• 한국소음진동공학회논문집
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• 제15권7호
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• pp.799-805
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• 2005

This paper describes the development process of high stiffness body for ride and handling performance. High stiffness and light weight vehicle is a major target in the refinement of Passenger cars to meet customers' contradictable requirements between ride and handling performance and fuel economy This paper describes the analysis approach process for high stiffness body through the data level of body stiffness. According to the frequency band. we can suggest the design guideline about lg cornering static stiffness, torsional and lateral stiffness, body attachment stiffness. The ride and handling characteristic of a vehicle Is significantly affected by vibration transferred to the body through the chassis mounting points from front and rear suspension. It is known that body attachment stiffness is an important factor of ride and handling performance improvement. And high stiffness helps to improve the flexibility of bushing rate tuning between handling and road noise. It makes possible to design the good handling performance vehicle and save vehicles to be used in tests by using mother car at initial design stage. These improvements can lead to shortening the time needed to develop better vehicles.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.358-361
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• 2004

This paper describes the development process of high stiffness body for ride and handling performance. High stiffness and light weight vehicle is a major target in the refinement of passenger cars to meet customers' contradictable requirements between ride and handling performance and fuel economy. This paper describes the analysis approach process for high stiffness body through the data level of body stiffness. According to the frequency band, we can suggest the design guideline about Is cornering static stiffness, torsional and lateral stiffness, body attachment stiffness. The ride and handling characteristic of a vehicle is significantly affected by vibration transferred to the body through the chassis mounting points from front and rear suspension. It is known that body attachment stiffness is an important factor of ride and handling performance improvement. And high stiffness helps to improve the flexibility of bushing rate tuning between Handling and road noise. It makes it possible to design the good handling performance vehicle at initial design stage and save vehicles to be used in tests by using mother car at initial design stage. These improvements can lead to shortening the time needed to develop better vehicles.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.562-566
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• 2006

Lightweight body can cause a low stiffness due to the decrease of panel thickness and reinforcing member. The other way, high stiffness body demands an increase of mass. Front pillar section area is decreased due to driver's visual field. Global vehicle stiffness is affected by stiffness distribution ratio between upper part and lower part at side body structure. This paper will describe a process used to evaluate the stiffness distribution ratio based on research of strain energy analysis of the tip rotation method. In addition, optimum design schemes are presented for high stiffness and lightweight body structure considering the investigated stiffness distribution ratio. In this way the designer will be aided by a defined design guide and a set of supporting tool to help him work towards a good design

• 한국소음진동공학회논문집
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• 제17권10호
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• pp.901-906
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• 2007

Lightweight body due to the decrease of panel thickness and reinforcing member might cause low stiffness. On the other hand, high stiffness body requires an increase of mass. Front pillar section area has been decreased for increasing the driver's visual field. Global vehicle stiffness is affected by stiffness distribution ratio between upper part and lower part at a side body structure. This paper describes a process used to evaluate the stiffness distribution ratio based on strain energy. In addition, optimum design schemes are presented for high stiffness and lightweight body structure considering the investigated stiffness distribution ratio.

• International Journal of Automotive Technology
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• 제8권5호
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• pp.629-636
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• 2007

This paper describes the process of analyzing vehicle stiffness in terms of frequency band in order to improve vehicle handling. Vehicle handling and ride comfort are highly related to the systems such as suspension, seat, steering, and the car body design. In existing analytical processes, the resonance frequency of a car body is designed to be greater than 25 Hz in order to increase the stiffness of the body against idle vibration. This paper introduces a method for using a band with a frequency lower than 20 Hz to analyze how stiffness affects vehicle handling. Accordingly, static stiffness analysis of a 1g cornering force was conducted to minimize the deformation of vehicle components derived from a load on parts attached to the suspension. In addition, this technology is capable of achieving better performance than older technology. Analysis of how body attachment stiffness affects the dynamic stiffness of a bushing in the attachment parts of the suspension is expected to lead to improvements with respect to vehicle handling and road noise. The process of developing a car body with a high degree of stiffness, which was accomplished in the preliminary stage of this study, confirms the possibility of improving the stability performance and of designing a lightweight prototype car. These improvements can reduce the time needed to develop better vehicles.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.102-106
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• 2003

An experimental modal analysis and dynamic stiffness evaluation of a moving body structure of a high speed machining center are presented in this paper. The natural frequencies and corresponding modes, and dynamic compliance of a moving body structure of high speed machining center are investigated by using F.E.M., hydraulic exciter test, and impulse hammer test. The lowest three natural frequencies were found to be 56.6 Hz, 112.7 Hz, and 142.7 Hz by FEA respectively, while those were 55 Hz, 112 Hz, 131 Hz by experimental analysis. Furthermore, both computed and measured absolute dynamic compliances of the moving body structure in iso-direction showed good agreement especially at the first two mode frequencies. With our experimental data, the dynamic characteristics of the machining center can be exploited to get a new development of structural dynamic design and modification.

