Dimitrios Kallieris

Prediction of Cervical Spine Injury Risk for the 6-Year-Old Child in Frontal Crashes

This article presents a series of 49 km/h sled tests using the Hybrid III 6-year-old dummy in a high-back booster, a low-back booster, and a three-point belt. Although a 10-year review at a level I trauma center showed that noncontact cervical spine injuries are rare in correctly restrained booster-age children, dummy neck loads exceeded published injury thresholds in all tests. The dummy underwent extreme neck flexion during the test, causing full-face contact with the dummys chest. These dummy kinematics were compared to the kinematics of a 12-year-old cadaver tested in a similar impact environment. The cadaver test showed neck flexion, but also significant thoracic spinal flexion which was nonexistent in the dummy. This comparison was expanded using MADYMO simulations in which the thoracic spinal stiffness of the dummy model was decreased to give a more biofidelic kinematic response. We conclude that the stiff thoracic spine of the dummy results in high neck forces and moments that are not representative of the true injury potential.

QUANTIFICATION OF SIDE IMPACT RESPONSES AND INJURIES

Side impacts have been shown to produce a large portion of both serious and fatal injuries within the total automotive crash problem. These injuries are produced as a result of the rapid changes in velocity an automobile occupants body experiences during a crash. Any improvement to the side impact problem will be brought about by means which will ultimately modify the occupants rapid body motions to such a degree that they will no longer produce injuries of serious consequence. Accurate knowledge of both the bodys motion and resulting injuries under a variety of impact conditions is needed to achieve this goal. Possession of this knowledge will then permit development of accurate anthropomorphic test devices and injury criteria which can be used to create effective injury countermeasures in vehicles.

Comparison Between Child Cadavers and Child Dummy by Using Child Restraint Systems in Simulated Collisions

At present, numerous restraint systems for children applied in vehicles are in general considered for the use on the back seats. Up to now, only impact tests with dummies and animals have been carried through by these systems. Out of the great number of children, seats and belts we used a system (deformable safety impact table combined with a lap-belt) which has been investigated by us during frontal impacts utilizing two dummies and four cadavers of children in the age of 2 5 up to 11 years having body weights of 16 up to 31 kg. The tests have been conducted on the deceleration-sled track at the Institute of Legal Medicine of the University Heidelberg. Impact velocities of 30 km/h and 40 km/h at a medium deceleration of 20g have been chosen. None of the test sugjects showed injuries to the inner organs; however, numerous muscular hemorrhages as well as hemorrhages of discs and ligaments were noticed. The HIC values lay between 100 and 500; accelerations in x-direction up to 44g and in z- direction up to 85g occurred at the head. Lap-belt forces of 160 up to 400 daN were measured. A weak point of the investigated system is that the childs movements are considerably limited, a factor also noticed in other child restraint systems; however, the protective function proved to be an advantage. The movements during the impact, pictured by high-speed cameras, essentially differ from those of adults wearing 3-point belts. The maximum flexion of the vertebral column is, due to the system, located in the transition of the thoracic to the lumbar vertebral column and the flexion angles amounted about 90 degrees. As expected were the maximum head displacements in relation to a sled-fixed axis dependent on the impact velocity and the body height, and ranged between 50 cm (crash velocity 30 km/h, body height 97 cm) and 90 cm (crash velocity 40 km/h, body height 139 cm). The movement will be analyzed; the anatomical and mechanical causes are going to be investigated. Finally, the results will be compared with similar dummy tests investigated by use. Due to these differences in the dummy and cadaver behavior, the necessity is pointed out to examine all restraint systems by cadaver tests. /Author/

Thoracic trauma assessment formulations for restrained drivers in simulated frontal impacts

Using cadaveric specimens, sixty-three simulated frontal impacts were performed to examine and quantify the performance of various contemporary automotive restraint systems. To characterize the mechanical responses during the impact, test-specimens were instrumented with accelerometers and chest bands. The resulting thoracic injury severity was determined using detailed autopsy and was classified using the Abbreviated Injury Scale.

Technical parameters influencing the severity of injury of front-seat, belt-protected car passengers on the impact side in car-to-car side collisions with the main impact between the front and rear seats (B-pillars)

