ABDOMINAL INJURIES, INJURY CRITERIA, INJURY SEVERITY ... · Abdominal injury criterion: Various studies highlight that, due to the viscous component of the abdomen in terms of dynamic

ABDOMINAL INJURIES, INJURY CRITERIA, INJURY SEVERITY LEVELS AND ABDOMINAL SENSORS FOR CHILD DUMMIES OF

THE Q FAMILY

HEIKO JOHANNSEN1, FRANÇOIS ALONZO2, CLÉMENT GOUBEL2, VOLKER SCHINDLER1

1Technische Universität Berlin, Berlin (TUB), Germany; 2INRETS - LBMC, Lyon, France

ABSTRACT This paper describes two different sensors systems for the assessment of abdominal loads of child

dummies together with the main background information concerning injury mechanism and sensor

philosophy. Both devices are able to give relevant information in the case of a frontal impact as well

as a lateral one. While one of the sensors assesses the intra-abdominal pressure and the pressure rate

combined in the abdominal injury criterion (P*V), the other measures the applied abdominal surface

load.

Preliminary load limits proposed are based on the first frontal accident reconstructions of the

CHILD programme.

The use of the abdominal sensors and the related load limits may allow a better evaluation of

current and future restraint systems and so have a positive effect on road safety.

Keywords: abdomen, child restraint systems, instrumentation, submarining, injury risk, Q dummies

Current dummies offer various possibilities to measure injury relevant loads. Regarding the Q child

dummy series these are acceleration at head, chest and pelvis, chest deflection for frontal or lateral

impacts, loads at upper neck, lower neck and lumbar spine – not all of the mentioned measurements

are applicable for every Q dummy.

In road accidents, the abdomen is a frequently injured body segment. Abdominal injuries are

mainly due to interaction with safety belt, shields or armrests. This kind of injury is less frequent than

head injury but when abdominal organs are involved (such as liver, spleen or intestines), the

associated injury level tends to be higher. Moreover, intra abdominal injuries are often not easy to

detect just after the collision and untreated consequently may lead to severe handicap or even death.

However, no appropriate measurement system for the assessment of abdominal loads is in use for

child dummies.

Within the EC CHILD project both INRETS and TUB developed an abdominal sensor. While the

INRETS sensor consists of two gel filled bladders to measure the intra abdominal overpressure with

two standard pressure cells, contact forces to the abdominal block can be measured with the TUB

sensor array.

The goals of the CHILD project are the improvement of CRS, dummies (development of Q0),

injury criteria and injury risk functions. This will be achieved by experimental reconstruction of real

world accidents. In addition human modelling of children will support the experimental work. Another

goal is to propose new mandatory test procedures.

ACCIDENT STATISTICS Based on GDV data of German accidents between 1990 and 1991 [Langwieder, 1997] 15 % of the

children using a CRS properly suffered abdominal injuries (see Fig. 1). The abdomen ranks as the

second body region suffering injuries. For further investigation the injury severity has to be taken into

account.

IRCOBI Conference - Prague (Czech Republic) - September 2005 201

head

48%

chest

7%

abdomen

15%

arms/legs

15%

cervical spine

14%

thoracic lumbar

spine

1%

Fig. 1 – Injuries of Children Using a CRS Properly [Langwieder, 1997]

Taking into account the “harm” (weighted injury frequency) of the different body regions, the

abdomen shows up as the second ranked region of harm followed by the extremities, neck and chest,

see Fig. 2.

0%

10%

20%

30%

40%

50%

60%

head cervical spine chest abdomen thoracic /

lumbar spine

arms / legs

"ha

rm"

[%]

Fig. 2 – Injuries of Children [Langwieder, 1997]

An older study based on the same accident data of 1990 and 1991 shows that the main problems for

children exists for those wearing a 3-point belt or a lap belt only [Langwieder, 1994]. Children suffer

abdominal injuries even when using a CRS.

