependence.

3. Since the masses were different, it was not sur-
prising that the peak deceleration, rate of
deceleration, and kinetic energy values would be

greater than those for acceleration of the head.

Kinetic Energy-Square of Area under
Deceleration Curve [(sq.in.)2]

Kinetic Energy-Square of Area under
Deceleration Curve [(sq.in.)2]

 

 

 

_ .A
ux .A A. 4A 55
:1- . OA 90
. .I .A
C)
m P O A
C) Al
N *- . ‘
Fig. nu. Kinetic Energy-Acceleration
vs.
Kinetic Energy-Deceleration,
,.7 Front Position
A X
(D
J ._-..-.--.........J...-- _..---.._ ..--_J-,_,..__-_...-..-- ...l . , I
4 8 1.2 1.6 2.0

12

Kinetic énergy--Square of Area Ender Acceleration
Curve [(sq.in.) ]

_ ‘. “

Fig. #5. Kinetic Energy-Acceleration
vs.
Kinetic Energy-Deceleration,

 

 

 

 

 

 

e Back Position
0 A
4 .A
i 0A ‘
i
i A . .
I A A
.A
P £3
AA .A
.A
- o 0
3f)
A 00
J. .-.-_. ...-..--,..i -i .- ..-...-.-....._L..... J l
.6 1.2 1.8 2.4 3.0

Kinetic Energy--Square of Area UBder Acceleration
Curve [(sq. in.) ]

Code for Impact Velocities (ft./sec.) 12--O 15e-A

18". 21--A

Uhder
1
2.0

Deceleration Curve [(sq.in.)2

Kinetic Energy-Square of Area

gnder

2

Kinetic Energy-Square of Area

Deceleration Curve [(sq.in.)

2.5

1.5

1

5.0

“.0

 

 

 

A. .A
A.
- ID
56
.A
*0
CD CD
A Fig. 46. Kinetic Energy-Acceleration
vs.
‘ A Kinetic Energy-Deceleration,
‘ Side Position

<3 .A

- C)
C)

()A

.A
’ C)
A I L _L _____ L L

.20 .30 .40 .50
Kinetic Energy--Square of Area nder Acceleration
Curve [(sq.in.) ]
k . Fig. 47. Kinetic Energy-
‘ Acceleration vs.
Kinetic Energy-
.A
Deceleration,

Top Position

 

 

0’
0*
(D _ .A A
' .A
«1 .A :2
O 00
Q: ” 0 ‘
(3 C)C) .A
,_ AM; 'A
p. C) “
C)
1 fi__ 1 _fi_~ifl1minm_,r .L l
01 02 ‘3 'u ’5

Kinetic Energy-~Square of Area Ogder Acceleration
1

Curve [(sq. in.)

Code for Impact Velocities (ft./sec.) 12~-O lS--A

18--e 21";

 

 

 

 

57
It was apparent from the data that the deceler-

ation values were more variable than those for
acceleration.

The over-all results indicate a strong relation-
ship exists between acceleration and deceleration

measures .

CHAPTER V

SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS

Summary
The objective of this study has been to evaluate

and compare certain measures used in the evaluation of foot-
ball helmets. This has been done by reviewing the existing
literature on brain injury and relating these findings to
the information secured from the impact testing data.

Thirty-nine football helmets were impacted by a
pendulum striker at four velocities (12, 15, 18, and 21
feet/sec.). The helmets, mounted on a wooden head, were
struck at four positions; front, back, side, and top. Two
accelerometers, one placed on the back of the pendulum and
the other inside the wooden head were employed. The output
from the accelerometer circuits was fed into a dual trace
oscilloscope. A Polaroid camera, mounted on the face of
the instrument, was used to record the acceleration-time
curves for both acceleration of the head and deceleration
of the pendulum striker.

A sample of 104 from the total of 62h blows was
chosen. The photographs were projected and plotted on graph
paper. Four measures were determined for.both acceleration
and deceleration: .(1) peak or maximum acceleration, (2)

rate of change of acceleration, (3) time duration of

59

acceleration, and (h) kinetic energy.

The interrelationship of these four measures for

acceleration of the head was determined from the plots of

the six combinations or pairs of measures. The acceler-

ation values were plotted against those for deceleration to

determine to what degree they are related.

Conclusions

 

1.

