• Title/Summary/Keyword: mass-spring model

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Estimation of damage for composite laminates using sound pressure (음압을 이용한 복합 적층판의 손상평가)

  • Kim, Sung-Joon;Lee, Sang-Wook;Chae, Dong-Chul;Kim, Sung-Chan
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.503-507
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    • 2004
  • The radiated sound pressure induced by low-velocity impact is obtained by solving the Rayleigh integral equation. This paper established the sound analysis procedure using impact analysis model. For structurally radiated noise, the sound field is directly coupled to the structural motion. Therefore the impact response should be analyzed. The impact response is computed using the spring-mass model. And the influence of damage on the sound pressure and impacted force history of laminated were investigated. The results show that both radiated sound pressure and impact force history are strongly influenced by damage on laminated.

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A Study on Structure-Borne Noise Reduction for Resiliently Mounted Pumps for Ship (탄성지지된 박용 펌프의 고체음저감에 관한 연구)

  • Kim, Hyun-Sil;Kang, Hyun-Ju;Kim, Bong-Ki;Kim, Sang-Ryul
    • Journal of the Society of Naval Architects of Korea
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    • v.44 no.5
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    • pp.488-495
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    • 2007
  • In this paper, SBN (Structure-Borne Noise) reduction of resiliently mounted machinery and effect of the foundation impedance on mount performance is studied. SBN reduction through the mount is analyzed by using two theoretical models; mass-spring model and wave model, in which longitudinal wave propagation is included. It is found that floor impedance greatly affects SBN reduction through lower mount, while it is almost negligible to SBN reduction through upper mount. Comparisons between measurement and predictions shows that the mass-spring model is valid only in low frequency range below few hundred Hz, while for high frequency ranges longitudinal wave propagation in the mount must be considered.

Analysis and Small Scale Model Expriment on the Vertical Vibration of the KT-23 Type Passenger Vehicle (KT-23형 여객 차량의 상하 진동 해석 및 축소모형 실험)

  • 최경진;이동형;장동욱;권영필
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.4
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    • pp.266-273
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    • 2003
  • The purpose of this study is to obtain the effects of the parameters of the suspension system in railway rolling-stock for KT-23 type Passenger vehicle. According to the analysis and the small scale model car test. optimal condition was obtained for the stiffness ratio of secondary spring to primary spring of the suspension system and the mass ratio of the bogie frame to the car body. The analysis of the study shows that if the car body mass is increased or secondary stiffness Is lowered, the vertical vibration level is reduced and the passenger comfort can be improved. Especially, strong peaks are occurred in the frequencies corresponding to the rotational speed of driving axle and vehicle wheel. Hence, in order to obtain the dynamic characteristics through the small scale model car, the driving method of the vehicle on the test bench, rotational characteristics of the wheel and the natural modes of vehicle should be investigated and be modified.

Study on air spring modeling method for railway vehicle dynamics (동역학 해석용 Air Spring Modeling 방법에 대한 고찰)

  • Seong, Jae-Ho;Lee, Kang-Wun;Park, Gil-Bae;Yang, Hee-Joo
    • Proceedings of the KSR Conference
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    • 2008.06a
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    • pp.2236-2241
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    • 2008
  • To predict the dynamic behaviour of railway vehicle, the complex vehicle structure has been described by mathmatical model such as mass, spring and damper. Air-spring has played a major role to improve dynamic characteristics, vibration isolation and ride comfort. The mechanical behaviour of air spring is very complicated. The behaviour is based on fluid and thermodynamic mechanisms. The main parameters of air spring are stiffness due to compression of the air in the spring and surge reservoir, change of area stiffness and orifice damping. In this paper, we have studied an air-spring modeling method and compared the difference between calculation and test.

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Numerical study of propagation, reflection, and scattering of ultrasonic waves (초음파의 전파, 반사, 산란 현상에 대한 수치 시뮬레이션)

  • 임현준
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2002.04a
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    • pp.401-406
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    • 2002
  • A numerical model is introduced to simulate propagation, reflection, and scattering of elastic waves in solids. The model consists of mass points and linear springs, interconnected with in a lattice structure; hence, its name, the mass-spring lattice model (MSLM). The MSLM has successfully been applied to the numerical simulation and visualization of various elastic wave phenomena involved in ultrasonic nondestructive testing (NDT). This method is useful to simulate, design, or analyze actual testing. Some representative examples of numerical simulation using the MSLM are presented, and future work necessary for its further development Is addressed.

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Robust Design of Leaf Spring of a Polygon Mirror Scanner Motor Against Shock (충격에 강인한 폴리곤 미러 스캐너 모터의 판 스프링 설계)

  • Lee, Sang-Wook;Kim, Myung-Gyu;Jung, Kyung-Moon;Jang, Gun-Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.11a
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    • pp.515-520
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    • 2008
  • This paper develops a mite element model of a polygon mirror scanner motor supported by the sintered bearing and flexible supporting structures to analyze the shock response by using the finite element method and the mode superposition method. The validity of the proposed model is verified by comparing the simulated natural frequencies and shock response with the experimental ones. It investigates the displacement and the stress of the most vulnerable component, i.e. a leaf spring due to shock, and it proposes a robust design of leaf spring of a polygon mirror scanner motor against shock.