CRS 3 point only Lap only

65,4 % 61,9 % 66,7 %

25,0 % 26,2 % 16,7 %

11,5 % 14,3 % -

23,1 % 40,5 % 83,3 %

Basis

52 inj. = 100 %

Basis

42 inj. = 100 %

Basis

6 inj. = 100 %

Number of injuries AIS 1 – 6

CRS 3 point only Lap only

Head 34 26 4

Neck 13 11 1

Chest 6 6 -

Abdomen 12 17 5

Arms 5 9 1

Legs 5 5 2

T/L Spine - 2 1

Total 75 76 14

Fig. 3 – Number and Frequency of Injuries to Different Parts of the Body Depending on the Kind of Restraint System [Langwieder, 1994]

Based on French accidents of the years 1992/1993 and 1995/1996 Trosseille et al. [1997] came to

the conclusion, that abdominal injuries occur for older children with an age above 3 only. These were

cases with boosters or without any CRS.

Finally Arbogast et al. [2004] stated a relatively higher abdominal injury risk for children between

4 and 8 years old. The risk for children using a proper CRS or a belt routing booster is low.


ABDOMINAL SENSOR SYSTEMS As abdominal injuries are mainly a problem of children using a group II or III seat (according to

ECE R44, children with a weight of above 15 kg), which are mainly boosters with and without

backrest, the development of abdominal sensors started for Q3 and Q6.

Based on a short description of the Q dummy family with emphasis on the abdominal region, the

two sensor systems and their biomechanical background are described.

Q DUMMY FAMILY: The next generation of European child dummies – the Q family – offers the

following dummies: Q0 (newborn), Q1, Q1,5, Q3, Q6. The dummies are designed for multidirectional

use, which requires abdominal sensors able to cope with at least frontal and lateral impacts. The

modular design of the dummies allows to use the same philosophy of the abdominal sensors for

different dummy sizes.

Except for the Q0 the design of the “extended abdominal region” of all Q-dummies is composed of

a rigid thoracic spine which fixes a rib cage and houses a chest accelerometer and a chest deflection

measurement which can measure either in X or in Y direction. At the lower end of the thoracic spine

an elastomer lumbar spine is mounted, which connects the thorax with the pelvis. Between lumbar

spine and pelvis a load cell can be installed. In addition the pelvis houses another accelerometer. An

abdominal block made of PU foam and covered with skin (see Fig. 4 middle) simulates the abdomen

itself. The dummy is clothed with a wet suit. In this context it has to be mentioned, that the Q-

dummies are designed for seated and standing posture use. This requires spherical hip joints and a

small gap between the thighs and the pelvis (see Fig. 4 right).

Fig. 4 – Design of the Abdominal Region of the Q3

ABDOMINAL PRESSURE TWIN-SENSOR: Based on INRETS’ experience acquired during the

EC CREST programme (1996-2000), a new version of a pressure sensor was developed.

CAD model of the pressure cells

embedded into the standard

abdominal insert of the Q3 dummy

Prototype with details of

pressure cell inserted in the

upper cap

The sensor embedded into the

standard abdominal insert of the Q3

dummy

Fig. 5 – INRETS Pressure Sensor

The objectives of these sensors are to detect and measure the dynamic loads applied on the

abdomen during frontal and lateral crash tests; or more precisely, to acquire the signal of the over-


pressure generated by a compression or/and a penetration of the abdominal area – due to safety belt or

other equipment – as a function of time.

The second goal is to derive an injury criterion for the abdomen and finally an injury risk curve and

a protection reference value for approval purpose.

Since Q dummies have been developed to be used for lateral and frontal impact, it is necessary to

develop sensors designed and located for measuring loads applied along these two main axes. For the

lateral impact, the use of a left and a right bladder enable to assess the injury risk, not only on the side

of impact, but also on the opposite side which could be struck, for example, by another CRS or an

occupant. For the frontal impact, a twin-sensor enables correlations between measurements taken on

the right side and injuries of ascendant intestine, liver or right kidney, or measurements taken on the

left side and injuries of spleen, descendant intestine, etc.

In order not to modify the initial abdominal response to compression, each bladder is made of

smooth 35 shore A polyurethane-rubber and filled with gel. The pressure is measured using industrial

pressure cells screwed into the aluminium caps (see Fig. 5).

Abdominal injury criterion: Various studies highlight that, due to the viscous component of the

abdomen in terms of dynamic stiffness, it is necessary to take into account not only the reaction force

correlated with deflection magnitude but also the additional force correlated with rate of compression

[Mertz, 1997; Rupp; 2001; Lau, 1986; Prasad, 1984].

