• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.12
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• pp.1159-1165
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• 2011

This paper presents ride comfort characteristics of a quarter-vehicle magneto-rheological(MR) suspension system with respect to different tire pressure. As a first step, controllable MR damper is designed and modeled based on both the optimized damping force levels and mechanical dimensions required for a commercial full-size passenger vehicle. Then, a quarter-vehicle suspension system consisting of sprung mass, spring, tire and the MR damper is constructed. After deriving the equations of the motion for the proposed quarter-vehicle MR suspension system, vertical tire stiffness with respect to different tire pressure is experimentally identified. The skyhook controller is then implemented for the realization of the quarter-vehicle MR suspension system. Finally, the ride comfort analysis with respect to different tire pressure is undertaken in time domain. In addition, a comparative result between controlled and uncontrolled is provided by presenting vertical RMS displacement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.480-481
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• 2014

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.208-211
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• 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 Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.495-499
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• 2000

The booming noise of a vehicle is usually caused by the vibration of the vehicle's body transmitted from the engine through the mounting system. Thus the engine mounting system must be cautiously designed to reduce the noise. Vector synthesis analysis is performed to predict the booming noise when the characteristic of the engine mounting system is changed., i.e., when magnitudes and phases of vibratory forces after the mounts are altered. To effectively use the method, the concept of 'effectiveness' is introduced to identify the contributions of each vibration sources and transmission paths to interior noise. When the magnitudes and phases of the forces due to the engine vibration are changed, the synthesized interior booming noise level is predicted by the vector synthesis diagram. Thus, the optimum characteristics of the forces are obtained through the simulations of the vector synthesis analysis. It is shown that the vector synthesis method can be used to obtain the optimum design characteristic of the mounting system to control the interior booming noise of a vehicle.

• Journal of the Korean Society of Safety
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• v.14 no.4
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• pp.71-77
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• 1999

Exposed gas pipeline in underground, especially subway construction site, has been continuously vibrated by vehicle above ground. Because this vibration can cause unexpected damages to pipeline, we had measured and analyzed the vibration. This paper presents results of the vibration analysis of exposed gas pipeline and the results are as follows. The major vertical vibration frequency of pipeline was about 13 Hz and the other frequency components disappeared when the vibration transmitted to I-beam and wire rope. Existence of wooden casement had not affect vibration of exposed gas pipeline. The results of modal analysis by experimental and analytical methods have good agreement and it is also shown that exposed pipeline has possibility of resonance at second mode.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.431-437
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• 2017

In this study, based on the RPS algorithm, the application results to an electrically controlled suspension system using previewed road information are presented. Reducing the excessive vibration induced by a disturbance transmitted to the system and secure its stability is a major issue. In particular, in the automotive industry, the demand is constantly being raised. A typical external disturbance causing vibration and instability of a vehicle is an irregular roadway surface that contacts a running vehicle tire. Therefore, obtaining such profile information is an important process. The RPS algorithm using a multi sensor system was constructed and implemented in a real car. Through experimental work using the RPS system included non-contact type optical sensors, it could robustly reconstruct the road input profiles from the intermixed data onto the vehicle's dynamic motion while traveling at an uneven roadway surface. A controller with a preview control was designed in the framework of a semi-active suspension system based on the 7 degrees of freedom full vehicle model. The control performance of the system was evaluated through simulations and the results were compared with the passive vehicle condition. These results highlight the feasibility of the presented control frame.

• Journal of Industrial Technology
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• v.10
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• pp.21-32
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• 1990

Car body resonance often generates severe vibrational and noise problems in vehicle compartment. In this study, vibrational characteristics of 2-D vehicle compartment model is investigated and structural modification is carried out by numerical simulation to shift natural frequencies and to reduce stresses in resonance. To this end, ring models of the compartment are manufactured and analysed by FEA. The results are verified to be in good agreement with those of experimental modal testing. And the results of this study offer efficient strucural modification technique for vibration reduction of real cars.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.47-52
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• 1996

Interior noise, engine speed and vehicle speed are measured under road-load condition and interior noise signal is transformed by using the transient signal analysis methods such as the spectrogram and wavelet transform. Using the analyzed results, subjective noise criteria such as the loudness, noisiness and articulation index at each vehicle speed can be estimated and characteristics of interior noise for various running mode can be discussed in the viewpoint of noise quality.

• 연구논문집
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• s.23
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• pp.81-92
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• 1993

In this study, quarter vehicle model is used to analyse vibration control effects for ride comfort and handling safety according to this three kinds of control methods, which are the modal control, the sky-hook control and the linear viscous damping control. We performed theoretical analysis and experiments and compared two results. In experiments, electro-magnetic actuator was employed as a force actuator. It is shown that all three methods can effectively control the vehicle model. The modal control method gives similar control results using gain less than the viscous damping control.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.1
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• pp.114-119
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• 2009

The authors have investigated the NVH problems of drive system in full vehicle test. However it is difficult to define the NVH problems of driveline system. Since it is hard to measure the rotating part and it is vague that only the drive system induces the NVH problem. Vibration in a driveline is presented in this paper. In the experiment, the rear sub-frame and propeller shafts and axle were composed and mounted with rubber each other. For applying the vibration input instead of the torsional vibration effect of an engine, the shaker was taken. In particular, torsional vibration due to fluctuating forced vibration excitation across the joint between driveline and rear sub-frame was carefully examined. Accordingly, the joint response was checked from experiments and the FE-simulation using FRF (frequency response function) analysis was performed. All test results were signal processed and validated against numerical simulations. In present study, the new test bench for measuring the vibration signal and simulating the vehicle chassis system was proposed. The modal value and the mode shape of components were analyzed using the CAE model to identify the important components affecting driveline noise and vibration. It could be reached that the simplified test bench could be well established and be used for design guide and development of the vehicle chassis components.