• 접착 및 계면
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• 제7권4호
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• pp.60-64
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• 2006

In modern vehicle construction the search for means of weight reduction, improving durability, increasing comfort and raising body stiffness are issues of priority to the design engineer. The intelligent usage of many materials such as high strength steel, light-alloys and plastics enables a significant vehicle weight reduction to be achieved. The classical joining techniques used in the automobile industry need to be newly-evaluated since they often do not present workable solutions for such mixed-material connections, for example aluminium/steel. Calculation/simulation methods have made progress as a key factor for broader and more cost-effective implementation of structural bonding. This will lead to reduction of spotwelds and accelerate the car development. A special focus of the paper is the use of high strength steel grades. It will be shown that adhesive bonding is a key tool for yielding the potential of advanced high strength steel for low gauging without compromising the stiffness. The latest status of adhesive development has been described. Improvements with physical strength and glass temperature as well as of process relevant properties are shown. Also the situation regarding occupational hygiene is treated, showing that by further spotweld point reduction the emission around the working area can be even lowered against the current praxis. High performing lightweight design cannot longer do without high performing crash durable adhesives.

• 한국화재소방학회논문지
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• 제11권1호
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• pp.47-54
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• 1997

소방자동차를 비롯한 모든 자동차의 비툴립 강성이 약하면 차체에 크혜이 발생함과 동시에 고유진 동수가 낮아져 진동소음 발생의 원인이 된다. 이 논문은 최소한의 중량증가로 비틀림 강성을 최대한 중 가시키는 방안올 제시한 것에 관한 것으로, 방안 검토를 위하여 탄성론을 이용한 이론해석을 실시하였 고, 또한 이의 검증을 위하여 유한요소법에 의한 해석 및 실제 차체를 이용한 실험을 질시하였다. 본 논 문에서 사용한 자동차는 숭용차를 사용하였다. 그 이유는 실험 및 계산이 용이하고, 또한 계산결과를 소방자동차 퉁을 비롯한 모든 자동차에 적용 할 수 있기 때문이다.

• 한국운동역학회지
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• 제28권1호
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• pp.61-67
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• 2018

Objective: The human body is often modelled as a spring-mass system. Lower extremity stiffness has been considered to be one of key factor in the performance enhancement of running, jumping, and hopping involved sports activities. There are several different classification of lower extremity stiffness consisting of vertical stiffness, leg stiffness, joint stiffness, as well as muscle and tendon stiffness. The primary purpose of this paper was to review the literature and describe different stiffness models and discuss applications of stiffness models while engaging in sports activities. In addition, this paper provided a current update of the lower extremity literature as it investigates the relationships between lower extremity stiffness and both functional performance and injury. Summary: Because various methods for measuring lower extremity stiffness are existing, measurements should always be accompanied by a detailed description including type of stiffness, testing method and calculation method. Moreover, investigator should be cautious when comparing lower extremity stiffness from different methods. Some evidence highlights that optimal degree of lower extremity stiffness is required for successful athletic performance. However, the actual magnitude of stiffness required to optimize performance is relatively unexplored. Direct relationship between lower extremity stiffness and lower extremity injuries has not clearly been established yet. Overall, high stiffness is potentially associate risk factors of lower extremity injuries although some of the evidence is controversial. Prospective injures studies are necessary to confirm this relationship. Moreover, further biomechanical and physiological investigation is needed to identify the optimal regulation of the lower limb stiffness behavior and its impact on athletic performance and lower limb injuries.

• 한국산학기술학회논문지
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• 제20권12호
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• pp.797-803
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• 2019

본 연구는 동력분산형 고속열차의 횡방향 진동을 저감하기 위하여 진행되었다. 동역학 해석을 통한 연구에서 동력분산형 고속열차 시제차량(HEMU-430X)은 고속열차에서 주로 사용되는 차륜프로파일(XP55, GV40, S1002)에 관계없이 낮은 등가답면구배에서 횡방향 진동이 커지고, 차륜 마모가 진행되어 등가답면구배가 커지면 횡진동이 감소하는 경향을 보였다. 이는 HEMU-430X에 적용된 현가장치 특성치들의 조합된 결과로 인해 등가답면구배가 낮을 때 차체와 대차가 1.4Hz의 주파수로 공진하여 차체 헌팅이 발생되기 때문이다. 고속열차의 횡방향 진동저감에 대한 해외 사례에서 요댐퍼의 유압강성(Hydraulic stiffness)을 낮추어 진동을 개선한 사례를 고찰하였다. 요댐퍼의 시리즈 강성은 유압강성과 탄성조인트의 조합인데 본 연구에서는 유압강성 조정대신 비교적 간단하게 할 수 있는 탄성조인트의 강성을 낮추어 횡방향 진동을 개선하고자 하였다. 신규 제작된 탄성조인트를 적용한 요댐퍼의 시리즈 강성은 기존 요댐퍼 대비 60% 수준으로 낮았다. 60% 수준의 시리즈 강성이 적용된 요댐퍼를 HEMU-430X의 TC~M2 3량에 설치하여 시운전 시험을 수행하였다. 시운전 시험 결과 TC를 선두로 한 하행 주행 시 TC~M1의 횡방향 진동이 개선되고, MC를 선두로 한 상행 주행 시 후미 TC차량의 횡진동이 개선되는 결과를 보였다. 본 연구의 진동저감 방안은 향후 영업운전을 위해 도입되는 EMU-250 및 EMU-320의 횡방향 진동 문제 발생 시 해결책으로 적용할 수 있다.