Moreover, it is well known that the injury risk for organs like intestines, spleen and liver are not

only linked to the global compression acting on the abdominal muscle envelope but also to the surface

on which this compression is applied to.

These two considerations lead to the hypothesis that the most pertinent criterion for injuries

sustained by inner abdominal organs could be the product of the intra-abdominal pressure with the rate

of pressure change (Fig. 6).

Abdominal Injury Criterion: Intra-abdominal pressure * Rate of pressure change

AIC [bar2/s] = P [bar] * V [bar/s]

Fig. 6 – Example of Recorded Overpressure Signal and Corresponding P*V

First experiments: Quasi-static compression tests show that the PU bladders sustain a total

compression applied by a compression plate of 50 mm without damage and that pressure signal is well

correlated with compression force and compression surface.

Dynamic experimentations performed on a free fall test rig with a standard safety strap (Fig. 7 left)

exerting forces on the abdomen of a Q3 dummy at various energy levels (Fig. 7 centre) on various

abdomen regions (Fig. 7 right) show that intra-abdominal pressure increases with impact energy and

varies depending on strap location.

-0,2

0

0,2

0,4

0,6

0,8

1

1,2

0 0,1 0,2 0,3 0,4 0,5

time [s]

pre

ssu

re [

ba

r]

-40

-30

-20

-10

0

10

20

30

P*V

[b

ar²

/s]

P (bars)

P*V

pressure


Test set up Influence of impact velocity Influence of strap position

Fig. 7 – Free Fall Device Tests

Validation sled tests: A series of more than 30 sled tests at three severity levels (Fig. 8 left) has

been performed with Q3 and Q6 dummies and will be completed in order to evaluate and validate the

new abdominal measurement device.

Q3 and Q6 dummies have been placed on a child seat with harness group I, on a booster with and

without backrest group II using the 3 point safety belt and finally on a child seat with shield.

Examples of the most relevant results are given below:

sled pulses 5-point-harness booster with backrest

Fig. 8 – Sled Test Results

The graphs depict that P*V is increasing with the kinetic energy. However the values of

overpressure and the subsequent P*V are higher for the booster using the adult 3-point belt (Fig. 8

right) than for the child seat fitted with a harness (Fig. 8 centre). The cause of such differences in

terms of injury risk is clearly known: for the child seat the forces restraining the lower torso and the

legs are applied on the abdomen by a large buckle and four straps while the straps of the safety belt,

principally the lap strap, have to penetrate into the abdomen to establish the balance between acting

and reacting forces.

FORCE SENSOR SYSTEM: Several studies showed that the surface load applied to the abdomen

correlates with abdominal injury severity [Trollope, 1973; Rouhana, 1986; Miller, 1989; Viano, 1989;

Miller, 1991; Talantikite, 1993; etc.]. In addition it was shown, that the corresponding load limit

depends on the impact location – for example is the lower abdomen more vulnerable than the upper

part [Beckman, 1971; Stalnaker, 1973; Miller, 1991]. Based on these findings possibilities were

analysed how to measure the abdominal surface load taking into account the following boundary

conditions:

1. measurement of the contact force applied to soft dummy parts (abdomen)

2. possibility for the assessment of the location of the load

3. time history information of the applied forces available

4. no significant influence on the dummy response during the test

5. usable in normal crash test conditions

6. low price

7. robust to damages

8. reliable sensor outputs

0

20

40

60

80

100

120

140

R44 30 km/h R44 50 km/h Crest 56 km/h

test condition

P*V

[bar²

/s]

0

20

40

60

80

100

120

140

R44 30 km/h R44 50 km/h Crest 56 km/h

test condition

P*V

[b

ar²

/s]

-0,5

0,0

0,5

1,0

1,5

2,0

2,5

0,00 0,01 0,02 0,03 0,04 0,05 0,06

time [s]

pre

ssu

re [

ba

r]

top

middle

bottom

-400

-350

-300

-250

-200

-150

-100

-50

0

0 0,02 0,04 0,06 0,08 0,1 0,12 0,14

time [s]

acce

lera

tio

n [m

/s²]

56 km/h - CREST

50 km/h - ECE R44

30 km/h - ECE R44

-0,5

0,0

0,5

1,0

1,5

2,0

2,5

0,00 0,02 0,04 0,06 0,08 0,10 0,12 0,14time [s]

pre

ssu

re [

ba

r]

25 km/h

10 km/h

15 km/h

20 km/h


All of these criteria seemed to be fulfilled by the FlexiForce sensor. For the measurement of

abdominal loads it is necessary to combine several single sensors to an abdominal sensor array.

