• Title, Summary, Keyword: Large Deformation

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Analyses of Large Deformation Problems in Geotechnical Engineering using Particle Method (입자법을 이용한 지반공학 대변형 문제 해석)

  • Park, Sung-Sik
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.1090-1094
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    • 2009
  • Many problems in geotechnical engineering such as slop failure, debris flow, ground heaving due to embankment, and lateral flow caused by liquefaction are related to large deformation rather than small deformation. Traditional numerical methods such as finite element and finite difference methods have a difficulty to solve such large deformations because they use grids. A particle method was developed for fluid dynamics. The particle method can solve large deformation problems because it uses particles to discretize differential equations. It can also include soil constitutive model and thus solve soil behavior on various boundary conditions. In this study, a particle method, which is based on particles rather than grids, is introduced and used to simulate large deformation including soil failure. The developed method can be applied for various large deformation problems in geotechnical engineering because it incorporates soil constitutive models.

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A Numerical Study on Mechanical Behavior with Cyclic Deformation of Anterior Cruciate Ligament (슬관절 전방 십자 인대의 반복 변형하에서의 역학적 거동에 관한 수치적 연구)

  • Ban, Yong;Choi, Deok-Kee
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.12
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    • pp.1366-1374
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    • 2009
  • Anterior cruciate ligament(ACL) of human body experiences a large deformation. May during everyday when large deformation is repeated by various activities such as outdoor activity, ACL easily get damaged. In order to acknowledge the effect of the cyclic large deformation to ACL, the constitutive equations for ACL are derived from experiment data. The concept of the objective stress rate plays a important role wherever large deformation occurs. In order to obtain the objective stress rates the eigenprojection technique is used. A comparison is made for four different cases: Jaumann rate, Green-Naghdi rate, logarithmic rate and twirl tensor of Eulerian triad rate for an isotropic material subject to cyclic deformation, such as simple shear motion. Four different materials are studied to compare the behavior of the materials for ACL using different objective rates. Finally, more complicated model with fibers for soft tissues is used to calculate the behavior subjected to cyclic large deformation.

Finite Element Analysis for Plastic Large Deformation and Anisotropic Damage

  • Nho, In-Sik;Yim, Sahng-Jun
    • Journal of Hydrospace Technology
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    • v.1 no.1
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    • pp.111-124
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    • 1995
  • An improved analysis model for material nonlinearity induced by elasto-plastic deformation and damage including a large strain response was proposed. The elasto-plastic-damage constitutive model based on the continuum damage mechanics approach was adopted to overcome limitations of the conventional plastic analysis theory. It can manage the anisotropic tonsorial damage evolved during the time-independent plastic deformation process of materials. Updated Lagrangian finite element formulation for elasto-plastic damage coupling problems including large deformation, large rotation and large strain problems was completed to develop a numerical model which can predict all kinds of structural nonlinearities and damage rationally. Finally a finite element analysis code for two-dimensional plane problems was developed and the applicability and validity of the numerical model was investigated through some numerical examples. Calculations showed reasonable results in both geometrical nonlinear problems due to large deformation and material nonlinearity including the damage effect.

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Remeshing Criterion for Large Deformation Finite Element Analyses Based on the Error Calculation (오차계산에 기초한 대변형 유한요소 해석에서의 요소망 재구성 기준)

  • 김형종;김낙수
    • Transactions of Materials Processing
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    • v.4 no.1
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    • pp.92-104
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    • 1995
  • It often happens some elements are so largely distorted during a large-deformation finite element analysis that further calculation becomes impossible or the approximation error increases rapidly. This problem can be overcomed only by remeshing at several suitable stages. The present study aimed to establish the criterion based on the error estimators, and examined in the simulation and posterior error analysis of ring compression test to demonstrate the usefulness of them. The distribution of each error estimator and its variation during deformation were investigated. All the error estimators were increased monotonously with deformation and decreased rapidly at remeshing stage. It was shown that the error estimators suggested in this study are good measures as remeshing criterion for large deformation finite element analyses.

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Automatic Quadrilateral Mesh Generation for Large Deformation Finite Element Analysis (대변형 유한요소해석을 위한 요소망 자동 생성기법)

  • 김동준;최호준;장동환;임중연;이호용;황병복
    • Transactions of Materials Processing
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    • v.12 no.3
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    • pp.194-201
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    • 2003
  • An automatic quadrilateral mesh generator for large deformation finite element analysis such as metal forming simulation was developed. The NURBS interpolation method is used for modeling arbitrary 2-D free surface. This mesh generation technique is the modified paving algorithm, which is an advancing front technique with element-by-element resolving method for paving boundary intersection problem. The mesh density for higher analysis accuracy and less analysis time can be easily controlled with high-density points, maximum and minimum element size. A couple of application to large deformation finite element analysis is given as an example, which shows versatility and applicability of the proposed approach and the developed mesh generator for large deformation finite element analysis.

A Fundamental Study on Forecast of the Thin Plate Welding Deformation by Numerical Simulation (수치시뮬레이션에 의한 박판 용접 변형 예측에 관한 기초적 연구)

  • 김종명;박창수;김영표;방한서
    • Journal of Welding and Joining
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    • v.21 no.1
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    • pp.93-98
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    • 2003
  • For construction of steel structures, thin steel plates have been often used and welding is the main manufacturing process. However, welding processes cause some problems(welding residual stresses, welding deformations, etc.). In these problems, welding deformation is extremely harmful to the safety of structures especially. Therefore, in this study, a numerical analysis program based on large deformation plate theory has been developed to analyze and predict the welding deformation in thin plates. From the result of numerical analyse, we can find two parameters, thermal cycles and mechanical restraints affecting the welding deformation of structures. It is considered that large difference of thermal cycles and mechanical restraints in the width direction bring about welding deformation. Results of simulation have the same tendency of deformation distribution in width direction as experimental formulas.

