Vehicle Body Structure Research Articles

Optimizing Technique to Reduce Vehicle Booming Noise Using Response Surface Method.

The location optimizing technique by response surface method with the basis vector of holographic neural network, is applied to effectively reduce the vehicle interior noise by roof rail and dynamic damper, which is influenced by the acoustic-structural coupling between compartment and vehicle body structure. The physical meaning of optimized result is studied about and interpreted as being equivalent with minimizing the spatially integrated volume displacement or volume acceleration of boundary panel over in-phase region of acousic mode. This structural management could be applied to lowering actual vehicle interior noise.

Section property method and section shape method for the optimum design of vehicle body structures

Recently, automotive manufactures are concentrating their interests upon lightweight vehicles. Improvement of the body structure has become a big issue for effective fuel cost down and reducing the environmental pollution by exhaust gas. On the other hand, accompanying the increase of the required performance such as the improvement of safety and the reduction of vibration and noise, the weight of vehicles tends to increase. In order to solve the problem, attention has been paid to the design technique for the optimisation of structures, in which a computer derives the optimal solution based on conditions defined by designers. Especially, the results of the research and the applications to the vehicle body structure have been reported in great numbers of papers. In this study, two methods for the optimisation of vehicle body structure are proposed for practical application. One is the "section property method" which uses section properties as design variables. This method shows the tendency of an optimum section approximately. The other method is the "section shape method" which utilises geometric parameters of section as design variables. Practical solutions are obtained by this method. These two methods are compared through several sample problems. The finite element method is used for the structural and sensitivity analyses.

A high mileage vehicle body joint degradation estimation method

High Mileage NVH (Noise, Vibration and Harshness) performance is one of the major concerns in vehicle design for long term customer satisfaction. One of the main causes of the high mileage NVH degradation is the loss of joint stiffness of body structure due to fatigue, corrosion, loosening, wear and aging. Traditional joint test methods for determining joint stiffness before and after the mileage accumulation require joints to be cut from a vehicle body and are very time consuming and expensive. This paper presents a computational/experimental diagnostic method which can be used to identify the degradation in the stiffness of the joints of a vehicle body structure using frequency response functions measured on a body before and after mileage accumulation. The key idea in this method is to develop and use an equation relating the change in the dynamic response of the zero and high mileage vehicles to the change in the vehicle structure joint stiffness. The method is validated using a body-in-white (B-I-W) CAE model of a production vehicle.

A Study On Section Property Method And Section Shape Method For The Optimum Design Of Vehicle Body Structure

In this study, two methods for the optimization of vehicle body structure are proposed for practical application. One is the "section property method which uses section properties as design variables. This method shows the tendency of an optimum section approximately. The other method is the "section shape method" which utilizes geometric parameters of section as design variables. Practical solutions are obtained by this method. These two methods are compared through several sample problems. The finite element method is used for the structural and sensitivity analyses.

Microstructural and Mechanical Investigation of Aluminum Tailor-Welded Blanks

The push to manufacture lighter-weight vehicles has forced the auto industry to look to alternative materials than steel for vehicle body structures. Aluminum is one such material that can greatly decrease the weight of vehicle body structures and is also consistent with existing manufacturing processes. As in steel structures, cost and weight can be saved in aluminum structures with the use of tailored blanks. These blanks consist of two or more sheets of dissimilar thicknesses and/or properties joined together through some type of welding process. This enables the design engineer to “tailor” the blank to meet the exact needs of a specific part. Cost savings can be gained by the elimination of reinforcement parts and the stamping dies used to manufacture them. Weight savings can be attained based on the fact that one thicker piece is more efficient than a welded structure and therefore can allow for down-gauging of parts.

The Effects of Tire Properties and Their Interaction with the Ground and Suspension on Vehicle Dynamic Behavior — A Finite Element Approach

Abstract The effects of tire properties and their interaction with the ground and the suspension system on vehicle dynamic behavior was studied using a newly developed finite element analysis method. This analysis method used the explicit nonlinear dynamic code LS-DYNA as a solver and contained finite element models for both the vehicle body structure and subsystems like chassis/suspension. The case presented in this paper is curb impact. Different tire properties such as tire/wheel assembly mass, tire stiffness, tire inflation pressure, tire size, etc., as well as different curb heights, were used with the same vehicle body and suspension system. Simulation results of the impact forces, wheel center jumps, and vehicle body roll/pitch angles at impact are compared for different parameters of the tires and the curb. The analyses presented in this paper provided an accurate and practical method for tire and vehicle dynamics analysis.

