• The Journal of the Acoustical Society of Korea
• /
• v.38 no.3
• /
• pp.334-339
• /
• 2019

In this study, the vibration test method to nondestructively evaluate the possibility of vehicle BSR (Buzz, Squeak, Rattle) noise generation in spot-welded structures was proposed. The weld quality was predicted by analyzing the local vibration transmission characteristics for the beam-shaped structure attached to testing spots. The bending stiffness was evaluated from the identified vibration properties. From the change in the stiffness, the weld quality was evaluated. For verification of the proposed method, the welded specimens were fabricated with partial changes in welding parameters. The local vibration transfers were measured. The frequency bands affected by the weld quality was identified. The capability of evaluating the welding parameters including defect position and quality variations was investigated. The proposed method enables fast quality evaluation to minimize the possibility of BSR noise generation in the manufactured vehicle.

• The Journal of the Acoustical Society of Korea
• /
• v.19 no.3E
• /
• pp.3-11
• /
• 2000

A structural modification technique for reducing structure-borne noise of vehicles using a sensitivity analysis is suggested. To estimate the noises generated by the vibration response, a semi structure-acoustic coupling analysis was exploited. As a result of the coupling analysis, severe noise generating positions are identified whose vibrations should be cured through structural modifications. Formulation for the sensitivity analysis of those severe vibration responses with respect to the design changes is derived to enhance the vibration response. Special attention is given in this paper to the use of the experimentally measured vibration responses in the sensitivity analysis. As a result of the proposed method, the structural modifications can be peformed accurately by using experimental data instead of using the finite element method though the higher vibration modes are considered as long as the vibration measurement and acoustic mode calculations are accurate. Effectiveness of this method was examined using an example model by experiments.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.11b
• /
• pp.208-211
• /
• 2005

This paper describes the development process of steering system for reduce idle vibration through the data level of frequency and sensitivity. High stiffness and light weight vehicle is a major target in the refinement of passenger cars to meet customers' contradictable requirements between NVH performance and fuel economy. The target frequency of the steering system is set by benchmarking of a competitive vehicle and the vibration mode map is used to separate steering column modes from resonance of body structure and engine idle rpm. This paper descirbes the analysis approach process for high stiffness of steering system and the design guideline is suggested about steering column and support system by using mother car at initial design stage. We used a patent map in order to analyze accurately a technical trend and suggested the design process using dynamic damper of steering system considering sensitivity. And we established techniques of analysis on steering system and evaluated the level of accuracy of analysis through correlating the test and analysis results. It makes possible to design the good NVH performance vehicle at initial design stage and save vehicles to be used in tests. These improvements can lead to shortening the time needed to develop better vehicles.

• Proceedings of the KSME Conference
• /
• 2001.06b
• /
• pp.533-539
• /
• 2001

In this research, design Sensitivity Analysis is presented for commercial vehicle such as large scale structural system. The proposed method is based on vibration analysis of the total structure and design sensitivity to identify the contribution factor of the component structure to the total system structure. In addition, approximated equations derived from response surface method are used for representative section properties of the thin walled beams.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.04a
• /
• pp.361-364
• /
• 2011

In this paper, This work demonstrates a experimental evaluation for vehicle road noise NVH performance from the component-level NVH measurements of Tire. The power unit noise from tire emitted by cars has been reduced. It has been found that tire noise dominates noise produced by the power train when vehicles are driven at high constant speed. Therefore tire pattern noise is affected by pattern and vehicle and transmission loss. Tire noise mechanism is generated by several mechanisms. The sound of tire can propagate either through the air or through the structure of vehicle. Pattern noise is the result of pressure variations through the air to the interior side of vehicle. Especially, smooth asphalt, the periodicity of tread design, groove depth is important factor, which have an influence on the reduction of tire pattern noise.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.10 no.4
• /
• pp.31-37
• /
• 2011

Fuel tank sloshing noise of vehicle is caused by flow impact on the tank wall during sudden braking, and the sloshing vibration of tank wall is a coupled phenomenon of the fuel inside tank and tank wall structure. Therefore, Fluid-Structure Interface(FSI) analysis technology should be adopted to predict accurately the sloshing vibration. In this study, FSI approach was employed to analyze sloshing phenomenon for a simple tank model with velocity change of the actual vehicle test. First, the simulated results for rigid tank model were compared with those for deformable tank model. Next, influence of baffle location and shape of baffle holes on the acceleration magnitude and the maximum stress of tank wall was investigated. In addition, sloshing analysis for tank with another baffle type was carried out.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1994.10a
• /
• pp.288-294
• /
• 1994

A study of prediction and qualification techniques for structure borne booming noise is presented in this paper. Result from acoustic normal mode finite element analysis of a 1/2 size vehicle cavity sample model is compared to the that from an experiment. Coupled structural-acoustic analysis is performed on a 1/4 size vehicle cavity sample model surrounded by 2 mm thick normal steel plates. Interior noise levels around passensger's ear position are predicted and reduced by structural modification based on panel participation factor analysis about the sample cavity model. Futhermore, optimization technique in application of anti-vibration pad is studied.

• Journal of KSNVE
• /
• v.8 no.5
• /
• pp.862-869
• /
• 1998

The interior noise generated by the windshield wiper system including a wiper motor, the motor mountings and linkages is considered as a structure-borne noise. The structureborne noise is closely related with the system vibration which was transmitted into interior cabin through the car body. In this study, the frequency characteristics of vibration in the wiper motor system were first identified through the frequency analysis. Then effects of the wiper motor mountings and linkages on the vehicle interior noise were studied through in-vehicle measurements. Finally a possibility of noise reduction at a certain frequency was revealed from the study.

• Journal of Industrial Technology
• /
• v.9
• /
• pp.87-99
• /
• 1989

It is desirable to predict the noise and vibration problems of a passenger car in its design stage for a better ride quality. Dominant frequencies of the noise inside a car range from about 50 Hz to 300 Hz and these are frequently caused by the coupling of the acoustic normal modes of the compartment cavity and structural modes of the body. In this paper, car interior noise problem is investigated in view of vibration-acoustic modes coupling and numerical simulation is performed on the interior noise. In the simulation, experimental modal data of the vehicle structure are utilized to improve the accuracy of the analysis. The results are in good agreement with those of experiment on a half scaled vehicle compartment model. Especially, strongly coupled modes can be predicted, which give useful informations to solve noise problems of real car at design stage.

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.12
• /
• pp.107-116
• /
• 2008

The excitation force of a powertrain is one of major sources for the interior noise of a vehicle. This paper presents a novel approach to predict the interior noise caused by the vibration of the power rain by using the hybrid TPA (transfer path analysis) method. Although the traditional transfer path analysis (TPA) is useful for the identification of powertrain noise sources, it is difficult to modify the structure of a powertrain by using the experimental method for the reduction of vibration and noise. In order to solve this problem, the vibration of the power rain in a vehicle is numerically analyzed by using the finite element method (FEM). The vibration of the other parts in a vehicle is investigated by using the experimental method based on vibrato-acoustic transfer function (VATF) analysis. These two methods are combined for the prediction of interior noise caused by a power rain. Throughout this research, two papers are presented. This paper presents a simulation of the excitation force of the power rain exciting the vehicle body based on numerical simulation. The other paper presents a prediction of interior noise based on the hybrid TPA, which uses the VATF of the car body and the excitation force predicted in this paper.