Development of triangular flat-shell element using a new thin-thick plate bending element based on semiLoof constrains

Chen, Yong-Liang,Cen, Song,Yao, Zhen-Han,Long, Yu-Qiu,Long, Zhi-Fei Techno-Press 2003 Structural Engineering and Mechanics, An Int'l Jou Vol.15 No.1

A new simple 3-node triangular flat-shell element with standard nodal DOF (6 DOF per node) is proposed for the linear and geometrically nonlinear analysis of very thin to thick plate and shell structures. The formulation of element GT9 (Long and Xu 1994), a generalized conforming membrane element with rigid rotational freedoms, is employed as the membrane component of the new shell element. Both one-point reduced integration scheme and a corresponding stabilization matrix are adopted for avoiding membrane locking and hourglass phenomenon. The bending component of the new element comes from a new generalized conforming Kirchhoff-Mindlin plate element TSL-T9, which is derived in this paper based on semiLoof constrains and rational shear interpolation. Thus the convergence can be guaranteed and no shear locking will happen. Furthermore, a simple hybrid procedure is suggested to improve the stress solutions, and the Updated Lagrangian formulae are also established for the geometrically nonlinear problems. Numerical results with solutions, which are solved by some other recent element models and the models in the commercial finite element software ABAQUS, are presented. They show that the proposed element, denoted as GMST18, exhibits excellent and better performance for the analysis of thin-think plates and shells in both linear and geometrically nonlinear problems.

Nonlinear interaction behaviour of plane frame-layered soil system subjected to seismic loading

Ramakant Agrawal,M.S. Hora 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.41 No.6

The foundation of a tall building frame resting on settable soil mass undergoes differential settlements which alter the forces in the structural members significantly. For tall buildings it is essential to consider seismic forces in analysis. The building frame, foundation and soil mass are considered to act as single integral compatible structural unit. The stress-strain characteristics of the supporting soil play a vital role in the interaction analysis. The resulting differential settlements of the soil mass are responsible for the redistribution of forces in the superstructure. In the present work, the nonlinear interaction analysis of a two-bay ten-storey plane building frame- layered soil system under seismic loading has been carried out using the coupled finite-infinite elements. The frame has been considered to act in linear elastic manner while the soil mass to act as nonlinear elastic manner. The subsoil in reality exists in layered formation and consists of various soil layers having different properties. Each individual soil layer in reality can be considered to behave in nonlinear manner. The nonlinear layered system as a whole will undergo differential settlements. Thus, it becomes essential to study the structural behaviour of a structure resting on such nonlinear composite layered soil system. The nonlinear constitutive hyperbolic soil model available in the literature is adopted to model the nonlinear behaviour of the soil mass. The structural behaviour of the interaction system is investigated as the shear forces and bending moments in superstructure get significantly altered due to differential settlements of the soil mass.

Nonlinear interaction behaviour of plane frame-layered soil system subjected to seismic loading

Agrawal, Ramakant,Hora, M.S. Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.41 No.6

The foundation of a tall building frame resting on settable soil mass undergoes differential settlements which alter the forces in the structural members significantly. For tall buildings it is essential to consider seismic forces in analysis. The building frame, foundation and soil mass are considered to act as single integral compatible structural unit. The stress-strain characteristics of the supporting soil play a vital role in the interaction analysis. The resulting differential settlements of the soil mass are responsible for the redistribution of forces in the superstructure. In the present work, the nonlinear interaction analysis of a two-bay ten-storey plane building frame- layered soil system under seismic loading has been carried out using the coupled finite-infinite elements. The frame has been considered to act in linear elastic manner while the soil mass to act as nonlinear elastic manner. The subsoil in reality exists in layered formation and consists of various soil layers having different properties. Each individual soil layer in reality can be considered to behave in nonlinear manner. The nonlinear layered system as a whole will undergo differential settlements. Thus, it becomes essential to study the structural behaviour of a structure resting on such nonlinear composite layered soil system. The nonlinear constitutive hyperbolic soil model available in the literature is adopted to model the nonlinear behaviour of the soil mass. The structural behaviour of the interaction system is investigated as the shear forces and bending moments in superstructure get significantly altered due to differential settlements of the soil mass.

