TESTS ON THE PROTECTION AFFORDED BY VARIOUS

TESTS ON THE PROTECTION AFFORDED BY VARIOUS FABRICS AND LEATHERS IN A
S I MULATED IMPACT OF A MOTORCYCLIST ON A ROAD SURFACE
* D r . D . M . P r ime , Br i t ish Leather Manufact ure r s ' Research Assoc iat i o n ,
By
Leather Trade House , Moulton Par k , Northampto n , NN3 lJD
and D r . R . I . Woods ,
Phys iological Laboratory , Downing S t r e et , Camb r i dge , CB2 3EG.
ABSTRACT
A l i f e s ize dummy has been used to test the response of fab r i cs and
l eathers in a simulated accident , in which the r i der s k i d s and f a l l s o f f h i s
machine o n t o the road s u r fac e .
The resu l t s have been cor related w i th
laboratory tests on the mat e r i a l s .
On the road s urface used, clothing
mat e r i a l s would requ i re a b r e a k i ng load of above 1 2 0 0 N/5 0 mm wide s t r i p , o r a
tear i ng load above 1 0 0 N when tested according to BS 3 1 4 4 , and an abrasion
resistance of more than 1 0 , 0 0 0 revolutions of a Taber Abrader w i th H l 8 whee l s
An
and a l k g load , i f they a r e t o remain intact i n a 1 12 k m . h - 1 impact .
exception is Kevlar fab r i cs which would have adequate s t rength to wi thstand
Ma jor
1 12 km . h - 1 impacts i f they r e s i st 6 0 0 revolutions of the Taber Abrade r .
impact poi nt s l i k e knee s , elbow s , hips and shoulders would probably need two
layers of mat e r i a l to prevent i n j u r i e s .
No mat e r i a l or sewing thread would be
acceptabl e if it degraded or softened when its tempe rature was very b r i e f l y
r a i sed to 3 0 0°c.
Some cotton or Kevlar f a b r i cs , and some bovine , goat or p i g
leather may b e o f adequate s t re ng t h to prevent s o f t t i ssue i n j u r i e s a t 1 1 2
k m . h - 1 ; they certainly should a t 5 6 km . h - 1 .
INTRODUCTION
These experiments were per formed in ord e r to determine if any clothing
can prevent open soft t i ssue i n j u r i e s to motorcyl i s t s in accidental impacts on
road s u rfaces and to cor relate laboratory test data with road test dat a .
Various woven f a b r i cs and l eathe r s have been tested o n a dummy i n a s i m u l ated
accident and also examined by laboratory tests .
Fel dkamp et a l . ( 1 ) reported
that p rotec t ive clothing reduced i n j u r i e s .
T h i s was emphasised by K a l be e t
( 3)
who showed that the bone i n fections following s k i n and muscle
al. ,
cont u s i o n , open wounds or d i st u r bances o f bone blood supply, are pa r t i cu la r ly
s i g n i f i cant comp l i cations of f r ac t u r e s and not i n f r equently lead t o
amputat i o n .
Otte et a l . , ( 4 ) found nearly h a l f o f motocycl i s t s ' i n j ur i es were
to soft t i ssue s , and that 7 3% occurred d u r i ng the run out phase of accide n t s .
Our d ummy simulates t h i s phase of accident s .
The pos s i b i l i ty that s u i ta b l e
clothing could p r e vent many soft t i ssue i n j ur i e s w a s emphasised b y the Folksam
study ( 2 ) which concluded that goat leather was the best mate r i a l ava i la b l e
for motorcycl i s t s '
suits.
O u r experiments have o n l y concerned clothing mate r i a l s .
Actual garments
w i l l have to be made with care i f the inherent strength of the mat e r i a l s i s
not t o b e negated by inadequate sewing techniques or seam placement .
There
are also other important charac t e r i st i cs of motorcycl i s t s ' clothing that mu st
be taken i nt o account such as windproofing and i nsulat ion ( 5 ) .
* Pre sent addre s s : B r i tish Standards Inst i t ut i o n ,
2 Pa r k S t r e e t , London, WlA 2BS
25 3
METHODS
Road Tests
A l i fe- s i ze dummy weigh i ng 70 k g was bui l t .
I t has a square section
welded steel tube f rame , high tensile steel bolt or u n i versal j o i nt
It was f l e shed with polyurethane foam, neoprene foam shee t ,
a r t iculat ions.
and hessian s t r i p bound together i n successive layers w i t h 5 0 mm wide duct
s e a l i ng tape.
Bony protuberances at the shoulde r s , e l bows , hips and knees
were machined out of sol id nylon stock or hockey bal l s .
The head was based on
a polypropylene tank float .
The durnrny was dre ssed in a cotton jacket and
t rous e r s , and over these were f ixed the test samples or protec t i ve cotton
canvas sheet s .
The durnrny ' s f l ex ib i l i ty with the samp l e s attached i s , we
bel i eve, simi l ar to that of a motorcycl i st in heavy leathe r s .
Samp l e s were attached with 5 0 mm duct tape to the left knee , r ight
The shoulder sample is secured across the dummy ' s
shoulder and r i g ht h i p .
back to the left arm.
