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Examining the noise reduction of a motorcycle, the requirement of an effective method of reducing a drive chain noise has been a pending issue similarly to noise originating from an engine or exhaust system, etc. Through this study, it became clear that the mechanism of chain noise could be classified into two; low frequency noise originated from cordal action according to the degree of chain engagement and high frequency noise generated by impact when a chain roller hits sprocket bottom. An improvement of urethane resin damper shape, mounted on a drive side sprocket, was effective for noise reduction of the former while our development of a chain drive that combined an additional urethane resin roller with an iron roller worked well for the latter. The new chain system that combined this new idea has been proven to be capable of reducing the chain noise to half compared with a conventional system.

In CFD (Computational Fluid Dynamics) verification of vehicle aerodynamics, detailed velocity measurements are required. The conventional 2D-PIV (Two Dimensional Particle Image Velocimetry) needs at least twice the number of operations to measure the three components of velocity ( u,v,w ), thus it is difficult to set up precise measurement positions. Furthermore, there are some areas where measurements are rendered impossible due to the relative position of the object and the optical system. That is why the acquisition of detailed velocity data around a vehicle has not yet been attained. In this study, a detailed velocity measurement was conducted using a 3D-PIV measurement system. The measurement target was a quarter scale SAE standard vehicle model. The wind tunnel system which was also designed for a quarter scale car model was utilized. It consisted of a moving belt and a boundary suction system.

One of the primary issues in the interpretation of vehicle impact response data, observed from vehicle crash test events, is coping with variability. This vehicle response inconsistency generally causes test results to be unpredictable and makes CAE test validation work difficult as well. This paper, considering the uncertain characteristics of vehicle impact events, has implemented a stochastic assessment of vehicle NCAP response variation through a CAE vehicle impact model, and it has accomplished the three primary study objectives as stated follows: 1) Identify the response variation causing factors stochastically from various structural and environmental factor candidates and quantify the degree of their influences on crash response, 2) Develop a methodology for interpreting the significance of the factor effects in conjunction with vehicle impact mechanics and physics, and 3) Implement a stochastic improvement of the vehicle NCAP responses and their repeatability

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.

A computer simulation method for motorcycle rider motion in a collision on a passenger car has been developed. The computer simulation results were in two cases of collision, at 45 degree and 90 degree angles against the side of a passenger car. The simulated results were compared to the test results for validation. The simulation software of explicit finite element method (FEM) has been used, because of its capability for expressing accurate shape and deformation. The mesh size was determined with consideration for simulation accuracy and calculation time, and an FEM model of a motorcycle, an airbag, a dummy, a helmet and a passenger car were built. To shorten the calculation time, a part of the model was regarded as a rigid body and eliminated from the contact areas. As a result, highly accurate dummy posture and head velocity at the time of contact on the ground were simulated in the two cases of collision.

In stereo photogrammetry, the accuracy of calculating the location of a point in space, decreases as the angle between the two cameras decreases. For vehicle crash testing, the need for accurate 3D data conflicts with the need for flexible positioning of the cameras, to enable unobstructed views of the targets inside the vehicle throughout the impact event. This paper discusses a method for increasing the quantity and quality of film analysis data when small subtended angles are used. The method uses the 3D information developed through triangulation of two cameras as input to a single camera analysis.

In order to minimize occupant injury in a vehicle collision, an approach was attempted to address this issue by optimizing the waveform of the vehicle body deceleration to reduce the maximum deceleration applied to the occupant. A previous study has shown that the mathematical solution to the optimal vehicle deceleration waveform comprised three stages: high deceleration, negative deceleration, and constant deceleration. A kinematic model with separated mass of the vehicle was devised to generate the optimal vehicle deceleration waveform comprising three stages including a one with negative deceleration in the middle. The validity of this model has been confirmed by a mathematical study on a one-dimensional lumped mass model. The optimal vehicle deceleration waveform generated by this method was then validated by a three-dimensional dummy simulation.

