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Occupant protection performance in frontal crashes has been developed and assessed for mainly front seat occupants over many years, and in recent years protection of rear seat occupants has also been extensively discussed. Unlike the front seats, the rear seats are often occupied by children seated in rear- facing or forward - facing child restraint systems, or booster seats. In the European New Car Assessment Program (NCAP), child occupant protection assessments using 18-month-old and 3-year-old test dummies in the rear seat are already being conducted. In addition, studies are under way concerning the development and introduction of test dummies of 6-year-old (6YO) and 10.5-year-old children. In this study, we focused on 6-year-old children sitting in belt-positioning booster seats. Offset frontal crash tests were conducted using two types of test dummies, a Hybrid III 6YO and a 6YO Q-series dummy (Q6), positioned in the rear seat.

Rollover tests are performed to design the algorithms for deployment of countermeasures to mitigate occupant ejection in rollover situations. The ditch fall-over test is one of the rollover test methods in which a vehicle on a steep slope, representing a ditch embankment, is subjected to a forced steering operation that results in a turnover. An accurate prediction method is needed to determine the specifications of the ditch fall-over test equipment and test conditions because a test-based trial-and-error process involves high cost of performing repeated experiments and preperation for various types of related test equipment. This paper presents a newly developed numerical simulation method for simulating vehicle behavior in ditch fall-over tests.

A new 1.2L inline 3-cylinder supercharged gasoline engine was developed to improve fuel efficiency and to meet EURO 5 emission regulations. The engine was designed with a high compression ratio, heavy exhaust gas recirculation (EGR), and a long stroke to improve fuel efficiency. The Miller cycle and a direct fuel injection system were applied to this engine in order to mitigate the occurrence of knock due to the high compression ratio. In addition, a supercharging system was adopted to compensate for the decline in charging efficiency due to the Miller cycle. The design of a direct injection gasoline engine involves a lot of problems such as reduction of oil dilution, stabilization of combustion at first idle retarded, improvement of air-fuel mixing homogeneity, and strengthening of the gas flow. It is hard to resolve these problems independently due to their complexities and difficult nature. Reducing wall wetting by the fuel spray can improve oil dilution in a small engine.

Public concern about the crashworthiness of vehicles has been continuously rising in recent years. Crashworthiness is evaluated under various crash configurations, including frontal collisions, in regulatory testing and in New Car Assessment Programs. Accordingly, vehicle manufacturers must deploy sophisticated product development strategies and redouble their engineering efforts in order to develop vehicles that satisfy the specified requirements for crashworthiness. Computer simulation is one effective approach to resolving this issue in that it provides a valuable tool for conducting multiple parameter studies and iterations in a short period of time. However, it is no easy task for CAE engineers to analyze the large volumes of calculation results obtained in frontal crash simulations and to understand the phenomena involved.

The causes of injuries suffered by drivers in “small-overlap frontal crashes” (SOFC) were examined. These crashes were defined as ones in which vehicles are loaded outside their longitudinal side members. SOFC accident data sets stored in the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) database were investigated. Percentages of cases sustaining injury to each body region of drivers were calculated, and the differences between the percentages of injury by body region were examined. To investigate the injury mechanisms, SOFC tests with two types of rigid barrier were then conducted. Injury values in each body region were analyzed to validate the reproducibility of SOFC test as a relevant test.

Stress induced by an excessive difference in pressure between the air and the hydrogen in polymer electrolyte fuel cells degrades membrane durability. Controlling such stress improves the durability and solves one of the problems hampering commercialization of fuel cell electric vehicles. Hydrogen pressure can be raised more rapidly than the air pressure by regulating the pressure of the high-pressure hydrogen storage tank. However, the response for reducing the hydrogen pressure varies depending on the level of current generation. The air pressure can be reduced rapidly by releasing air, whereas it takes longer to raise the air pressure owing to compression of the air taken in from the atmosphere.

