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

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1 ABDOMINAL INJURIES, INJURY CRITERIA, INJURY SEVERITY LEVELS AND ABDOMINAL SENSORS FOR CHILD DUMMIES OF THE Q FAMILY HEIKO JOHANNSEN, FRANÇOIS ALONZO, CLÉMENT GOUBEL, VOLKER SCHINDLER Technische Universität Berlin, Berlin (TUB), Germany; INRETS - 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 Q), 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 and [Langwieder, ] % of the children using a CRS properly suffered abdominal injuries (see Fig. ). 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

2 arms/legs % abdomen % head % thoracic lumbar spine % chest % cervical spine % Fig. Injuries of Children Using a CRS Properly [Langwieder, ] 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.. % % % "harm" [%] % % % % head cervical spine chest abdomen thoracic / lumbar spine arms / legs Fig. Injuries of Children [Langwieder, ] An older study based on the same accident data of and shows that the main problems for children exists for those wearing a -point belt or a lap belt only [Langwieder, ]. Children suffer abdominal injuries even when using a CRS. CRS point only Lap only, %, %, %, %, %, %, %, % -, %, %, % Basis inj. = % Basis inj. = % Basis inj. = % Number of injuries AIS CRS point only Lap only Head Neck Chest - Abdomen Arms Legs T/L Spine - Total Fig. Number and Frequency of Injuries to Different Parts of the Body Depending on the Kind of Restraint System [Langwieder, ] Based on French accidents of the years / and / Trosseille et al. [] came to the conclusion, that abdominal injuries occur for older children with an age above only. These were cases with boosters or without any CRS. Finally Arbogast et al. [] stated a relatively higher abdominal injury risk for children between and years old. The risk for children using a proper CRS or a belt routing booster is low. IRCOBI Conference - Prague (Czech Republic) - September

3 ABDOMINAL SENSOR SYSTEMS As abdominal injuries are mainly a problem of children using a group II or III seat (according to ECE R, children with a weight of above kg), which are mainly boosters with and without backrest, the development of abdominal sensors started for Q and Q. 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: Q (newborn), Q, Q,, Q, Q. 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 Q 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. 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. right). Fig. Design of the Abdominal Region of the Q ABDOMINAL PRESSURE TWIN-SENSOR: Based on INRETS experience acquired during the EC CREST programme (-), a new version of a pressure sensor was developed. CAD model of the pressure cells embedded into the standard abdominal insert of the Q dummy Prototype with details of pressure cell inserted in the upper cap Fig. INRETS Pressure Sensor The sensor embedded into the standard abdominal insert of the Q dummy 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- IRCOBI Conference - Prague (Czech Republic) - September

4 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 shore A polyurethane-rubber and filled with gel. The pressure is measured using industrial pressure cells screwed into the aluminium caps (see Fig. ). 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, ; Rupp; ; Lau, ; Prasad, ]. 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. ). Abdominal Injury Criterion: Intra-abdominal pressure * Rate of pressure change AIC [bar /s] = P [bar] * V [bar/s], pressure P (bars) P*V,,,, - - P*V [bar²/s] -,,,,, -, - time [s] Fig. 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 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. left) exerting forces on the abdomen of a Q dummy at various energy levels (Fig. centre) on various abdomen regions (Fig. right) show that intra-abdominal pressure increases with impact energy and varies depending on strap location. IRCOBI Conference - Prague (Czech Republic) - September

