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Accident data have shown that the pedestrian injuries resulting from contact with the ground are serious and may even be worse than the injuries resulting from the primary contact with the vehicle. The landing mechanisms, including the pedestrian trajectory and subsequent sequential body region contacts to the ground, are the basis for understanding the ground impact injuries of pedestrians. However, the landing mechanisms of pedestrian are too complicated to be categorized via investigation of the collision information after an accident has occurred. Nowadays, pedestrian kinematics after vehicle impacts can be observed from the accident videos that have been recorded by road monitoring and driver recorders. This study was aimed at investigating the pedestrian landing mechanisms and analyzing the influencing factors.

Injuries to the lower extremities are one of the major issues in vehicle-to-pedestrian collisions. To evaluate pedestrian lower extremity protection, the Transport Research Laboratory (TRL) legform impact tests have been conducted according to the specifications in the EU directive. The TRL legform impactor consists of a tibia and a femur steel shaft connected by deformable knee bars. A Flexible Pedestrian Leg-form Impactor (Flex-PLI), which has flexible femur and tibia, is examined in the Global Technical Regulation (GTR). Previous studies compared the responses of both impactors; however, the relation between the tibia acceleration in the TRL legform impactor and the maximum bending moment in the Flex-PLI (both injury measures are for the tibia fracture) is not understood sufficiently.

Accident data show that the injury risks to children seated in child restraint systems (CRSs) are higher in side collisions than any other type of collision. To investigate child injury in the CRS in a side impact, it is necessary to understand the occupant responses in car-to-car crash tests. In this research, a series of full car side impact tests based on the ECE R95 test procedure was conducted. In the vehicle's struck-side rear seat location, a Q3s three-year-old child dummy was seated in a forward facing (FF) CRS, and a CRABI six-month-old (6MO) infant dummy was seated in a rear facing (RF) CRS and also was placed in car-bed restraint. In the non-struck side rear seat location, the RF CRSs also were installed. In addition to testing the CRSs installed by a seatbelt, an ISOFIX FF CRS and an ISOFIX RF CRS were tested. For the evaluations, occupant kinematic behavior and injury measures were compared.

In the current Japanese and European side impact regulation, occupant protection is evaluated based on anthropomorphic test device (hereafter referred to as the more commonly used term “dummy”) measurements recorded in a stationary car impacted by a moving deformable barrier (MDB). In order to validate and improve the side impact test procedures of the regulation and the associated new car assessment program, it is necessary to compare the side impact test procedure with car-to-car side impact tests conducted in various conditions. In this research, a series of car-to-car side impact tests using a small sedan as the target vehicle was conducted as follows: (1) A striking car impacted against the stationary car at 50 km/h at an impact angle of 90 degrees. (2) A 1BOX vehicle impacted the stationary car at 50 km/h at an impact angle of 90 degrees. (3) Both cars were moving, and the striking car impacted the struck car at an impact angle of 90 degrees.

This research focuses on the further development of a child finite element model whereby implementation of pediatric cadaver testing observations considering the biomechanical response of the neck of children under tensile and bending loading has occurred. Prior to this investigation, the biomechanical neck response was based upon scaled adult cadaver behaviour. Alterations to the material properties associated with ligaments, intervertebral discs and facet joints of the pediatric cervical spine were considered. No alteration to the geometry of the child neck finite element model was considered. An energy based approach was utilized to provide indication on the appropriate changes to local neck biomechanical characteristics. Prior to this study, the biomechanical response of the neck of the child finite element model deviated significantly from the tensile and bending cadaver tests completed by Ouyang et al.

This research focuses on the response of the Q3, Hybrid III 3-year-old dummy and a child finite element model in a simulated 213 sled test. The Q3 and Hybrid III 3-year old child finite element models were developed by First Technology Safety Systems. The 3-year-old child finite element model was developed by Nagoya University by model-based scaling from the AM50 (50 percentile male) total human model for safety. The child models were positioned in a forward facing, five-point child restraint system using Finite Element Model Builder. An acceleration pulse acquired from an experimental 213 sled test, which was completed following the guidelines outlined in the Federal Motor Vehicle Safety Standard 213 using a Hybrid III 3-year-old dummy, was applied to the seat buck supporting the child restraint seat. The numerical simulations utilizing the Q3, Hybrid III 3-year-old and the child finite element model were conducted using the explicit non-linear finite element code LS-DYNA.

