• Title/Summary/Keyword: Forced displacement

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A Fracture Study on the Bonded DCB Specimen of the Mode III Type with Aluminum Foam (알루미늄 폼으로 된 Mode III 형의 접합된 DCB 시험편에 대한 파괴 연구)

  • Lee, Jung-Ho;Cho, Jae-Ung;Cheon, Seong-Sik
    • Composites Research
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    • v.28 no.4
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    • pp.191-196
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    • 2015
  • In this study, the static analysis and experiment were carried out on DCB specimens manufactured with aluminum foam in order to investigate the fracture toughness at the adhesive joint of the structure bonded with adhesive. In case of static analysis, all specimen models were shown to have the maximum reaction force when the forced displacement proceeded as much as 5 mm. The maximum reaction forces became 0.25 kN, 0.28 kN and 0.5 kN respectively in cases of specimen thicknesses of 35 mm, 45 mm and 55 mm. Two specimens in case of static experiment were selected to verify these analysis results. The maximum reaction forces were shown when the forced displacement proceeded as much as 5 to 6 mm. The maximum reaction forces became 0.22 kN and 0.3 kN respectively in cases of specimen thicknesses of 35 mm and 45 mm. By comparing the derived results, it could be shown that there was not much difference between the data of analyses and experiments. Therefore, It is inferred that the study data can be secured with only analysis by no extra experimental procedure. It is thought that the mechanical properties at the structure bonded of DCB with the type of mode III can be analyzed systematically.

Forced vibrations of an elastic rectangular plate supported by a unilateral two-parameter foundation via the Chebyshev polynomials expansion

  • Zekai Celep;Zeki Ozcan
    • Structural Engineering and Mechanics
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    • v.90 no.6
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    • pp.551-568
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    • 2024
  • The present study deals with static and dynamic behaviors including forced vibrations of an elastic rectangular nano plate on the two-parameter foundation. Firstly, the rectangular plate is assumed to be subjected to uniformly distributed and eccentrically applied concentrated loads. The governing equations of the problem are derived by considering the dynamic response of the plate, employing a series of the Chebyshev polynomials for the displacement function and applying the Galerkin method. Then, effects of the non-essential boundary conditions of the plate, i.e., the boundary conditions related to the shearing forces, the bending moments and the corner forces, are included in the governing equation of motion to compensate for the non-satisfied boundary conditions and increase the accuracy of the Galerkin method. The approximate numerical solution is accomplished using an iterative process due to the non-linearity of the unilateral property of the two-parameter foundation. The plate under static concentrated load is investigated in detail numerically by considering a wide range of parameters of the plate and the foundation stiffnesses. Numerical treatment of the problem in the time domain is carried out by assuming a stepwise variation of the concentrated load and the linear acceleration procedure is employed in the solution of the system of governing differential equations derived from the equation of motion. Time variations of the contact region and those of the displacements of the plate are presented in the figures for various numbers of the two-parameter of the foundation, as well as the classical and nano parameters of the plate particularly focusing on the non-linearity of the problem due to the plate lift-off from the unilateral foundation. The effects of classical and nonlocal parameters and loading are investigated in detail. Definition of the separation between the plate and the two-parameter foundation is presented and applied to the given problem. The effect of the lift-off on the static and dynamic behavior of the rectangular plate is studied in detail by considering various loading conditions. The numerical study shows that the effect of nonlocal parameters on the behavior of the plate becomes significant, when nonlinearity becomes more profound, due to the lift-off of the plate. It is seen that the size effects are significant in static and dynamic analysis of nano-scaled rectangular plates and need to be included in the mechanical analyses. Furthermore, the corner displacement of the plate is affected more significantly from the lift-off, whereas it is less marked in the time variation of the middle displacement of the plate. Several numerical examples are presented to examine the sensibility of various parameters associated with nonlocal parameters of the plate and foundation. Both stiffening and softening nonlocal parameters behavior of the plate are identified in the numerical solutions which show that increasing the foundation stiffness decreases the extent of the contact region, whereas the stiffness of the shear layer increases the contact region and reduces the foundation settlement considerably.

FRF Analysis of a Vehicle Passing the Bump Barrier (둔턱 진행 차량의 주파수응답 분석)

  • Kim, Jong-Do;Yoon, Moon-Chul
    • Journal of Convergence for Information Technology
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    • v.12 no.3
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    • pp.151-157
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    • 2022
  • The purpose of this study was to investigate the frequency characteristics of forced vibration considering the vehicle progress. And the vibration characteristics in frequency domain that occur, when vehicle passes the bump, were analyzed. The responses such as displacement, velocity and acceleration were obtained through numerical analysis, and FFT processing was performed to analyze the frequency response function(FRF) characteristics. In particular, the location of vehicle eigenmodes and external excitation modes was clearly shown and analyzed. In the forced vibration model by external force, the behavior of the eigenmode in power spectrum and real and imaginary parts were also analyzed. The mode characteristics were also analyzed in each FRF. It was approximated by assuming total excitation force by considering the exciting frequency using impulse and sine wave forces, which can give the amplitude and frequencies. The response characteristics of forced oscillations having different mass, damping and stiffness have been systematically discussed.

An Experimental Study on the Numerical Process of the Acceleration Signal for the Estimation of the Displacement Response of Bridges. (교량의 변위응답 추정을 위한 가속도 신호의 수치처리에 대한 실험적 연구)

  • 정진환;계만수;제순모
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1999.10a
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    • pp.275-282
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    • 1999
  • In this study, the algorithm which can estimate displacements from the acceleration data is developed. For proving the validity of this study, the calculated displacements are compared with the measured displacements through the forced vibration tests in the laboratory. So the sampling frequency and filtering range for the estimation of the displacements are proposed. Finally, these results are applied to estimate displacements from the acceleration data obtained from the real bridge.

