• Title, Summary, Keyword: 비선형 동적해석

Search Result 558, Processing Time 0.069 seconds

Random Vibration Analysis of Nonlinear Stochastic System under Earthquake Using Statistical Method (지진하중을 받는 비선헝 추계적 시스템의 불규칙진동해석)

  • Moon, Byung-Young;Kang, Gyung-Ju;Kang, Beom-Soo
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.5 no.6
    • /
    • pp.55-64
    • /
    • 2001
  • Industrial machines are sometimes exposed to the danger of earthquake. In the design of a mechanical system, this factor should be accounted for from the viewpoint of reliability to analyze a complex nonlinear structure system under random excitation is proposed. First, the actual random excitation, such as earthquake, is approximated to the corresponding Gaussian process for the statistical analysis. The modal equations of overall system are expanded sequentially. Then, the perturbed equations are synthesized into the overall system and solved in probabilistic way. Several statistical properties of a random process that are of interest in random vibration are evaluated in each substructure. Comparing with the results of the numerical simulation proved the efficiency of the proposed method.

  • PDF

Dynamic bucking of orthotropic cylindrical shells (직교이방성 원통쉘의 동적좌굴)

  • Lu, Sung Y.;Kim, Chon w
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.5 no.4
    • /
    • pp.266-273
    • /
    • 1981
  • 갑자기 작용하는 외압을 받는 직교이방성원통쉘의 동적좌굴을 해석하였다. Donnell-Karnam 형의 비선형방정식을 유도하였으며 쉘의 초기불완전성도 고려하였다. Galerkin의 방법을 사용하여 운동방정식을 구하고 Runge-Kutta 수직해법으로 비선형방정식을 풀었다. 쉘의 직교이방성특성이 처짐-하중 관계식의 비선형성에 미치는 영향을 검토하였으며 동적산출하중의 판별법을 정의하였다. 본 연구의 결과, 직교이방성원통쉘은 쉘의 초기불완전성에 그리 민감하지 않음을 보여주었다.

Dynamic Analysis of Gimbal Structure System Including Nonlinear Elastic Rubber Vibration Isolator with Shock Acceleration (비선형 탄성 방진 고무부에 충격 가속도를 받는 짐발 구조 시스템의 동적 해석)

  • Lee, Sang Eun;Lee, Tae Won
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.40 no.4
    • /
    • pp.415-422
    • /
    • 2016
  • When shock acceleration is applied to a mechanical system, it may cause malfunctioning and damage to the system. Hence, to prevent these problems when developing a gimbal structure system for observation reconnaissance, the MIL-STD-810G shock standard must be satisfied as a design specification. Rubber vibration isolators are generally assembled on the base of the system in order to reduce the shock transferred from the aircraft. It is difficult to analyze the transient behavior of the system accurately, because rubber has a nonlinear load-deformation curve. To treat the nonlinear characteristic of the rubber, bilinear approximation was introduced. Using this assumption, transient responses of the system under base shock acceleration were calculated by the finite element method. In addition, experiments with a true prototype were performed using the same conditions as the analytical model. Compared with experimental data, the proposed numerical method is useful for the transient analysis of gimbal structure systems, including rubber vibration isolators with nonlinear stiffness and damping.

Evaluation and Application of Dynamic Soil Properties for SSI Analysis (지반-구조물 상호작용해석시 동적지반특성의 평가 및 적용)

  • Lee, Myung Jae;Shin, Jong Ho;Chon, Chun Su
    • Journal of The Korean Society of Civil Engineers
    • /
    • v.10 no.2
    • /
    • pp.103-112
    • /
    • 1990
  • This study examines the characteristics of soil behavior which includes many uncertainties in seismic design, evaluates the dynamic soil properties and studies the soil-structure interaction to generalize the applicability and economy of the available sites. An example analysis is performed for soil-structure system response assuming a containment structure built on site which includes soil layers using both elastic halfspace analysis and FEM analysis against the seismic loads from the actual design. This exercise is performed as a part of the safety analysis and economic assessment of the nuclear power plant built on soils. It includes the preparation of computer program capable of incorporating large nonlinearity in the analysis, resonable evaluation procedures to determine input soil data. Nonlinear FEM analysis of Seed and Idriss model is found suitable for the accurate analysis of dynamic response of soils. Linear FEM analysis using dynamic soil properties at strain level obtained by one-dimensional seismic response, and elastic half-space analysis using dynamic soil properties at strain level under static loads are recommended to evaluate the dynamic soil properties.

