• Title/Summary/Keyword: Linear Spring

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A Study on Dynamic Characteristics of a Catenary System (가선계의 동특성에 관한 연구)

  • 김정수;최병두
    • Journal of KSNVE
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    • v.9 no.2
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    • pp.317-323
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    • 1999
  • Dynamic characteristics of catenary that supplies electrical power to high-speed trains are investigated. A simple catenary is composed of the contact and messenger wires connected by droppers possessing bi-directional stiffness properties. For slender, repeating structures such as catenary, both the wave propagation and vibration properties need to be understood. The influence of parameters that determine catenary dynamics are investiaged through numerical simulations involving finite element models. The effects of the tension and flexural rigidity of the contact wire is first investigated. The effects of dropper characteristics are then investigated. For linear droppers wave propagation as well as modal properties are determined. For large catenary motion, droppers can be modeled as bi-directional elements possessing low stiffness in compression and high stiffness in tension. For this case, impulse response is computed and compared with the cases of linear droppers. It is found that the catenary dynamics are primarily determined by contact wire tension and dropper properties, with large responses observed in 5∼40 Hz frequency range. In particular, the dropper stiffness and spacing are found to have dominant influence on the response frequency and the wave transmission characteristics.

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A Yield Estimation Model of Forage Rye Based on Climate Data by Locations in South Korea Using General Linear Model

  • Peng, Jing Lun;Kim, Moon Ju;Kim, Byong Wan;Sung, Kyung Il
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.36 no.3
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    • pp.205-214
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    • 2016
  • The objective of this study was to construct a forage rye (FR) dry matter yield (DMY) estimation model based on climate data by locations in South Korea. The data set (n = 549) during 29 years were used. Six optimal climatic variables were selected through stepwise multiple regression analysis with DMY as the response variable. Subsequently, via general linear model, the final model including the six climatic variables and cultivated locations as dummy variables was constructed as follows: DMY = 104.166SGD + 1.454AAT + 147.863MTJ + 59.183PAT150 - 4.693SRF + 45.106SRD - 5230.001 + Location, where SGD was spring growing days, AAT was autumnal accumulated temperature, MTJ was mean temperature in January, PAT150 was period to accumulated temperature 150, SRF was spring rainfall, and SRD was spring rainfall days. The model constructed in this research could explain 24.4 % of the variations in DMY of FR. The homoscedasticity and the assumption that the mean of the residuals were equal to zero was satisfied. The goodness-of-fit of the model was proper based on most scatters of the predicted DMY values fell within the 95% confidence interval.

Pounding Characteristics of a Bridge Superstructure on Rubber Bearings (교량 상부구조물의 탄성받침 설치에 따른 충돌특성 분석)

  • Choi, Hyoung-Suk;Kim, Jung-Woo;Gong, Yeong-I;Cheung, Jin-Hwan;Kim, In-Tae
    • Journal of the Earthquake Engineering Society of Korea
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    • v.15 no.4
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    • pp.13-21
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    • 2011
  • Seismic structure pounding between adjacent superstructures may induce the destruction of pier and bridge superstructures and cause local damage that leads to the collapse of the whole bridge system. The pounding problem is related to the expansion of joints, gap distance and seismic response of the abutments. In this research, methods of the contact element approach, the linear spring model, the Kelvin-Voigt model and the Hertz model were studied to analyse the pounding characteristics. The shaking table test for a model specimen such as a bridge superstructure with elastomeric bearings was performed to evaluate the contact element approach methods. Relationships between the time history response from the numerical analysis results and the measured response from the shaking table test are compared. The experimental results were not well matched with the numerical analysis results using the existing pounding stiffness models. Therefore, in this study, coefficients are proposed to calculate the appropriate pounding stiffness ratio.

Optimal design of car suspension springs by using a response surface method (반응 표면 분석법을 활용한 자동차용 현가스프링 최적화 설계)

  • Yoo, Dong-Woo;Kim, Do-Yeop;Shin, Dong-Gyu
    • Proceeding of EDISON Challenge
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    • 2016.03a
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    • pp.246-255
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    • 2016
  • When spring of the suspension is exerted by an external load, a car should be designed to prevent predictable damages and designed for a ride comfort. We used experiments design to design VON-MISES STRESS and K, a constant, of spring of suspension which is installed in a car as a goal level. We analyzed the result from Edison's Elastic - Plastic Analysis SW(CSD_EPLAST) by setting D, d, n as external diameter of coil, internal diameter of coil, the number of total coil respectively. The experiment design let the outcome be as Full-second order by using Box-Behnken which is one of response surface methods. Experimented and analyzed results based on the established experiments design, We found out design parameter which has desired VON-MISES STRESS and the constant K. Additionally, we predicted life time of when the external load was exerted by repeated load by using fatigue equation, and verification of plastic deformation has also been made. Additionally we interpreted a model, which is formed by optimized design parameter, with linear analysis and non-linear analysis, at the same time we also analyzed plastic deformation with the values from the both models. Finally, we predicted fatigue life of optimized model by using fatigue estimation theory and also evaluated a ride comfort with oscillation analysis.