유한 요소법을 이용한 비선형 슬러싱 문제 해석

경조현,배광준,김장환,조석규 한국해양환경·에너지학회 2004 한국해양환경·에너지학회지 Vol.7 No.4

A nonlinear sloshing problem is numerically simulated. During excessive sloshing the sloshing-induced impact load can cause a critical damage on the tank structure. A three-dimensional free-surface flow in a tank is formulated in the scope of potential flow theory. The exact nonlinear free-surface condition is satisfied numerically. A finite-element method based on Hamiltons principle is employed as a numerical scheme. The problem is treated as an initial-value problem. The computations are made through an iterative method at each time step. The hydrodynamic loading on the pillar in the tank is computed. 본 논문에서는 3차원 비선형 슬러싱 유동에 대한 수치해법을 개발하였다. 탱크내에서 과도한 슬러싱 유동이 일어 나는 경우에는 슬러싱 유동에 의해 유기되는 유체 충격력에 의해 탱크 내부 부재나 탱크 자체의 손상을 야기할 수 있다. 비선형 슬러싱 유동을 포텐셜 유동 이론에 근거한 자유표면파 문제로 정식화하고, 엄밀한 비선형 자유표면 경 계조건을 적용하여 수치적으로 해석하였다. 안정된 수치 해법 개발을 위해 해밀톤 원리에 근거한 변분법을 사용하 였으며 얻어진 변분식에 유한 요소법을 적용하여 해석하였다. 비선형 자유표면 유동은 시간영역에서의 초기치 문제 로 해석하였으며 자유표면의 위치는 매 계산 시간 간격마다 반복계산에 의해 결정되었다. 수치 해석 결과로는 탱크 내에 위치한 파이프에 비선형 슬러싱 유동에 의해 야기되는 유체 충격력을 구하였다.

Large amplitude free vibration analysis of laminated composite spherical shells embedded with piezoelectric layers

Subrata K. Panda,Vijay K. Singh 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.16 No.5

Numerical analysis of large amplitude free vibration behaviour of laminated composite spherical shell panel embedded with the piezoelectric layer is presented in this article. For the investigation purpose, a general nonlinear mathematical model has been developed using higher order shear deformation mid-plane kinematics and Green-Lagrange nonlinearity. In addition, all the nonlinear higher order terms are included in the present mathematical model to achieve any general case. The nonlinear governing equation of freely vibrated shell panel is obtained using Hamilton\'s principle and discretised using isoparametric finite element steps. The desired nonlinear solutions are computed numerically through a direct iterative method. The validity of present nonlinear model has been checked by comparing the responses to those available published literature. In order to examine the efficacy and applicability of the present developed model, few numerical examples are solved for different geometrical parameters (fibre orientation, thickness ratio, aspect ratio, curvature ratio, support conditions and amplitude ratio) with and/or without piezo embedded layers and discussed in details.

비선형 유한요소해석 프로그램을 이용한 차체 구조물의 동강성 및 정강성 해석

김성현(Sunghyun Kim),김형일(Hyungil Kim),변형배(Hyungbai Byun),김동석(Dongseok Kim),이용훈(Yonghoon Lee),김일환(Ilhwan Kim),허승진(Seung Jin Heo),임홍재(Hong Jae Yim) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5

In this study, dynamic stiffness analysis and static stiffness analysis were conducted by using nonlinear finite element analysis program and linear finite element analysis respectively to compare the results and to confirm reliability about results of nonlinear finite element analysis program. First, dynamic stiffness analysis has been performed on side out panel, crash box, sub-frame and BIW(Body In White) that has been connected with front bumper, rear bumper and sub-frame. Second, static stiffness analysis has been conducted on crash box and hood that has been modeled with spot weld elements and rigid body elements. Consequently, differences of dynamic and static stiffness analysis results through nonlinear finite element analysis program and linear finite element analysis were below 6 % but difference was more than 6 % as to dynamic stiffness of BIW.

Evaluation of the seismic performance of off-centre bracing system with ductile element in steel frames

Mohammad Bazzaz,Ali Kheyroddin,Mohammad Ali Kafi,Zahra Andalib 국제구조공학회 2012 Steel and Composite Structures, An International J Vol.12 No.5

In order to evaluate the dynamic behavior of passive energy dissipation system, two steps need to be considered for prediction of structural response in the presence of ductile element in an off-centre bracing system. The first is a detailed analysis of the proposed ductile element and the second is the effect of this ductile element on an off-centre bracing system. The use of ductile bracing system is expanding in steel structures in order to increase the force reduction factor. Therefore, regarding the nonlinear behavior of steel material used in an off-centre bracing systems and using ductile element in OBS bracing systems, the seismic evaluation of the mentioned systems seems to be necessary. This paper aims to study linear and nonlinear behavior of steel frames with off-centre bracing system and ductile element, in order to get the best position of these bracing elements. To achieve this purpose, the modeling has been done with ANSYS software. The optimum eccentricity has been obtained by modeling three steel frames with different eccentricities and evaluating the results of them. The analytical results showed that the model OBS-C with 0.3 eccentricities has higher performance among the models.