The hip sample i s secured to a length o f cotton denim
Fabric sample s were 3 5 0 x 4 5 0 mm.
Leather
wound around the thigh beneath i t .
samp l e s were 2 5 0 x 2 5 0 mm and sewn into cotton canvas sheets 4 5 0 x 6 0 0 mm.
Cotton
and Kevl a r f a b r i cs were prepared as m u l t i l ayer samples because these mat e r i a l s
a r e o f t e n used that way i n protective cloth i ng .
For analys i s o f r e s u l t s
it
has been assumed t hat the l ay e r s perform independ e n t ly and that each va l u e
obtained i n the laboratory tests o n one layer may b e doubled for two l ay e r s .
Hole s i z e s w e r e determined separately o n each laye r .
Leathers were not tested
in two layers though it is possible that thin ones could be used in t h i s way.
The durnrny sat on a cha i r - l i ke seat w h i ch was supported on i ts right side
When a
by a steel t u be held in a support i n the back o f a laboratory van.
catch was released the dummy rotated to i ts left under gravity and f e l l of f
i t s seat simulating a motorcycl i st skidding on a l e f t- hand corner .
After
leavi ng the cha i r the dummy was f r e e o f a l l const rai n t .
The impact o n the road retarded the dummy ' s l e f t s ide and a s i t bounced
up clear of t he road i t rotated to its right s i d e , struck the road with i t s
r i g h t s i d e , and generally s l i d to r e s t i n t h i s a t t i t ud e .
I f i t rol led over ,
sat up or otherwise behaved atypically the resu l t s w e r e d i scarded .
F i g u re 1
shows two common patterns of f a l l s .
The s l ides may b e concentrated on the
right hip or right shoulder or shared between them.
The left knee rec e i ved
two i n j u r i e s : the i n i t ial impact , and the subsequent s l ide when the dummy was
Other body po i nt s rec e i ved variable a n d sometimes severe damag e ,
on i t s f a c e .
but the l e f t knee, r i ght shoulder and right h i p gave most consistent r e s u l t s .
The data f rom a l l three s i t e s has been pooled for the analyses in t h i s paper .
The road surface was normally damp rather than wet , as i t i s very often i n
Samples were photogr aphed after test , and v i s u a l ly examined.
The
B r i tai n .
ho les in the samp l e s were t raced on to card with f i rm lateral pressur e , and
t he i r areas measured on a Quantimet Image Analysing Computer .
Drops were car r i ed out at 1 4 , 2 8 , 56 & 1 1 2 km . h - 1 ( 8 . 7 5 , 1 7 . 5 , 3 5 , & 7 0
mph ) .
One s e r i e s o n 1 3 March 1 9 8 4 was o n t o a County Class B road that had
been resurfaced on 5 August 1 9 8 3 w i th 10 mm slag chippings and a binder o f
cut - back bitumen spread a t 1 . 3 l . m 2 .
All t h e o t h e r drops between 1 8 Ju ly
1 9 8 3 and 13 March 1 9 8 4 were on to a 15 year old hot ro l l ed asphalt w i th f l int
gravel aggregate road laid to BS 5 9 4 .
-
254
N
U1
U1
�
to rest
OF
at 55 m
TRACINGS
F I LM
�
CINE
OF
r ight
C.
MA N I K I N
D R O PS
AT
5 and 7 of 8.
1
1 1 2 k m . h- .
C . Shows every frame a t 6 4 fps o f a sequence between f i g ure·s
and i m p a c t s its r i ght side at the end of the sequence.
8 . l t slides o n i t s
s h ou l d er.
on
drops :
A . The m a n i k i n slides
its r i ght h i p .
Two representa t ive
��,-4
A.
sl ide
Fig. 1
The
man i k i n
bounces. rotates
3m
100 msec
3m
100 msec
Laboratory Tests
Sample t h i c k ness was measured with a micrometer gauge with a 0 . 5 k g . cm- 2
1.
2 5 measureme nts on each leather square
jaw pressure according to BS 3 1 4 4 .
and 1 0 o n each fabric were averaged.
2.
Te a r i ng load was measured according to B S 3 1 4 4
3.
B r e a k i ng load
was measured acco r d i ng to BS 2 5 7 6 on 5 0mm w i d e s t r i p s .
B r e a k i ng load was a l s o measured according to BS 3 1 4 4 o n 1 0 mm wide
specimens .
The results obtained on leather and t ight ly woven fabr i cs by the
BS 3 1 4 4 and BS 2 5 7 6 methods were in close agreement , but loosely wove n , and
Ke v l a r f a b r i cs , could only be tested adequately by the BS 2 5 7 6 method .
4.
Abrasion r e s i stance was measured w i t h a Teledyne Taber Abrader u s i n g H l 8
carborundum wheels and a 1 kg load, accord i ng to Revised B S 1 6 5 1 * .
RESULTS AND A DISCUSSION OF THE RESULTS
Table 1 summarises a l l the data f rom the tests at 5 6 & 1 1 2 km . h - 1 .
