Beam finite element model of a vibrate wind blade in large elastic deformation

Hedi Hamdi,Khaled Farah 한국풍공학회 2018 Wind and Structures, An International Journal (WAS Vol.26 No.1

This paper presents a beam finite element model of a vibrate wind blade in large elastic deformation subjected to the aerodynamic, centrifugal, gyroscopic and gravity loads. The gyroscopic loads applied to the blade are induced by her simultaneous vibration and rotation. The proposed beam finite element model is based on a simplex interpolation method and it is mainly intended to the numerical analysis of wind blades vibration in large elastic deformation. For this purpose, the theory of the sheared beams and the finite element method are combined to develop the algebraic equations system governing the three-dimensional motion of blade vibration. The applicability of the theoretical approach is elucidated through an original case study. Also, the static deformation of the used wind blade is assessed by appropriate software using a solid finite element model in order to show the effectiveness of the obtained results. To simulate the nonlinear dynamic response of wind blade, the predictor-corrector Newmark scheme is applied and the stability of numerical process is approved during a large time of blade functioning. Finally, the influence of the modified geometrical stiffness on the amplitudes and frequencies of the wind blade vibration induced by the sinusoidal excitation of gravity is analyzed.

Beam finite element model of a vibrate wind blade in large elastic deformation

Hamdi, Hedi,Farah, Khaled Techno-Press 2018 Wind and Structures, An International Journal (WAS Vol.26 No.1

This paper presents a beam finite element model of a vibrate wind blade in large elastic deformation subjected to the aerodynamic, centrifugal, gyroscopic and gravity loads. The gyroscopic loads applied to the blade are induced by her simultaneous vibration and rotation. The proposed beam finite element model is based on a simplex interpolation method and it is mainly intended to the numerical analysis of wind blades vibration in large elastic deformation. For this purpose, the theory of the sheared beams and the finite element method are combined to develop the algebraic equations system governing the three-dimensional motion of blade vibration. The applicability of the theoretical approach is elucidated through an original case study. Also, the static deformation of the used wind blade is assessed by appropriate software using a solid finite element model in order to show the effectiveness of the obtained results. To simulate the nonlinear dynamic response of wind blade, the predictor-corrector Newmark scheme is applied and the stability of numerical process is approved during a large time of blade functioning. Finally, the influence of the modified geometrical stiffness on the amplitudes and frequencies of the wind blade vibration induced by the sinusoidal excitation of gravity is analyzed.

Introducing/Reproducing of Welding Distortion and Residual Stress in Analysis for Elastic-Plastic Behaviors of Steel Plates under Compressive Loads

You-Chul Kim,박도현,Mikihito Hirohata,Shingo Tamagawa 한국강구조학회 2010 International Journal of Steel Structures Vol.10 No.4

A series of analyses was carried out to elucidate treatment of welding imperfection for simulating elastic-plastic behaviors of steel plates under compressive loads. A thermal elastic-plastic analysis based on infinitesimal deformation theory was carried out on a single-pass butt-welding of thin steel plates to predict welding distortion and welding residual stress. The obtained welding distortion and welding residual stress were introduced into an elastic-plastic large deformation analysis as initial imperfection. However, it was elucidated that welding distortion and welding residual stress could not be reproduced precisely due to unbalanced force caused by the difference between both analysis theories. Therefore, it should be confirmed whether the introduced welding distortion and welding residual stress were reproduced with high accuracy. Consequently, if welding distortion and welding residual stress cannot be reproduced, the treatment such as the convergence calculation method applied in this study should be done for precise elucidation of the elastic-plastic behavior of plates under compressive loads.

A numerical analysis of the large deflection of an elastoplastic cantilever

Wang, B.,Lu, G.,Yu, T.X. Techno-Press 1995 Structural Engineering and Mechanics, An Int'l Jou Vol.3 No.2

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.

대형부체구조물(大型浮體構造物)의 유(流)·탄성(彈性) 연성거동에 관한 실험적 고찰

이상엽 한국공간구조학회 2001 한국공간구조학회지 Vol.1 No.2

A large floating structure is attracting great attention in recent years from the view of ocean space utilization. Its huge scale in the horizontal directions compared with the wavelength and relatively shallow depth make this type of floating structure flexible and its wave-induced motion be characterized by the elastic deformation. In this paper, a boundary integral equation method is proposed to predict the wave-induced dynamic response mat-like floating offshore structure. The structure is modeled as an elastic plate and its elastic deformation is expressed as a superposition of free-vibration modes in air. This makes it straightforward to expand the well-established boundary integral technique for rigid floating bodies to include the hydroelastic effects. In order to validate the theoretical analysis, we compare with the experimental result of reduced model test. Satisfactory agreement is found between theory and experiment.

