• Title/Summary/Keyword: Nonlinear Finite Element Method

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3-Dimensional Nonlinear Analysis of Low Velocity Impact On Composite Plates (복합재료 평판의 비선형 3차원 저속 충격 해석)

  • 김승조;지국현
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2000.04a
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    • pp.38-42
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    • 2000
  • In this study, the low velocity impact behavior of the composite laminates has been described by using 3 dimensional nonlinear finite elements. To describe the geometric nonlinearity due to large deformation, the dynamic contact problem is formulated using the exterior penalty finite element method on the base of Total Lagrangian formulation. The incremental decomposition is introduced, and the converged solution is attained by Newton-Raphson Method. The Newmark's constant-acceleration time integration algorithm is used. To make verification of the finite element program developed in this study, the solution of the nonlinear static problem with occurrence of large deformation is compared with ABAQUS, and the solution of the static contact problem with indentation is compared with the Hertz solution. And, the solution of low velocity impact problem for isotropic material is verificated by comparison with that of LS-DYNA3D. Finally the contact force of impact response from the nonlinear analysis are compared with those from the linear analysis.

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An Analysis on the Nonlinear Behavior of Block Pavements using Multi-Load Level Falling Weight Deflectometer Testing (다단계 FWD 하중을 이용한 블록포장의 비선형 거동 분석)

  • Park, Hee Mun;Kim, Yeon Tae;Lee, Su Hyung
    • International Journal of Highway Engineering
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    • v.18 no.6
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    • pp.35-40
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    • 2016
  • OBJECTIVES : The objective of this study is to analyze the nonlinear behavior of block pavements using multi-load level falling weight deflectometer (FWD) deflections. METHODS : Recently, block pavements are employed not only in sidewalks, but also in roadways. For the application of block pavements in roadways, the structural capacities of subbase and subgrade are important factors that support the carry traffic load. Multi-load level FWD testing was conducted on block pavements to analyze their nonlinear behavior. The deflection ratio due to the increase in load was analyzed to estimate the nonlinearity of block pavements. Finite element method with nonlinear soil model was applied to simulate the actual nonlinear behavior of the block pavement under different levels of load. RESULTS : The results of the FWD testing show that the center deflections in block pavements are approximately ten times greater than that in asphalt pavements. The deflection ratios of the block pavement due to the increase in the load range from 1.2 to 1.5, indicating that the deflection increased by 20~50%. The material coefficients of the nonlinear soil model were determined by comparing the measured deflections with the predicted deflections using the finite element method. CONCLUSIONS : In this study, the nonlinear behavior of block pavements was reviewed using multi-load level FWD testing. The deflection ratio proposed in this study can estimate the nonlinearity of block pavements. The use of nonlinear soil model in subbase and subgrade increases the accuracy of predicting deflections in finite element method.

Nonlinear Numerical Analysis and Experiment of Composite Laminated Plates (복합재 적층판재의 비선형 수치해석 및 실험)

  • 조원만;이영신;윤성기
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.12
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    • pp.2915-2925
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    • 1993
  • A finite element program using degenerated shell element was developed to solve the geometric, material and combined nonlinear behaviors of composite laminated plates. The total Lagrangian method was implemented for geometric nonlinear analysis. The material nonlinear behavior was analyzed by considering the matrix degradation due to the progressive failure in the matrix and matrix-fiber interface after initial failure. The results of the geometric nonlinear analyses showed good agreements with the other exact and numerical solutions. The results of the combined nonlinear analyses considered both geometric and material nonlinear behaviors were compared to the experiments in which a concentrated force was applied to the center of the square laminated plate with clamped four edges.

ERROR ESTIMATION FOR NONLINEAR ELLIPTIC PROBLEMS USING THE h-p-MIXED FINITE ELEMENT METHOD IN 3 DIMENSIONAL SPACE

  • Lee, Mi-Young
    • Bulletin of the Korean Mathematical Society
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    • v.38 no.2
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    • pp.237-260
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    • 2001
  • The approximation properties for $L^2$-projection, Raviart-Thomas projection, and inverse inequality have been derived in 3 dimensional space. h-p-mixed finite element methods for strongly nonlinear second order elliptic problems are proposed and analyzed in 3D. Solvability and convergence of the linearized problem have been shown through duality argument and fixed point argument. The analysis is carried out in detail using Raviart-Thomas-Nedelec spaces as an example.

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Nonlinear Analysis of the Monoleaflet Polymer Valve According to Shape of Supporting Members (지지대 형상에 따른 단엽식 고분자 판막의 비선형 해석)

  • 한근조;안성찬;심재준;김성윤
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.748-751
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    • 2001
  • Monoleaflet polymer artificial heart valve was known to show remarkable improvement in antithrombosis and pressure drop compared with other type of artificial valve. In this investigation monoleaflet the vertical and horizontal deflection pattern of polymer heart valve with three types of supporting members straight member, and two curved members was analysed using the large deformation nonlinear finite element method.