5 ,, top,,,, km/h km/h km/h km/h,,,, middle bottom,,,,,,,,,,,,,,,,, time [s] time [s] -, -, Test set up Influence of impact velocity Influence of strap position Fig. Free Fall Device Tests Validation sled tests: A series of more than sled tests at three severity levels (Fig. left) has been performed with Q and Q dummies and will be completed in order to evaluate and validate the new abdominal measurement device. Q and Q dummies have been placed on a child seat with harness group I, on a booster with and without backrest group II using the point safety belt and finally on a child seat with shield. Examples of the most relevant results are given below:,,,,,,, - time [s] acceleration [m/s²] km/h - ECE R km/h - ECE R km/h - CREST P*V [bar²/s] R km/h R km/h Crest km/h test condition sled pulses -point-harness booster with backrest Fig. 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 -point belt (Fig. right) than for the child seat fitted with a harness (Fig. 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, ; Rouhana, ; Miller, ; Viano, ; Miller, ; Talantikite, ; 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, ; Stalnaker, ; Miller, ]. Based on these findings possibilities were analysed how to measure the abdominal surface load taking into account the following boundary conditions:. measurement of the contact force applied to soft dummy parts (abdomen). possibility for the assessment of the location of the load. time history information of the applied forces available. no significant influence on the dummy response during the test. usable in normal crash test conditions. low price. robust to damages. reliable sensor outputs P*V [bar²/s] R km/h R km/h Crest km/h test condition IRCOBI Conference - Prague (Czech Republic) - September

6 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 A sensor is a thin (. mm), flexible printed circuit. It is mm wide and mm in length. The active sensing area is a. 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 %. Sensor array as abdominal sensor: sensors are used and arranged as a matrix on the abdomen of the dummy. The arrangement is shown in the following figure. Fig. Sensor Array for Q Dummy (left) and Sensors Fitted at Q 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 Q abdomen follows the same principle. For more detailed information concerning the sensor system see Johannsen []. 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 ). 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 : A Citroen Xantia left the road and collided purely frontal with a tree with an off-set of % at the right side. The maximum deformation was mm, which is calculated to be a delta-v of IRCOBI Conference - Prague (Czech Republic) - September

7 km/h. The female driver sustained MAIS injuries, the female front seat passenger MAIS. The year-old child using a booster cushion with sufficient lap belt routing devices at the right rear seat sustained MAIS 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 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, bar at the right and, bar at the left side (buckle), the P*V criterion is, bar²/s and, bar²/s, respectively. CASE : A Ford Escort travelled in a right hand bend in the UK into a Volvo driving in the opposite direction. Both vehicles collided with % overlap with an angle of. The maximum crush at the left front was mm for the Ford, mm for the Volvo. The delta-v was calculated to be about km/h for the Ford and about km/h for the Volvo. The female driver of the Escort sustained MAIS injuries. The female months old child using a booster with backrest at the left rear seat suffered MAIS injuries. Besides head (AIS ) and neck injuries gastric superficial tears (AIS ), mesentery bruising (AIS ), 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 injuries. The experimental reconstruction of this accident took place according to Fig.. A Q dummy was used to simulate the fatally injured child. Standing VOLVO Moving ESCORT km/h Fig. Crash Situation Case The analysis of the abdominal sensors showed a sum force of the force sensors of 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.. The pressure sensors show, bar at the right and, bar on the left side, the P*V criterion is, bar²/s and, bar²/s, respectively. The pressure sensor also shows more mechanical load to the right side. left sensing columns right upper R R R R lower R rows sum force pressure right pressure left,,, time [ms] Fig. Load Distribution and Time History of Case CASE : A Renault Laguna II went off its line and collided straight ahead ( o clock direction) with a tree on his left side. A maximum intrusion of mm was measured after the impact. The EES was calculated as km/h. The male driver sustained MAIS, the female front seat passenger MAIS injuries. A two years old child sitting on the left rear seat in a -point-harness seat stayed uninjured, while the seven years old child using a booster with backrest sustained MAIS injuries. The abdominal injuries (liver rupture AIS, intestine laceration AIS, pancreas rupture AIS, IRCOBI Conference - Prague (Czech Republic) - September

