• Title, Summary, Keyword: dynamic characteristics

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A Numerical Study on the Dynamic Characteristics of Power Metal using Split Hopkinson Pressure Bar (홉킨스바 장치를 이용한 분말금속의 동적 특성에 관한 수치해석적 연구)

  • Hwang, Du-Sun;Lee, Seung-U;Hong, Seong-In
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.12
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    • pp.2972-2979
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    • 2000
  • Dynamic characteristics of powder metal is very important to mechanical structures requiring high strength or endurance for impact loading. But owing to distinctive property of powder metal, that is relative, it has been investigated restrictively compared to static characteristics. The objectives of this study is to investigate dynamic characteristics of powder metal and compare it to a fully density material. To find the characteristics, an explicit finite element method is used for simulation of Split Hopkinson Pressure Bar experiment based on the stress wave propagation theory. We obtained a dynamic stress-strain relationship and dynamic behavior of powder metal, as well as the variation of material properties during dynamic deformation.

Dynamic characteristics of the compressor-combined condenser system (압축기 계가 결합된 응축기의 동특성)

  • Kim, Jae-Dol
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.22 no.7
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    • pp.1001-1012
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    • 1998
  • This paper reports the analysis of dynamic characteristics of air-cooled condenser. At first, there is an assumption that the superheated vapor flows into the condenser inlet. And in order to consider the effect of pressure change in the dynamic characteristics of the condenser the combined system of condenser and compressor was used. By using the equation of energy balance and the equation of mass balance, the basic equation for describing the dynamic characteristics of condenser can be derived. The transfer function for describing dynamic response of the condenser to flow rate change outlet can be obtained from using linearizations and Laplace transformations of the equation. From this transfer function, analytical investigation which affects the frequency responses of condenser has been made. Through this study, it became possible that the information about the dynamic characteristics of air-cooled condenser is offered. While the average heat transfer coefficient of the refrigerant side necessary for the theoretical calculation of the dynamic characteristics is given by calculation method for the tube length and pressure drop of air-cooled condenser.

Comparison of Performance of the Exciter and Impact Hammer Test for Dynamic Characteristics Analysis of Floor Slabs (건물바닥 슬래브의 동특성 분석을 위한 가진기와 Impact Hammer의 성능 비교)

  • Ahn, Sang-Kyung;Moon, Yeong-Jong;Oh, Jung-Keun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.117-120
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    • 2007
  • The floor slabs of building structures are often subjected to the periodic force which is induced by vibrating machines or human activity(walking, jumping, running etc). These periodic forces cause excessive oscillation. In order to examine the dynamic characteristics of floor slabs, the dynamic characteristics test is accomplished. Generally, the Impact Hammer and Dynamic Exciter test is used to dynamic characteristics test. But the Impact Hammer test is not suitable to apply in building slabs. In this paper, It compared the performance of the Exciter and Impact Hammer test for dynamic characteristics analysis of floor slabs.

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Wireless monitoring of typhoon-induced variation of dynamic characteristics of a cable-stayed bridge

  • Park, Jae-Hyung;Huynh, Thanh-Canh;Kim, Jeong-Tae
    • Wind and Structures
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    • v.20 no.2
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    • pp.293-314
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    • 2015
  • In this paper, wireless monitoring of typhoon-induced variation of dynamic characteristics of a cable-stayed bridge is presented. Firstly, cable-stayed bridge with the wireless monitoring system is described. Wireless vibration sensor nodes are utilized to measure accelerations from bridge deck and stay cables. Also, modal analysis methods are selected to extract dynamic characteristics. Secondly, dynamic responses of the cable-stayed bridge under the attack of two typhoons are analyzed by estimating relationships between wind velocity and dynamic characteristics. Wind-induced variations of deck and cable vibration responses are examined based on the field measurements under the two consecutive typhoons, Bolaven and Tembin. Finally, time-varying analyses are performed to investigate non-stationary random properties of the dynamic responses under the typhoons.

Analysis of the dynamic characteristics for the change of design parameters of an underwater vehicle using sensitivity analysis

  • Jeon, Myungjun;Yoon, Hyeon Kyu;Hwang, Junho;Cho, Hyeon Jin
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.10 no.4
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    • pp.508-519
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    • 2018
  • In order to design the hull form of an underwater vehicle in the conceptual design phase, the dynamic characteristics depending on the hull form parameters should be identified. Course-keeping stability, turning ability, yaw-checking ability, and mission competence are set to be the indices of the dynamic characteristics, and the geometric parameters for the bare hull and rudder are set to be the hull form design parameters. The total sensitivity of the dynamic characteristics with respect to the hull form parameters is calculated by the chain rule of the partial sensitivity of the dynamic characteristics with respect to the hydrodynamic coefficients, and the partial sensitivity of the hydrodynamic coefficients with respect to the hull form parameters. Based on the sensitivity analysis, important hull form parameters are selected, and those optimal values to satisfy the required intercept time of mission competence of a specific underwater vehicle and turning rate are estimated.