The front and back positions responded similarly.
This was also true for the top and side positions.
This is probably due to the similarity in con-
struction of the helmets at these positions.
Three measures; peak acceleration, rate of accel-
eration and kinetic energy, increased as the
severity of the blow increased. The fourth
measure, time duration, decreased.

In general, a positive relationship was indicated
between acceleration, rate of acceleration, and
kinetic energy. These three measures were
negatively correlated with time duration of
acceleration.

Because these relationships exist it is concluded

that under these test conditions the measurement

,of peak acceleration alone is sufficient.

The acceleration values were for the most part

directly related to the deceleration values.

60
This was especially true of time duration,
peak acceleration, and rate.
0n the basis of these findings, and the fact
that greater importance is usually attached to
measurements of the head rather than the pendulum,
it is concluded that observing the phenomemn of
deceleration of the striker at impact is no longer
necessary for this type of helmet testing.

Recommendations

1.

Experimental work relating to the magnitude of the
acceleration of the head incurred in football
games is of primary importance.

The evidence indicates that along with acceler-
ation, pressure changes within the head at impact
are related to brain injury. An attempt should

be made to measure pressure changes and acceler-
ation simultaneously under laboratory conditions
to determine to what extent they are related.

This necessarily would involve the use ofa head
form filled with a gelatinous substance to
simulate the human brain at impact. Strain gauges
could be used to record the pressure at the points
desired.

The response obtained for acceleration of the head
with low velocity impacts should be compared with
data on human subjects. This could be done by

securing the accelometer on the subject's head
within the helmet to record acceleration at

impact.

61

10.

"110

12.

BIBLIOGRAPHY

Chason, J. L., W. G. Hardy, J. E. Webster, E. S.
Gurdjian, "Alterations in Cell Structure of the Brain
Associated with rimental Concussion." Journal of

Neurosurgery 15 (2 ; March, 1958. pp. 135-143.

 

Cole, G. D., J. K. MacNamee, C. M. Herget. "Brain
Injury From Local Impact Without Skull Fracture."
Military Surgeon, 111:6, December, 1952, p. 428-432.

 

Committee on Injuries and Fatalities, American Football
Coaches Association, Dr. Floyd R. Eastwood, Chairman.
January, 1959.

Courville, C. D., "Contre-Coup Mechanism of Cranio-
Cerebral Injuries," Archives of Surgery, 45: pp. 19-43,
19 2.

Courville, C. D., Commotio Cerebri; San Lucas Press,
Los Angeles, 1953.

Denny-Brown, D., and W. R. Russell, "Experimental
Cerebral Concussion," Journal of Physiology, 1940,

99:153.

Denny-Brown, D., "Cerebral Concussion," Physiological
Reviews, 25:296-325, 1945.

 

Denny-Brown, D., and w. R. Russell, "Experimental
Cerebral Concussion," Brain, 64:93, 1941.

Dye, E. R., "Development of the Beam Pad and Geodetic

- Suspension Helmet." Contract Number SOD-8; Report

Number 00-684-D-3 Cornel Aeronautical Laboratory, Inc.,
April 30, 1952, 45 pp.

Dye, E. R. '"Protecting the Head From Impact Injuries,"
Safety Education, April, 1953, pp. 8-11.

Dye, E. R., "Recommendations for Football Protective
Headgear," Confidential Report on Present Research on
Football Helmets and;Ffiture Stud’RNeeds ‘Los AngéIes
State College, December 31, 1956, pp. I—lO.

Eden, K., and J. H. A. Turner, "Loss of Consciousness in
Different Types of Head Injuries," Proceedings of the
Royal Societz_of Medicine, 34:685, 1941.

 

13.

14.
15.
16.
17.
18.
19.
20.
:21.

22.

’23.

/24.

63

Edwards, L. H., "An Evaluation of Acceleration of the
Head and the Deceleration of a Striking Force on
Impact with various Football Helmets." Unpublished
Master's Thesis, Michigan State University, 1958.

Foltz, E. L., F. L. Jenkner, and A. A. Ward, Jr.,
"Experimental Concussion," Journal of Neurosurgery,
10:342-352, July, 1953.

Gay, J. R. "Trauma of the Brain Caused by Football

Accidents " Penns lvania Medical Journal, 61 (6):
June, 1958, pp. 883—886.