8 haemoperitonea AIS, splenic vein wound AIS, duoderco jejunal rupture AIS, retro peritonea haematoma AIS and wound of the stomach AIS ) 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 Q instrumented with both abdominal sensors was used. The car was towed against a rigid pole with an impact velocity of km/h. The belt routing for the Q corresponded to the probable situation in the accident. Analysis of the abdominal sensors showed a sum force of the force sensors of 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.. The pressure sensors show, bar at the right and, bar at the left side, the P*V criterion is, bar²/s and, bar²/s, respectively. The pressure sensor shows an equal result for right and left side. left sensing columns right R upper R R R R lower rows sum force pressure right pressure left,,, time [ms] Fig. Load Distribution and Time History of Case CASE : 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. The closing speed was calculated to be km/h. The driver of the Scenic sustained MAIS injuries, while the years old child using a booster with backrest at the left rear seat suffered an AIS liver and an AIS haemoperitoneum injury. The belt caused both injuries. In contrast to case no. no evidence for misuse exists. The reconstruction of this case took place as shown in Fig.. An upgraded Q instrumented with both abdominal sensors represented the injured child in the left rear seat of the Renault. Standing km/h Fig. Crash Situation Case Analysis of the abdominal sensors shows a sum force of the force sensors of 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.. The pressure sensors show, bar at the right and, bar at the left side, the P*V criterion is bar²/s and 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. IRCOBI Conference - Prague (Czech Republic) - September

9 left sensing columns right upper R R R R lower R rows sum force pressure right pressure left,,, time [ms] Fig. - Load Distribution and Time History of Case CASE : A VW Vento collided frontal with a velocity of km/h with a tree. The years old girl seated at the right rear seat was restrained just by the vehicle s belt. She sustained injuries at the head (AIS ), chest (AIS ) as well as liver tear (AIS), spleen rupture (AIS ) and rupture of the left renal vein. The child died within 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 lung injuries but survived. For the reconstruction of this case a Q 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 N mostly applied to the lower left part of the abdomen. The pressure sensors show, bar at the right and, bar at the left side, the P*V criterion is bar²/s and 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. left sensing columns right Rupper R R R Rlower rows sum force pressure right pressure left,,, time [ms] Fig. - Load Distribution and Time History of Case CASE : 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 km/h. The driver of the Espace suffered MAIS injuries while the adult occupants of the Laguna sustained AIS injuries only, the 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 or higher. For the reconstruction the Laguna ran with km/h against the standing Espace. The injured child was simulated by an upgraded Q with underarm use of the shoulder belt. The analysis of the abdominal sensors showed a sum force of N and the pressure sensor measured, bar and 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. IRCOBI Conference - Prague (Czech Republic) - September

10 left sensing columns right Rupper R R R Rlower rows sum force pressure left,,, time [ms] Fig. - Load Distribution and Time History of Case CASE : 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 km/h. While the driver of the Opel sustained only minor injuries the female years old front seat passenger suffered MAIS injuries. A years old girl sitting on a pillow at the left rear passenger seat sustained AIS thorax and abdomen (haemoperitoneum) as well as head injuries with unknown severity. For the reconstruction both cars ran with km/h. The injured child was simulated by a Q sitting on a pillow. The analysis of the abdominal sensors showed a sum force of N and the pressure sensor measured, bar at the left side and, bar at the right side. The P*V is bar²/s at the left and bar²/s at the right. Both sensors show higher loads at the right side. left sensing columns right R upper R R R R lower rows sum force pressure right pressure left time [ms],,, Fig. - Load Distribution and Time History of Case 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 Case Case Case Case Case Case Closing speed km/h km/h km/h km/h km/h km/h km/h CRS Booster Booster w. Booster w. Booster w. Car belt Booster w. Pillow cushion backrest backrest backrest only backrest Used dummy Q Q Q Q Q Q Q Misuse No Yes Yes No Yes Yes Yes Abdomen AIS (+) Pressure. bar, bar, bar, bar, bar, bar, bar P*V. bar²/s bar²/s bar²/s bar²/s bar²/s bar²/s bar²/s Sum force N N N N N N N Table Reconstruction Cases Summary IRCOBI Conference - Prague (Czech Republic) - September