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Analysis on the Measured Natural Frequencies Due to the Structure-Exciter Interaction (구조물-가진기 상호작용에 의한 공진주파수 변동에 대한 해석)

  • Han, Sang-Bo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.7
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    • pp.2108-2117
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    • 1996
  • The purpose of this paper is to investigate the influence of the exciter attached for the measurement of natural frequencies when extracting the frequency response functions of the test structure in experimental modal analysis. The procedure is first to model the attached exciter as an additional degree of freedom system and next to verify the suggested model by experimentally extracting the natural frequencies of the test structure with various values of exciter mass, stinger stiffness and attachment position of the exciter on the test structure. It is concluded that as additional degree of freedom system which includes the natural frequency of the exciter itself and axial stiffness of stinger should be considered to quantatively define the coupling effects of structure-exciter interaction on the measured natural frequencies. It is not the mass of the exciter itself but the coupling effect of the additional degree of freedom mass-spring system consisting of exciter body and armature coil that characterizes the natural frequency deviation. Therefore, when the natural frequency of this additional mass-spring system is outside of the test frequency range, the coupling effect of structure-exciter interaction can be minimized.

Anti Roll Bar Force Computation Algorithm for Real Time Multibody Vehicle Dynamics (실시간 차량 동역학 해석을 위한 안티 롤 바 힘 계산 알고리듬)

  • Kim, Sung-Soo;Jeong, Wan-Hee;Ha, Kyoung-Nam
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.2
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    • pp.170-176
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    • 2008
  • Anti roll bar model for real time multibody vehicle dynamics model has been proposed using kinematic constraint. Anti roll bar have been modeled by kinematic relationship, and mass properties are neglected. Relative angle of torsion bar spring is computed by constraint about drop-link using Newton-Raphson iteration, and then the torque of torsion bar spring can be computed with the angle and torsion spring stiffness. Finally anti roll bar force acting on both knuckle can be calculated. To validate the proposed method, half car simulations of McPherson strut suspension and full car simulations are also carried out comparing with the ADAMS vehicle model with anti roll bar. CPU times are also measured to see the real-time capabilities of the proposed method.

Comparison of semi-active and passive tuned mass damper systems for vibration control of a wind turbine

  • Lalonde, Eric R.;Dai, Kaoshan;Bitsuamlak, Girma;Lu, Wensheng;Zhao, Zhi
    • Wind and Structures
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    • v.30 no.6
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    • pp.663-678
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    • 2020
  • Robust semi-active vibration control of wind turbines using tuned mass dampers (TMDs) is a promising technique. This study investigates a 1.5 megawatt wind turbine controlled by eight different types of tuned mass damper systems of equal mass: a passive TMD, a semi-active varying-spring TMD, a semi-active varying-damper TMD, a semi-active varying-damper-and-spring TMD, as well as these four damper systems paired with an additional smaller passive TMD near the mid-point of the tower. The mechanism and controllers for each of these TMD systems are explained, such as employing magnetorheological dampers for the varying-damper TMD cases. The turbine is modelled as a lumped-mass 3D finite element model. The uncontrolled and controlled turbines are subjected to loading and operational cases including service wind loads on operational turbines, seismic loading with service wind on operational turbines, and high-intensity storm wind loads on parked turbines. The displacement and acceleration responses of the tower at the first and second mode shape maxima were used as the performance indicators. Ultimately, it was found that while all the semi-active TMD systems outperformed the passive systems, it was the semi-active varying-damper-and-spring system that was found to be the most effective overall - capable of controlling vibrations about as effectively with only half the mass as a passive TMD. It was also shown that by reducing the mass of the TMD and adding a second smaller TMD below, the vibrations near the mid-point could be greatly reduced at the cost of slightly increased vibrations at the tower top.

Stability of Stepped Columns Subjected to Nonconservative Force (비보존력이 작용하는 불연속 변단면 기둥의 안정성)

  • Oh, Sang-Jin;Mo, Jeong-Man;Lee, Jae-Young
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.11a
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    • pp.801-804
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    • 2006
  • The purpose of this paper is to investigate the stability of stepped cantilever columns with a tip mass of rotatory inertia and a translational spring at one end. The column model is based on the Bernoulli-Euler theory which neglects the effects of rotatory inertia and shear deformation. The governing differential equation for the free vibration of columns with stepwise variable cross-section and subjected to a subtangential follower force is solved numerically using the corresponding boundary conditions. And the bisection method is used to calculate the critical divergence/flutter load. The frequency and critical divergence/flutter load for the stepped column with a single step are presented as functions of various non-dimensional system parameters: the segmental length parameter, the section ratio, the subtangential parameter, the mass, the moment of inertia of the mass, and the spring parameter.

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