SMA Pseudoelastic Finite Strains. Theory and Numerical Application

1999 ◽  
Vol 121 (1) ◽  
pp. 44-47 ◽  
Author(s):  
M. L. Boubakar ◽  
S. Moyne ◽  
C. Lexcellent ◽  
Ph. Boisse
Keyword(s):  
Stress Condition ◽  
Shell Element ◽  
Element Model ◽  
Small Strain ◽  
Calculation Algorithm ◽  
Numerical Application ◽  
Equation Solving ◽  
Proposed Model ◽  
Consistent Tangent Operator ◽  
Transverse Shear Locking

A tridimensional finite element model of isothermal pseudoelastic deformations is proposed in order to analyze and predict the behavior of shape memory alloys (SMA). To perform finite strain calculations, the mechanical modeling is based on a formulation in a non material rotating frame. The constitutive equations in a particular configuration are closed form of those developed with small strain assumption. This leads naturally to a numerical scheme composed of an elastic prediction and a possible pseudoelastic correction. To insure the convergence of the equilibrium equation solving method, a consistent tangent operator with the stress calculation algorithm is defined. In the case of thin structures, the proposed model is consistent with the zero normal stress condition within a three node shell element based on a mixed interpolation in order to avoid transverse shear locking. Numerical results are presented to show the accuracy of the proposed approach.

scholarly journals Numerical aspects for efficient welding computational mechanics

2014 ◽  
Vol 18 (suppl.1) ◽  
pp. 139-148
Author(s):  
Tarek Aburuga ◽  
Aleksandar Sedmak ◽  
Zoran Radakovic
Keyword(s):  
Residual Stresses ◽  
Three Dimensional ◽  
Shell Element ◽  
Element Model ◽  
Mechanical Analysis ◽  
Tensile Test Specimen ◽  
Integrity Assessment ◽  
Mass Scaling ◽  
Three Dimensional Models ◽  
Thermal Mechanical Analysis

The effect of the residual stresses and strains is one of the most important parameter in the structure integrity assessment. A finite element model is constructed in order to simulate the multi passes mismatched submerged arc welding SAW which used in the welded tensile test specimen. Sequentially coupled thermal mechanical analysis is done by using ABAQUS software for calculating the residual stresses and distortion due to welding. In this work, three main issues were studied in order to reduce the time consuming during welding simulation which is the major problem in the computational welding mechanics (CWM). The first issue is dimensionality of the problem. Both two- and three-dimensional models are constructed for the same analysis type, shell element for two dimension simulation shows good performance comparing with brick element. The conventional method to calculate residual stress is by using implicit scheme that because of the welding and cooling time is relatively high. In this work, the author shows that it could use the explicit scheme with the mass scaling technique, and time consuming during the analysis will be reduced very efficiently. By using this new technique, it will be possible to simulate relatively large three dimensional structures.

Contrastive Study on Finite Element Models of High-Strength Pipelines Crossing Active Faults

2016 ◽  
Vol 850 ◽  
pp. 957-964
Author(s):  
Wei Zheng ◽  
Hong Zhang ◽  
Xiao Ben Liu ◽  
Le Cai Liang ◽  
Yin Shan Han
Keyword(s):  
Finite Element ◽  
Design Method ◽  
Active Faults ◽  
Shell Element ◽  
High Strength ◽  
Element Model ◽  
Beam Element ◽  
Finite Element Models ◽  
Fixed Boundary ◽  
Equivalent Boundary

There is a potential for major damage to the pipelines crossing faults, therefore the strain-based design method is essential for the design of buried pipelines. Finite element models based on soil springs which are able to accurately predict pipelines’ responses to such faulting are recommended by some international guidelines. In this paper, a comparative analysis was carried out among four widely used models (beam element model; shell element model with fixed boundary; shell element model with beam coupled; shell element model with equivalent boundary) in two aspects: differences of results and the efficiency of calculation. The results show that the maximum and minimum strains of models coincided with each other under allowable strain and the calculation efficiency of beam element model was the highest. Besides, the shell element model with beam coupled or equivalent boundary provided the reasonable results and the calculation efficiency of them were higher than the one with fixed boundary. In addition, shell element model with beam coupled had a broader applicability.