Description of sensor elements: The standard FlexiForce A102 sensor is a thin (0.1 mm), flexible

printed circuit. It is 14 mm wide and 203 mm in length. The active sensing area is a 9.5 mm diameter

circle at the end of the sensor. The sensors are constructed of two layers of substrate, such as a

polyester film. On each layer, a conductive material (silver) is applied, followed by a layer of

pressure-sensitive ink. Adhesive is then used to laminate the two layers of substrate together to form

the sensor.

The FlexiForce single element sensor acts as a resistor in an electrical circuit. When the sensor is

unloaded, its resistance is infinitely high. When a force is applied to the sensor, the resistance

decreases. For the use in crash tests, it is reasonable that the sensors are connected to a Wheatstone’s

Bridge. In this configuration the sensor behaves linearly with a linearity error of approximately 5 %.

Sensor array as abdominal sensor: 20 sensors are used and arranged as a matrix on the abdomen of

the dummy. The arrangement is shown in the following figure.

1 2

3

4

5

6

7

8

9

10

20

17

18

19

15

16

13

14

12 11

Fig. 9 – Sensor Array for Q6 Dummy (left) and Sensors Fitted at Q3 Abdomen (right)

The chosen matrix for the sensor array guarantees that no load applied to the abdomen is lost,

because the distance between two “neighbour” sensors is less than any belt width of CRS on today’s

market. In addition a symmetrical and equally spaced arrangement allows optimal coverage of the

abdomen and comparable results. The alignment for the Q3 abdomen follows the same principle. For

more detailed information concerning the sensor system see Johannsen [2004].

Injury criterion: It has to be noted, that the measured force does not represent the total load applied

to the abdomen, as the single sensors do only measure the force applied to their sensing area, which is

much smaller than the entire abdomen. The following possibilities to compensate for this will be

analysed in the future:

• assessment of surface pressure and taking into account maximum local pressure and

average pressure,

• correction factor taking into account sensing area and representative abdominal area,

• no compensation.

CASE STUDY Both abdominal sensors are used in the CHILD real world accident reconstruction programme. In

these experimentations, in the aim to acquire correlations between physical parameter values and

injury severities, abdominal sensors are used even if the corresponding injured child(ren) did not

suffer any abdominal injury (AIS 0).

Unfortunately only four cases have been reconstructed so far. Therefore a statistical analysis is not

possible yet. However, the case study gives indications for a reliable correlation of injury severity and

measurement results.

CASE 1: A Citroen Xantia left the road and collided purely frontal with a tree with an off-set of

20 % at the right side. The maximum deformation was 740 mm, which is calculated to be a delta-v of


45 – 50 km/h. The female driver sustained MAIS 1 injuries, the female front seat passenger MAIS 4.

The 4 year-old child using a booster cushion with sufficient lap belt routing devices at the right rear

seat sustained MAIS 1 injuries, which were located at neck and legs. The abdomen remained

uninjured.

The analysis of the results of the abdominal sensors shows a sum force of the force sensor of

195 N. Unfortunately some channels of the force sensors did not work during this test, therefore the

results underestimate the real load. The pressure sensors show 0,24 bar at the right and 0,41 bar at the

left side (buckle), the P*V criterion is 3,1 bar²/s and 7,7 bar²/s, respectively.

CASE 2: A Ford Escort travelled in a right hand bend in the UK into a Volvo 340 driving in the

opposite direction. Both vehicles collided with 100 % overlap with an angle of 165°. The maximum

crush at the left front was 600 mm for the Ford, 400 mm for the Volvo. The delta-v was calculated to

be about 55 km/h for the Ford and about 57 km/h for the Volvo. The female driver of the Escort

sustained MAIS 2 injuries. The female 30 months old child using a booster with backrest at the left

rear seat suffered MAIS 4 injuries. Besides head (AIS 4) and neck injuries gastric superficial tears

(AIS 2), mesentery bruising (AIS 2), abrasion and bruising of the abdominal wall were observed. The

child died due to its internal injuries. The male driver of the Volvo sustained MAIS 2 injuries.