 

fl

Goggio, A. F., "The Mechanism of Contre-Coup Injuries,
Journal of Neurologyand Psychiatry, 4:11, 1941.

Groat, R. A., H. W. Magoun, F. L. Dey, and W. F.
Windle, "Functional Alterations in Motor and Supra-
nuclear Mechanisms in Experimental Concussion,"
Arerican Journal of Prysiologyy 141:117, 1944.

 

Gross, A. G., "A New Theory of the Dynamics of Brain
Concussion and Brain Injury," Report N2-R1 Gross
Research Laboratories, Inc., May 15, 1957.

Gross, A. G., "On the Impact Thresholds of Brain Con-
cussion," Report N2-R1 Gross Research Laboratories,
Inc., May 15, 1957.

Gross, A. G., "A New Theory 0n the Dynamics of Brain
Concussion and Brain Injury," Journal of Neurosurgery,
15 (5), September, 1958, pp. 548-561.

Gross, A. G., "Impact Thresholds of Brain Concussion,"
Journal of Aviation Medicine; 29 (10), October, 1958,
DP. 7255732.

Gurdjian, E. S., and H. R. Lissner, "Mechanism of Head
Injury as Studied by the Cathode Ray Oscilloscope,
Preliminary Report, Journal of Neurosurgery, 1:1944,
PP. 393-399.

Gurdjian, E. S., and H. R. Lissner, "Deformations of

the Skull.and Head Injury Studied by the Stresscoat

Technique; Quantitative Determinations " The JOurnal
519—533“_'

of Surgery Gygecolggy_and Obstetrics, 83: - ,
ugus , .

Gurdjian, E. S., and H. R. Lissner. "Deformations of
the Skull and Head Injury as Studied by the Stresscoat
Technique," American Journal of Surggry, 73:269-281,
February, 1947.

 

 

 

25.

26.

27.

28.

29.

/30.

31.

x32.

33.

34.

Gurdjian, E. S., and J. E. Webster, ”Experimental
Head Injury with Special Reference to Mechanical

Factors and Acute Trauma," Sgrgery, Gynecology, and
Obstetrics, 76:623, 1943.

Gurdjian, E. S., and J. E. Webster, "Experimental and
Clinical Studies on the Mechanism of Head Injuries"
(Association for Research in Nervous and Mental Dis-
orders Proceedings, 1943), Trauma of the Central

Nervous S stem. The Williams and Wilkins Company,
HEIEIEore, MEryland, 1945.

 

 

Gurdjian, E. S., and J. E. Webster, "Mechanism and
Management of Injuries of the Read," Journal of
American Medical Association, 134:1072-1077, July 26,

Gurdjian, E. S., and J. E. Webster, "Recent Advances
in the Knowledge of the Mechanism, Diagnosis and

Treatment of Head Injury, American Journal of the
Medical Sciences, 26:21 -220, August, 1953.

Gurdjian, E. 8., H. R. Lissner, J. E. Webster, F. R.
Latimer, and B. F. Haddad. "Studies on Experimental
Concussion-Relation of Physiologic Effect to Time
Duration of Intracranial Pressure Increase at Impact,"
Neurology, 4 (3), March, 1954, pp. 674-681.

Gurdjian, E. S., H. R. Lissner, F. R. Latimer, B. F.
Haddad, and J. E. Webster, "Quantitative Determination
of Acceleration and(Intra-cranial Pressure in Experi-
mental Read Injury Preliminary Report , Neurology,
3-6, June, 1953, pp. 417-423.

Gurdjian, E. 8., J. E. Webster, and H. R. Lissner,
"Observations on the Mechanism of Brain Concussion,

Contusion, and Laceration," Sur e G ecology, and
Obstetrics, 101:680-690, Decemfigr, 1955.

Gurdjian, E. S., J. E. Webster, and H. R. Lissner,
"Mechanism of Scalp and Skull Injuries, Concussion,

Contusion and Laceration," Journal of Neurosurgery,
15 (2), March, 1958, pp. 125:128.

Haddad, B. F., H. R. Lissner, J. E. Webster, and E. S.
Gurdjian, "Experimental Concussion; Relation of Accel-
eration to Physiologic Effect," Neurology, 5:798-800,
November, 1955.