Seven types of damage were observed :
Progressive lass of thick ness by abrasion.
1.
and leathe r )
( Only on very thick wovens
2.
N o n- penetrating surface cuts - particularly on leather .
3.
T e a r i ng and expo.sure of u nd e r ly i ng mat e r i a l s by folding back ( weak
wovens and sheep s k i n s ) .
4.
M e l t i ng or softening of the f a b r i c with possibly !arge scale lass of
mat e r i a l ( th e rmoplastics l i k e Cordu r a , Nomex , Acrylan and Nylon ) .
5.
Appa rent heat hardening of leather .
6.
Glazi ng of the s u r f ace o n fatty leather or very waxy fab r i c s .
7.
F a b r i c d i st o r t i on produc i ng a hole by the s l i d i ng o f warp o n wef t or
( Only seen on Kevlar mat e r i a l s ) .
vice ve r s a .
Notes on the damage to individual mat e r i a l s
! . TEXTILES
A . Waxed Cotton Canvas 0 . 7 3 mm thick .
T h i s was the most predictable
I t d i d not tear .
Surface abrasion thi nned t h e f a b r i c unt i l
mater i a l t e s t e d .
holes appe a r e d , which then e x t e nded a s the fab ric wore away.
A t the edges of
holes the warp and weft f i b r e s p a rted s l ightly.
Repeated drops of the same
samples merely extended the hole area.
This mat e r i a l was used to protect a l l
impact p o i n t s not under study.
The f a b r i c i s hard and s t i f f .
The wax has a
high me l t i ng po i nt .
* Revi sion i n course of preparat i o n .
256
TAB L E 1
0:
<
„
ROAD TESTS WITH SIMILAR IMPACT PATTERNS
8
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0
�
3
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MATERIALS
U)
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<.l
X
"'
"'
8
z
<
�
-2
COTTON CANVAS
350 9 . m
.
X
0. 73
.
1.53
2 LAYERS
MOTORCYCLE CLOTHING WAXED COTTON
.
"
z
<
„
2 LAYERS
"
�
0:
CS o
8 „
:c
0
..'l
8
!
z
�
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n.
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z
0
f::
:::>
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0
>
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0:
0:
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i
�
"'
U) .c
"'
e
O .><
Z N
o �
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8
u „
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8
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149
1420
-
-
70
-
0.38
1100
o . 79
953
-
-
-
0.35
AS ABOVE WITHOUT WAX
1850
<
0:
0
„
..'l
0
"'
--
2:
8
305
198
65
0/34
-
56 k m . h
-1
112
2
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0
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t
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X
:::>
z
:> Cl
O OI
X ..'l
:X �
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... ...
0: X
-
-
-
-
-
-
0
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8
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U)
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U)
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8
U)
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z
35
713
24
1930
6830
5200
9
24
546
946
812
1740
7920
5910
1 .3
-
9
0
13
-
-
-
-
-
-
-
-
12
12
183
1850
1290
-
-
-
-
12
3270
10300
7940
-
12
488
4220
2980
9/12
1070
-
-
-
120
-
3/3'
3
2079
2340
2250
-
12
595
662
594
24
-
24
12/12
0.20
o. 70
1 100
-
CORDURA/PTFE/NYLON LAMINATED FABRIC
0.52
1630
235
583
1 /36
TYPE 2
0.60
1000
77
708
2/9
TYPE 2
0.64
1090
135
363
1/24
26
TYPE 4
0.74
1140
157
-
7180
295
4/18
0.34
0/24
-
.
.
.
KEVLAR , ARVILLE TEXTILES,
.
D235
.
.
KEVLAR/NOMEX/GLASS.
TBA,
.
0.68
2 LAYERS
0.36
FKV 2 6 9
0.67
2 LAYERS
1.53
KC600
.
3.39
2 LAYERS
-
-
-
505
.
B
1.02
1260
"
I
1 . 19
644
"
p
1 . 09
1.40
Q
.
'
'
1440
1.29
247
-
4660
A
BOVINE HIDE
'
-
40
-
-
0/9
-
-
0/9
-
1170
919
-
-
-
-
24
-
-
-
-
-
-
-
6
49
1670
-
9
253
586
541
9
746
1180
1030
9
51
0
17
8
742
2530
1850
8
334
156
186
18
276
96
1078
1700
1500)
401
2787
1990)
40
425
-
-
-
0/18
-
-
2690
7/15
-
4210
0/18
-
-
-
76
1 100
129
216
4810
1/12
s
1 .7 1
1770
146
7370
0/15
-
1.31
998
78
12500
5/24
3
GOAT SKINS FROH 3 ANIMALS
1 . 14
1470
86
5210
0/12
3
SHEEP SKINS FROH 9 ANIMALS
1.17
765
41
1420
14/38
20
.