Modified Johnson-Cook model for vehicle body crashworthiness simulation

Dynamic response prediction of vehicle bodies is important for vehicle crashworthiness evaluation. The dynamic behaviour of vehicle body materials is dependent on material strain rates. One of the typical high strain rate tensile tests is the split Hopkinson bar test. In this paper, experiments have been conducted based on a new split Hopkinson bar apparatus specially designed,for the dynamic tensile test of sheet metals. Results from both quasistatic and dynamic tests show that the strain rate hardening effect for sheet metals cannot be described by the original Johnson-Cook constitutive relation. This relation has been modified to include a higher-order term for the hardening effect. The modified constitutive relation represents a more accurate simulation than the original model for the dynamic behaviour of vehicle body structures.

Design Sensitivity Analysis of Noise, Vibration, and Harshness of Vehicle Body Structure*

ABSTRACT A continuum design sensitivity analysis (DSA) approach to noise, vibration, and harshness (NVH) of vehicle body structure is developed using Mindlin plate and Timoshenko beam theories. Linear shape functions used for numerical meth ods of DSA cause a deficiency in bending energy that is accounted for. For large scale NVH applications, linear and bilinear isoparametric elements require much less analysis time. To handle complex vehicle built-up structures, the warped plate element and general cross-sectional beam element with offset effects are included in the numerical method for DSA. A variational approach is used to obtain the continuum design sensitivity formulation. Thickness of plates and nonprincipal section parameters of beams are selected as design variables. A numerical implementation method for continuum DSA is developed by postprocessing analysis results from established finite element analysis (FEA) codes to obtain NVH design sensitivity. The numerical method is tested using large-scale concept and detailed passenger vehicle models. Design sensitivity results are validated using reanalysis results.

Dynamic Simulation of Taipei EMU Train

SUMMARY Simplified train dynamics for the trains of the Taipei Metro are presently being studied, with the aid of numerical methods, to avoid possible dangerous conditions of coupler failure and to understand the deformation of the “mechanical fuse” in a train collision. A multiple degree-of-freedom system is utilized to simulate the EMU train. Equations of motion are set up in a matrix and solved to calculate the transient responses of the couplers. Analytical solutions are checked by comparison with the results of the Runge-Kutta method. Energy absorption devices such as the coupler and the “mechanical fuse” as well as the vehicle body structure are taken into consideration to complete an integrated study of the structural crashworthiness. It is found that sudden failure of couplers would not happen for a train at coupling speeds up to 5 km/h. Coupler force for a train running at a normal acceleration from the start or at an emergency stop are also investigated. In addition, it is found that damage is confined to the fuse structures and the fuse deformation is less than the maximum allowable deformation designed in the trains, under an impact speed of 25 km/h.

Study on vehicle body structure in frontal collision — Part II: Development of body structure study method with genetic algorithm Kenji Takada (Honda R & D), Kentaro Sato (NKK), Akihisa Maruyama (Nissan Motor), Kouyou Kawamura (Toyota Auto Body), Masahiro Awano (Mitsubishi Motors), Masaaki Watanabe (Tokyo Univ. of Agric. and Teck.)

Study on vehicle body structure in frontal collision — Part II: Development of body structure study method with genetic algorithm Kenji Takada (Honda R & D), Kentaro Sato (NKK), Akihisa Maruyama (Nissan Motor), Kouyou Kawamura (Toyota Auto Body), Masahiro Awano (Mitsubishi Motors), Masaaki Watanabe (Tokyo Univ. of Agric. and Teck.)

Study on vehicle body structure in frontal collision part IV: Effective structural design of thin-walled curved beams Hiroshi Suganuma (Subaru Research Center), Akira Oda (Isuzu), Hironori Tomizawa (Kanio Auto Works), Hsiao Mikami (Daihatsu), Akihito Norioka (Nissan Diesel), Kentaro Sato (NKK), Masaaki Watanabe (Tokyo Univ. of Agric. and Tech.)

Study on vehicle body structure in frontal collision part IV: Effective structural design of thin-walled curved beams Hiroshi Suganuma (Subaru Research Center), Akira Oda (Isuzu), Hironori Tomizawa (Kanio Auto Works), Hsiao Mikami (Daihatsu), Akihito Norioka (Nissan Diesel), Kentaro Sato (NKK), Masaaki Watanabe (Tokyo Univ. of Agric. and Tech.)