Buckling and stability of elastic-plastic sandwich conical shells

Jerzy Zielnica 국제구조공학회 2012 Steel and Composite Structures, An International J Vol.13 No.2

Shell structures are very interesting from the design point of view and these are well recognized in the scientific literature. In this paper the analysis of the buckling loads and stability paths of a sandwich conical shell with unsymmetrical faces under combined load based on the assumptions of moderately large deflections (geometrically nonlinear theory) is considered and elastic-plastic properties of the material of the faces are taken into considerations. External load is assumed to be two-parametrical one and it is assumed that the shell deforms into the plastic range before buckling. Constitutive relations in the analysis are those of the Nadai-Hencky deformation theory of plasticity and Prandtl-Reuss plastic flow theory with the H-M-H (Huber-Mises-Hencky) yield condition. The governing stability equations are obtained by strain energy approach and Ritz method is used to solve the equations with the help of analytical-numerical methods using computer.

유한요소법에 의한 평판의 용접 변형에 관한 기초적 연구

방한서(Han-Sur Bang),고민성(Min-Seong Go),방희선(Hee-Seon Bang) 한국해양공학회 1997 韓國海洋工學會誌 Vol.11 No.4

When structures are constructed by welding, heat conduction brings welding deformation. This is accompanied by complicated mechanical phenomenon such as material nonlinear and geometric nonlinear behavior.<br/> Hitherto, the research of welding deformation has been accomplished by an analytical method and experimental data in Korea.<br/> In this paper, the computer program by F.E.M.(finite element method) which could analyze the deformation of thin plate considering phenomena(both material and geometric nonlinear behavior) has been developed and verified. The production mechanism and charactristics in the welding deformation of plate are studied by the results.

대변형 탄소성 해석의 유한요소 프로그램의 개발과 활용

천영조(Young-Jo Cheon),김현규(Hyun-Gyu Kim) 한국항공우주학회 2018 한국항공우주학회 학술발표회 논문집 Vol.2018 No.11

Stress wave propagation in 1-D and 2-D media using Smooth Particle Hydrodynamics method

Liu, Z.S.,Swaddiwudhipong, S.,Koh, C.G. Techno-Press 2002 Structural Engineering and Mechanics, An Int'l Jou Vol.14 No.4

The paper involves the study on the elastic and elasto-plastic stress wave propagation in the 1-D and 2-D solid media. The Smooth Particle Hydrodynamics equations governing the elastic and elasto-plastic large deformation dynamic response of solid structures are presented. The proposed additional stress points are introduced in the formulation to mitigate the tensile instability inherent in the SPH approach. Both incremental rate approach and leap-frog algorithm for time integration are introduced and the new solution algorithm is developed and implemented. Two examples on stress wave propagation in aluminium bar and 2-D elasto-plastic steel plate are included. Results from the proposed SPH approach are compared with available analytical values and finite element solutions. The comparison illustrates that the stress wave propagation problems can be effectively solved by the proposed SPH method. The study shows that the SPH simulation is a reliable and robust tool and can be used with confidence to treat transient dynamics such as linear and non-linear transient stress wave propagation problems.

섬유다발의 굴곡도에 따른 유연직물복합재료의 등가탄성계수 예측

서영욱(Young W. Suh),김성준(Sung-Joon Kim),안석민(Seok-Min Ahn) 한국항공우주연구원 2010 항공우주기술 Vol.9 No.2

본 연구에서는 비선형 유한요소 해석을 수행하여 굴곡도에 따른 유연직물복합재료의 등가 탄성계수를 예측하였다. 해석은 상용 유한요소 해석 프로그램인 ABAQUS를 사용하여 수행되었다. 해석에서는 섬유다발의 재료적 비선형성과 대변형 시 발생하는 기하학적 비선형성이 고려되었으며, 섬유다발의 대 전단 변형으로 발생하는 기하학적 비선형성을 고려하기 위하여 사용자 부프로그램을 작성하여 이를 ABAQUS내에 삽입하였다. 결과에서는 일축하중 상태에 있는 유연직물복합재료의 응력-변형률 거동을 예측하여 이로부터 계산된 등가탄성계수를 시험결과와 비교하였으며, 다양한 섬유 굴곡도를 갖는 유연직물복합재료에 대한 등가탄성계수를 계산하였다. In this study, the equivalent elastic modulus of flexible textile composites was predicted by nonlinear finite element analysis. The analysis was carried out considering the material nonlinearity of fiber tows and the geometrical nonlinearity during large deformation using commercial analysis software, ABAQUS. To account for the geometrical nonlinearity due to the large shear deformation of fiber tows, a user defined material algorithm was developed and inserted in ABAQUS. In results, nonlinear stress-strain curve for the flexible textile composites under uni-axial tension was predicted from which effective elastic modulus was obtained and compared to the test result. The effective elastic moduli were calculated for the various finite element models with different waviness ratio of fiber tow.