• Title/Summary/Keyword: Equivalent Stiffness Model

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Finite Elements Analysis Application to the Structural Design of the Frame Type Furniture (골조형(骨造型) 가구구조설계(家具構造設計)에의 유한요소해석 응용)

  • Chung, Woo-Yang;Eckelman, Carl A.
    • Journal of the Korean Wood Science and Technology
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    • v.23 no.3
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    • pp.8-15
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    • 1995
  • This analytical study was carried out to make quality and productivity up in designing the frame-type furniture with semi-rigid joint by understanding the mechanical and structural behavior of the joint and by evaluating the validity of application of the time-saving Finite Element Method to its structural analysis. Slope deflection equation for rigid joint was modified to describe the moment-rotation behavior of semi-rigid joint and the joint stiffness factor(Z) could be calculated to lessen the experimental expense. It was proved that Finite Element Analysis with imaginary elements having equivalent MOE to the semi-rigid joint could be the alternative method for the structural analysis of the frame-type furniture, comparing the internal rotation of the 2-dimensional beam-to-column model with two-pin(wooden dowel) from the finite element method with other available theoretical and experimental rotation value.

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An Observation of the Application of a Magnetic Force to the Bicycle Cushion System and its Nonlinearity (자석 척력의 자전거 쿠션장치 적용 및 비선형성 고찰)

  • Yun, Seong-Ho
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.17 no.1
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    • pp.42-47
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    • 2018
  • This paper describes the dynamical behavior of the bicycle and its nonlinear effect when magnetic repulsive forces are applied to the bicycle cushion system. A finite-element method was used to obtain its reliabilities by comparing the experimental and numerical values and select the proper magnet sizes. The Equivalent spring stiffness values were evaluated in terms of both linear and nonlinear approximations, where the nonlinear effect was specifically investigated for the ride comfort. The corresponding equations of linear and nonlinear motion were derived for the numerical model with three degrees of freedom. Dynamic behaviors were observed when the bicycle ran over a curvilinear road in the form of a sinusoidal curve. The analysis in this paper for the observed nonlinearity of magnetic repulsive forces will be a useful guide to more accurately predict the cushion design for any vehicle system.

Investigation of wall flexibility effects on seismic behavior of cylindrical silos

  • Livaoglu, Ramazan;Durmus, Aysegul
    • Structural Engineering and Mechanics
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    • v.53 no.1
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    • pp.159-172
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    • 2015
  • This paper is concerned with effects of the wall flexibility on the seismic behavior of ground-supported cylindrical silos. It is a well-known fact that almost all analytical approximations in the literature to determine the dynamic pressure stemming from the bulk material assume silo structure as rigid. However, it is expected that the horizontal dynamic material pressures can be modified due to varying horizontal extensional stiffness of the bulk material which depends on the wall stiffness. In this study, finite element analyses were performed for six different slenderness ratios according to both rigid and flexible wall approximations. A three dimensional numerical model, taking into account bulk material-silo wall interaction, constituted by ANSYS commercial program was used. The findings obtained from the numerical analyses were discussed comparatively for rigid and flexible wall approximations in terms of the dynamic material pressure, equivalent base shear and bending moment. The numerical results clearly show that the wall flexibility may significantly affects the characteristics behavior of the reinforced concrete (RC) cylindrical silos and magnitudes of the responses under strong ground motions.

Solution of yielding steel arch supports used in mining

  • Lenka Koubova
    • Steel and Composite Structures
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    • v.51 no.5
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    • pp.575-586
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    • 2024
  • Steel arch supports are used in mines and underground structures to provide stability. Most of the supports are made up of overlapping arches. They can behave either yieldingly or unyieldingly. If the normal force at any point of overlapping equals the slip resistance, the slide occurs. This paper presents a solution procedure for determining the load-carrying capacity of steel arch supports in the yielding implementation. This solution considers the effects of several significant elements, including differing materials and the number of clamps in yielding friction joints. The direct stiffness method is applied. The solution contains geometric, physical, and structural nonlinearity. The results obtained from numerical modeling using the provided procedure are compared to laboratory tests conducted at GIG Katowice in 2012. They show a good correlation with previously collected data from equivalent laboratory conditions.

A Study on the Vibration Reduction of an Automobile Fuel Pump (자동차용 연료펌프의 진동 저감에 대한 연구)

  • Kim, Byeong Jin;Won, Hong In;Lee, Seong Won;Park, Sang Jun;Chung, Jintai
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.04a
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    • pp.772-777
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    • 2013
  • This article presents the reduction of vibration generated by an automobile fuel pump. In order to analysis the vibration of the fuel pump, a simplified dynamic model is established, which is composed of a rigid rotor and a equivalent springs. The equivalent stiffnesses of the upper and lower assemblies are evaluated by the comparison of modal testing results and the finite element analysis. the stiffness for the oil film of the journal bearing is extracted by using Reynold's equation. In addition, the time responses for the vibration of the fuel pump are computed by using a commercial multi-body dynamics software, RecurDyn. Based on these results, some design suggestions are proposed to reduce the vibration of an automobile fuel pump.

