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Technical Paper

New Materials Technology for Achieving Both Crashworthiness and Weight Reduction Using Energy-Absorbing Steel with Higher Strain-Rate Sensitivity

This paper presents a new material technology that can achieve both crashworthiness and weight reduction of the vehicle body. This new technology is based on three fundamental approaches. One is a technique for evaluating high-speed material deformation characteristics related to the crush behavior of energy-absorbing structures. A second is the material concept of high tensile steel featuring both increased material strength and higher strain-rate sensitivity in order to improve its energy-absorbing capacity. We have found 590N/mm2-class dual-phase (DP) steel consistent with this concept. The third is a technique for estimating the crush behavior of body structures, taking into account the plate thickness reduction and work hardening distribution resulting from the press-forming process. Finally, it was shown that the use of DP steel results in a 15% reduction in the weight of absorbing structures without affecting crashworthiness.
Technical Paper

An Analysis of Deformation Mechanism in Head-On Collision

A study of the deformation mechanism in head-on collision was conducted. A simple dynamic model of vehicle structure was assumed, and the model analyzed by using a high-speed computer; the solutions were then compared with the experimental results. Following are the findings obtained from the solutions: 1. In the case of a vehicle with independent rear suspension, the power train can provide much more resistance to the deformation as compared with a vehicle with conventional suspension. 2. The strength of front end structure has much effect on the deformation of passenger compartment.
Technical Paper

Datsun 280ZX – Integration of Aerodynamics and Appearance

It is essential for today’s sports car to have excellent aerodynamic characteristics and a sophisticated style. These factors are dependent and often inconsistent with each other. It is desirable that they are integrated rather than compromised in such cases. In the early stages of development of the 280ZX, we thoroughly investigated the relationship between a style and its aerodynamic characteristics. A three-dimensional smoke tunnel and a 1/5-scale model was used for this purpose. Several improvements were examined mainly on the front end of the model, which strongly affect both aerodynamic characteristics and styling, such as the hood, bumper, chin spoiler, engine-compartment opening and others. The resultant values of the principal aerodynamic coefficients of the realized 280ZX are CD=0.385, CLF=0.11 and CYM=0.04 (CD and CLF at a yaw angle of 0 degree and CYM at 10 degrees).
Technical Paper

Reduction of Automobile Booming Noise Using Engine Mountings That Have an Auxiliary Vibrating System

This paper presents a new concept concerning engine mountings that can reduce engine booming noise by utilizing an additional vector. Booming noise in passenger cars, particularly those with a four-cylinder engine, is caused by exciting forces such as the second harmonic of engine intertial force. We have found that exciting forces transmitted from the engine to the body structure through the engine mountings are reduced by adding another vector which cancels out these exciting forces. This new vector can be obtained by using a mass-controlled region of a vibrating system possessing either a single degree or two degrees of freedom. When this optimally designed mechanism is adopted on a small passenger car, booming noise can be significantly reduced.
Technical Paper

Development of Fender Structure for Pedestrian Protection

In a typical passenger car-to-pedestrian collision, it is noted that the pedestrian’s body rotates after the initial contact with the hood leading edge. Consequently, the head often crashes into a stiff part of the car body, resulting in serious or life-threatening head injuries. Therefore, to reduce pedestrian fatalities, it is important to improve vehicle structures so as to mitigate head injuries. Front fenders are one example of such stiff body parts with small impact energy absorption capability. This paper reports on the development of a new front fender structure designed to mitigate pedestrian head injuries in passenger car-to-pedestrian collisions. The new structure is characterized by fender supporting brackets that incorporate a break-off mechanism in the riveted joints between the fender and brackets.
Technical Paper

Effects of Driver’s Head Motion and Visual Information on Perception of Ride Comfort

This study investigated the mechanism by which a flat ride is perceived as low-frequency motion during highway driving. Vehicle motion was measured using a GPS receiver and an inertial navigation system. The driver’s head motion relative to the vehicle was measured with a motion capture system consisting of cameras attached to the vehicle. The results of an analysis showed that a flat ride could be quantified based on the amount of absolute head motion. Laboratory tests were also conducted to investigate the effects of motion in the visual field on the perception of ride comfort, and the results showed that perceptions of even the same motion varied depending on the visual conditions, such as the location of the hood, and such differences in motion perception affected the evaluation of a flat ride.
Technical Paper

Load Path Analysis of Vehicle Body Structures under Eigenmode Deformation of Bending Vibration

The load path U* analysis is an effective tool for investigating the load paths in body structures. In the present study, a new index U** is introduced to investigate structures under distributed loading. The new parameter U** is a complementary concept of U*. Although the conventional index U* cannot be applied to cases of distributed loading conditions, the new index U** can be applied to those cases. This paper describes the application of a load path U** analysis to improve efficiently the first eigenvalue of the vertical bending mode in a vehicle body structure model. It also explains how target parts for shape optimization are interpreted on the basis of a load path U** analysis when a load is applied to reproduce the first vertical bending mode.
Technical Paper

An Application of Car Crash Test Technology to a Causal Investigation of a Revolving Door Accident

On March 26, 2004, a fatal accident occurred when the head of a 6-year-old child was trapped in a large revolving door in a high-rise building in Tokyo. To investigate the cause of the accident, Prof. Yotaro Hatamura, representing Hatamura Institute for the Advancement of Technology, gathered experts in various fields including architecture and door manufacture, and initiated the “Door Project,” with the cooperation of the building company. Nissan Motor Co. participated in this project, and conducted load measurement tests on various doors. Applying car crash test technology, including production of special door test dummies and high-speed photography, it was possible to simulate the accident while taking human movement into account. As a result, we obtained important data for accident cause investigation.