Deformation and stress behavior analysis of high concrete dam under the effect of reservoir basin deformation

  • Zheng, Dongjian;Xu, Yanxin;Yang, Meng;Gu, Hao;Su, Huaizhi;Cui, Xinbo;Zhao, Erfeng
    • Computers and Concrete
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    • v.18 no.6
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    • pp.1153-1173
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    • 2016
  • According to deformation data measured in some high concrete dams, for dam body deformation, there is a complex relationship with dam height and water head for different projects, instead of a simple monotonic relationship consistently. Meanwhile, settlement data of some large reservoirs exhibit a significant deformation of reservoir basin. As water conservancy project with high concrete dam and large storage capacity increase rapidly these decades, reservoir basin deformation problem has gradually gained engineers' attentions. In this paper, based on conventional analytical method, an improved analytical method for high concrete dam is proposed including the effect of reservoir basin deformation. Though establishing FEM models of two different scales covering reservoir basin and near dam area respectively, influence of reservoir basin on dam body is simulated. Then, forward and inverse analyses of concrete dam are separately conducted with conventional and proposed analytical methods. And the influence of reservoir basin deformation on dam working behavior is evaluated. The results of two typical projects demonstrate that reservoir basin deformation will affect dam deformation and stress to a certain extent. And for project with large and centralized water capacity ahead of dam site, the effect is more significant than those with a slim-type reservoir. As a result, influence of reservoir basin should be taken into consideration with conducting analysis of high concrete dam with large storage capacity.

Study on the Rheological Properties and Effects of Tannin components of Acorn Starch Gel (도토리 전분 묵의 Rheology 특성과 Tannin성분의 영향에 대하여)

  • 구성자
    • Journal of the Korean Home Economics Association
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    • v.23 no.1
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    • pp.33-47
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    • 1985
  • The rheological properties of acorn starch gel were investigated in region of small and large deformation. The properties were compared with those of potato and wheat starch gel. On the physical characteristics and the effect of tannin contents of acorn starch were examined. RESULTS : 1. X-ray diffractogram of acorn starch showed C-type and its granules swelled gradully with heating. 2. Hardness, brittleness and both small and large deformation of the acorn starch gel were remarkably large, also the concentration dependence of the acorn starch gel could be recognized in small deformation and hardness. 3. The Young's modulus of Hookean body in small deformation and the rupture stress in large deformation differed obviously from the parameters of rheological properties in various gels. 4. It was found that the selling power, viscosity and rhelogical properties were affected obviously by the tannin.

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A numerical analysis of the large deflection of an elastoplastic cantilever

  • Wang, B.;Lu, G.;Yu, T.X.
    • Structural Engineering and Mechanics
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    • v.3 no.2
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    • pp.163-172
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    • 1995
  • A simple numerical method is applied to calculate the large deflection of a cantilever beam under an elastic-plastic deformation by dividing the deformed axis into a number of small segments. Assuming that each segment can be approximated as a circular arc, the method allows large deflections and plastic deformation to be analyzed. The main interests are the load-deflection relationship, curvature distribution along the beam and the length of the plastic region. The method is proved to be easy and particularly versatile. Comparisons with other studies are given.

Large deformation modeling of flexible manipulators to determine allowable load

  • Esfandiar, Habib;Korayem, Moharam H.;Haghpanahi, Mohammad
    • Structural Engineering and Mechanics
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    • v.62 no.5
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    • pp.619-629
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    • 2017
  • This paper focuses on the study of complete dynamic modeling and maximum dynamic load carrying capacity computation of N-flexible links and N-flexible joints mobile manipulator undergoing large deformation. Nonlinear dynamic analysis relies on the Timoshenko theory of beams. In order to model the system completely and precisely, structural and joint flexibility, nonlinear strain-displacement relationship, payload, and non-holonomic constraints will be considered to. A finite element solution method based on mixed method is applied to model the shear deformation. This procedure is considerably more involved than displacement based element and shear deformation can be readily included without inducing the shear locking in the element. Another goal of this paper is to present a computational procedure for determination of the maximum dynamic load of geometrically nonlinear manipulators with structural and joint flexibility. An effective measure named as Moment-Height Stability (MHS) measure is applied to consider the dynamic stability of a wheeled mobile manipulator. Simulations are performed for mobile base manipulator with two flexible links and joints. The results represent that dynamic stability constraint is sensitive when calculating the maximum carrying load. Furthermore, by changing the trajectory of end effector, allowable load also changes. The effect of torsional spring parameter on the joint deformation is investigated in a parametric sensitivity study. The findings show that, by the increase of torsional stiffness, the behavior of system approaches to a system with rigid joints and allowable load of robot is also enhanced. A comparison is also made between the results obtained from small and large deformation models. Fluctuation range in obtained figures for angular displacement of links and end effector path is bigger for large deformation model. Experimental results are also provided to validate the theoretical model and these have good agreement with the simulated results.