11 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 Q and Q to define a reliable limit for P*V. At the very most, an indication for a limit of P*V for AIS+ by 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 N and between minor and serious injuries of about to N. Taking into account the average surface pressure the values correspond to the findings of Trosseille et al. [], 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. GRD-CT--). REFERENCES Arbogast, K.B.; Chen, I.; Nance M.L.; Durbin, D.R.; Winston, F.K.: Predictors of Pediatric Abdominal Injury Risk; th Stapp Conference, Augenstein; Perdeck; Williamson; Stratton; Horton; Digges; Malliaris; Lombardo: Injury Pattern among Air Bag Equipped Vehicles; th ESV Conference, Windsor (CANADA), Beckman, D.L.; McElhaney, J.H.; Roberts, V.L.; Stalnaker, R.L.: Impact Tolerance Abdominal Injury; NTIS No. PB, IRCOBI Conference - Prague (Czech Republic) - September

12 Johannsen, Heiko: Injury Risks of Children Possibilities to Detect Abdominal Injuries; nd International Conference Protection of Children in Cars, Cologne, ; see also Johannsen.pdf Langwieder, Klaus; Hummel, Thomas: Biomechanical Risk Factors for Children in Cars and Aggravation by Misuse of Restraint System; th ESV Conference, Munich, Langwieder, K.; Stadler, P.; Hummel, T.; Fastemeier, W.; Finkbeiner, F.: Verbesserung des Schutzes von Kindern in Pkw; BASt Report M, Bergisch Gladbach, (in German) Lau, I. V.; Viano, D.C.: The viscous Criterion Bases and Applications of an Injury Severity Index for Soft Tissues; SAE, Mertz, H.J; Prasad, P.; Irwin, A.L: Injury Risk Curves for Children and Adults in Frontal and Rear Collisions; SAE, Miller, Marcy Alice: The Biomechanical Response of the Lower Abdomen to Belt Restraint Loading; Journal of Trauma, Miller, Marcy Alice: Tolerance to Steering Wheel-Induced Lower Abdominal Injury; Journal of Trauma Vol. No., Prasad, P.; Daniel, R.P.:A Biomechanical Analysis of Head, Neck and Torso Injuries to Child Surrogates Due to Sudden Torso Acceleration; th Stapp Conference, SAE, Rouhana, Stephen W.; Ridella, Stephen A.; Viano, David C.: The Effects of Limiting Impact Force on Abdominal Injury: A Preliminary Study; th Stapp Conference, SAE, Rupp, Jonathan D.; Desantis Klinich, Kathleen; Moss, Steve; Zou, Jennifer, Pearlman, Mark D.; Schneider, Lawrence W.: Development and Testing of a Prototype Pregnant Abdomen for the Small- Female Hybrid III ATD; th Stapp Car crash Conference, San Antonio, Texas, November, Stalnaker, R. L.; Roberts, V. L.; McElhaney J. H.: Side Impact Tolerance to Blunt Trauma; th Stapp Conference, Talantikite, Y.; Brun-Cassan, Françoise; Lecoz, Jean-Yves; Tarriere, Claude: Abdominal Protection in Side Impact Injury Mechanisms and Protection Criteria; IRCOBI Conference, Eindhoven, September Tekscan; Website December Trollope M. L.; Stalnacker, R. L.; McElhaney J. H.; Frey, C.F.: The mechanism of Injury in Blunt Abdominal Trauma; Journal of Trauma, Vol. Nr., Trosseille, Xavier; Chamouard, François; Tarriere, Claude: Abdominal Injury Risk to Children and its Prevention; IRCOBI Conference, Hanover, September Viano, David C.; Lau, I. V.; Asbury, C.; King, A. I.; Begeman, P.: Biomechanics of the Human Chest, Abdomen and Pelvis in Lateral Impacts; rd Association for the Advancement of Automotive Medicine, IRCOBI Conference - Prague (Czech Republic) - September