Clamping effects on the dynamic characteristics of composite tool bars (고정부 조건이 복합재료 공구용 바의 동적 특성에 미치는 영향)

  • 황희윤;김병철;이대길
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.199-202
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    • 2003
  • The dynamic characteristics of composite tool bars depend on the clamping conditions such as clamping force, stiffness and surface characteristics of clamping parts as well as the basic structures. Therefore, in this work, the effects of clamping part conditions on the dynamic characteristics of cantilever type composite machine tool structures with clamped joint were investigated because the cantilever type machine tool structures are ideal cases for composite application to increase the natural frequency and damping of structures. New design of the clamping part was developed in order to improve shear properties of the clamping part and dynamic characteristics of composite tool bars. From FE analysis and Impulse response tests, dynamic characteristics were obtained with respect to the clamping part conditions of the new design.

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Vibration Mode of the Drivesystem Considered the Vehicle Body's Dynamic Characteristics (차체의 동특성을 고려한 구동시스템의 진동모드)

  • 유충준
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.2
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    • pp.148-159
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    • 2004
  • This paper discusses vibration mode of the drivesystem considered the vehicle body's dynamic characteristics to study the influence of the vehicle body's dynamic characteristics on the vibration mode of the engine mount system and the ride quality of a vehicle. The simulation model consists of the engine mount system, the powertrain and the rigid or elastic vehicle body. Variables used in this study are the stiffnesses of an engine mount system and the excitation forces. The Goals of the study are analyzing both the vibration transmitted to the vehicle body including the drivesystem and the influence of the vehicle body's dynamic characteristics on the engine mount system. The mode of drivesystems with a rigid and a elastic vehicle body was compared. From the result of the forced vibration analysis for the drivesystem with a elastic vehicle body, it is shown that the vehicle body's dynamic characteristics influence on the engine mount system reciprocally.

Experimental Review on Dynamic Characteristics of the Commercial Mounts for Vibration Reduction (상업용 방진마운트의 동적 특성에 관한 실험적 고찰)

  • Moon, Seok-Jun;Shin, Y.H.;Chung, J.H.;Song, C.K.
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.24 no.9
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    • pp.687-694
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    • 2014
  • The mount suppliers are providing limited information on the dynamic characteristics of the mounts to some designers and some manufacturers of the high-precision machines. In this technical study, the experimental review was carried out about dynamic characteristics of five kinds of commercial passive mounts sold in the market. The dynamic characteristics, natural frequency and damping ratio, extracted from experimental tests were compared to the materials supplied by mount makers. In order to predict the performance of the high-precision machines with mounts, exact values of the dynamic characteristics of mounts should be used in the stage of numerical analysis.

Flexibility Effects of Frame for Vehicle Dynamic Characteristics (차량 동특성에 대한 프레임의 유연성 효과)

  • 이상범
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.11 no.2
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    • pp.80-86
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    • 2002
  • Previous method of computer simulation to predict the dynamic response of a vehicle has been based on the assumption that vehicle structure is rigid. If the flexibility of the vehicle structure becomes too large to ignore, rigid body assumption will no longer give good estimation of the dynamic characteristics. Therefore, in order to predict more precise vehicle dynamic characteristics, flexible multi-body dynamic analysis of a vehicle is necessary. This paper investigates dynamic characteristics of vehicle systems with flexible frames numerically. Joint reaction forces, vertical accelerations, pitch accelerations are analyzed for the vehicle systems with various flexible frames using multi-body dynamic analysis code and finite element analysis code.

Analysis of the Dynamic Characteristics of A Passenger Car Automatic Transmission (승용차용 자동변속기의 동특성 해석)

  • 김영흡;박찬일
    • Transactions of the Korean Society of Automotive Engineers
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    • v.5 no.3
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    • pp.172-181
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    • 1997
  • The dynamic characteristics during gear ratio change including the disturbance of output torque has been one of the most important issues in the study of automatic transmissions of passenger cars. In this paper, to investigate the dynamic characteristics of a passenger car automatic transmission during gear ratio change, a dynamic model of the driveline of a passenger car focused on the automatic transmission is proposed and the dynamic simulation program is developed. The results of the simulation show good agreements with the experimental data, which process the use fullness of the dynamic model and the simulation of the driveline.

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