 

 

Hendler, 3., and s. M. Wurzel (MC) USN, "Design and
Evaluation of Aviation Protective Helmets," Journal of
Aviation Medicine, 27:64-70, February, 1956.

‘ _ 35.

36.

3/41 .

42.
/43.
'/44.

“5.

46.
47.

48.

65

Holbourn, A. H. S., "Mechanics of Head Injuries," The
Lancet Journal of British and Foreign Medicine, 2,
JuIy-Uecemfiér, 1943, pp. 438-441.

 

Lewin, W., and W. F. C. Kennedy, "Motorcyclists Crash
Helmets and Head Injuries," British Medical Journal,
1:1253-59, June 2, 1956.

Lissner, H. R., E. S. Gurdjian, and J. E. Webster,
"Mechanics of Skull Fracture," Erperimental Stresg

Analysis, pp. 61-70.

Lombard, C. F., "How Much Force Can Body Withstand?,"
Aviation Week, January 17, 1949, pp. 20-28.

Lombard, C. F., "Confidential Report on Present Research
on Football Helmets," American Football Coaches
Association, Injury and Fatality Committee, December 31,

1956.

Lombard, C. F., gg,g;., "New Helmet Theory Advanced,"
Aviation Week, January 24, 1949, pp. 18-20.

 

Lombard, C. F., S. W. Ames, H. P. Roth, and S. Rosen-
field, "veluntary Tblerance of Humans to Impact Accel-
eration of the Read," Journal of Aviation Medicine,
April, 1951. '

 

Mindlin,R. D., "Dynamics of Package Cushioning," Bell
System Technical Journal, 24:353, 1945.

Pudenz?i R.iC.H.Asae%gog,fandDg. S. gestarski, "The

no e var - e 0 or rv on ghe
rain," 30nrna1m6f_Neurosurgery, §$fi§7-?3§, Nov., 154 .
Rawlins, J. S. P., "Design of Crash Helmets, éMotor-
cycle-Aircrew)Lancet, 2:719-724, October 6,.1 56.

 

Russell, W. R., and F. Schiller, "Crushing Injuries to
the Skull: Clinical and Experimental Observations,"

Journal of Neurology[ Neurosurggry, and Psychiatry,
2 " ’ Fe mry’ 90

Russell W. R., "Head Injury," British Medical Bulletin,
10: 65"$, 195”.

Scott, W. W., "Physiology of Concussion," Archives of
Neurologyrand Psyghiatry, 43:270-283, 1940.

 

 

 

Sjovall, R., "Genesis of Skull and Brain Injury, Acta
Pathologica et Microbiologica Scandinavica, Supplement
.9 9 pp- 1'159-

 

49.

50.
51.
52.

53.

54.

55.
-f/56.
57.
58.

59.

66

Snively, G. G., C. Kovacic, and C. 0. Chichester,
"Design of Football Helmets," Proceedings National
Conference on the Medical Aspects of Sports, AMA,
November 30, 1959.

Snively, G. G., and C. 0. Chichester, "Safety in
Racing,’ Sports Cars Illustrated, 1959

 

"Statistics on Football Injuries," Journal of the Iowa
Medical Society, 48:35, January, 1958.

Stapp, J. P., "Human Tolerance to Deceleration,"
Journal of Aviation Medicine, February, 1951, p. 42.

 

Strand, 0. T., Jr., "Protective Helmet Impact Testing
Equipment," AF Technical Report Number 5820, May, 19 9,
published by USAF Air Materiel Command, Wright-Patter-
son Air Force Base.

Strand, 0. T., Jr., "Impact Effect on TWo Types of
Protective Helmet,‘ AF Technical Report Number 6020,
May, 1950, published by USAF, AMC Wright Patterson Air
Force Base, Dayton, Ohio.

Walker, A. E., J. J. Kollross, and T. J. Case," The
Physiological Basis of Concussion," Journal of Neuro-
surgery, 1:103, 1944.

Ward, A. A., Jr., "Physiological Basis of Concussion,"
Journal of Neurosurgery, 15 (2): March, 1958, pp. 129-

 

Ward, J. W., C. L. Montgomery, and S. L. Clark, "A
Mechanism of Concussion: A Theory," Science, 107:349-
352, 1948.