In order to prevent lower extremity injuries to a pedestrian when struck by a car, it is important to elucidate the loadings from car front structures on the lower extremities and the injury mechanism caused by these loadings. In this study, using a human finite element (FE) model, a bending moment diagram and a stress diagram of tibia were introduced to examine the effects of loading from car structures. By the lower absorber of the car, the bending moment was distributed over the tibia with small moment at the upper tibia location that can reduce knee injury risk. Certain positions of the lower absorber reduced the tibia fracture risk. An FE analysis of a legform impact test using the TRL legform impactor was also conducted, and a relation was found between the injury criteria of the TRL legform impactor and the human FE model. High acceleration of the TRL legform impactor corresponded to the tibia fracture or MCL rupture of the human FE model.

The THUMS (Total HUman Model for Safety) 3-year-old child finite element (FE) model was developed by Toyota Central R&D Labs (TCRDL) by model-based scaling from the AM50 (50 percentile male) human FE model. The objective of this paper is to present a comparison between the kinematics of a child FE model developed from the adult THUMS model and a HYRID III 3-year-old child dummy using observations from numerical simulations of a CMVSS 208 frontal crash. Both the child models were positioned in a forward facing, five point child restraint systems (CRS). An acceleration pulse acquired from a vehicle crash test in accordance with Canadian Motor Vehicle Safety Standards (CMVSS) 208 was applied to the seat buck supporting the CRS. Numerical simulations with both the child model and the Hybrid III child dummy were conducted using LS-DYNA version 970.

Test procedures to assess vehicle compatibility were investigated based on a series of crash tests. Structural interaction and compartment strength are significant for compatibility, and full-width tests and overload tests have been proposed to assess these key factors. Full-width rigid and deformable barrier test results were compared with respect to force distributions, structural deformation and dummy responses. In full-width deformable tests, forces from structures can be clearly shown in barrier force distributions. The average height of force (AHOF) determined in full rigid and deformable barrier tests were similar. From car-to-car tests, it was demonstrated that stiffening the compartment of small cars is an effective and direct way to improve compatibility. To evaluate the compartment strength, five overload tests were carried out. The rebound force is proposed as a compartment strength criterion.

This paper examines the effect that test barriers currently used for frontal and side impact tests have had on collision compatibility between different-sized vehicles. The peak force levels generated by the vehicles’ front structures are one of the significant factors in determining vehicle compatibility. It is shown from principles of mechanics that the use of fixed barriers as a test device may lead to higher force levels for front ends of larger vehicles and thus increase the incompatibility between large and small vehicles. Review of data from various sources supports this conclusion that the peak force levels of vehicles’ front ends have increased in proportion to their test mass. Available crash data is also examined for a relationship between NCAP ratings of vehicles and the likelihood of serious and fatal injuries to occupants of those vehicles. These data do not show any relationship between the frontal NCAP ratings of vehicles and their rate of serious or fatal injuries.

The strength of the passenger compartment is crucial for occupant safety in severe car-to-car frontal offset collisions. Car-to-car crash tests including minicars were carried out, and a low end of crash force was observed in a final stage of impact for cars with large intrusion into the passenger compartment. From overload tests, the strength could be evaluated from collapsing the passenger compartment. Based on the test, the end of crash force as well as the maximum forces might be important criteria to determine the passenger compartment strength, which in turn could predict the large intrusion into the passenger compartment in car-to-car crashes. A 64 km/h ODB test was insufficient to evaluate the potential strength of the passenger compartment because the maximum forces could not be determined in this test.

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 compatibility problems of the mini car in car-to-car frontal collision and car-pedestrian accident are discussed using accident data and computer simulations. In our analysis of the accident data in Japan, the number of fatalities was investigated using the vehicle masses and classes. It was found that the cars with identical mass are most compatible since the injuries per accident are minimal and injury risks to the driver in both cars are the same. The analysis of the car class indicated that the mini car and the sports utility vehicle are the most incompatible car types, with low and high aggressivity, respectively. Our accident analysis in the present study shows that the safety of mini cars is the key point in achieving the compatibility in Japan. Computer simulations using MADYMO were carried out of crashes of mini car into a rigid wall and into a large car.