The experimental reconstruction of this accident took place according to Fig. 10. A Q3 dummy was

used to simulate the fatally injured child.

Moving ESCORT

112 km/h

Standing VOLVO 340

15°

Fig. 10 – Crash Situation Case 2

The analysis of the abdominal sensors showed a sum force of the force sensors of 200 N. The

single sensors show, that the main part of the load is applied to the middle and lower abdomen with

emphasis on the right side, see Fig. 11. The pressure sensors show 1,4 bar at the right and 1,0 bar on

the left side, the P*V criterion is 133,3 bar²/s and 43,3 bar²/s, respectively. The pressure sensor also

shows more mechanical load to the right side.

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11

R1

R2

R3

R4

R50

20

40

60

80

100

120

forc

e[N

]

sensing columns row

s

left

right

upper

lower

0

100

200

300

400

500

600

700

800

900

1000

0 25 50 75 100 125 150

time [ms]

forc

e[N

]

0

0,5

1

1,5

2

2,5

pre

ssu

re[b

ar]

sum force pressure right pressure left

Fig. 11 – Load Distribution and Time History of Case 2

CASE 3: A Renault Laguna II went off its line and collided straight ahead (12 o’ clock direction)

with a tree on his left side. A maximum intrusion of 920 mm was measured after the impact. The EES

was calculated as 60 km/h. The male driver sustained MAIS 2, the female front seat passenger MAIS

3 injuries. A two years old child sitting on the left rear seat in a 5-point-harness seat stayed uninjured,

while the seven years old child using a booster with backrest sustained MAIS 5 injuries. The

abdominal injuries (liver rupture AIS 5, intestine laceration AIS 5, pancreas rupture AIS 5,


haemoperitonea AIS 4, splenic vein wound AIS 4, duoderco jejunal rupture AIS 4, retro peritonea

haematoma AIS 3 and wound of the stomach AIS 2) were all caused by the wrongly routed belt. The

lap belt was positioned above the lower – belt routing – wings.

For the reconstruction of the accident a Q6 instrumented with both abdominal sensors was used.

The car was towed against a rigid pole with an impact velocity of 65 km/h. The belt routing for the Q6

corresponded to the probable situation in the accident.

Analysis of the abdominal sensors showed a sum force of the force sensors of 450 N. The single

sensors show, that the main part of the load is applied to the middle and lower abdomen. While the

lower abdomen sustained more load at the left side, the main load to the middle abdomen was applied

to the right side, see Fig. 12. The pressure sensors show 0,6 bar at the right and 0,4 bar at the left side,

the P*V criterion is 23,8 bar²/s and 21,3 bar²/s, respectively. The pressure sensor shows an equal result

for right and left side.

12

34

56

78

910

11

R1

R2

R3

R4R50

20

40

60

80

100

120

forc

e[N

]

sensing columns row

s

left

right

upper

lower

0

100

200

300

400

500

600

700

800

900

1000

0 25 50 75 100 125 150

time [ms]

forc

e[N

]

0

0,5

1

1,5

2

2,5

pre

ssu

re[b

ar]


Fig. 12 – Load Distribution and Time History of Case 3

CASE 4: The driver of a Citroen Xantia turned left and did not see a Renault Scenic coming from

the opposite direction. Both cars collided with an angle of 25°. The closing speed was calculated to be

95 km/h. The driver of the Scenic sustained MAIS 1 injuries, while the 3 years old child using a

booster with backrest at the left rear seat suffered an AIS 4 liver and an AIS 3 haemoperitoneum

injury. The belt caused both injuries. In contrast to case no. 3 no evidence for misuse exists.

The reconstruction of this case took place as shown in Fig. 13. An upgraded Q3 instrumented with

both abdominal sensors represented the injured child in the left rear seat of the Renault.

25°

95 km/h

Standing

Fig. 13 – Crash Situation Case 4

Analysis of the abdominal sensors shows a sum force of the force sensors of 415 N. The single

sensors show, that the main part of the load is applied to the upper abdomen with emphasis on the

right side, see Fig. 14. The pressure sensors show 0,6 bar at the right and 0,5 bar at the left side, the

P*V criterion is 28 bar²/s and 34 bar²/s respectively. The pressure sensor shows an equal result for

right and left side. In contrast to the force sensor the P*V criterion indicates higher loads at the left

side. However, the differences between left and right are minor for both sensors.