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Analytical Study on Fatigue Behavior of Resilient Pad for Rail Fastening System (레일체결장치용 방진패드의 피로거동에 관한 해석적 연구)

  • Choi, Jung-Youl
    • The Journal of the Convergence on Culture Technology
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    • v.7 no.2
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    • pp.405-410
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    • 2021
  • In this study, a finite element analysis was performed applying a nonlinear material model and fatigue load conditions to evaluate the service life and spring stiffness of the resilient pad for rail fastening system. As a result of the fatigue analysis, the rate of change in spring stiffness compared to the initial condition was about 16%, indicating that fatigue hardening occurred. As for the stress generated in the longitudinal direction of the resilient pad, the difference between the stress generated at the center and the edge was about 10 times or more. In addition, it was analyzed that the equivalent stress of the outer boundary was more than twice as large as that of the central part. Therefore, it was analyzed that the damage and deformation of the resilient pad are the corners of the resilient pad under actual service conditions. The fatigue life diagram of the resilient pad (S-N curve) was derived using the equivalent stress of the resilient pad according to the fatigue cycles. Using the fatigue life diagram of the resilient pad derived in this study, it is considered that it can be used to predict the fatigue life under the relevant conditions by calculating the equivalent stress of the resilient pad under various load conditions.

Evaluation of Compressive Strength of Assembled Column System Reinforced with Cross-Arms and Stayed Struts (수평재 및 사재로 보강된 조립기둥시스템의 압축강도 평가)

  • Kim, Kyung Sik;Park, Hyun Yong
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.33 no.6
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    • pp.2169-2179
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    • 2013
  • The compressive strengths of simply supported columns may be significantly increased by reinforcing them with an assemblage of cross-arms and stayed struts connecting both ends of the columns and the cross-arm members. The purpose of the stayed struts and cross-arms is to introduce partial restraints against translation and rotation, thereby decreasing the effective buckling length of the column. In this study, buckling strengths of the assembled column system have been quantitatively evaluated from the theoretical methods based on both the equivalent spring model and the stiffness matrix formulation. And the results were compared with those from elastic/inelastic analysis using a finite element analysis package program, ABAQUS, for verification purpose. Expected compressive strength curves have been proposed for the assembled column system as a function of slenderness ratio of the simply supported column.

Vibration Analysis of AFM Microcantilevers Using an Equivalent Stiffness Element Model (등가강성요소 모델을 이용한 AFM 마이크로캔틸레버의 진동해석)

  • Han, Dong Hee;Kim, Il Kwang;Lee, Soo Il
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.39 no.5
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    • pp.461-466
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    • 2015
  • Atomic force microscopy (AFM) is powerful tool for determining properties of samples based on interactions between the sample surface and an approaching probe tip. In this study, we modeled the interactions between the sample and the tip of the AFM microcantilever as a single nonlinear spring with an equivalent stiffness element and simulated the dynamic behaviors of the AFM microcantilevers using the finite element method (FEM) and ANSYS software. With the simulation results, we analyzed the complex dynamic responses of the AFM cantilever using proper orthogonal decomposition (POD). In addition, we compared the simulation and experimental results using the same method. Consequently, we suggest an effective method to express the interaction between the tip and sample, and we confirm that the influence of the higher order model due to the interaction between the tip and sample is increased.

Theoretical Investigation of 2DOF Vibrating System and Its Application to Dynamic Vibration Absorber (2자유도 진동계에 관한 이론적 고찰 및 진동흡진기로의 응용)

  • Jang, Seon-Jun;Brennan, M.J.;Rustigh, E.;Jung, Hyung-Jo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.22 no.4
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    • pp.371-377
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    • 2009
  • In this paper, the dynamic characteristic of vibrating system which has translational and rotational degrees of freedom is studied. The moment of inertia of the system is modeled here as the inerter and the equivalent model to the system is proposed using dynamic stiffness method. It is shown that the size of inerter plays a major role to determine the dynamic characteristic of the system. This two degree of freedom system(DOF) is applied as a dynamic vibration absorber(DVA) to the elimination of single peak of main body. The solution for the undamped DVA is presented in analytical form while the damped DVA is designed using fixed point theory. The numerical examples are presented for verifying the methods.

Dynamic Analysis of Tie-rod-fastened Rotor Considering Elastoplastic Deformation (탄소성 변형을 고려한 타이로드 고정 회전체의 동역학 해석)

  • Dongchan Seo;Kyung-Heui Kim;Dohoon Lee;Bora Lee;Junho Suh
    • Tribology and Lubricants
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    • v.40 no.1
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    • pp.8-16
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    • 2024
  • This study conducts numerical modeling and eigen-analysis of a rod-fastened rotor, which is mainly used in aircraft gas turbine engines in which multiple disks are in contact through curvic coupling. Nayak's theory is adopted to calculate surface parameters measured from the tooth profile of the curvic coupling gear. Surface parameters are important design parameters for predicting the stiffness between contact surfaces. Based on the calculated surface parameters, elastoplastic contact analysis is performed according to the interference between two surfaces based on the Greenwood-Williamson model. The equivalent bending stiffness is predicted based on the shape and elastoplastic contact stiffness of the curvic coupling. An equation of motion of the rod-fastened rotor, including the bending stiffness of the curvic coupling, is developed. Methods for applying the bending stiffness of a curvic coupling to the equation of motion and for modeling the equation of motion of a rotor that includes both inner and outer rotors are introduced. Rotordynamic analysis is performed through one-dimensional finite element analysis, and each element is modeled based on Timoshenko beam theory. Changes in bending stiffness and the resultant critical speed change in accordance with the rod fastening force are predicted, and the corresponding mode shapes are analyzed.