This paper describes the development of the drive motor used on a newly developed electric vehicle (EV) that has been specifically designed and engineered as the world's first mass-produced EV. Producing maximum torque of 280 Nm and maximum power of 80 kW, this synchronous motor was selected as the first electrified powertrain to be named to Ward's 10 Best Engines list for 2011. In developing this motor, magnetic field simulations were conducted in the process of adopting the following in-house technologies to achieve a compact motor size, high output and high efficiency. The rotor shape has the interior permanent magnets arranged in a ▽-shaped that achieves a superior balance of torque and power. The flux barriers located on the outer periphery are designed to reduce iron loss. The V-shaped flux barriers provide both excellent mechanical strength and outstanding performance during high-speed motor operation.

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.

Hybrid powertrain technology, which combines an internal combustion engine and an electric motor as power sources, is penetrating auto markets as a practical approach for reducing vehicle fuel consumption and exhaust emissions. This paper describes the development of an integrated powertrain simulation technology for predicting the fuel economy and exhaust emissions of hybrid electric vehicles with high accuracy and computation speed. Primary paths of kinetic, electric, chemical and thermal energies and their management were modeled. The predicted exhaust emissions and temperatures of the coolant and lubrication oil agreed well with experimental data in various vehicle driving conditions. This simulation was used to study an air-fuel ratio control strategy for reducing NOx at engine restart and to examine an exhaust heat recovery method for reducing fuel consumption and exhaust emissions under cold start conditions.

Customers desire to keep the interior of their vehicles as clean as possible. A field survey was made of the types of dirt and stains found on interior trim parts as the starting point for the development of products that meet this need. The survey findings showed that soiled stains resulting from long periods of use are commonly found on seat surfaces and cloth seats also have beverage stains. Dirt stains are typically seen on plastic trim parts. An analysis of the components of soiled stains revealed the presence of higher fatty acids that tend to adhere to the urethane coating on the surface of genuine leather seat covers and to the polyester fibers of cloth seat covers. A coating technology was then developed for bringing dirt to the surface so that it can be easily removed by wiping with a wet cloth.

This paper describes a new 1.2-liter three cylinder gasoline engine named HR12DDR, with the target to achieve the lowest level CO2 in the European B-segment market and also, to satisfy the customer's driving pleasure through high output performance. This engine is developed with the consideration of meeting further strict regulations in the years ahead and of the possibility of being an alternative powertrain of diesel in the future as well. As a first step this engine was applied on the European Nissan Micra in 2011; achieving 95g/km CO2 emissions(NEDC mode). This low fuel consumption was realized mainly through technologies which scope to maximize thermal efficiency with high compression ratio, and to minimize the mechanical friction loss. The combustion was optimized by Direct injection (DI)system. To obtain the better fuel economy performance without sacrificing high output, we chose the supercharger system with bypass valve and electromagnetic clutch.

The pole side impact test has been mandatory in Euro NCAP since 2009 and it includes, in addition to the head, assessments on other critical body regions that might be affected such as the chest, abdomen and pelvis. This paper describes a new test method for predicting Anthropomorphic Test Device responses to calculate injury index in side impact tests of a rigid pole under Euro NCAP conditions. Simplified sled tests are very effective in reducing the cost and time of development of more advanced side impact safety devices. To accomplish sled tests successfully, it is necessary to reconstruct accurately the combined dynamic deformation behavior of door and seat in pole impact. That behavior varies among different dummy response regions. Conventional sled test methods, published in previous literature, can reconstruct the deformation of the entire door using a single actuator at constant intrusion velocity but actual door velocity isn't constant in full scale vehicle crash tests.

Evaluation of pedestrian leg protection performance using the Flex-PLI-GTR (Flexible Pedestrian Legform Impactor Global Technical Regulation) impactor is initiated in JNCAP in 2011. Therefore, a finite element (FE) model of Flex-PLI-GTR is needed for use in digital car development in order to satisfy pedestrian leg protection performance requirements. This paper describes the FE model of Flex-PLI-GTR that has been developed to meet this need. There are three important features of this FE model for obtaining sufficient simulation accuracy. First, the shapes of all Flex-PLI-GTR structures were modeled in detail. Shape information of the inner structures was obtained by computerized tomography scanning and shape information of the inner structures of the outer skin was obtained by laser measurement. Furthermore, the shape of the wrapped skin was incorporated into the FE model based on a wrapping simulation.