Webster, J. E., and N. E. Freeman, "Studies on the
Cerebro-spinal Fluid Pressure in Uhanesthetized Dogs,"
Annals of Surgery, 113:556-571, 1941.

Wright, J. C.“ J. R. Brooks, J. C. Goldthwait, and

R. D. Adams, Changes in Brain volume and Blood Content
After Experimental Concussion," Annals of Surgery, 118:
619-633, 1941.

 

APPENDIX A

HELMETS

LETTER CODE, BRAND NAMES, AND WEIGHTS OF HELMETS

 

Letter Replicate Weights (Grams)

 

 

Code Brand Name Model 1 2 3

A Riddell RK-4 829.5 828.8 832.6
B Wilson r2104 933.0 911.5 921.4
c Riddell TK-S . 780.7 783.5 782.8
D MacGregor E-700 795.3 793.6 786.7
E Wilson F2110 858.5 869.6 865.4
F MacGregor E-705 771.1 748.5 761.2
G Spalding 3122 880.2 870.0 878.9
H Nokona WAR 825.8 812.0 826.3
I Reach SMBR 845.5 868.2 871.5
J ' MacGregor H612 1004.8 1023.9 1057.7
K Wilson F2010 881.2 882.5 852.5
L Spalding 3131 979.4 971.6 941.7
M Rawlings BMR 1117.7 1115.4 1113.9

 

APPENDIX B

HELMET TEST MEASURES FOR ACCELERATION
AND DECELERATION

O

7.

 

 

 

E! “H!

‘

 

wom.em em.mmH mHm. HHo.H wee m H
HmH.mmH eo.mom one. mmm.H eme m m
mee.me mm.emw Hmm. ome.w m e m m
mme.meH mm.emm eHm. ewe.m moe m n
mme.me mm.oeH mHm. new. man Hm m m
eme.omm me.Hem mew. omm.H mum H :
mmm.oom ee.eem mom. eme.m emm H x
mom.HHm we.00m How. mem.H mmm H H
oem.emH Hm.mmH Hmm. «mm. one m c
mee.HHm me.mmm emu. e H.m hoe m H
oem.mmm oe.emm omH. moo.H omm mH H m
mme. mH.ooH owe. mew.H omm H o
mmm.eH em.om ewe. maH. nee m z
mmm.ooH we.meH mom. mom. awe m m
www.mm mm.eHH eem. om . mme m a
HeH.mw m.mm one. Hm . mme m a
eem.mmH me.eom mmm. eoe. woe mH m m
omo.mH m>.maH emu. Hmm. can u m
owe.wm mH.mHH owe. m m. eem w e
mmH.eoH mm.mmH mmm. meH. mem H c
mom.mm mm.mo owe. mmm. HemH H m
mHm.m m .mm moo.H owe. mme m o
who.HH e .me mew. HHe. owe m H
e .eH oo.eo mm». own. mum «H w e
m m.eH we.me Hmw. eem. mmm H a
«mo.mm me.om mum. mmm. emm H m
.omfi\m.o n.o :H A.oommuonv m—A.cH.umvmmn<H .oz huHoonb oumoHHaom Homo:
.Hooo< .Hooo< :oHumhsn ouonm nomaeH poEHom
no comm xmmm camp

 

  

COHumnoHoeo<

\I'I.‘ I. ll 'Ill'l‘.:.“.’l|sll .l’lll lil|I|71|I I. I..\| I ‘Ii' III 'II' . III. It.. I I II 1

 

 

 

ZOHBHmOm Ko<mnummmbm<mzwemmfi Bmzqmm

1""

 

 

7. wmw.eom mH.eoo «mm. Hme.mH wee m H
www.Hw~ oo.oem mHm. mHm.e eee m m
mom.emm em.mHo eHm. mme.mH «me m m
mHe.Hem Ho.omw mew. omm.m moe m a
mme.me mo.emm wee. amm.m mam Hm m m
Hmm.Hwe mm.eem mmm. mme.» mum H 2
0mm.mmm mm.mme eeH. HmH.m ewm H x
Hme.oee om.Hme meH. mHe. mmm H H
moo.mme me.mem Hmm. mH.e ome m c