Study on vehicle body structure in frontal collision — Part III: Application of body structure study method with genetic algorithm Kouyou Kawamura (Toyota Auto Body), Akihisa Maruyama (Nissan Motor), Masahiro Awano (Mitsubishi Motors), Kentaro Sato (NKK), Kenji Takada (Honda R & D), Masaaki Watanabe (Tokyo Univ. of Agric. and Tech.)

Study on vehicle body structure in frontal collision — Part III: Application of body structure study method with genetic algorithm Kouyou Kawamura (Toyota Auto Body), Akihisa Maruyama (Nissan Motor), Masahiro Awano (Mitsubishi Motors), Kentaro Sato (NKK), Kenji Takada (Honda R & D), Masaaki Watanabe (Tokyo Univ. of Agric. and Tech.)

Radiated Noise from Tire/Wheel Vibration

Abstract As a general trend, vehicle sound quality has significantly improved in recent years. This is primarily due to improved body structure and powertrain design. As demand for better vehicle sound quality increases, it is important to study all possible noise sources contributing to noise, vibration, and harshness (NVH). Tire vibration has long been recognized as a source of airborne noise. Some effects of wheel design on tire noise have also been well understood for sometime. But the dynamic interaction between tire and wheel designs and its effect on vehicle NVH, although frequently observed for many years, has only recently been identified in the 200–350 Hz frequency range. Different wheels can produce perceptible differences in vehicle interior sound pressure levels in a road test. Hence, the authors have developed a process to quantify and reduce noise caused by a vibrating tire/wheel assembly. This paper discusses the general flow of the process, which begins with the identification of NVH issues on a total vehicle level. Modeling and optimization of the aluminum wheel was chosen as the focus of this project for two reasons. First, the interior sound pressure level (SPL) around 285 Hz is about 5–7 dBA higher in a vehicle equipped with aluminum wheels rather than a steel design. Second, modifying the wheel is far more economical and faster due to its simplicity of design than the complexity of either the vehicle body structure or a tire.

Optimum constitution of vehicle body structure

Optimum constitution of vehicle body structure

Vehicle Vibration Reduction by Transfer Function Phase Control on Hydraulic Engine Mounts.

In major low-frequency vehicle vibration phenomena, such as shake and idle vibration, engine mounts play an important. To reduce shaking, the engine mounts must suppress Vibration by increasing their damping. In addition, in an idle state, the engine mounts should be soft enough to isolate the engine vibration from the vehicle body structure. These two requirements are difficult to be achieved in conventional engine mount design. This paper presents a new design method for solving the above-mentioned problem. Two key elements are used in this new method. The first is the phase control on vibration transmission utilizing the fluid resonance in the hydraulic engine mounts. The other in the vector synthesis approach in treating multiple vibration input to the vehicle body.

Development of a Sensitivity Analysis Method for Dynamic Nonlinear Problems. (3rd Report).

A new approach to a sensitivity analysis in dynamic nonlinear problems has been investigated in this study. The objective of the study is to increase the crash energy absorption of vehicle body structures. In the first and second reports, we investigated the dynamic collapse behavior of elastic columns under axial compression. The relationship between impact velocity and collapse mode was shown. The sensitivity of buckling load matches the gain of collapse load of redesigned columns at slow impact, whereas it does not always match it at fast impact. In this report, the effect of the direction of design domains against the direction of the impact wave is investigated. The effectiveness and the limitation of a sensitivity analysis in dynamic problems are also discussed.

Railway Passenger Vehicle Design Loads and Structural Crashworthiness

The loading specifications to which passenger vehicle body structures are designed seek to fulfil two basic requirements. Firstly, normal service loads experienced over the life of the vehicle must be met without loss of serviceability. Secondly, passengers and crew must be afforded protection against loads outside the normal service experience. In the specifications used in Europe and the United States there is an emphasis on ‘proof’ loading, that is loading which causes no permanent deformation. This requirement is in conflict with the absorption of energy which is necessary to cushion passengers and crew involved in an accident. The author examines UK accident statistics and proposes alternative ways in which the basic aims of structural crashworthiness can be met.

Noise isolation for a fuel system

An electric motor driven fuel pump is mounted in a fuel tank with noise isolators to decouple the fuel pump and the fuel lines from the fuel tank and the vehicle body structure. The fuel discharge line is isolated from the pump discharge passage by an elastomeric connector, and both the fuel discharge and fuel return lines are isolated from the fuel tank by resilient elastomeric grommets. A reaction mass is connected to the discharge line and the return line and isolated from the fuel tank. The reaction mass provides a significant change in the mechanical impedance of the system and thereby absorbs a majority of the fuel pump vibratory energy.