SummaryAuthentic car-to-car side collisions (n = 30) with the main impact area at the B-pillar were analyzed to find technical parameters corresponding with the injury severities of the front seat, belt-protected car passengers on the impact side. EES (Energy Equivalent Speed) and Av (delta v, change in velocity) were highly significant predictors of the severity of thoracic and abdominal injuries and total injury severity coded according to the Abbreviated Injury Scale (AIS). At an EES or Δ v ≥ 40 km/h all front-seat car passengers on the impact side sustained a total injury severity of Maximum AIS (MAIS) ≥ 4 and died. Although a passenger could survive the crash without injury to one or more body regions up to the highest EES- and Av-values, at EES or Δ v ≥ 40 km/h fatal injuries were sustained in at least one body region. At an EES ≥ 35 km/h or a Av ≥ 15 km/h no front-seat car passenger on the impact side remained uninjured.Zusammenfassung30 reale Pkw-Pkw-Seitenkollisionen mit Hauptanstoßpunkt B-Holm and stoßnah sitzenden angegurteten Frontinsassen wurden mit forensischer Genauigkeit rekonstruiert and die technischen Parameter mit der Verletzungsschwere, codiert nach AIS (Abbreviated Injury Scale) 1985, in Beziehung gesetzt. EES (Energy Equivalent Speed) and Geschwindkeitsänderung Δv waren hochsignifikante Prädiktoren der Thorax-, Abdominal- and Gesamtverletzungsschwere. Ab einer EES oder Δ v ≥ 40 km/h erlitten die stoßnahen Insassen eine Gesamtverletzungsschwere MAIS ≥ 4 and starben. Auch wenn Insassen bis zu höchstens EES- oder Av-Werten in einer oder mehreren Körperregionen unverletzt bleiben konnten, erlitten sie ab einer EES oder Av≥40 km/h tödliche Verletzungen in mindestens einer Körperregion. Ab einer EES ≥ 35 km/h oder einer Av ≥ 25 km/h blieb kein stoßnaher Insasse mehr unverletzt.

Human Response to and Injury from Lateral Impact

Lateral impacts have been shown to produce a large portion of both serious and fatal injuries within the total automotive crash problem. These injuries are produced as a result of the rapid changes in velocity that an automobile occupants body experiences during a crash. In an effort to understand the mechanisms of these injuries, an experimental program using human surrogates (cadavers) was initiated. Initial impact velocity and compliance of the lateral impacting surface were the primary test features that were controlled, while age of the test specimen was varied to assess its influence on the injury outcome. Instrumentation consisted of 24 accelerometer channels on the subjects along with contact forces measured on the wall both at the thoracic and pelvic level. The individual responses and resulting injuries sustained by 11 new subjects tested at the University of Heidelberg are presented in detail. An examination of the relationship between forces applied and responses observed in the thorax is discussed. The average injuries for different sled test conditions are presented based on a total of 42 cadaver tests (11 of which are the ones discussed above). The comparison of rigid wall and padded wall sled tests is made based on these average injuries. For the covering abstract of the conference see HS-036 716. (Author/TRRL)

Use of radiographs in the forensic autopsy

The X-ray examination of corpses is a most useful tool in the field of medicolegal diagnosis. Sometimes the cause of death can already be seen before autopsy. The following modes of application are reviewed: search for foreign bodies, identification of poison, air-embolism, pneumothorax, air-filled lungs and gastro-intestinal organs in newborns, diagnosis of tuberculosis in corpses, visibility of hidden fractures, structure of bones as a factor of biomechanical load capacity, identification and determination of age and experimental research with corpses.

RESPONSE AND VULNERABILITY OF THE UPPER ARM THROUGH SIDE AIR BAG DEPLOYMENT

Tests of higher injury risk configurations with dummies and cadavers were performed to account for the mechanical responses and the injuries of the arm under the influence of a side air bag. High speed cameras were used to record the deployment phase as well as the arm movement. The interaction of the dummy with the side air bag was different from that of the cadaver. The general motion of the cadavers arm was different to the dummy due to the different behavior of the airbag. The results indicate that even old people can endure the inflation of a side air bag without suffering humerus fracture.

An Evaluation of Pedal Cycle Helmet Performance Requirements

This paper aims to investigate aspects of bicycle helmet performance by drawing on the results of contemporary published research and selected experimental programs. This examination will be used to determine the levels of headform acceleration, head coverage and test impact energy, which can be applied to optimise helmet effectiveness. The combination of increasing head coverage over the lateral aspect of the head, improving energy attenuation to below 200g, and requiring at least a 1.5 m drop height for impact attenuation tests would promote the development and use of more effective helmets.

On the synergism of the driver air bag and the 3-point belt in frontal collisions

Forty-eight kph frontal collisions were performed using human cadavers. The results show, that by using a combined standard 3-point belt (6% and 16% elongation)/driver air bag, the thoracic injury pattern remained located under the shoulder belt. Chest contours derived from the chest bands showed high local compression and deformation of the chest along the shoulder belt path. In tests where the air bag was the only available torso restraint, forces were distributed uniformly over the front of the chest. This study investigates if it is possible to obtain both the thoracic injury mitigating benefits of an air bag only restraint and the all-impact-direction benefits of the belt from a combination restraint system by adding a force limiter to the shoulder belt. For this reason, tests with force limiters were performed. Initially, the investigation was carried out with Hybrid III dummies using two different levels of force limiters: 4 kN and 5 kN.By using the same restraint combination and force limiter, comparable vertebral accelerations and chest compressions were measured in cadaver testing. Analytical simulations were also conducted using different size occupants in both the baseline and the optimized belt/air bag restraint and in other crash conditions. For the covering abstract of the conference see IRRD 882980.