A New Nonlinear Stress-Strain Model for Soils at Various Strain Levels

2013 ◽  
Vol 631-632 ◽  
pp. 782-788
Author(s):  
Cheng Chen ◽  
Zheng Ming Zhou
Keyword(s):  
Compression Test ◽  
Triaxial Compression ◽  
Small Strain ◽  
Empirical Formulas ◽  
Stress Strain ◽  
Strain Behaviour ◽  
Proposed Model ◽  
Nonlinear Stress ◽  
London Clay ◽  
Strain Model

Soils have nonlinear stiffness and develops irrecoverable strains even at very small strain levels. Accurate modeling of stress-strain behaviour at various strain levels is very important for predicting the deformation of soils. Some existing stress-strain models are reviewed and evaluated firstly. And then a new simple non-linear stress-strain model is proposed. Four undetermined parameters involved in the proposed model can be obtained through maximum Young’s module, deformation module, and limit deviator stress and linearity index of soils that can be measured from experiment directly or calculated by empirical formulas indirectly. The effectiveness of the proposed stress-strain model is examined by predicting stress-strain curves measured in plane-strain compression test on Toyota sand and undrained triaxial compression test on London clay. The fitting results of the proposed model are in good agreement with experimental data, which verify the effectiveness of the model.

Analysis of Shear-critical reinforced concrete columns under variable axial load

2022 ◽  
pp. 1-24
Author(s):  
Dimitrios K. Zimos ◽  
Panagiotis E. Mergos ◽  
Vassilis K. Papanikolaou ◽  
Andreas J. Kappos
Keyword(s):  
Reinforced Concrete ◽  
Axial Load ◽  
Shear Failure ◽  
Progressive Collapse ◽  
Full Range ◽  
Element Model ◽  
Independent Verification ◽  
Lateral Response ◽  
Proposed Model ◽  
Compressive Axial Load

Older existing reinforced concrete (R/C) frame structures often contain shear-dominated vertical structural elements, which can experience loss of axial load-bearing capacity after a shear failure, hence initiating progressive collapse. An experimental investigation previously reported by the authors focused on the effect of increasing compressive axial load on the non-linear post-peak lateral response of shear, and flexure-shear, critical R/C columns. These results and findings are used here to verify key assumptions of a finite element model previously proposed by the authors, which is able to capture the full-range response of shear-dominated R/C columns up to the onset of axial failure. Additionally, numerically predicted responses using the proposed model are compared with the experimental ones of the tested column specimens under increasing axial load. Not only global, but also local response quantities are examined, which are difficult to capture in a phenomenological beam-column model. These comparisons also provide an opportunity for an independent verification of the predictive capabilities of the model, because these specimens were not part of the initial database that was used to develop it.

scholarly journals Development of a New Bi-Arc Dynamic Numerical Model for Modeling AC Flashover Processes of EHV Ice-Covered Insulators

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2792
Author(s):  
Marouane Jabbari ◽  
Christophe Volat ◽  
Issouf Fofana
Keyword(s):  
Numerical Model ◽  
High Accuracy ◽  
Arc Length ◽  
Calculation Algorithm ◽  
Water Conductivity ◽  
Arc Model ◽  
Proposed Model ◽  
Flashover Voltage ◽  
Extra High Voltage ◽  
Future Work

This paper presents the development of a new bi-arc dynamic numerical model for predicting AC critical flashover voltage (FOV) of ice-covered extra-high voltage (EHV) insulators. The proposed model is based on a generic calculation algorithm coupled with commercial finite element method software designed to solve the Obenaus/Rizk model. The proposed model allows one to implement the Nottingham and Mayr approaches and compare the results obtained as a function of the arcing distance, the freezing water conductivity, and the initial arc length. The validation of the model demonstrated high accuracy in predicting the FOV of ice-covered post-type insulators and its capability to simulate the interaction of the two partial arcs during the flashover process. In particular, the results showed that the Nottingham approach is sensibly more accurate than the Mayr one, especially in simulating the dynamic behavior of the partial arcs during the flashover process. Based on the encouraging results obtained, a multi-arc calculation algorithm was proposed using the bi-arc dynamic numerical model as a basis. The basic idea, which consists in dividing the multi-arc model in several bi-arc modules, was not implemented and validated but will serve as a promising concept for future work.

