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Studies show that the pedestrian population at high risk of injury consists of both young children and adults. The goal of this study is to gain understanding in the mechanisms that lead to injuries for children and adults. Multi-body pedestrian human models of two specific anthropometries, a 6year-old child and a 50th percentile adult male, are applied. A vehicle model is developed that consists of a detailed rigid finite element mesh, validated stiffness regions, stiff structures underlying the hood and a suspension model. Simulations are performed in a test matrix where anthropometry, impact speed and impact location are variables. Bumper impact occurs with the tibia of the 50th percentile adult male and with the thigh of the 6-year-old child. The head of a 50th percentile male impacts the lower windshield, while the 6-year-old child's head impacts the front part of the hood.

This research investigates the variation of pedestrian stance in pedestrian-automobile impact using a validated multi-body vehicle and human model. Detailed vehicle models of a small family car and a sport utility vehicle (SUV) are developed and validated for impact with a 50th percentile human male anthropometric ellipsoid model, and different pedestrian stances (struck limb forward, feet together, and struck limb backward) are investigated. The models calculate the physical trajectory of the multi-body models including head and torso accelerations, as well as pelvic force loads. This study shows that lower limb orientation during a pedestrian-automobile impact plays a dominant role in upper body kinematics of the pedestrian. Specifically, stance has a substantial effect on the subsequent impacts of the head and thorax with the vehicle. The variation in stance can change the severity of an injury incurred during an impact by changing the impact region.

The goal of this study was to develop and validate a finite element (FE) model of the Polar-II pedestrian dummy. An upper body model consisting of the head, neck, shoulder, thorax, and abdomen was coupled with a previously validated model of the lower limb The viscoelastic material properties of the dummy components were determined from dynamic compression tests of shoulder urethane, shoulder rubber and abdominal foam. For validation of the entire upper body, the model was compared with NHTSA response requirements for their advanced frontal dummy (Thor) including head and neck pendulum tests as well as ribcage and abdominal impact tests. In addition, the Polar-II full body FE model was subjected to simulated vehicle-pedestrian impacts that recreated published experiments. Simulated head and pelvis accelerations as well as upper body trajectories reasonably reproduced the experiment.

An impact test procedure with a legform addressing lower limb injuries in car-pedestrian accidents has been proposed by EEVC/WG17. Although a high frequency of lower limb fractures is observed in recent accident data, this test procedure assesses knee injuries with a focus on trauma to the ligamentous structures. The goal of this study is to establish a methodology to understand injury mechanisms of both ligamentous damages and bone fractures in car-pedestrian accidents. A finite element (FE) model of the human lower limb was developed using PAM-CRASH™. The commercially available H-Dummy™ lower limb model developed by Nihon ESI for a seated position was modified to represent the standing posture of pedestrians. Mechanical properties for both bony structures and knee ligaments were determined from our extensive literature survey, and were carefully implemented in the model considering their strain rate dependency in order to simulate the dynamic response of the lower limb accurately.

The goal of this study was to develop injury probability functions for the leg bending moment and MCL (Medial Collateral Ligament) elongation of the Flexible Pedestrian Legform Impactor (Flex-PLI) based on human response data available from the literature. Data for the leg bending moment at fracture in dynamic 3-point bending were geometrically scaled to an average male using the standard lengths obtained from the anthropometric study, based on which the dimensions of the Flex-PLI were determined. Both male and female data were included since there was no statistically significant difference in bone material property. Since the data included both right censored and uncensored data, the Weibull Survival Model was used to develop a human leg fracture probability function.

A finite element (FE) model that can predict impact response and injuries to a human pelvis and lower limb was developed in PAM-CRASH™ by accurately representing human anatomical structures. In our previous study, three-dimensional (3D) geometry of the thigh, leg and knee joint was developed based on MRI scans from a human volunteer. 3D geometry of a bony pelvis created in this study was based on CT scans from a Post Mortem Human Subject (PMHS). The model was validated using published quasi-static and dynamic test results with human pelves and lower limbs. The thigh and leg models were validated against recently published dynamic 3-point bending test results with off-center loading. The validation results showed that this model can reproduce force-deflection and moment-deflection responses of a human thigh and leg in various loading conditions along with average force and moment at fracture.