oo.m e me.mem meH. mm.e eoe m H
emo.mem oe.mHm meH. mHo.m omm wH H m
moe.mmH em.Hme wee. mmm.m omm H o
Hem.om mm.mow mow. emm.m mee m z
mHm.eHm ee.mom mmm. Hom.m ewe m M
mem.mmm we.oem emu. Hmm.e moe m n
Hmm.mm mm.mom oem. m m.w mme m a
mmm.wme mm.wmm 0mm. m w.m woe mH m m
omm.mmm mo.omm mHm. woe.H omm m m
mme.me Ho.emm mHe. mem.H eem m e
mme.mmm mH.omm Hmm. on.H mem H e
HHm.me em.mmH mmm. mmm.m Hem H m
mom.em oo.om new. HHo.m mme m o
www.mm oo.ooH one. «me.H owe m H
H e.mm oo.oHH emm. mmH.H mum NH m e
mme.mm mm.eHH owe. emm.H mmm H a
mom.em mw.meH mam. mom.m emm H m
.oom\e.c n.o 2H A.oom nonv NHA.=H.UmVeon<H .oz thoOHob mumeHHdom Homo:
.Hoooa .Hmooa :OHmenmn ouozm vommsn posHom
no ovum xaom uses

 

:oHpmhoHooon

'Il 1.1 ll
ll I‘ll NIH I!

poacapcooauZOHBHmom ¥o<mrummmbm<mz.9wma fimzqmm

 

 

 

 

 

 

 

2 ""11 IE IN“! 18H
7. emu e mm.He mom.H ewe. meu m o
emu Hu mm.uoH eoe. o u. Huu m e
eou uu me.He new. mmm. omu u m
umm .eH ee.ee eee. emu. eHu u m
eee .ee me.eoH mom. emu. eou Hu H H
Hoe mu eu.mm eHm. mmH H e
we». mH me.em ewe. meu. emH H o
oeo.oe em.mm ume. Huu. HeH H o
omm.ee me.mHH Hum. ueH. uHm m V x
AHH.oH so.mu emm.H umu. umu m u
mmm e we.Hm meH.H omm. meu mH u m
eee mH ue.mm mmm. mmm. oHu H z
eeH e mo.mm ouu.H woe. emH H o
eee. e me.um eem. ueH. meu u m
oem m ee.mm eeo.H meu. muu u o
Hum m Hu.mu umo.H emu. mHu mH u m
eHm H >o.em Hmm. mHu. emH H H
uem m me.Hm eeu.H mHm. umH H m
Hem e o .Hm ouH.H eeH. oeu m e
memo m m .mH emm.H mHu. eeu u H
ue.mu emu. omH. umu u H
eem m Hu. H m .H meH. muu u o
eHm e He.ou me . ueH. mou uH H :
mue.m u». mH mma.H meu. emH. H n
ume.m me. eH eue.H eHu. HMH H m
emm.e Mm. uu ueH.H uHu. e H H m
.omM\n.e m.o :H A.oom uonv uHA.cH.vmvmoH<H .oz muHoOHm> oumoHHmom Homo:
.Hoooe .Hmooe :oH «use oponu HomoeH poaHom
do seem xeou oeHe
COHDGHOHOOHE

 

 

 

 

ZOHBHmOm mQHmuammmDm¢mz.Bmm9 9mzqmm

73

 

 

 

muu.ee eH.mm eoH.H emm.u mmu m H
eeo.ue em.mmu uHu. eee.u Heu m e
Fem.emH mm.euH mes. mem.u omu u m
uum.eH ee.ee uem. ueH. eHu u m
eme.oeH eo.Heu ueu. ouo.H sou Hu H H
Hum.me eemmou eHe. eHu.H mmH H u
eum.ee me.ee Hmm. mmu.H eeH H o
eme.oe mo.HeH uue. eHe. HeH H o
eeu.omH mm.eHm meu. eme. uHm m x
mHe.moH oe.muH eHe.H wee.H umu m m
mHo.mu eo.em emo.H eme.u meu eH u m
eHu.mm me.em eHe. eHe.H oHu H z
mHo. H eu.me eoH.H wue.H eeH H o
emm.um me.um eeo.H mem. man u u
emo.om mm.me ouo.H eHm.u muu u o
muo.eH mm.me ouH.H ome.u mHu mH u m
mHo.em ee.ee Hom. mme. emH H H
muu.eH oo.ee eHH.H e u.H umH H m
eeH.eH me.oe emu. 5mm.H oeu m e
Heu.eu ee.mm eme. meo.H eeu u H
m m.em oH.me eee. on. ueu u H
e e.ee eu.mm mee. uee. euu u H
emu.mH oo.ee uem. mHe. mou uH H :
eeH.mH um.em me.H eee. emH H n
umo.eu ee.em mHe.H oHe. HwH H m
umm.mu oo.ee eeo.H uoo.H eeH H m
.ooM\m.o n.o :H 5.00» -oHHv «HA.:H.UanoH<H .oz mpHooHo>_ onsoHHmem Homo:
.Hmoon .Hoooo :oH when ouonm oommeH poeHom
no ovum xsom oEHB
GOHDGHOHCOCQ