12

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11

R1

R2

R3

R4

R50

20

40

60

80

100

120

forc

e[N

]

sensing columns row

s

left

right

upper

lower

0

100

200

300

400

500

600

700

800

900

1000

50 75 100 125 150 175 200

time [ms]

forc

e[N

]

0

0,5

1

1,5

2

2,5

pre

ssu

re[b

ar]


Fig. 14 - Load Distribution and Time History of Case 4

CASE 5: A VW Vento collided frontal with a velocity of 60 km/h with a tree. The 8 years old girl

seated at the right rear seat was restrained just by the vehicle’s belt. She sustained injuries at the head

(AIS 3), chest (AIS 4) as well as liver tear (AIS2), spleen rupture (AIS 2) and rupture of the left renal

vein. The child died within 3 days after the accident because of brain injuries. The female driver and

front seat passenger also died because of their injuries. The rear seat adult passenger sustained AIS 5

lung injuries but survived.

For the reconstruction of this case a Q6 instrumented with both abdominal sensors was used.

According to the accident the child was restrained with the car belt only.

Analysis of the abdominal sensor shows a sum force of 810 N mostly applied to the lower left part of

the abdomen. The pressure sensors show 1,4 bar at the right and 1,7 bar at the left side, the P*V

criterion is 47 bar²/s and 119 bar²/s, respectively. The pressure sensor shows an equal result for right

and left side. That means that both sensors show higher loads at the left side of the dummy.

12

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11

R1

R2

R3

R4R50

20

40

60

80

100

120

140

160

180

forc

e[N

]

sensing columns row

s

left

right

upper

lower

0

100

200

300

400

500

600

700

800

900

1000

0 25 50 75 100 125 150

time [ms]

forc

e[N

]

0

0,5

1

1,5

2

2,5

pre

ssu

re[b

ar]



CASE 6: The female driver of a Renault Espace left her lane and collided frontal without offset with a

Renault Laguna driving in the opposite direction. The closing speed was calculated to be 110 km/h.

The driver of the Espace suffered MAIS 2 injuries while the adult occupants of the Laguna sustained

AIS 1 injuries only, the 4 years old boy using a booster with backrest in the right rear seat died

because of his internal abdominal injuries (organ ruptures) at the scene. The abdominal injuries were

caused by the belt; due to underarm wear of the shoulder belt. The detailed injury is not known in this

case. However, due to the rupture of internal organs the abdominal AIS can be estimated to 3 or

higher.

For the reconstruction the Laguna ran with 110 km/h against the standing Espace. The injured child

was simulated by an upgraded Q3 with underarm use of the shoulder belt.

The analysis of the abdominal sensors showed a sum force of 285 N and the pressure sensor measured

1,4 bar and 103 bar²/s at the left side. Due to electrical problems of the right pressure sensor no results

exist for this side. The main forces are applied to the middle of the abdomen with emphasis at the left.


12

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11

R1

R2

R3

R4R50

20

40

60

80

100

120

forc

e[N

]

sensing columns row

s

left

right

upper

lower

0

100

200

300

400

500

600

700

800

900

1000

0 25 50 75 100 125 150

time [ms]

forc

e[N

]

0

0,5

1

1,5

2

2,5

pre

ssu

re[b

ar]

sum force pressure left


CASE 7: A Renault Megane left its lane in a right hand curve and collided frontal with an oncoming

Opel Vectra. The closing speed was calculated to 130 km/h. While the driver of the Opel sustained

only minor injuries the female 72 years old front seat passenger suffered MAIS 3 injuries. A 6 years

old girl sitting on a pillow at the left rear passenger seat sustained AIS 3 thorax and abdomen

(haemoperitoneum) as well as head injuries with unknown severity.

For the reconstruction both cars ran with 65 km/h. The injured child was simulated by a Q6 sitting on

a pillow.

The analysis of the abdominal sensors showed a sum force of 793 N and the pressure sensor measured

1,4 bar at the left side and 1,8 bar at the right side. The P*V is 68 bar²/s at the left and 167 bar²/s at the

right. Both sensors show higher loads at the right side.