-
-
-
-
(15'
-
-
( 6
-
-
12
-
-
12
199
33
72
18
0
21
335
108
113
9
17
96
70
18
540
418
459
0
6
0
180
3020
4
POOLED
0
1720
SAMPLE PULLED APART
(5)
PROBABLY MELTED NOT TORN
(2)
SAMPLE DEGREASED TO PREVENT
(6)
WHEEL CLOGGING
(7)
DATA FROH NOMEX TYPES 2 , 3 &
ALL SAMPLES TESTED ON SLAG CHIP SURFACE
(8)
SAMPLES FROH
(3)
WHEELS ALWAYS CLOGGED
NINE SAMPLES DID NOT HOLE IN
REVOLUTIONS.
12000
Q &
"'
156
-
(1)
(4)
.
476
1560
0/8
758
-
2070
-
135
27
1610
6430
1890
-
2940
-
1010
-
7850
9
40
86
-
3580
24
-
132
•
3400
4500
-
0
-
1190
-
-
-
-
4/14
-
-
-
-
6
-
2710
1410
NOTE S :
-
-
1.27
PIG SKINS FROH 8 ANIMALS
-
-
R
"
205
-
-
.
-
•
-
-
-
-
110
186
1510
9
44/60
NYLON/POLYURETHANE WATERPROOF FABRICS
FOTHERGILL & HARVEY,
�
32
-
KEVLAR ,
..'l
1 940
-
.
0: X
U)
...
41
39
"
" "'
... ...
8
667
-
NOMEX/PTFE/ACRYLAN LAMINATED FABRIC,
U)
„
24
-
96
X ..'l
U) 8
8 0.
X
..'l
::> o
O OI
24
909
2 LAYERS
t
„
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0
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8
"'
-
0. 75
.
"'
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0:
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0
-
0. 34
.
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0
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.
J
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WAXED CUPRAMMONIUM TREATED COTTON
.
1
2
MEAN HOLE AREA nun
MEAM P.OLE AREA nun
0
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0
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km:h-
1
294
R COMBINED
END POINT ESTIMATED
FROH THICKNESS LOSS AT 1 2000 REVS
257
B . Waxed Cotton
This is a trad i t i onal motorcycle
( i ) waxed Cotton 0 . 3 8 mm t hi c k .
c l o t h i ng f a b r i c in B r i ta i n .
The wax is liquid a t room tempe rature and the
It behaved as canvas except that t he holes extended by
fab ric is st i c k y .
The f a b r i c was u sed i n seve r a l layers and the lower layers suf fered
tear i ng .
Two layers per f o rmed well a t 5 6 km. h- 1
much less damage than the s u r f ace one .
Thi s i s the above
( i i ) Waxed cotton - before wax i ng 0 . 3 5 mm thick .
mater i al without the wax .
I t behaved s l ightly worse than the waxed product .
( i i i ) Waxed cotton, previously treated i n a Cuprammonium bath 0 . 3 4 mm
T h i s was a hard f a b r i c and i t was considerably weakened by par t i a l
thi c k .
conve r sion to ' rayon ' .
Where s u r f ace abrasion b a d n o t q u i t e penetrated the
f a b r i c the s u r f ace f ibres were flattened and fused t ogether .
They remai ned
stuck after de- wax i ng .
T h i s was never seen with pure cotton.
A f u s i ng
temperature was not determined i n t he laboratory as char r i ng occurred f i r st .
This was the only f a b r i c
Nylon coated with po lyurethane 0 . 2 0 mm thi c k .
1
.
km
.
h
Holes occurred par t icular ly on the lef t knee and the
t e s t e d at 14
hole edges and fabric sur face s howed mel t i ng .
A simi l a r appearance was
produced in the laboratory at 2 30°c with pressure and tension.
c.
D.
' Cord u r a '/PTF E/Nylon ' 6 6 ' laminate 0 . 5 2 mm t hic k .
The Cordura high
tens i l e nylon outer su rface behaved l i ke normal nyl o n , but only damaged a t
h i g he r speed s .
Both the Cordura and the Nylon ' 6 6 ' inner layer melted at
I n the laboratory t h i s occur red at
some hole edges even at 28 km. h - 1 .
2 3 o oc .
On the r i g ht shoulder the Nylon ' 6 6 ' inner often f used to the denim
cotton beneath w i t hout any hole appe a r i ng in the ' Cord u r a ' out er .
A
t �mpe rature of 2so0c at the Nylon ' 6 6 ' /cotton i nterface was required to
produce f u s i ng under pressure i n the laboratory.
km . h- 1 areas o f f a b r i c were s h redded o r m i s s i ng .
After road tests at 1 1 2
A t 2 8 km. h - 1 and above
Nomex/PTFE/Acryla n laminates 0 . 6 0 - 0 . 7 4 mm t hic k .
E.
the Acrylan and Nomex layers s howed me l t i ng and fusion of f i b r e s .
The inner
Acrylan layer often fused and shrank and d i storted the outer layer without
any hole occur r i ng in the outer l ayer .
I n the laboratory the Acrylan fused
a t 1 2 5oc and the Nomex at 2 8 0°c under pressure and tension.
Large areas of
fab r i c were lost at 1 1 2 km. h - 1 .