 

 

ooseHucoo--oneHmou uon--.mmmom<mz SB. sesame

 

|-|'.' all llil 1.4.8111

.' '|O.l\|"|-’l-'l‘ll|ulll I‘l’li‘

     

 

 

 

 

coHasHoHoood

III... 111' I. III

III

ZOHBHmom gemMnnmmm—Hgmz Emma 983mm

eeo.mmu oo.oHu oou. omu.H mmH m H
wem.ewH oo.emu emu. uw.H meH m H
euo.uuH oo.m H weu. ww. mHH m o
meH.eou oo.uou ouu. omu.H mHH m m
wmm.eeH uw.HwH euu. mHH.H on Hu u z
eme.oeu wH.wuu- emH. Huu.H ow u H
Nee.mmH wH.me mmu. wee. oe u e

wm. mH Hm.oeH ueu. emm. eH H H
meu.Hou oo.emH euu. moH.H umH m e
ewe.mw ou.HmH mHm. ku.. uHH m e
ewH.meH me.ueH mmu. uw. mw u m
mHm.oeH Hm.omH omu. uu. Hw wH H o
eem.muu oo.owH . uwH. mwo. ee H a
Hom.ee mm.ouH oum. ueu. mH H o
emH.eHH oo.umH wuu. Hmu. emH m m
Hem.ueH oo.me eeu. Hwe. HuH m H
omw.me Hu.eHH eeu. woe. eoH u z
mee.ee me.HoH Heu. eeH. uw mH u o
wwe.we eu.mw eHm. omu. ee u H
oH .eHH uu.muH. euu. woe. on H H
em .eoH oo.ouH mmu. ewe. mu H H
umm.wm oe.ee Hme. ewH. eeH m o
Heo.em mm.we oem. ewH. me u w
mme.me oo.uw mmu. emu. e uH H a
mHe.oHH me.moH uHu. eHm. m H H
un.ee ee.we meu. mem. m H m
.ooM\w.¢ u.o :H A.oou noHHV unA.:H.uwvson<H .oz mpaoon> oumoHHnom Homo:

.Hooo< .Hooo< coH mesa ouonm HemHEH HoeHom
«0 spew xeou sees

75

 

1'1“.“

 

 

 

umH eHe eo.eee ueH. ewe.m mmH m H
eee emm me.mee muu. Hem.e meH m H
mwm new wH.moe mew. mme.m mHH m o
Hem.wmm em.mee omH. emw.m mHH m m
«Hm mm mm.mem mmH. m o. moH Hm a z
mmm Hm mm.mmm H. mmo.u ow u m
eeu.eeu oe.emm emu. ewH.e oe u e
mme.mwe ee.HHe e u. me.e eH u H
HHm.mme me.mee ecu. moe.m umH m a
Hem.emw ee. 00m Hem. Hm.H uHH m d
oHo mmm me. owm eHu. uow.m mw u m
emH emu om. .me mm. mam. Hm H c
mHe eee om. m m eH. mwo.m me H w
MMH on mm.mee mam. mow. H H o
wme uuu mm.wmm omu. eee.H emH m H
«mm mum Hm.HmM mum. eHu.: HNH m o
ewe mm.e w wmw. mmw.w @0H m 2
«mm eH mo.emw m. me. mm m o
eeH.um um.omH uum. eueW ee u m
eHm oum mH.mme emu. Ween om H H
eee.mem oH.wee euu. ou. .e mu H H
Hme ”eoH «.mmH mm w H m h
mHe. we m.ouH mwm mm. mm u m
eoo mmu mH.umu emu. mem.u ee H x
eem.mwm we.oem ewH. emm.m mm H H
muo.eou we.on ueu. me.e w H m
.oem\u.u w.c :H A. use aonv «HA. sH. unvson<H .oz mpHooHe>. ousoHHHom Homo:
.Hooon .Hooon eoH when ouonm posnsH neaHom
no spam xsom mafia

coHusHoHoooa

 