Injury assessment by using a whole-body pedestrian dummy is one of the ways to investigate pedestrian safety performance of vehicles. The authors’ group has improved the biofidelity of the lower limb and the pelvis of the mid-sized male pedestrian dummy (POLAR III) by modifying those components. This study aims to evaluate the biofidelity of the whole-body response of the modified dummy in full-scale impact tests. The pelvis, the thigh and the leg of POLAR III have been modified in a past study by optimizing their compliance by means of the installation of plastic and rubber parts, which were used for the tests. The generic buck developed for the assessment of pedestrian dummy whole-body impact response and specified in SAE J3093 was used for this study. The buck representing the geometry of a small family car is comprised of six parts: lower bumper, bumper, grille, hood edge, hood and windshield.

The evaluation of pedestrian safety performance of vehicles required by regulations and new car assessment programs (NCAPs) have been conducted. However, the behavior of a pedestrian in an actual car-pedestrian accident is complex. In order to investigate injuries to the pedestrian lower body, the biofidelity of the lower limb and the pelvis of a pedestrian dummy called the POLAR II had been improved in past studies to develop a prototype of the next generation dummy called the POLAR III. The biofidelity of the thigh and the leg of the POLAR III prototype has been evaluated by means of 3-point bending. However, the inertial properties of these parts still needed to be adjusted to match those of a human. The biofidelity of the pelvis of the POLAR III prototype has been evaluated in lateral compression. Although the experiment using PMHSs (Post Mortem Human Subjects) was conducted in dynamic condition, the dummy tests were performed only in quasi-static condition.

Japanese accident statistics show that despite the decreasing trend of the overall traffic fatalities, more than 1,000 pedestrians are still killed annually in Japan. One way to develop further understanding of real-world pedestrian accidents is to reconstruct a variety of accident scenarios dynamically using computational models. Some of the past studies done by the authors' group have used a simplified vehicle model to investigate pedestrian lower limb injuries. However, loadings to the upper body also need to be reproduced to predict damage to the full body of a pedestrian. As a step toward this goal, this study aimed to develop a simplified vehicle model capable of reproducing pedestrian full-body kinematics and pelvis and lower limb injury measures. The simplified vehicle model was comprised of four parts: windshield, hood, bumper and lower part of the bumper. Several different models were developed using different combinations of geometric and stiffness representation.

The high frequency of fatal head injuries is one of the important issues in traffic safety, and Traumatic Brain Injuries (TBIs) without skull fracture account for approximately half of them in both occupant and pedestrian crashes. In order to evaluate vehicle safety performance for TBIs in these crashes using anthropomorphic test dummies (ATDs), a comprehensive injury criterion calculated from the rotational rigid motion of the head is required. While many studies have been conducted to investigate such an injury criterion with a focus on diffuse brain injuries in occupant crashes, there have been only a limited number of studies focusing on pedestrian impacts. The objective of this study is to develop a comprehensive injury criterion based on the rotational rigid body motion of the head suitable for both occupant and pedestrian crashes.

Recently, the global increase of elderly vehicle users has become an issue to be considered in the effort of enhancing safety performance of vehicle restraint system. It is thought that an evaluation tool for the system representing properties of age-specific human body will play a major role for that. In previous research, the authors had developed age-specific component finite element (FE) models for the lower limb, lumbar spine, and thorax representing the adult and elderly occupants. However, the models have not been validated in terms of full body kinematics. It is essential for such models to be validated in terms of full body kinematics in order to ensure validity of the results of the assessment of the safety performance of restraint systems. In the present research, the adult and elderly occupant full body FE models were developed by incorporating the lower limb, lumbar spine and thorax of the adult and elderly FE models established in previous research.