A new transparent resin material developed by uniformly dispersing a nano-filler (boehmite particles, 5 nm in diameter and 197 nm long) in polycarbonate resin combines a flexural modulus of 5.9 GPa, a linear expansion coefficient of 35 ppm/K, and excellent mechanical toughness with excellent optical characteristics (transparency with 1.1% haze at 1 mm thick). These characteristics make this material highly suitable as a replacement for automotive glass that allows innovative design, a liberating sense of openness for automobiles.

Pedestrian crashes are the most frequent cause of traffic-related fatalities worldwide. The high number of pedestrian accidents justifies more active research work on passive and active safety technology intended to mitigate pedestrian injuries. Post-impact pedestrian kinematics is complex and depends on various factors such as impact speed, height of the pedestrian, front-end profile of the striking vehicle and pedestrian posture, among others. The aim of this study is to investigate the main factors that determine post-crash pedestrian kinematics. The injury mechanism is also discussed. A detailed study of NASS-PCDS (National Automotive Sampling System - Pedestrian Crash Data Study, US, 1994-1998), showed that the vehicle-pedestrian interaction in frontal crashes can be categorized into four types: “Thrown forward”, “Wrapped position”, “Slid to windshield” and “Passed over vehicle”.

This study proposes an impact-triggered automatic braking system as a potential safety improvement based on the characteristics of the Multiple Impact Crashes (MICs). The system activates with a signal of airbag deployment in a collision to reduce the vehicle speed in the subsequent collisions. The effectiveness was estimated by an in-depth review of the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS). The cases were extracted on the basis of the 3-point lap and shoulder belted occupants, incurring Maximum Abbreviated Injury Scale level 3 to 6 injuries (MAIS 3+), in the crashes occurred from 2004 to 2006, without vehicle rollover or occupant ejection, where the involved vehicles were 2000 and newer model year cars and light trucks.

The thin-shell structured beams that are used extensively in the vehicle body need to satisfy both strength requirements for crash safety and demands for weight reductions for environmental friendliness. This study focused on the loading rate dependence of reaction force, especially the maximum value, which is generated in thin-shell structured beams as a result of axial force inputs in a frontal crash. The mechanism generating the reaction force was made clear through a comparison with classical Euler buckling(1) and von Karman's effective width expression(2). It was observed that a square cross section displays markedly large loading rate dependence, which can be approximated well by considering the effect of inertial force in the high loading rate region and by von Karman's effective width solution in the low loading rate region. Essentially, this dependence is governed by Euler buckling.

A method including Multi-Body Dynamics (MBD) and fatigue assessment process with modal approach was developed to predict Light Commercial Van (LCV) Rear French Doors open/close durability performance during early design stage to improve test detect ability. The nonlinear properties of joints, such as those on bolted housings or spot welds sheets and hem flange areas, can substantially influence the local and global results of a dynamic simulation. The Modal approach considers joint contact, by way of Joint Interface Modes (JIMs) by using Contact Subroutine (MAMBA) to co-simulate with MBD software to improve result quality. One of the main challenges is measuring the dynamic stiffness for the weather strip. A novel test method was used to measure the weather strip dynamic stiffness by conducting an “in-situ” test. For CAE simulation results, positive feedback was received from design and test engineers.

This paper describes a newly developed NOx trap catalyst that achieves cleaner exhaust gas using much smaller quantities of precious metals. The precious metal loading of this NOx trap catalyst has been halved by developing a technique for inhibiting precious metal sintering even under exposure to high temperature exhaust gas and a trap material with improved catalyst functions at low temperature. This NOx trap catalyst is used on the Nissan X-TRAIL fitted with a diesel engine, which was the first vehicle to comply with Japan's Post New Long term Exhaust Emission Regulations.

This paper presents a mathematical investigation of the influence of the slot/pole number combination on the iron loss of permanent magnet (PM) motors. A simplified electromagnetic model of PM motors was used to develop a mathematical method of evaluating iron loss for any combination of slots and pole pairs. An investigation of the magnetomotive force distribution of stator teeth and its expression as a complex Fourier series expansion revealed that the coordinate system can be easily transformed, thereby enabling rotor iron loss to be calculated. A core factor was defined on the basis of the calculated iron losses and a map of slot/pole number combinations was created. Several promising combinations were selected from the map and their respective advantages and disadvantages were identified. A new promising combination was found featuring windings with a coil pitch of two slots.