• Title/Summary/Keyword: Stiffness Improvement

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A Study on Improvement of Torsional Vibration Characteristics of a Driveline Using a Module-Type-Vibration Analysis System (모듈형 진동 해석시스템을 이용한 구동계 비틀림 진동 특성 개선에 관한 연구)

  • Kim, Ki-Sei;Hwang, Won-Gul
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.2 s.95
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    • pp.183-193
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    • 1999
  • In the previous study, a module-type vibration analysis system using modular approach is developed for the purpose of analyzing the torsional vibration of vehicle driveline. In the present paper, the system is utilized to investigate the torsional vibration of the driveline of a middle duty truck. The driveline with driving condition is modeled and the torsional vibration response is simulated. The resonance 45Hz is found at engine speed 900rpm and the resultant vibration is very high. It shows favorable agreements with reference data. The effects of parameter change on torsional vibration are also investigated, so it is clarified that clutch characteristics, axle shaft stiffness are very influential on reduction of vibratio. So the countermeasure is proposed for the clutch characteristics. The reduction of torsonal vibration by 8rad/sec is obtained.

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A Study on an Optimal Design of Engine Mount System (엔진 마운트계의 최적설계에 관한 연구)

  • 황원걸
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.1
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    • pp.16-26
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    • 1998
  • The major effective factors on the ride quality of a vehicle are the vibration and noise of the engine and drive system. Engine contributes about 80% of the vibration and noise in the vehicle, and exciting forces of the engine are transmitted onto the vehicle frame through the engine mount. This paper studies the vibration reduction of a vehicle through the improvement of the engine mount. A computer program for optimal design is developed and the engine mount conditions are optimized to reduce the WRMS of PSD of acceleration at the driver's seat, which are caused by the exciting forces at the idle speed. Design variables are selected as the stiffness, mount angle and the location of the engine mount rubber. It is shown through computer simulation that the PSD of acceleration at the driver's seat can be improved by redesigning the engine mount system.

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Stochastic Analysis for Vehicle Dynamics using the Monte-Carlo Simulation (Monte-Carlo 시뮬레이션을 이용한 확률적 차량동역학 해석)

  • Tak, Tae-Oh;Joo, Jae-hoon
    • Journal of Industrial Technology
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    • v.22 no.B
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    • pp.3-12
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    • 2002
  • Monte-Carlo simulation technique has advantages over deterministic simulation in various engineering analysis since Monte-Carlo simulation can take into consideration of scattering of various design variables, which is inherent characteristics of physical world. In this work, Monte-Carlo simulation of steady-state cornering behavior of a truck with design variables like hard points and busing stiffness. The purpose of the simulation is to improve understeer gradient of the truck, which exhibits a small amount of instability when the lateral acceleration is about 0.4g. Through correlation analysis, design variables that have high impacts on the cornering behavior were selected, and significant performance improvement has been achieved by appropriately changing the high impact design variables.

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A Study on Design Factors of Geogrid-Encased Stone Column in Soft Ground (연약지반에서 지오그리드 보강 쇄석기둥 공법의 설계 영향인자에 관한 연구)

  • Yoo, Chung-Sik;Song, Ah-Ran;Kim, Sun-Bin;Lee, Dae-Young
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.03a
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    • pp.327-334
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    • 2008
  • This paper presents the results of investigation on the influencing factors for GESC(Geogrid-Encased Stone Column) method in soft ground. A parametric study was then conducted on the influencing factors such as replacement ratio, geogrid stiffness and thickness of soft ground using stress-porepressure coupled analysis. The results indicate that the relationship between these parameters and settlement ratio, and the relationship between these parameters and stress concentration factor can be identified.

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Evaluation of Structural Capacity for Concrete Beams Reinforced Simultaneously with GFRP and Steel rebar (GFRP와 철근 보강근으로 복합 휨보강된 보 시험체의 구조성능 평가)

  • Sim, Jong-Sung;Park, Cheol-Woo;Oh, Hong-Seob;Ju, Min-Kwan;Lim, Jun-Hyun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05a
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    • pp.518-521
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    • 2006
  • The purpose of this study is to evaluate structural performance of concrete beam reinforced simultaneously with GFRP and steel rebar. Because the GFRP has lower elastic modulus than steel or CFRP, serviceability for concrete structure can be an issue. According to the test result, the hybrid reinforced specimen showed better stiffness improvement than the specimen reinforced with only GFRP rebar. From an additional research on design parameter and reliability analysis, the field adaptability can be proved.