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11

R1

R2

R3

R4R50

50

100

150

200

250

forc

e[N

]

sensing columns row

s

left

right

upper

lower

0

100

200

300

400

500

600

700

800

900

1000

0 25 50 75 100 125 150

time [ms]

forc

e[N

]

0

0,5

1

1,5

2

2,5

pre

ssu

re[b

ar]



ANALYSIS AND DISCUSSION OF THE CASE STUDY The following table summarises the findings of the field study to analyse the test results with

respect to injury severity correlation.

Case 1 Case 2 Case 3 Case 4 Case 5 Case 6 Case 7

Closing speed 50 km/h 112 km/h 65 km/h 95 km/h 60 km/h 110 km/h 130 km/h

CRS Booster

cushion

Booster w.

backrest

Booster w.

backrest

Booster w.

backrest

Car belt

only

Booster w.

backrest

Pillow

Used dummy Q3 Q3 Q6 Q3 Q6 Q3 Q6

Misuse No Yes Yes No Yes Yes Yes

Abdomen AIS 0 2 5 4 4 (3+) 3

Pressure 0.4 bar 1,4 bar 0,6 bar 0,6 bar 1,7 bar 1,4 bar 1,8 bar

P*V 7.7 bar²/s 133 bar²/s 24 bar²/s 34 bar²/s 119 bar²/s 103 bar²/s 167 bar²/s

Sum force 195 N 200 N 450 N 415 N 810 N 285 N 793 N

Table 1 – Reconstruction Cases Summary


Analysing the results it is obvious that the two sensor systems do not show a comparable trend in

every case. Based on the small number of test results it is not possible to explain this behaviour.

It is well known that the method of “accidentology” consisting in investigating collision conditions

(speed, overlap, angles, etc.) and consequences (car deformations, types and severities of occupant

injuries) and then in performing accident reconstructions with dummies is not only complex but also

rather approximate. This is due to the fact that numerous accident parameters are assessed and hence

not precisely reproduced in the crash. For example, child pre-crash posture, CRS attachment, routing

and slack of safety belt or harness are often not very well documented in the accident report.

Moreover, dynamic behaviour of crash dummies is not totally human-like and thus can lead to

difficulties for identifying injury mechanisms. It is the reason why it is presently not possible, to

exploit values of only seven accident cases including two different sizes of dummies – Q3 and Q6 – to

define a reliable limit for P*V. At the very most, an indication for a limit of P*V for AIS2+ by 75

bar²/s can be proposed.

Regarding the force sensor system only, there is an indication for a load limit for the shift between

no and minor injuries in the region of 200 N and between minor and serious injuries of about 200 to

300 N. Taking into account the average surface pressure the values correspond to the findings of

Trosseille et al. [1997], who derived force limits for different age groups based on the assumption, that

the surface pressure limit will be the same for all individuals.

It has to be mentioned that the final criteria and corresponding limits can be fixed after finalising

the CHILD accident reconstruction has been finalised.

CONCLUSION Abdominal injuries are normally very severe injuries. Especially because of the biomechanical

properties of children – missing iliac crest, less protection of organs etc. – the risk for children is

higher than for adults. This is the reason why the development of abdominal sensors in the frame of

the European projects CREST and CHILD has been considered as a prioritary objective. They

represent a first technological implementation towards the protection of children regarding injury risk

at abdomen. Reliable injury risk curves for this fragile and complicated body segment will need a

large number of in-depth accident investigations completed with accident reconstructions and their

complementary parametric sled tests.

Analysis of published biomechanical tests does not show a clear picture concerning an appropriate

abdominal injury criterion. Intra organic pressure, compression and compression multiplied with

compression rate as well as surface force are in discussion. The described sensor cope either with the

contact force or intra organic pressure together with the pressure rate. Both sensors have been used for

the CHILD accident reconstruction program to define injury criteria and injury risk curves for the

abdomen. Based on a preliminary analysis of the CHILD project’s reconstruction programme it can be

expected that both presented abdominal sensors will perform well with respect to prediction of injury

severity. Further reconstruction tests will allow to define statistically proven injury risk curves.

ACKNOWLEDGEMENT The European Community funds the development of the abdominal sensors under the CHILD

project (Contract no. G3RD-CT-2002-00791).

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ABDOMINAL INJURIES, INJURY CRITERIA, INJURY SEVERITY ... · Abdominal injury criterion: Various studies highlight that, due to the viscous component of the abdomen in terms of dynamic