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Dynamic System Analysis of Machine Tool Spindles with Magnet Coupling

  • Kim, Seong-Keol
    • International Journal of Precision Engineering and Manufacturing
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    • v.3 no.4
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    • pp.87-93
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    • 2002
  • In this study, basic concepts of magnet were introduced, and dynamic characteristics of magnet coupling were explored. Based on these characteristics, it was proposed how to analyze transverse and torsional vibrations of a spindle system with magnet coupling. Proposed theoretical approaches were applied to a precision power transmission system machined for this study, and the transverse and torsional vibrations were simulated. The force on magnet coupling was shown as a form of nonlinear function of the gap and the eccentricity. Also, the form of torque transmitted by magnet coupling was considered as a sinusoidal function. Main spindle connected to a coupling of a follower part was assumed to be a rigid body. Nonlinear partial differential equation was derived to be as a function of angular displacement. By using the equation, torsional vibration analysis of a spindle system with magnet coupling was performed. Free and forced vibration analyses of a spindle system with magnetic coupling were explored by using FEM.

A study on dynamic behavior of bidirectional SMA Actuator with forced-cooling (강제공냉 차동식 형상기억합금 액츄에이터의 동작특성에 관한 연구)

  • 정상화;김현욱;차경래
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2003.10a
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    • pp.47-52
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    • 2003
  • In the recent years, as the research and the development of micro and precision machinery become active, the interest of micro actuators using SMA(Shape Memory Alloy) has been increased. The dynamic characteristic analysis of SMA is necessary for actuator application and many common researches report the material characteristics of SMA sufficiently. However, the research on dynamic characteristics is very deficient. In this paper, the helical spring are fabricated with NiTi SMA wire of high resistivity. The force, response speed, temperature, and displacement are measured by digital force gauge, infrared thermometer, and laser displacement sensor so that the dynamic characteristics of this SMA is analyzed. Also, bidirectional actuator was fabricated and experimented fir its performance.

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An Experimental Study on the Runout Characteristics of Spindle State Monitoring Using an Optical Fiber Displacement Sensor (광 파이버 변위 센서를 이용한 주축 모니터링 시 나타나는 런아웃 특성에 대한 실험적 고찰)

  • 신우철;박찬규;정택구;홍준희;이동주
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2003.04a
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    • pp.472-477
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    • 2003
  • Spindle state monitoring is getting more and more important according to the technology trend of spindle that is accurate and automated. Spindle state monitoring is to measure the state of rotation vibrations. The spindle rotation error motion detected by sensing device includes rotation object's unbalance, external forced vibrations, shape error of spindle, as well as measuring error of monitoring device. In this paper, we have inspected the runout characteristics. Also, we introduce the way to exclude the runout element that appear while you monitor a spindle state.

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Seismic response control of irregular asymmetric structure with voided slabs by distributed tuned rotary mass damper devices

  • Shujin Li;Irakoze Jean Paula;Ling Mao
    • Earthquakes and Structures
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    • v.25 no.6
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    • pp.455-467
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    • 2023
  • This study focuses on demonstrating the effectiveness of vibration control of tuned rotary mass damper (TRMD) for reducing the bidirectional and torsional response of the irregular asymmetric structure with voided slabs under earthquake excitations. The TRMD arranged in plane of one-story eccentric structure is proposed as a distributed tuned rotary mass damper (DTRMD) system. Lagrange's equation is used to derive the equations of motion of the controlled system. The optimum position and number of TRMD are numerically investigated under harmonic excitation and the control effects of different distributions are discussed. Furthermore, a shaking table test is conducted under different excitation cases, including free vibration, forced vibration and seismic wave to investigate the absorption performance of the device. The numerical simulations of different distributions of the TRMDs show that the DTRMDs are more effective in reduction of the displacement response of the asymmetric structure under the same mass ratio, even when the degree of eccentricity becomes large. However, with small degree of eccentricity, the unreasonable asymmetrical arrangement may cause the increase of the peak value of the rotational angular displacement. Finally, the experimental investigations exhibit similar results of translational displacement of the structure. It is concluded that the vibration of the irregular asymmetric structure can be controlled more economically and effectively by reducing the mass ratio through reducing the quantity of TRMDs at the high stiffness end.

A Study on Simulation of Cavity and Relaxation Zone Using Finite Element Method (유한요소법을 이용한 지반 공동 및 이완영역 모사에 관한 연구)

  • You, Seung-Kyong;Kim, Joo-Bong;Han, Jung-Geun;Hong, Gi-Gwon;Yun, Jung-Mann;Lee, Kang-Il
    • Journal of the Korean Geosynthetics Society
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    • v.16 no.4
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    • pp.67-74
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    • 2017
  • In order to prevent the ground subsidence accidents caused by the occurrence of underground cavity, it is necessary to evaluate the mechanical characteristics in the relaxation zone of the underground cavity. Also, the relaxation zone including underground cavity be appropriately reinforced. This paper described analysis results based on finite element method that was conducted to analyze the mechanism for occurrence of the relaxation zone around the underground cavity. The finite element analysis applied in forced displacement was carried out to simulate the underground cavity and relaxation zone, and then there were compared with previous research results. The analysis results showed that the void distribution of soil around the underground cavity has figured out. As a result, the area of the relaxation zone could be quantitatively presented by reduction characteristics of the shear stress.