Kevlar f a b r i cs
T h i s is a thick f a b r i c o f
( i ) TBA Fortamid KC 6 0 0 1 . 5 3 mm thi ck .
compos i t e Kev l ar , Nomex a n d G l ass f i bre y a r n .
Some h o l e s appeared i n the
The holes d i d not
outer layer and t he f ibres appeared to have snappe d .
extend much by warp and weft sepa rat ion and second layer holes were very
Considerable s u rface abrasion appeared t o have occur red before. the
smal l .
f ibres snapped .
Thi s i s a very loose
( i i ) A r v i l l e Tex t i le L t d . FKV 269 0 . 3 6 mm thi c k .
Abrasion holes occu r red and also
weave f a b r i c of untwisted pure Kevlar y a r n .
considerable fabric d i stortion due to s l ippage of warp on weft and vice ve r s a .
T h i s i s a t ight ly woven
( i i i ) Fothergi l l and Har vey 0 2 3 5 0 . 3 4 mm thick .
Some holes were abraded i n i t .
There was
untwisted pure Kevlar yarn f a b r i c .
A few f ibres s howed
Usua l ly broken f i bres were f rayed.
l i tt l e fabric los s .
F.
f l attening , and had globular ends and a curly shape .
They may have snapped
while hot .
S i m i l ar appearances were produced in the laboratory when t i ghtly
stretched yarn was snapped whi le i t was p ressed f i rmly against a soft support
w i t h a solde r i ng i r o n .
This was not achieved below 3 2 o oc .
258
2 . LEATHERS
It
U nl i ke manufactured products leather is a non- u n iform mater i a l .
varies according t o the spec i e s and age of the anima l , the tanni ng process
used and the precise site of o r i g i n on the anima l .
The f i n i shed thick ness o f
leather
and
t
h
e
above
variables
determine
t
he
physical
prope r t i es o f t he
the
leathe r .
Thi s var i ab i l ity i s r e f l ected in the range of values obtained i n
laboratory and road t e s t s .
Small s ki n s f rom p i g s , goats and sheep provided
so few samp l es that all the data from each species has been pooled.
Sheep Leather 0 . 9 5 - 1 . 4 mm t h i c k .
The g r a i n* layer of wool sheep s k i n tended to tear away
( i ) Wool Sheep.
f rom the cori um.
Once holed there was a tendency to tear also.
As expected
from the low t e a r i ng loads and abrasion resi stances of wool sheep s k i n s ,
the i r performance was unsat i s f actory a t 1 1 2 k m . h- 1 .
Many were seve r e ly
damaged at 5 6 km. h - 1 .
( i i ) H a i r Sheep H a i r sheep s k i n s were stronger but usually thi nner than
wool sheep skins and tended to abrade to a hole a t 1 1 2 km . h- 1
A.
None o f t he samples tested t o r e i n road
B.
Goat Leather 1 . 0 5 - 1 . 1 8 mm t h i c k .
Goat Leather u s u a l ly s t r e tched and occasional a b r a s i o n h o l e s occur re d
tests.
where i t folded.
The goat s ki n s u s e d , w h i c h had been supplied f o r motorcycle
leathers were strong and abrasion resistant .
c.
Pig Leather 1 . 0 9 - 1 . 7 0 mm thi c k .
Some g r a i n p i g s k i n s exhi bi ted sma l l tears b u t
( i ) G r a i n Pig s k i n s .
they lost l i t t le t h i c k ness d u r i ng road t e s t i ng .
Suede Pig s kins r a r e ly tore but often appeared
( i i ) Suede Pig s k i n s .
They too lost l i tt l e thick ness
g lazed and comp r e ssed after road testing .
d u r i ng test.
Pig skin has t he same dense s t r uc t u r e th roughout its t h i c k ne s s
It is a promising mate r i a l for motorcycle
u n l ik e the other leathe r s tested.
leat her s .
o.
Bovine Leather 1 . 0 2- 1 . 7 1 mm thick
Seven h i d es f rom three d i f fe r e nt
sources were tested :
( i ) SOURCE 1 . H i d e A .
T h i s hide ' s tear i ng load and breaking load were
both low, and it tore extens ively i n road t e st i ng .
H i d e s B , I and P .
H i d e B was t h i n and the refore had a
( i i ) SOURCE 2 .
low abrasion resi stance and was holed d u r i ng road t e st i ng .
Hides I and P
which had similar charac t e r i st ics i n laboratory tests , were road tested on
d i f f e re n t road s u r f aces ( se e Table 1 ) .
The g ra i n was cut by the stones and
also abraded.
Once the g ra i n had been abraded away the corium tended to
Some r i g h t hip specimens showed l i near s h r i nkage and
stretch and tear .
hardening due to comp r e s s i o n , f r i ction or impact heating .
( i i i ) SOURCE 3 . Hides Q , R , & s .
These a l l had high b r e a k i ng load s .
Leathers Q and R were p a r t i c u l a r ly soft and f l e x i b l e and appeared t o impact
Leather s
down between road stones and s uf f e r more damage than leather s .
was considerably thicker than leathers Q and R and was much more abrasion
It pe rformed we l l i n road tests and i t s c or i um was no t rapid l y
resista nt .
revealed i n road t e s t s i n which i t performed w e l l at 1 1 2 km . h- 1 .