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Analytical Technique on CFTA Girder Bridge Considering Construction Sequence (시공단계를 고려한 CFTA 거더교의 해석기법)

  • Park, Seung-Jae;Kim, Yong-Jae;Jeon, Jong-Su;Park, Myoung-Gyun;Park, Kyung-Hoon
    • Proceedings of the Korea Concrete Institute Conference
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    • 2009.05a
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    • pp.167-168
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    • 2009
  • The CFT structure is applied to newly developed CFTA girder because of improvement of ductility deformation, stiffness and internal force of structure owing to the interaction between steel tube and core concrete. CFTA girder is the structure which can reduce tensile stress due to external loads by using its arch shape and prestress force. This paper proposed constructional stage procedure and represented analytical technique considering constructional stage to investigate the safety against bridge collapse on construction and on operation.

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A Study on the improvement of damping and optimal design of beam flexure for the passive vibration isolator (수동형 음강성 저주파 제진기의 감쇠 성능 향상과 빔 유연체의 최적 설계에 관한 연구)

  • Lee, Gil-Yong;Chang, Hee-Doh;Park, Young-Ho;Park, In-Hwang;Han, Dong-Chul
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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    • pp.189-195
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    • 2008
  • The vibration isolator system(VIS) which has very low natural frequency could be designed by applying an axial compressive force to the beam-column flexure(BCF). In this paper a new shape of the BCF is suggested. It has stepwise axially varying properties by viscoelastic damping layer. So it has internal structural damping by damping layer during deformation. First the analytic solution is obtained for the BCF. And its critical load, buckling mode, stiffness and stress distributions are investigated. Also the dynamic properties of the VIS consist of the damping layered BCF are studied. Finally the optimal design procedure of damping layered BCF for the VIS is suggested. The improved performance of suggested VIS is verified by some experiments.

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Load Transfer Characteristics of Rock-Socketed Drilled Shafts Considering Hole Roughness (굴착면 거칠기를 고려한 암반 근입 현장타설말뚝의 주면하중전이 특성)

  • Seol, Hoon-Il;Jeong, Sang-Seom;Woo, Sang-Yoon
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.494-505
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    • 2006
  • In this study, using constant normal stiffness(CNS) direct shear tests, side shear load distribution were analyzed by the influencing parameters of unconfined compressive strength, surface roughness, confining stress, and material properties. Based on the CNS tests, side shear load transfer function of drilled shafts in rock is proposed using geological strength index(GSI), which indicates discontinuity and surface condition of rock mass in Hoek-Brown criterion. Though comparisons with results of nine drilled shafts's load tests, it is found that the load-transfer curve by this study is in good agreement with the general trend observed by in situ measurements, and thus represents a significant improvement in the prediction of bearing capacity of drilled shaft.

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Identification of joint dynamics of mechanical structures using condensed F.E.M. model and experimental modal analysis (축약된 유한요소 모델과 실험적 모우드 해석을 이용한 기계구조물의 연결부 동특성 규명)

  • 최병욱;박병호;김광준
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.3
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    • pp.426-439
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    • 1988
  • Dynamic properties such as stiffness and damping of mechanical joints are essential for the accurate prediction of the dynamic behaviors of the system and subsequent improvement of the design. So far several techniques, analytical, experimental, or both have been developed. A technique using condensed F.E.M. model and Experimental Modal Analysis is presented to identify the joint structural parameters. First, modal parameters of structure are measured by certain complex frequency obtained from experiment to match with the order of the Experimental Modal Analysis model. Finally by equating the modal parameters obtained from experiment with those of the condensed system, the unknown joint structural parameters can be identified. A simulation study is conducted to investigate the accuracy of technique. The experiments are performed with ball bearings in a rotor bearing system.

Improvement of the Thermal Behavior of Linear Motors through Insulation Layer (단열재에 의한 리니어모터의 열특성의 향상)

  • Eun, L.D.;Lee, C.M.;Chung, W.J.;Choi, Y.H.
    • Proceedings of the KSME Conference
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    • 2001.11a
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    • pp.785-790
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    • 2001
  • Linear motors can drive a linear motion without intermediate gears, screws or crank shafts. Linear motors can successfully replace ball lead screw in machine tools, because they have a high velocity, acceleration and good positioning accuracy. On the other hand, linear motors emit large amounts of heat and have low efficiency. In this paper, heat sources of a synchronous linear motor with high velocity and force are measured and analyzed. To improve the thermal stiffness of the linear motor, an insulation layer with low thermal conductivity is inserted between cooler and machine table. Some effects of the insulation layer are presented.

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