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Numerous studies of pelvic tolerance to lateral impact aimed at protecting car occupants have been conducted on Post Mortem Human Subjects (PMHSs) in a sitting posture. However, it remains unclear whether or not the results of these studies are relevant when evaluating the injury risk to walking pedestrians impacted by a car. Therefore, the first objective of the present study is to determine the injury tolerance and to describe the injury mechanisms of the human pelvis in lateral impacts simulating car-pedestrian accidents. The second objective is to obtain data for validation of mathematical models of the pelvis. In-vitro experiments were conducted on twelve PMHSs in simulated standing position. The trochanter of each PMHS was hit by a ram at speed of 32 km/h, and the pelvic motion was constrained by a bolt. This type of pelvic constraint is difficult to simulate in mathematical models.

Current accident analysis shows that the head of the pedestrian impacts most frequently into or around the windscreen since cars in recent have a short hood. Therefore, the injury risks to the head in contact with various locations of the car including the windscreen and its frame were examined on the basis of headform impact tests. The HIC is high from contact with the cowl, lower windscreen frame or A pillar, and it is low with increasing distance from these structural elements. In the windscreen center, the HIC is less than 500. The headform impact test results were compared between earlier and current car models. The HICs in the bonnet top area are similar in either type car except for the car built especially for pedestrian safety. However, on the A pillar, the HICs are much greater for current cars. From child headform impact tests for the WAD of 1000 mm, the HIC of SUV is higher than cars, and the SUV with steel bull bar leads to high injury risk.

In vehicle-pedestrian impacts, the kinematics and severity of pedestrian injuries are affected by vehicle front shapes. Accident analyses and multibody simulations showed that for mini vans the injury risk to the head is higher, while that to the legs is lower than for bonnet-type cars. In mini-van pedestrian impacts, pedestrians ran high risks of a head impact against stiff structures such as windshield frames. When pedestrians are struck by a car with a short hood length, their heads are likely to strike into or around the windshield. The injury risks to the head by such an impact were examined by head form impact tests. The HIC rises from contact with the cowl, windshield frame or A pillar, and it lessens with increasing distance from these structural elements.

The main objective of this study is to determine the damage tolerance and describe the damage mechanisms of the extended human knee when it is exposed to lateral impact loads in car-pedestrian accidents, particularly those that occur at a low velocity (20 km/h), and compare the results with those obtained at a high velocity (40 km/h). In-vitro experiments with human subjects were conducted where only the purest possible shearing deformation or the purest possible bending deformation affected the knee region at the time. Five experiments were performed in the shearing setup and another five in bending setup. The peak values of the shearing force and the bending moment related to the damage of knee ligaments and bone fractures were calculated at the knee joint level. Damages were assessed by dissecting the lower extremity. When the knee joint was exposed to the “purest possible shearing deformation”, the common initial damagemechanism was ligament damage related to ACL (60% of cases).

The main objective of this study is to determine the damage tolerance and to describe the damage mechanisms of the extended human knee when it is exposed to lateral impact loads in pedestrian accidents, particularly those that occur at high velocity. An experimental method for assessing the damage tolerance of the knee region to loads acting at the extended lower extremity was developed. In-Vitro experiments with human subjects were conducted where only the purest possible shearing deformation or the purest possible bending deformation affected the knee region at the time. Ten experiments at a velocity level of 40 km/h were performed in a shearing and a bending setup, respectively. The peak values of the shearing force and the bending moment related to the damage of knee ligaments and bone fractures were calculated at knee joint level. Damages were assessed by dissecting the lower extremity.

Twelve volunteers participated in the experiment under the supervision of Tsukuba University Ethics Committee. The subjects sat on a seat mounted on a newly developed sled that simulated actual car impact acceleration. We selected impact speeds (4, 6 and 8 km/h), seat stiffness, neck muscle tension, and alignment of the cervical spine for the parameter study of the head-neck-torso kinematics and cervical spine responses. The effects of those parameters were studies without headrest. The muscle activity was measured with surface electromyography. The cervical vertebrae motion was recorded by cineradiography (90 frames/s X-ray) and analyzed to quantify the rotation and translation of cervical vertebrae at impact. Furthermore, the motion patterns of cervical vertebrae in the crash motion and in the normal motion were compared. Subject's muscles in the relaxed state did not affect the head-neck-torso kinematics upon rear-end impact.

The shearing and bending injury mechanisms of the knee joint are recognised as two important injury mechanisms associated with car-pedestrian crash accidents. A study on shearing and bending response of the knee joint to a lateral impact loading was conducted with a 3D multibody system model of the lower extremity. The model consists of foot, leg and thigh with concentrated upper body mass. The body elements are connected by joints, including an anatomical knee joint unit that consists of the femur condyles, tibia condyles and tibia1 intercondylar eminence as well as ligaments. The biomechanical properties of the model were derived from literature data. The model was used to simulate two series of previously performed experiments with lower extremity specimens at lateral impact speeds of 15 and 20 km/h.

Analysis of the results of previous simulations of pedestrian collision performed with different commercial dummies have indicated that test results do not always correspond with observations in simulations with cadavers. It seems that determining the risk of injury to pedestrians from these dummy tests may be very difficult. To study injury-related parameters in connection with mechanical dummies, 21 crash tests were performed at the Institute of Forensic Medicine at the Medical University of Hannover. Various front structures and velocities of vehicles were simulated. Two measuring tools were used for verification: a standard Hybrid II dummy, and the lower part of a Rotationally Symmetrical Pedestrian Dummy (RSPD) with no representation of the upper body. RSPD was previous developed at the Department of Injury Prevention at Chalmers University in Göteborg.

A 3D pedestrian knee joint model was developed as a first step in a new description of the whole pedestrian body for computer simulations. The model was made to achieve better correlation with the results from previous tests with biological material. The model of the knee joint includes the articular surfaces, ligaments and capsule represented by the ellipsoid and plane elements as well as the spring-damping elements, respectively. The mechanical properties of the knee joint were based on available biomechanical data. To verify the new developed model with results from tests with biological material previously performed at the Department of Injury Prevention, Chalmers University of Technology, the computer simulations were carried out with the model of the knee joint using the MADYMO 3D program.

Injuries to motorcyclists lead to permanent disability more often than injuries to car occupants (10 percent versus 6 percent). The use of helmets has decreased the risk of head injuries. Other injuries leading to permanent disability are currently concentrated on the extremities (about 70 percent). Almost all are due to fractures located in joints where knees, elbows, shoulders, and ankles are the modest common spots. In a study based on 200 motorcycle accidents, it was shown the existing protective clothing had no effect on the incidence of fractures to knees, elbows, and shoulders. Based on that knowledge, a new motorcycle suit was constructed. The main goal was to find a shock-absorbing material to protect knees, elbows, and shoulders in an accident. Confor Foam, a medium-density urethane foam, was tested and found to possess relevant characteristics.