 

coscfiucoouuonBHmom BZOfihuummm5m<ms.BmMH Bmzqmm

 

76

 

 

soHumHoHoooe

ZOHEHmOm moenummmbm<mz_9mm9 amzqmm

Hom.mu ee.ew wue. oom. eue m H
ewo.uu mm.we oem. uwu. omm m o
ome.o Hu. me weu. H. wee Hu u H
umm.e ew. umH eem. mu. eHm H H
mmm.w me.me Hom. ueu. Hweu H m
eue e ee.em eoe. H wem. mew. u H
eee m mw.um eme.H uoe. new wH u m
owm em me.em mum. Huu. uHm H H
wme om ee.m Hme. meH. eue m H
uwu HH mm.e Heo. H mwu. eoe m H
uoe uH mm.mu moe. mHH. ewe m e
eme e oo.eu mem. H weu. owe u z
umm HH me.mu mee.H eeu. emm u o
emm.e eH. u mme.H weu. emm mH u m
omu e em.om mmo.H Huu. me H o
ewe eH mm.we Hom. emH. eom H m
me e mu.ou on.H weu. HmeH H H
uuo w ee.wH omo.H HmH. mue m H
mmo.m .om eem. omH. moe m m
wme.m e .eu wm .H omu. emm m H
mow m eH.uu ewe. oeo. me m e
mme e eu.mH mmm. umo. eee uH u e
er m me.ou ewe.H muu. emm u o
ewu e um.mH ome.H eou. uem u H
mew. m eo.ou uou.H meH. wmm u o
eeH. e me.eH wem.H eeH. euw H :
.oofi\n.o u.H HH H.oewunonv mHH.:H.duvsen<H .oz HuHoonp. ousoHHHom Homo:
.Hoooe .Hoooe soHuensH oponu uoeHsH HoeHom
no spam xsou meme

 

  

 

 

 

emm.we mw.eeu wee. eHm.u eu m H
wme.emH ee.me mee. em .H omm m o
on.mHu eH.eee Hom. ueu.H mew Hu u H
wHe.mou mH.emm eoe. ume.e eHm H x
HmH.eu mH.meH umm. uoe.e Hwe H m
mHo.me oo.em emH.H mmm.m mew u H
uHe.mm mm.me umm.H wee.m mew wH u w
Hee.eoH wm.mme mmm. mme.m uHm H H
meH.mw mo.Heu mwm. mmm.H eue m H
wHu.ee ee.we mww. mee.H eoe m H
mwo.ueH mo.HHH mHe. eoe.u ewm m e
eHe.uH em.oe Hmm.H mee.u owm u z
eHm.wu em.oe mew. eeo.H emm u o
mwm.wm H.me wum.H Hme.u ewe mH u m
eem.um e.mm meH.H eHm.u eHm H n
eee.eu mH.emH mum. ewo.m eom H m
wom.ee eH.mw ueu.H meo.m HmeH H H
mHe.eH me.um muw. mmm. mue m H
ome.eH eo.ee mmw. emw. moe m m
ueo.me ow.oe eom. Huu. emm m m
eeH.um eH.moH uwe. mee. me m e
oue.we eu.oe mum. eme.H eem uH u e
eow.eH em.ee mHm.H uoe.u ewe u o
mmu.Hm mm.we oeo.H mHe.H uem u H
Hmo.mm mm.em mem. mHe.H wmm u o
u H.uu ue.em emu.H Hmm.H eum H z
.ooj\u.c n.o cH A.oowmnonV NRA.HH.deHoH<H .oz auHoOHm> oudoHHHmm Homo:
.Hmoom .Hooon :oHHmHsn oponm HomasH uoEHom
Ho spew xeou meHe

coHHmHeHmomn

’l'li

 

 

cmfichcoouuonBHmom mOBInmmmDm<mz Emmy Bmzqmm

it

 

 

M

2"/