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Nonlinear Analysis of the Monoleaflet Polymer Valve according to Shape of Supporting Members (지지대 형상에 따른 단엽식 고분자 판막의 비선형 해석)

  • 한근조;안성찬;심재준;김성윤
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.3
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    • pp.120-124
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    • 2003
  • Monoleaflet polymer artificial heart valve was known to show remarkable improvement in antithrombosis and pressure drop compared with other type of artificial valve. In this investigation of monoleaflet heart valve the vertical and horizontal deflection pattern of polymer heart valve with three types of supporting members, straight member and two curved members were analysed using the large deformation nonlinear finite element method.

Ambient vibration based structural evaluation of reinforced concrete building model

  • Gunaydin, Murat;Adanur, Suleyman;Altunisik, Ahmet C.
    • Earthquakes and Structures
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    • v.15 no.3
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    • pp.335-350
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    • 2018
  • This paper presents numerical modelling, modal testing, finite element model updating, linear and nonlinear earthquake behavior of a reinforced concrete building model. A 1/2 geometrically scale, two-storey, reinforced concrete frame model with raft base were constructed, tested and analyzed. Modal testing on the model using ambient vibrations is performed to illustrate the dynamic characteristics experimentally. Finite element model of the structure is developed by ANSYS software and dynamic characteristics such as natural frequencies, mode shapes and damping ratios are calculated numerically. The enhanced frequency domain decomposition method and the stochastic subspace identification method are used for identifying dynamic characteristics experimentally and such values are used to update the finite element models. Different parameters of the model are calibrated using manual tuning process to minimize the differences between the numerically calculated and experimentally measured dynamic characteristics. The maximum difference between the measured and numerically calculated frequencies is reduced from 28.47% to 4.75% with the model updating. To determine the effects of the finite element model updating on the earthquake behavior, linear and nonlinear earthquake analyses are performed using 1992 Erzincan earthquake record, before and after model updating. After model updating, the maximum differences in the displacements and stresses were obtained as 29% and 25% for the linear earthquake analysis and 28% and 47% for the nonlinear earthquake analysis compared with that obtained from initial earthquake results before model updating. These differences state that finite element model updating provides a significant influence on linear and especially nonlinear earthquake behavior of buildings.

A Study on the Mixed Finite Element Models of Nonlinear Beam Bending Based on the Unconventional Residual Minimizing Method (비전통적 오차 최소화 방식에 기초한 비선형 빔의 휨에 대한 혼합형 유한요소해석 모델 연구)

  • Kim, Woo-Ram;Choi, Youn-Dae
    • Journal of the Korea Institute of Military Science and Technology
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    • v.12 no.6
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    • pp.785-795
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    • 2009
  • In this paper, new type of finite element models for the analysis of nonlinear beam bending are developed by using unconventional residual minimizing method to increase accuracy of finite element solutions and overcome some of computational drawbacks. Developing procedures of the new models are presented along with the comparison of the numerical results of existing beam bending models.

Soil-Structure Interaction Analysis Method in Time Domain considering Near-Field Nonlinearity (근역지반의 비선형성을 고려한 시간영역 지반-구조물 상호작용 해석기법의 개발)

  • 김문겸;임윤묵;김태욱;박정열
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2001.04a
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    • pp.309-314
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    • 2001
  • In this study, the nonlinear soil structure interaction analysis method based on finite element and boundary element method is developed. In the seismic region, the nonlinearity of near field soil has to be considered for more exact reflection of soil-structure interaction effect. Thus, nonlinear finite element program coupled with boundary elements is developed for nonlinear soil-structure interaction analysis. Using the developed numerical algorithm, the nonlinear soil-structure interaction analysis is performed and responses due to dynamic forces and seismic excitation are investigated. The developed method is verified by comparing with previous studies.

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Augmented Displacement Load Method for Nonlinear Semi-analytical Design Sensitivity Analysis (준해석적 비선형 설계민감도를 위한 개선된 변위하중법)

  • Lee, Min-Uk;Yoo, Jung-Hun;Lee, Tae-Hee
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.492-497
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    • 2004
  • Three methods for design sensitivity such as numerical differentiation, analytical method and semi-analytical method have been developed for the last three decades. Although analytical design sensitivity analysis is exact, it is hard to implement for practical design problems. Therefore, numerical method such as finite difference method is widely used to simply obtain the design sensitivity in most cases. The numerical differentiation is sufficiently accurate and reliable for most linear problems. However, it turns out that the numerical differentiation is inefficient and inaccurate because its computational cost depends on the number of design variables and large numerical errors can be included especially in nonlinear design sensitivity analysis. Thus semi-analytical method is more suitable for complicated design problems. Moreover semi-analytical method is easy to be performed in design procedure, which can be coupled with an analysis solver such as commercial finite element package. In this paper, implementation procedure for the semi-analytical design sensitivity analysis outside of the commercial finite element package is studied and computational technique is proposed, which evaluates the pseudo-load for design sensitivity analysis easily by using the design variation of corresponding internal nodal forces. Errors in semi-analytical design sensitivity analysis are examined and numerical examples are illustrated to confirm the reduction of numerical error considerably.

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