* The g r a i n layer of a leather i s the natural s u r f ace layer and it i s u s u a l ly
denser than the corium which forms the bulk of t he t hickness of f in i s he d
leathe r .
I n most � e c i e s of animal t h e deeper cor i um layers a r e
proqressivelv looser .
A Suede leather cons i sts e nt i re lv o f c o r i u m .
259
COMPARI SON OF ROAD DATA AND LABORATORY DATA
Graphical analys i s of mean hole diameter against tear i ng load
( F igure
2) suggests that leather and woven mat e r i a l s behave d i f ferently but that
e i ther would requ i r e a t e a r i ng load of above 300 N to remain without any
holes on impact above 1 1 2 k m . h- 1 .
The Kevlar f a b r i cs are not i ncluded i n
t h i s graph a s they p u l l apa r t i n the laboratory t e s t .
Graphical analysis of mean hole diameter against b re a k i ng load ( F i g u r e
Without
3 ) again suggests that leather and wove ns behave d i f fe r ently .
consid eri ng t he p u r e Kevl a r f a b r i c s , a b reak i ng load in excess of
3 , 5 0 0 N/5 0mm wide s t r i p appea r s necessary if the mate r i als are to remain
However D 2 3 5 has a b r e a k i ng load of 7 1 8 0 N
i ntact in impac ts on the road .
and t h i s s t i l l develops holes i n the top layer on impact , which suggests
other fact ors may be important in add i t ion to tensi l e streng t h .
Graphical analysis o f mean hole d iameter against abrasion r e s i stance o n
t h e Taber Abrader ( F i g u r e 4 ) suggests that w i t h t h i s measurement leathers and
I t appe a r s that
wovens behave s i m i lar ly , if the Kevlar f a b r i cs are excluded .
a mater ial needs to w i thstand, over 1 0 , 0 0 0 revolutions of the abrader i f i t
i s t o resist h o l i ng on impact at 1 1 2 km. h - 1 .
Tear i ng load and b reaki ng load determinations measure similar streng t h
character i st i cs o f mate r i a l s , except for t h read s l i d i ng such as occurs i n
some woven Kevlar fabrics which was only revealed i n tear t e st i ng .
Abrasion
r e s i stance, tear i ng load and breaking load all i ncrease with an increase i n
Behaviour on impact w i t h a road w i l l depend o n
t h e t hickness of a mat e r i a l .
t ear i ng and break i ng loads and abrasion resistance o f mat e r i a l s and these a r e
A mat e r i a l which t e a r s a t a low load w i l l
partly dependent on thicknes s .
t ear whatever i t s abrasion r e s i stance prope r t i e s .
A f a b r i c with a high
b r e a k i ng or t e a r i ng load fai l s i f it has a low abrasion resi stance, or if
removal of part of its thi c k ness d i sproportionately weakens i t .
A
sat i s f actory mate r i a l needs to have a c e r t a i n streng t h , to abrade slowly and
t o retain a reasonable proportion o f its strength whi l e abrading .
From Table 1 i t can be seen that s i g n i f icant tears are not often found
i n mat e r i a l s which tear a t a load above about 1 0 0 N or break at a load above
about 1 2 0 0 N/5 0 mm wide s t r i p , see also Figure 6 .
These values are much
lower than those predicted f rom f igures l & 2 ( 3 0 0 N & 3 0 0 0 N ) and suggest
that t e n s i le strength as determined i n the b r e a k i ng and t e a r i ng t e s t s is only
one factor .
I t possibly can be partly e l iminated by exclud i ng a l l f a b r i cs
If those w i t h t e a r i ng
and leathers w i t h low t e a r i ng and b r e a k i ng loads.
loads below 1 00 N or breaking loads below l , 2 0 0N / 5 0mm wide strip are removed
f rom f i g u r e 4 , f i gu r e 5 i s obtai ned .
A much clearer relationship of hole
s i ze to abrasion r e s i stance is then seen.
Woven f ab r i cs and leather l i e on
F i g u re 5 suggests that
one l i n e w i t h a l l the Kevlar fabrics quite separate .
lack o f abrasion r e s i stance i s i ndeed a major f actor i n hole formation in
impacts on road s u r f ace s .
The leather points i n F igures 4 & 5 s how considerable scatter and thi s
could be related to the d i f f erences between the road and laboratory t e s ts .
I n the Taber test the leather i s only minimally subjected to tension and does
not hea t .
The scatter may also be due to i nt eraction between t e a r i ng and
b r e a k i ng , and abrasion r e s i s tance prope r t i e s .
The point s marked ' P ' are pig
s ki n s which fall below t he chosen b r P.a k i na l na n
t. h r P. s hn l n o f 1 7. 0 0 N . h 1 1 �
260
\
\X
100
E
E
...
Cl>
-
E0
Cl>
0
.s::.
75
)(
50
�\
25
0
c
;[
Cl>
0
35
60
100
E
E
-
„
Cl>
E
Cl>
)(
50
......