In order to minimize occupant injury in a vehicle crash, an approach was attempted to address this issue by making the wave form of vehicle body deceleration optimal to lower the maximum value of the occupant deceleration. Prior study shows that the mathematical solutions for the optimal vehicle deceleration wave form feature consisting of three aspects: high deceleration, negative deceleration, and constant deceleration. A kinematical model which has separated mass of the vehicle was devised to generate an optimal vehicle deceleration wave form which consists of three segments including a segment of negative deceleration in the middle. The validity of this model has been certified by a mathematical study by using a one-dimensional lumped mass model. The effectiveness of the optimal vehicle deceleration wave form generated by this method was validated by a simulation with a three-dimensional dummy.

The Frequency Response Function (FRF) is a fundamental component to identifying the dynamic characteristics of a system. FRF's have a significant impact on modal analysis and root cause analysis of NVH issues. In most cases the FRF can be easily measured, but there are instances when the measurement is unobtainable due to spatial constraints. This paper outlines a simple experimental method for obtaining a high quality input-output FRF of a structure in areas where an impact hammer can not reach during impact testing. Traditionally, the FRF in such an area is obtained by using a load cell extender with a hammer impact excitation. A common problem with this device is a double hit, that yields unacceptable results.

With the increasing emphasis on Systems Engineering, there is a need to ensure that Electrical/Electronic (E/E) Systems Endurance Testing of vehicles, in a real world environment, prior to Production Launch, is performed in a manner and at a technological level that is commensurate with the high level of electronics and computers in contemporary vehicles. Additionally, validating the design and performance of individual standalone electronic systems and modules “on the bench” does not guarantee that all the permutations and combinations of real-world hardware, software, and driving conditions are taken into account. Traditional Proving Ground (PG) vehicle testing focuses mainly on powertrain durability testing, with only a simple checklist being used by the PG drivers as a reminder to cycle some of the electrical components such as the power window switches, turn signals, etc.

The purpose of this study is to examine compatibility test procedures proposed in the IHRA Vehicle Compatibility Working Group. Various crash tests were conducted with different vehicle weights and stiffness in our previous study, and each of the compatibility problems, namely mass; stiffness and geometric incompatibility were identified in these tests. In order to improve the compatibility, it is necessary to evaluate and control relevant vehicle characteristics of compatibility in test procedures. According to the IHRA study, relevant aspects for compatibility in frontal impact are: Good structural interaction; Frontal stiffness matching; Maintaining passenger compartment integrity; Control the deceleration time histories of impacting cars.

In order to minimize occupant injury in a vehicle crash, an approach was attempted to address this issue by making the wave form of vehicle body deceleration (deceleration curve) optimal to lower the maximum deceleration value applied to the occupant. A study with a one-dimensional, two-mass model was conducted to the kinetic mechanism between the body deceleration curve and the responding occupant''s motion while finding a mathematical solution for the optimal body deceleration curve. A common feature of the derived mathematical solutions is that they consist of three aspects: high deceleration, low or negative deceleration, and constant deceleration. This was demonstrated by simulation with a three-dimensional dummy. The results show that the response of the dummy closely agrees with that of the one-dimensional, two-mass model, thus proving the adequacy of the mathematical solution, and that occupant injury was reduced.

The primary advantage of an Adaptive Wall wind tunnel is that the test section walls and ceiling are contoured to closely approximate the ‘open road' flowfield around the test vehicle. This reproduction of the open road flowfield then results in aerodynamic forces and moments on the test vehicle that are consistent with actual open road forces and moments. Aerodynamic data measured in the adaptive wall test section do not require blockage corrections for adjusting the data to open road results. Extensive full scale experiments, published scale model studies, and Computational Fluid Dynamics (CFD) studies have verified the simulation capability of adaptive wall technology. For the CFD study described here, high-downforce, open-wheel race cars were studied. The numerical simulations with a race car in an Adaptive Wall Test Section (AWTS) wind tunnel are compared with simulations in ‘free air' condition and in a closed wall test section.

This paper discusses the characteristic flow field of the new Honda FIT/Jazz as determined from the aerodynamic development process, and introduces the technique that reduced aerodynamic drag in a full model change. The new FIT was the first model to take full advantage of the Flow Analysis Simulation tool (FAST), our in-house CFD system, in its development. The FAST system performs aerodynamic simulation by automatically linking the exterior surface design with a predefined platform layout. This allows engineers to run calculations efficiently, and the results can be shared among vehicle stylists and aerodynamicists. Optimization of the exterior design gives the new FIT a moderate pressure peak at the front bumper corner as compared to the previous model, resulting in a smaller pressure difference between the side and underbody.