  • PDF

A Study of Dynamic Behavior of Track and Train Interaction on Rail Open Gap (레일 개구부에서의 궤도-차량 상호작용에 대한 연구)

  • Kang, Yun Suk;Kang, Young Jong;Yang, Shin Chu;Cho, Sun Kyu;Han, Sang Yun
    • Journal of Korean Society of Steel Construction
    • /
    • v.19 no.4
    • /
    • pp.345-355
    • /
    • 2007
  • During winter, the CWR (continuous welded rail) may be broken when a temperature drop below the neutral level changes the axial force, causing tensile fracture and creating a rail gap. The passage of a train on a rail with an open gap may lead to very costly derailments. In this paper, the use of a track-and-train-coupled model whose rail has an open gap is proposed for dynamic interaction analysis. Linear track and train systems were coupled in this study by a nonlinear Herzian contact spring, and the complete system matrices of the total track-train system were constructed. Moreover, the interaction phenomenon considering the presence of an open gap in the rail was toughly defined by assigning the irregularity functions between the two sides of the gap. Time history analysis, which has an iteration scheme such as the Newmark-$\beta$ method (based on the Modified Newton-Raphson methods), was conducted to solve the nonlinear equation. .Finally, numerical studies were conducted to assess the effect of the various parameters of the system when applied to various speeds, open-gap sizes, and support stiffnesses of the rail.

Dynamic Interaction of Track and Train System on Open Gap by Rail Breaks (레일 파단시 장대레일 개구부에서의 궤도-차량 동적상호작용)

  • Kang, Yun Suk;Kang, Young Jong;Yang, Shin Chu
    • Journal of The Korean Society of Civil Engineers
    • /
    • v.28 no.6D
    • /
    • pp.895-904
    • /
    • 2008
  • CWR (Continuous Welded Rail) may be broken when a temperature drop below the neutral temperature changes in axial force, causing tensile fracture and rail gap, in winter. Rail-breaks may lead to the damage of the rail and wheel by dynamic load, and the reduction of running safety if not detected before the passage of a train. In this study, the track and train coupled model with open gap for dynamic interaction analysis, is proposed. Linear track and train systems is coupled by the nonlinear Herzian contact spring and the complete system matrices of total track-train system is constructed. And the interaction phenomenon considering open gap, was defined by assigning the irregularity functions between the two sides of a gap. Time history analysis, which have an iteration scheme such as $Newmark-{\beta}$ method based on Modified Newton-Raphson methods, was performed to solve the nonlinear equation. Finally, numerical studies are performed to assess the effect of various parameters of system, apply to various speeds, open gap size and the support stiffness of rail.

  • PDF

Dynamic Nonlinear Analysis of Ocean Cables Subjected to Wave Forces (파력을 받는 해양케이블의 동적 비선형 해석)

  • 김문영;김남일;이정렬
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.11 no.4
    • /
    • pp.173-188
    • /
    • 1999
  • Kim et al.(I999) presented a non-linear finite element formulation of spatial ocean cables using multiple noded cable elements. The initial equilibrium state of ocean cables subjected to self-weights, support motions, and current forces was determined using the load incremental method and free vibration analysis were performed considering added mass, In this paper, the methods to generate regular and irregular waves and calculate wave forces due to these waves are discussed and challenging example problems are presented in order to investigate dynamic non-linear behaviors of ocean cables subjected to wave loadings.

  • PDF

A Three-Dimensional Dynamic Analysis of Towed Systems Part 1. A Mathematical Formulation (수중예인시스템의 3차원 동역학 해석 1부: 수학모델 정식화)

  • Hong, Sub;Hong, Seuk-Won
    • Journal of Ocean Engineering and Technology
    • /
    • v.8 no.1
    • /
    • pp.16-22
    • /
    • 1994
  • 수중 예인시스템의 동적 거동 해석을 위한 3차원 비선형 수학모델이 제시되었다. 수중 예인체는 세장보로 이상화되었으며, 보요소의 굽임강성 및 비틈강성의 영향이 수학모델에 포함되었다. 축류가 지배적인 비정상 상대유동장내의 세장예인체의 횡방향 운동에 따른 유체동역학적 반력과 기진력에 관한 비선형 3차원 수학 정식화가 수행되었다.

  • PDF

Nonlinear Dynamic Behaviors of Laminated Composite Structures Containing Central Cutouts (중앙개구부를 갖는 복합신소재 적층 구조의 비선형 동적 거동)

  • Ji, Hyo-Seon;Lee, Sang-Youl
    • Journal of Korean Society of Steel Construction
    • /
    • v.23 no.5
    • /
    • pp.607-614
    • /
    • 2011
  • This study deals with thegeometrical nonlinear dynamic behavior of laminated plates made of advanced composite materials (ACMs), which contain central cutouts. Based on the first-order shear deformation plate theory (FSDT), the Newmark method and Newton-Raphson iteration wereused for the nonlinear dynamic solution. The effects of the cutout sizes and lay-up sequences on the nonlinear dynamic response for various parameters werestudied using a nonlinear dynamic finite element program that was developed for this study. The several numerical results agreed well with those reported by other investigators for square composite plates with or without central cutouts, and the new results reported in this paper showed significant interactions between the cutout and the layup sequence in the laminate. Key observation points are discussed and a brief design guide for laminates with central cutouts is given.