0
'O
Cl>
_g
c0
�Cl>
Ke y
200
600 1,000
)( ......
)(
......
350
X
600
"
0
0
1,000
Tober
O Leat her.
+
Kevlar
Other
50
0
>C
"'-
0
)(
2,CXXJ
0
o�
'
denotes
P
woven
f a b r i cs.
l/l
Cl>
0
l/l
ii1
Cl>
-
0
0
p
3,500 6,000 1 0,000
150
ä.
E
25
revol u t i ons
fa b r i c s .
+
6
0·6
X�
�+ +
'\
+
0
)(
....... �
.__
�
.__
�
....__.
... �
�����
o .__
100
......._
200
_._
350
.......
600
1,000
p
2,000 3,500 6,000 10,000
revo l u t i on s
)
l n c l u d e s dato from the second layer of f a b r i c s
p l o t t e d a s though t w o lay ers
have
t w i c e the
load and abrasion
tearing load, breaklng
resistance of a s i ng l e
layer.
(�}
Fig.6
samples w i t h
tears
Kevlar
4660 N
50
„
No
E
�00
Breaking
0 0
pig s k l ns.
100
�
15
Fig.5
Tober
Total
samples
0
10
k N / 50 mm
load
Cl>
.D
:::!
z
++
o
0 '..®o'o
p 0
75
)(
......
+
)(
)(
Brea k i n g
F i g.4
+
100
0
0·35
N.
)(
)(
+
+
+
25
o
"
l o ad
0
� +
25
200 350
Tearing
75
>'x
50
0
'O
�
Fig. 3
100
)(
X..
75
Fig. 2
load
fabrics a t
a n d 7180N
)
tears
in 1 8 samples
�00
N / 50 mm
width
261
per formed wel l and l i e to the ext reme rights of the f ig u r e s , because of t h e i r
v e r y h i g h abrasion resistance.
The effect o f padding beneath the sampl e
Two layers of waxed cotton were used i n tests at 1 1 2 km. h- 1 to determine
the effects of foam pad d i ng on hole f ormation in the fabric above the foam.
No ef fect was seen with a hard neoprene foam No 1 0 5E * or a soft polyurethane
foam No. RA52* .
An effect was found with both a soft neoprene foam N o .
RA1 0 2E a n d an EPDM synthetic rubber foam N o . RA25* o f s i m i l ar d e n s i t y .
All
the foams were 1 2 mm thic k .
The mean hole diameters for the right shou l d e r
a n d hip i n t h e outer and i nner layers o f waxed cotton were 8 3 mm and 3 1 mm
re spec t ively without foam, and 6 7 mm and 19 mm respectively w i t h foam.
8
drops were done without foam and 8 with RA25 or R A 1 0 2 E .
The ef fect o f the road s u r f ace
1 8 1 drops were done on the hot rol led asp h a l t surface at Oakington
Barrack s , and 1 1 on the s l ag chipping s u r f ace on a County Class B road .
5
I on asphalt with P o n slag chips, and sepa r a t e
bovine hides were compared :
samples o f Q R & S on e a c h s u rf a c e .
F o r a l l compa risons pooled t he mean hole
d i ameter increased by a factor o f 4 . 8 on the rougher s lag chippings.
CONCLUSIONS
1.
( i ) The materials reach s u rface tempe ratures of around 3 0 0°c i n the road
2 5 0°c i s reached w i t h i n t h e mat e r i a l layers when t h e outside h a s
impa c t s .
no t reached 2 3 0°c .
Some o f t he hea t i ng w i l l b e due to f r iction.
Most i s
probably f rom d i ssipation o f the impact force, even on the right - hand s ide of
t he body which hits t he road in a secondary impac t .
( i i ) I n the experimental impacts at 1 1 2 k m . h- 1 mat e r i a l s tend t o break
t
he
i r laboratory determined b r e a k i ng load i s less than 1200 N/50 mm w i d t h .
if
( i i i ) Abrasion of the mater i a l s consists of c u t s of various depths by
t he road s u rface .
Soft mat e r i a l s mould better to the stone s , and therefore
abrade mor e .
Laboratory t e s t i ng with a carborundum wheel i s not a perfect
s u b st i tut e for road tests except for compa r i ng mat e r i a l s of
s i m i l a r physical
Kevlar i s renowned f o r the d i f f iculty experi enced i n cutt ing
prope r t i e s .
I n a s u i table weave i t can res i s t road abrasion much better than the
it.
laboratory tests used could predict .
( iv ) The nature of the road surface has a s ig n i f icant effec t , as also
probably do the climatic cond i t ions .
( v ) S u i table shock absor b i ng padding may a s s i s t the clothing of a r i d e r
to stay i ntac t , a s we l l as reduc i ng i n j uries to t i ssues beneath i t .
( vi ) The damage t o f a b r i cs i s s i g n i f icantly re lated to veloc i ty o f the
r i d e r p r i o r to the impac t .
2.
The f o l lowing character i s t i cs appear d e s i r able i n any material t o be
used for motorcycle protec t i ve clot h i ng :
( i ) I t should not soften or degrade when b r i ef ly raised to 3 o o oc .
