• Title/Summary/Keyword: static and dynamic stability analysis method

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Analysis of Static and Dynamic Frictional Contact of Deformable Bodies Including Large Rotations of the Contact Surfaces

  • Lee, Kisu
    • Journal of Mechanical Science and Technology
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    • v.16 no.10
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    • pp.1276-1286
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    • 2002
  • The numerical techniques are presented to solve the static and dynamic contact problems of deformable bodies having large rotations of the contact surfaces. The contact conditions on the possible contact surfaces are enforced by using the contact error vector, and an iterative scheme similar to augmented Lagrange multiplier method is employed to reduce the contact error vector monotonically. For dynamic contact problems using implicit time integration, a contact error vector is also defined by combining the displacement, velocity, and acceleration on the contact surface. The suggested iterative technique is implemented to ABAQUS by using the UEL subroutine UEL. In this work, after the computing procedures to solve the frictional contact problems are explained, the numerical examples are presented to compare the present solutions with those obtained by ABAQUS.

Dynamic stability analysis of laminated composite plates in thermal environments

  • Chen, Chun-Sheng;Tsai, Ting-Chiang;Chen, Wei-Ren;Wei, Ching-Long
    • Steel and Composite Structures
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    • v.15 no.1
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    • pp.57-79
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    • 2013
  • This paper studies the dynamic instability of laminated composite plates under thermal and arbitrary in-plane periodic loads using first-order shear deformation plate theory. The governing partial differential equations of motion are established by a perturbation technique. Then, the Galerkin method is applied to reduce the partial differential equations to ordinary differential equations. Based on Bolotin's method, the system equations of Mathieu-type are formulated and used to determine dynamic instability regions of laminated plates in the thermal environment. The effects of temperature, layer number, modulus ratio and load parameters on the dynamic instability of laminated plates are investigated. The results reveal that static and dynamic load, layer number, modulus ratio and uniform temperature rise have a significant influence on the thermal dynamic behavior of laminated plates.

Estimation of Aircraft Stability Derivatives Using a Subsonic-supersonic Panel Method (아음속 초음속 패널법을 이용한 항공기 안정성 미계수 예측)

  • Gong, Hyo-Joon;Lee, Hyung-Ro;Kim, Beom-Soo;Lee, Seung-Soo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.40 no.5
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    • pp.385-394
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    • 2012
  • A computer program that can estimate static, dynamic stability and control derivatives using a subsonic-supersonic panel method is developed. The panel method uses subsonic-supersonic source and elementary horse shoe vortex distributions, and their strengths are determined by solving the boundary condition approximated with a thin body assumption. In addition, quasi-steady analysis on the body fixed coordinate system allows the estimation of damping coefficients of aircraft 3 axes. The code is validated by comparing the neutral point, roll and pitch damping of delta wings with published analysis results. Finally, the static, dynamic stability and control derivatives of F-18 are compared with experimental data as well as other numerical results to show the accuracy and the usefulness of the code.

A Study on Power System Voltage Stability Analysis by the Direct Lyapunov Function (Luapunov 직접법에 의한 전력계통 전압안정도 해석)

  • 문영현;박능수;이태식
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.43 no.5
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    • pp.693-702
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    • 1994
  • This paper deals with direct voltage stability analysis using a power system energy function. The structure preserved energy function is proposed as an energy function for voltage stability analysis. With the use of the proposed energy function voltage collapse conditions are derived, which yields the exactly same results with the Jacobian matrix approach. The voltage collapse phenomenon is analyzed by several methods, which shows that all of the methods produce the same voltage condition. This study also investigates the voltage collapse dynamics by using the proposed energy function. As a result, it has been found that the voltage collapse can be classified into two categories: static and dynamic instablilties which have quite different behaviors. In addition a new method is presented to calculate the power capacity limit of transmission lines with respect to voltage stability. The proposed method is tested for a 2-bus sample system, which shows the characteristics of voltage collapse phenomenon via the energy function.

The Stability of Composite Pipes Conveying Fluid (유체유동에 의한 복합재료 파이프의 안정성 연구)

  • 최재운;송오섭
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.904-910
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    • 2001
  • Static and oscillatory loss of stability of composite pipes conveying fluid is investigated. The theory of thin walled beams is applied and transverse shear, rotary inertia, primary and secondary warping effects are incorporated. The governing equations and the associated boundary conditions are derived through Hamilton's variational principle. The governing equations and the associated boundary conditions are transferred to eigenvalues problem which provides the information about the dynamic characteristics of the system. Numerical analysis is performed by using extended Gelerkin method. Critical velocity of fluid is investigated by increasing fiber angle and mass ratio of fluid to pipe including fluid.

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Static and Dynamic Instability Characteristics of Thin Plate like Beam with Internal Flaw Subjected to In-plane Harmonic Load

  • R, Rahul.;Datta, P.K.
    • International Journal of Aeronautical and Space Sciences
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    • v.14 no.1
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    • pp.19-29
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    • 2013
  • This paper deals with the study of buckling, vibration, and parametric instability characteristics in a damaged cross-ply and angle-ply laminated plate like beam under in-plane harmonic loading, using the finite element approach. Damage is modelled using an anisotropic damage formulation, based on the concept of reduction in stiffness. The effect of damage on free vibration and buckling characteristics of a thin plate like beam has been studied. It has been observed that damage shows a strong orthogonality and in general deteriorates the static and dynamic characteristics. For the harmonic type of loading, analysis was carried out on a thin plate like beam by solving the governing differential equation which is of Mathieu-Hill type, using the method of multiple scales (MMS). The effects of damage and its location on dynamic stability characteristics have been presented. The results indicate that, compared to the undamaged plate like beam, heavily damaged beams show steeper deviations in simple and combination resonance characteristics.

