• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.330-335
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• 2003

Analysis and experiment on dynamic characteristics of automotive roof have been carried out experimentally and numerically to design a lightweight roof. Finite element analysis of a conventional steel automotive roof was verified by experiments on vibration characteristics. The dynamic analysis of carbon fiber reinforced composite automotive roof shows that the roof stiffness changes as the fiber orientation of the laminated panel changes. Optimization results yielded a composite roof, which was 52% lighter, than the steel conventional steel automotive roof. This paper addresses a design strategy of composite roof for weight reduction.

• 한국자동차공학회논문집
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• 제13권6호
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• pp.31-37
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• 2005

This paper presents an experimental study on vibration characteristics of an automotive roof with damping material. The goal of the study is to extract modal parameters(natural frequency, loss factor, and mode shape) of automotive roof with damping materials treatment. To determine the effective positions and thickness of the damping material on a roof, vibration tests have been carried out for six cases; an aluminum plate with damping material on maximum strain energy positions, and an aluminum plate with damping material on nodal lines. From the result of aluminum plate, it is found that the damping material should be placed on the location with maximum strain energy part. For the automotive roof, patches of constrained damping material, which has two different density, have been attached to the positions of the maximum strain energy with four kinds of thicknesses. This paper shows that the proper positioning of the damping material is very important and the effective thickness is about twice that of the roof panel.

• 한국자동차공학회논문집
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• 제6권4호
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• pp.32-38
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• 1998

In order to investigate the relationship between the stiffness and structure of the automotive roof panels, two kinds of glass fiber reinforced plastic(GFRP) roof panels without and with insert material were fabricated by resin transfer molding(RTM) method. The stiffness test was performed at the same condition as it of actual driving. The structural design and material selection for improving the recyclability of GFRP roof panels were also covered.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.834-839
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• 2004

In this paper, we have studied on the active vibration control of an automotive roof in passenger car's structure using piezoelectric material as the actuator and sensor attached on the surface of the automotive roof, As a control algorithm, negative velocity feedback control method is used in the study and the position of the sensor is almost attached on the nearest position of maximum normal stresses occurring while the roof is vibrating due to disturbance or exciting, Also, the actuator is attached on the other side mostly collocated to the sensor. The optimum positions have the maximum stresses of the roof which have been found in the result of the finite element analysis using Nastran software, As the fundamental experiments, a beam and plate have also been implemented to verify the performance of vibration suppression. Finally the experiment of the roof has been carried out and The roof experiment has just given a possibility to an active vibration control of the automotive structure still not applied for passenger cars.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.994-998
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• 2004

Hybrid method is used to suppress vibration of an automotive roof surface. The hybrid method proposed in this paper is implemented experimentally using both viscoelastic and piezoelectric material. The piezoelectric material is used to control the vibration of automotive structure for lower range of frequencies and the experiment of vibration control using viscoelastic material has been carried out suppress vibrations of high frequency range mark. At first the plate controlled by using hybrid method has been .implemented to verify the performance for suppressing vibration. Then the experiment has been applied to the automotive roof structure.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.613-617
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• 2004

This paper presents an experimental study on vibration characteristics of an automotive roof with viscoelastic material. The goal of the study is to extract modal parameters (natural frequency, loss factor, and mode shape) of automotive roof with unconstrained and constrained layer damping treatment. To determine the effective position of the viscoelastic patch on a roof, vibration tests have been carried out for two cases; Aluminum plate with viscoelastic patch on maximum strain energy, and aluminum plate with viscoelastic patch on nodal line. From the result of aluminum plate, it is found that the viscoelastic patch should be attached on the Place with maximum strain energy Part. For the automotive root five Patches of unconstrained or constrained viscoelastic material have been attached on the position of maximum strain energy. This paper addresses that the proper position of viscoelastic patch is very important and the concept of maximum strain energy may be a good criterion f3r the placement of viscoelastic patch.

• 한국자동차공학회논문집
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• 제4권6호
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• pp.216-222
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• 1996

This paper presents a computational technique to predict roof crush resistance in early design stage of passenger car development. This technique use a simple F.E. model with nonlinear spring elements which represent plastic hinge behavior at weak areas. By assuming actual sections as equivalent simple sections, maximum bending moments which weak areas in major members can stand are theoretically calculated. Results from prediction of roof crush resistance are correlated well with test results.

• 한국자동차공학회논문집
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• 제18권5호
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• pp.91-99
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• 2010

The center of gravity on vehicle is a fundamentally important point for assessing and measuring the characteristics of vehicle dynamics. Especially, the center of gravity height on vehicles is the closest factor with respect to rollover accidents in a social issue nowadays. In this paper, the center of gravity height in conjunction with vehicle parameters of vehicle weight, driving axle and roof height after measured by vehicle weight and loading location by means of VCGM developed by KATRI with good performance that the accuracy was less than 0.6% and repeatability 0.3% for vehicles being used in the whole world was observed. As a result of study, the location of center of gravity height on vehicle was able to be estimated with only roof height on vehicle.

• 한국자동차공학회논문집
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• 제18권6호
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• pp.138-144
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• 2010

If the vibration is occurred in a large-sized bus roof, it makes people annoying and complaining the quality of a large-sized bus. So in design stage, it must be considered. To assess vibration at the roof which is equipped with air conditioner in design stage, finite element model is constructed. Computer simulation analysis and experimental method are performed. The dynamic characteristics of the large-sized bus are found by using eigenvalue method. It is related with dynamic behavior. The running conditions of a large-sized bus are velocity and road condition which followed experimental conditions. And the frequency response of a large-sized bus is well correlated with analysis result. Modal participation method is used for finding major modes at each peak. Using this method, we found that front and rear suspension system, engine mounting system and roof structure are the major reasons of the roof vibration. To reduce vibration level of roof in a large-sized bus, spring stiffness of front and rear suspension system, spring stiffness of engine mounting system and roof structure are properly combined. From this study, the vibration characteristics of the roof structure of a large-sized bus can be to a satisfactory level.

• 한국융합학회논문지
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• 제10권12호
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• pp.257-262
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• 2019

최근 취미로 다양한 레포츠를 즐기는 인구가 증가하였다. 그에 따라 차량 지붕위에 다양한 물건들을 적재한 차량들을 거리에서 쉽게 볼 수가 있다. 차량 지붕위에 적재를 할 수 있게 하는 장치는 랙 이라는 장치이며 차량마다 각기 다른 형상을 가지고 있다. 다양한 종류들이 있지만 무거운 짐을 적재하기 위해 강도 및 내구성을 가져야 한다. 본 연구에서는 루프 랙의 지지대 방식과 고정대의 형상에 따른 구조 해석을 하였다. 세 가지의 모델들 중, Model C가 가장 좋은 내구성을 가지고 있음을 보였다. 따라서 어떤 형상을 가진 루프랙이 가장 안정성이 있는 것을 본 연구 결과로서 알 수 있다. 본 결과를 토대로 얻은 자동차 루프랙의 형상에 따른 구조 해석에 통한 융합 연구에 대한 설계데이터를 활용함으로서 실생활에서의 자동차 부품에 융합하여 그 미감을 보일 수 있다.