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Analysis of a Variable Damper and Pneumatic Spring Suspension for Bicycle Forks using Hydraulic-Pneumatic Circuit Model (유공압 회로를 이용한 자전거 포크용 가변댐퍼-공압스프링 서스펜션의 해석)

  • Chang, Moon Suk;Choi, Young Hyu;Kim, Su Tae;Choi, Jae Il
    • Journal of Drive and Control
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    • v.16 no.1
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    • pp.7-13
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    • 2019
  • The objective of this study was to present a damped pneumatic suspension, a bike fork suspension, which can adapt itself to incoming road excitations is presented in this paper. It consists of a hydraulic damper and a pneumatic spring in parallel with a linear spring. The study also proposed a variable and switchable orifice, in the hydraulic damper, to select appropriate damping property. Hydraulic-pneumatic circuit model for the bike fork suspension was established based on AMESim, in order to predict its performance. In addition, elastic-damping characteristics of the fork such as spring constant and viscous damping coefficient were computed and compared, for validation, with those evaluated by experiment using the universal test machine. Through simulation analysis and test, it was established that the hydraulic-pneumatic circuit model is effective and practical for development of future MTB suspensions.

Methods to Obtain Approximate Responses of a Non-Linear Vibration Isolation System (비선형 진동절연 시스템의 근사적 응답을 구하는 방법)

  • Lee, Gun-Myung
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.6
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    • pp.23-28
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    • 2020
  • A non-linear vibration isolation system composed of a non-linear spring and a linear damper was presented in a previous study. The advantage of the proposed isolator is the simple structure of the system. When the base of the isolator is harmonically excited, the response component of the mass at the excitation frequency was approximated using three different methods: linear approximation, harmonic balance, and higher-order frequency response functions (FRFs). The method using higher-order FRFs produces significantly more accurate results compared with the other methods. The error between the exact and approximate responses does not increase monotonously with the excitation amplitude and is less than 2%.

ANALYSIS OF THE OPTIMIZED H TYPE GRID SPRING BY A CHARACTERIZATION TEST AND THE FINITE ELEMENT METHOD UNDER THE IN-GRID BOUNDARY CONDITION

  • Yoon Kyung-Ho;Lee Kang-Hee;Kang Heung-Seok;Song Kee-Nam
    • Nuclear Engineering and Technology
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    • v.38 no.4
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    • pp.375-382
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    • 2006
  • Characterization tests (load vs. displacement curve) are conducted for the springs of Zirconium alloy spacer grids for an advanced LWR fuel assembly. Twofold testing is employed: strap-based and assembly-based tests. The assembly-based test satisfies the in situ boundary conditions of the spring within the grid assembly. The aim of the characterization test via the aforementioned two methods is to establish an appropriate assembly-based test method that fulfills the actual boundary conditions. A characterization test under the spacer grid assembly boundary condition is also conducted to investigate the actual behavior of the spring in the core. The stiffness of the characteristic curve is smaller than that of the strap-wised boundary condition. This phenomenon may cause the strap slit condition. A spacer grid consists of horizontal and vertical straps. The strap slit positions are differentiated from each other. They affords examination of the variation of the external load distribution in the grid spring. Localized legions of high stress and their values are analyzed, as they may be affected by the spring shape. Through a comparison of the results of the test and FE analysis, it is concluded that the present assembly-based analysis model and procedure are reasonably well conducted and can be used for spring characterization in the core. Guidelines for improving the mechanical integrity of the spring are also discussed.

Geometrically Linear and Non-linear Analysis of Plates and Shells Resting on Arbitrary Elastic Edge Supports (임의의 탄성 경계 지점으로 지지된 판과 쉘의 기하학적 선형 및 비선형해석)

  • Lee, Won-Hong;Han, Sung-Cheon;Park, Weon-Tae
    • Journal of the Korean Society of Hazard Mitigation
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    • v.8 no.3
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    • pp.11-21
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    • 2008
  • A linear and non-linear analysis for plates and shells with arbitrary edge supports subjected to various loading was presented. The 9-node ANS(Assumed Natural Strain) hell element was employed and the spring element, which could express an arbitrary edge support using the six degrees of freedom, was introduced. For the application of his analysis, the plates and shells with various edge supports were analyzed, and the ending behavior with these edge supports were obtained accurately. For these edge supports, particularly elastic edge support was simulated by six springs and reasonable results were obtained. The results show that the present method can be widely used to analyze the bending behavior of plates and shells with arbitrary edge conditions.

Bifurcation Analysis of a Non-linear Hysteretic Oscillating System (비선형 히스테리시스 진동시스템의 분기해석)

  • 송덕근;최진권;장서일
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.289-294
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    • 2001
  • Three kinds of viscoelastic damper model, which has a non-linear spring as an element is studied analytically and numerically. The behavior of the damper model shows non-linear hysteresis curves which is qualitatively similar to those of real viscoelastic materials. The motion is governed by a non-linear constitutive equation and an additional equation of motion. Harmonic balance method is applied to get analytic solutions of the system. The frequency-response curves show that multiple solutions co-exist and that the jump phenomena can occur. In addition, it is shown that separate solution branch exists and that it can merge with the primary response curve. Saddle-node bifurcation sets explain the occurrences of such non-linear phenomena.

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Bifurcation Analysis of a Non-linear Hysteretic Oscillating System (비선형 히스테리시스 진동시스템의 분기해석)

  • 장서일;송덕근;최진권
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.1
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    • pp.57-64
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    • 2002
  • Three kinds of viscoelastic damper model, which has a non-linear spring as an element is studied analytically and numerically The behavior of the damper model shows non-linear hysteresis curves which is qualitatively similar to those of real viscoelastic materials. The motion is governed by a non-linear constitutive equation and an additional equation of motion. Harmonic balance method is applied to get analytical solutions of the system. The frequency-response curves sallow that multiple solutions co-exist and that the jump phenomena can occur. In addition, it is shown that separate solution branch exists and that it can merge with the primary response curve. Saddle-node bifurcation sets explain the occurrences of such non-linear Phenomena.