Nonlinear finite element analysis of loading transferred from column to socket base

Özgür ANIL,Burak UYAROĞLU 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.11 No.5

Since the beginning of the 90 s, depending on the growth of the industrial sector in Turkey,factory constructions have been increased. The cost of precast concrete buildings is lower than the steel ones for this reason the precast structural systems are used more. Precast concrete structural elements are mostly as strong as not to have damage in the earthquake but weakness of connections between elements causes unexpected damages of structure during earthquake. When looking at the previous researches, it can be seen that there is a lack of studies about socket type base connections although there were many experimental and analytical studies about the connections of precast structural elements. The aim of this study is to investigate the stress transfer mechanism between column and the socket base wall with finite element method. For the finite element analysis ANSYS software was used. A finite element model was created which is the simulation of experimental research executed by Canha et al. (2009) under vertical and horizontal forces. Results of experimental research and finite element analysis were compared to create a successful simulation of experimental program. After determining the acceptable parameters, models of socket bases were created. Model dimensions were chosen according to square section column sizes 400, 450, 500, 550 and 600 mm which were mostly used in industrial buildings. As a result of this study, stress distribution at center section of the socket base models were observed and it is found that stress distribution affects triangular at the half of socket bottom and top.

S. I. 기법을 이용한 유한요소모델의 신뢰도 제고에 관한 연구

양경택 한국전산구조공학회 1997 전산구조공학 Vol.10 No.2

본 연구에서는 경계부 및 연결부를 지닌 기계 구조물의 유한요소모델 수립시 상대적으로 불확실성이 많은 경계부 및 연결부를 정확히 모델링하여 전체 구조계에 대한 해석적 모델의 신뢰도를 제고하는데 그 목적을 두고, 현장에서 간단히 측정할 수 있는 측정 데이터와 축약된 형태의 유한요소모델을 이용하는 S.I.기법을 제시하였다. 제시된 방법은 연결부를 제외한 연속체를 유한요소법으로 모델링하고 연결부의 동적 계수를 변수 상태로 하여 시간 영역에서의 비선형 상태 방정식을 구성하였으며 계수 규명 문제를 비선형 상태 방정식의 상태 추정 문제로 변환하여 해결하였다. 두 가지 예제에 대한 수치 해석을 통하여 제시된 기법의 타당성을 검증하였다. Mechanical structures are composed of substructures connected by joints and boundary elements. While the finite element representation of plain substructures is well developed and reliable, joints have a lot of uncertainties in being accurately modelled and affect dynamic behavior of a total system. In order to improve the accuracy of a finite element model, a new method is proposed, in which reduced finite element model is combined with a system identification technique. After substructures except joints are modelled with finite element method and joint properties are represented by parameter states, non-linear state equation is derived in which parameter states are multiplied by physical states such as displacements and velocities. So the joint parameter identification is transformed into non-linear state estimation problem. The methods are tested and discussed numerically and the feasibility for physical application has been demonstrated through two example structures.

Formulation of Two Nodes Finite Element Model for Geometric Nonlinear Analysis of RHS Beams Accounting for Distortion and Shear Deformations

Meftah Sid Ahmed,Abdelouahed Tounsi,Pham Van Vinh 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.4

In this paper, the nonlinear buckling analysis of rectangular hollow sections (RHS) beams considering distortional and the shear fl exibility deformation eff ects is investigated. The kinematic model is based on the incorporation of non-classical terms, related to shear fl exibility, according to Timoshenko model and distortion and warping. This analysis is carried out by proposing a new 3D fi nite element, formulated in the context of large torsion, incorporating fl exural torsion, and distortion coupling eff ects. A 3D RHS beam element with two nodes and eleven degrees of freedom per node is proposed to perform the nonlinear buckling analysis. For this aim, the arc-length method is employed as a solution strategy to solve the nonlinear equilibrium equations, established as a function of the trigonometric functions of the twist angle. Many examples are proposed to check the validity of the proposed 3D fi nite element and the numerical procedure, either in pre-and postbuckling states. The present numerical results are compared to those of the commercial software ABAQUS using the brick fi nite elements. The incidences of the compressive load and the incorporated lateral stiff eners in the RHS beams in pre- and post-buckling behaviour are studied.