An aerodynamic styling evaluation system employed at an early automotive development stage was constructed. The system based on CFD consists of exterior model morphing, computational mesh generation, flow calculation and result analysis, and the process is automatically and successively executed by process automation software. Response surfaces and a parallel coordinates chart output by the system allow users to find a well-balanced exterior form, in terms of aerodynamics and exterior styling, in a wide design space which are often arduous to be obtained by a conventional CAE manner and scale model wind tunnel testing. The system was designed so that 5-parameter study is completed within approximately two days, and consequently, has been widely applied to actual exterior styling development. An application for a hatchback vehicle is also introduced as an actual example.

The Hybrid III family of dummies is used to estimate the response of an occupant during a crash. One recent area of interest is the response of the neck during air bag loading. The biomechanical response of the Hybrid III dummy's neck was based on inertial loading during crash events, when the dummy is restrained by a seat belt and/or seat back. Contact loading resulting from an air bag was not considered when the Hybrid III dummy was designed. This paper considers the effect of air bag loading on the 5th percentile female Hybrid III dummies. The response of the neck is presented in comparison to currently accepted biomechanical corridors. The Hybrid III dummy neck was designed with primary emphasis on appropriate flexion and extension responses using the corridors proposed by Mertz and Patrick. They formulated the mechanical performance requirements of the neck as the relationship between the moment at the occipital condyles and the rotation of the head relative to the torso.

Vehicle thermal protection is an important aspect of the overall vehicle development process. It involves optimizing the exhaust system routing and designing heat shields to protect various components that are in near proximity to the exhaust system. Reduced time to market necessitates an efficient process for thermal protection development. A robust procedure that utilizes state of the art CFD simulation techniques proactively during the design phase is described. Simulation allows for early detection of thermal issues and development of countermeasures several months before prototype vehicles are built. Physical testing is only used to verify the thermal protection package rather than to develop heat shields. The new procedure reduces the number of physical tests and results in a robust, efficient methodology.

To examine factors influencing side impact compatibility, as a first step, car-to-car tests were conducted to investigate the effect of sill interaction. As a result, it was found that sill interaction had a less significant effect on side impact performance than reducing the load aligned with the dummy. In addition, a series of Mobile Deformable Barrier (MDB) tests were performed to corroborate the conclusions of the car-to-car tests. Comparison of the results of these MDB tests showed that the effect of reducing loading aligned with the driver dummy is more significant than that of engagement with the target car's sill, which is consistent with the car-to-car test results.

Computer simulations, dummy experiments with a new enhanced upper extremity, and small female cadaver experiments were used to analyze the small female upper extremity response under side air bag loading. After establishing the initial position, three tests were performed with the 5th percentile female hybrid III dummy, and six experiments with small female cadaver subjects. A new 5th percentile female enhanced upper extremity was developed for the dummy experiments that included a two-axis wrist load cell in addition to the existing six-axis load cells in both the forearm and humerus. Forearm pronation was also included in the new dummy upper extremity to increase the biofidelity of the interaction with the handgrip. Instrumentation for both the cadaver and dummy tests included accelerometers and magnetohydrodynamic angular rate sensors on the forearm, humerus, upper and lower spine.

This paper describes the evaluation of flow characteristics inside a model engine cylinder using particle image velocimetry (PIV), laser Doppler anemometry (LDA), and numerical simulation by Partial Cells in Cartesian coordinate (PCC) method. The main goal of the study is to clarify the differences in the velocity characteristics obtained by these methods. The model engine head has a four-valve system. Single- and dual- valve opening conditions of the model engine head were tested by a steady flow test rig. The flow structures were completely different for these valve opening conditions. The mean velocities and their distributions obtained by the three methods show satisfactory agreement. However, there were differences in the turbulence intensities under several conditions and measuring positions. Taylor's hypothesis in the integral length scale of turbulence was also compared with single LDA and PIV measurements.