The Implementation of Probabilistic Security Analysis in Composite Power System Reliability (복합전력계통 신뢰도평가의 확률론적 안전도 도입)

  • Cha, Jun-Min;Kwon, Sae-Hyuk;Kim, Hyung-Chul
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.55 no.5
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    • pp.185-190
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    • 2006
  • The security analysis relates to the ability of the electric systems to survive sudden disturbances such as electric short circuits or unanticipated loss of system elements. It is composed of both steady state and dynamic security analyses, which are not two separate issues but should be considered together. In steady state security analysis including voltage security analysis, the analysis checks that the system is operated within security limits by OPF (optimal power flow) after the transition of a new operating point. On the other hand, dynamic security analysis deals that the transition will lead to an acceptable operating condition. Transient stability, which is the ability of power systems to maintain synchronism when subjected to a large disturbance, is a principal component in dynamic security analysis. Usually any loss of synchronism will cause additional outages. They make the present steady state analysis of the post-contingency condition inadequate for unstable cases. This is the reason of the need for dynamics of systems. Probabilistic criterion can be used to recognize the probabilistic nature of system components and shows the possibility of system security. A comprehensive conceptual framework for probabilistic static and dynamic assessment is presented in this paper. The simulation results of the Western System Coordinating Council (WSCC) system compare an analytical method with Monte-Carlo simulation (MCS). Also, a case study of the extended IEEE Reliability Test System (RTS) shows the efficiency of this approach.

Numerical Study on Earthquake Performance of Gravity Dam Considering Earthquake Frequencies (지진진동수에 따른 콘크리트 중력댐의 내진성능에 대한 해석적 사례연구)

  • Chai, Young-Suk;Min, In-Ki
    • Journal of the Korean Society of Safety
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    • v.31 no.4
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    • pp.64-74
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    • 2016
  • Recently, the seismic stability evaluation of concrete gravity dams is raised due to the failure of dams occurred by the Izmit, Turkey and JiJi, Taiwan earthquake in 1999. Dams failure may incur loss of life and properties around the dam as well as damage to dam structure itself. Recently, there has been growing much concerns about "earthquake - resistance" or "seismic safety" of existing concrete gravity dams designed before current seismic design provisions were implemented. This research develops three evaluation levels for seismic stability of concrete gravity dams on the basis of the evaluation method of seismic stability of concrete gravity dams in U.S.A., Japan, Canada, and etc. Level 1 is a preliminary evaluation which is for purpose of screening. Level 2 is a pseudo-static evaluation on the basis of the seismic intensity method. And level 3 is a detail evaluation by the dynamic analysis. Evaluation results on existing concrete gravity dams on operation showed good seismic performance under designed artificial earthquake(KHC earthquake).

Adaptive Flux Observer with On-line Inductance Estimation of an Interior PM Synchronous Machine Considering Magnetic Saturation

  • Jeong, Yu-Seok;Lee, Jun-Young
    • Journal of Power Electronics
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    • v.9 no.2
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    • pp.188-197
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    • 2009
  • This paper presents an adaptive flux observer to estimate stator flux linkage and stator inductances of an interior permanent-magnet synchronous machine considering magnetic saturation. The concept of static and dynamic inductances due to saturation is introduced in the machine model to describe the relationship between current and flux linkage and the relationship between their time derivatives. A flux observer designed in the stationary reference frame with constant inductance is analyzed in the rotor reference frame by a frequency-response characteristic. An adaptive algorithm for an on-line inductance estimation is proposed and a Lyapunov-based analysis is given to discuss its stability. The dynamic inductances are estimated by using Taylor approximation based on the static inductances estimated by the adaptive method. The simulation and experimental results show the feasibility and performance of the proposed technique.

A Study on the Modeling and Analysis of Chatter in Turning Operation (선반가공시 채터 모델링과 분석에 관한 연구)

  • 윤문철;조현덕;김성근;김영국;조희근
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.10 no.4
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    • pp.76-83
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    • 2001
  • In this study, the static and dynamic characteristics of turning process was modelled and the analytic realization of regen-erative chatter mechanism was discussed. In this regard, we have discussed on the comparative assessment of recursive times series modeling algorithms that can represent the machining process and detect the abnormal machining behaviors in precision turning operation. In this study, simulation and experimental work were performed to show the malfunction behaviors. For this purpose, new Recursive Extended Instrument Variable Method(REIVM) was adopted for the on-line system identification and monitoring of a machining process. Also, we can apply REIVE algorithms in real process for the detection of chatter frequency and dynamic property and analyze the stability lobe of the system by changing a parameter of cutting dynamics in regenerative chatter mechanics, if it is stable or unstable, Also, The stability lobe of chatter was analysed.

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