( i i ) I t should have a b re a k i ng load above 120 0 N/5 0 mm wide s t r i p s , or a
tear i ng load above 1 0 0 N by BS 314 4 .
*Rubber Ast i c & Co. L t d . , Wednesbury.
262
( i i i ) It should withstand 1 0 , 0 00 revo l ut ions on the Taber Abrader i f i t
i s a leather o r cotton wove n , but need only wit hstand 6 0 0 revolutions i f i t
i s a Kevlar f a b r i c .
( iv ) I t should nei the r b e so s o f t it moulds into the road surface on
impact nor too uncomfortably rigid to wear as c l o t h i ng .
The fol lowing mater i a l s appear t o show pos s i b i l i t ies for development for
3.
Cotton fabrics i ntermediate between the canvas and
use in this clothi ng :
t ra d i t i onal waxed cotton mate r i a l in thickness, Kevlar f a b r i cs , and bov i n e ,
The only s u itable mat e r i a l s known to be avai lable a t
goat and p i g leathe r s .
I t must be noted
the moment a r e Kevlar f a b r i cs a n d bovine and g o a t leathe r .
howeve r that not all bovine or goat leathers or even Kevlar f abrics a r e
Improved tannery selection procedures of leather specif i ca l ly
strong enough.
for motorcycl i s t s ' clothing are necessary to ensure t ha t leather for t h i s end
use is o f s u f f i c ient thick ness and has adequate tear i ng load, breaking load
and abrasion resi stance proper t i e s .
In add i t i o n p u r chasers of leather f o r
motorcyc l i st s ' clothing should specify that thi s i s t h e end use for w h i c h i t
i s requ i red .
Even the best mat e r i a l s tested devel oped some holes at 1 1 2
km. h- 1 , s o at the moment clothi ng cannot be expected t o e l iminate open
i n j u ries in high speed acc ide n t s , but it may s i g n i f i ca n t ly reduce t hem and
even prevent them at more moderate speeds such a s 56 km. h- 1 .
Tests o f whole
clothing assemb l i e s , and analysis of the i n j u r i e s caused in actual accide nts ,
and collection of data about accidents where no i n j u r i es occurred, w i l l be
required to establ ish t he app; icabi l i ty of the resu l ts of experiments l i k e
those reported above, t o r i d e r s i nvolved i n accident s .
REFERENCES
(1)
(2)
( 3)
(4)
(5)
F e l dkamp, G . , and Junghan n s , K . ( 19 7 6 ) .
The typical t raffic
accidents i n adolescent s : The motorcycle accident - some
epidemiologic features and the effec t i veness of safety helmets and
IRCOBI Proceedings Amsterdam 1 9 7 6 pp 7 5 - 8 0 .
clothing .
Gustafsso n , H . ( For F o l k sam) . U ndated, 1 9 8 2 ?
( P r otective clothing for
Skyddskladsel f o r motorcyk l i s ter .
motorcycl i s t s ) .
F o l k sam, Sweden.
Kalbe, P . , S u r e n , E .G . and O t t e , D. ( 1 98 1 ) .
Trauma
assessment of i n j u r ies and t he i r consequences i n accidents w i t h
1 98 1
pp
IRCOBI
Proceedings Sa lon- de- Provence.
two- whee l e r s .
1 6 6-1 7 5 .
O t t e , o . , Kalbe, P . and S u r e n , E .G . ( 1 981 ) .
Typical
i n j u r ies to t he soft body parts and f ractures of the motorized
two- whee l e r s .
IRCOBI
Proceedings Salon- d e- Provence.
1 98 1
pp.
14 8 - 1 6 5 .
Woods, R . I .
( 1983) .
Cooling o f motocyc l i s t s i n various
clot h i ng d u r i ng wi nt e r in B r ita i n .
E rgonomics 1.§_, 8 4 7 - 8 6 1
Acknowledgements
We would l ike to thank Camb ridge University and BLMRA for maj or
f i nancial support of t h i s p ro j ec t ;
The Commanding Of f icer of the Royal Ang l i an Regiment f o r the f r equent
use of t he i r a i r f i e l d ;
263
The Cambridgeshire Constabulary and County Council for cooporation i n
the use o f the highway;
Belstaff International Lt d . , Stoke- on- Trent, Staffordshi re ; Fotherg i l l
and Harvey , PLC, L i t t leboroug h , Lancash i r e ; w . L . Gore & Assoc iates ( U K ) L t d . ,
Dunferm l i ne, F i f e ; Edward Macbean & Co. Ltd . , K i r k i n t i l loch, Glasgow;
TBA
I nd u s t r i a l Products Ltd . , Rochda l e , Lancas h i r e ; and Member tanneries of
BLMRA , who provided most of the material used in these tests;
Hideout Leathe r s , Camb r id g e , who sewed leather samples for u s a t very
short not i c e ;
A n d t h e staff of the Phy s i ological Laboratory who l e f t the i r normal
dut ies to a s s i s t in the road experiments under sometimes unpleasant
cond i t ions .
264