Thermo-Mechanical Stability Analysis of Composite Cylindrical Panels

2013 ◽  
Author(s):  
P. V. Katariya ◽  
S. K. Panda
Keyword(s):  
Mechanical Stability ◽  
Shear Deformation Theory ◽  
Laminated Composite ◽  
Shell Element ◽  
Element Model ◽  
Computer Code ◽  
Substantial Effect ◽  
Stability Behavior ◽  
Support Conditions ◽  
Laminated Structures

In this article, stability behavior of laminated composite curved panels under thermo-mechanical loading is analyzed. A generalized panel model is developed based on higher order shear deformation theory by taking the nonlinearity in Green-Lagrange sense for thermal distortion. The critical buckling load (mechanical/thermal) parameters are obtained by using the developed finite element model validated for both ANSYS and homemade computer code. The model has been discretized in ANSYS using an eight-noded serendipity shell element (shell281) and a nine noded isoparametric element for the computer code. The convergence test has been carried out and the results are compared with those available published literature. In this analysis, a uniform temperature distribution through the thickness is taken and the material properties for the composites are assumed to be temperature invariant. We note substantial effect of different parameters (support conditions, number of layers, thickness ratio and modular ratio) on thermo-mechanical stability behavior of laminated structures.

An Investigation Into the Upper Arm Deformation Under Inflatable Cuff

2008 ◽  
Author(s):  
H. Lan ◽  
A. M. Al-Jumaily ◽  
A. Lowe
Keyword(s):  
Finite Element ◽  
Soft Tissues ◽  
Element Model ◽  
Upper Arm ◽  
Inflatable Cuff ◽  
Proposed Model ◽  
Materials Used ◽  
Tissue Deformations ◽  
Visible Human ◽  
Collapse Process

The human upper arm is simulated using a nonlinear geometrical and physical model. To create a more realistic simulation, the geometry of the model is based on the visible human body dataset. The model consists of four parts, humerus, brachial artery, muscle, and other soft tissues. All the materials used in this model are assumed to be incompressible and hyperelastic. The unique properties of each material are specified and described. Incorporating all of these facts, a finite element model is developed using the commercial programme ABAQUS®. The upper arm tissues’ deformations and artery collapse process under compression are simulated in this model. The proposed model has the potential to simulate the tissue deformations under inflatable cuffs exposed to arm movements.

Advanced joint slip model for single-angle bolted connections considering various effects

2020 ◽  
Vol 23 (10) ◽  
pp. 2121-2135
Author(s):  
Ahmed Hussain Ali Abdelrahman ◽  
Yao-Peng Liu ◽  
Siu-Lai Chan
Keyword(s):  
Plate Thickness ◽  
Direct Analysis ◽  
Element Model ◽  
Fe Model ◽  
Slip Model ◽  
Transmission Towers ◽  
Slip Effects ◽  
Proposed Model ◽  
Full Scale Tests ◽  
The Cost

Latticed structures are commonly used in transmission towers due to lightweight, fast fabrication, and easy installation, but they generally experience more complicated structural behaviors. The full-scale tests on transmission towers have revealed large discrepancies between the numerical simulation and experimental results because the significant joint slip effects have not well considered in the former. The existing joint slip models were so simple that many key parameters had not been taken into account. Thus, a comprehensive joint slip model is proposed in this article for better prediction and design of tower structures. First, a full-detailed finite element model based on ABAQUS incorporating more realistic parameters for a typical joint is developed and calibrated by the experimental data from the literature. Furthermore, the proposed FE model is used for parametric study of joint behaviors with considerations of bolt pretension, friction at contact face, angle sizes and plate thickness, steel and bolt grades, number of bolts, and hole tolerance. Finally, an advanced joint slip model is provided for further incorporation in the second-order direct analysis of transmission towers. This work is limited in the literature and will significantly improve safety and enhance the cost-efficiency of tower design. The proposed model shows high accuracy and can be simply determined by joint details in line with the component method specified in Eurocode 3-1-8.

Experimental Validation of Role of Cut-Out Parameters on Modal Responses of Laminated Composite — A Coupled FE Approach

2020 ◽  
Vol 12 (06) ◽  
pp. 2050068 ◽  
Author(s):  
Hukum Chand Dewangan ◽  
Subrata Kumar Panda ◽  
Nitin Sharma
Keyword(s):  
Composite Structure ◽  
Laminated Composite ◽  
Element Model ◽  
Composite Panel ◽  
Design Constraint ◽  
Isoparametric Finite Element ◽  
Proposed Model ◽  
Free Vibration Frequency ◽  
First Time

The free vibration frequency responses of the laminated composite structure with a cut-out of variable shapes (square/circular/elliptical), position (center/eccentric) and orientation (parallel/inclined) are investigated for the first time in this research including geometrical shapes. The eigenvalues are obtained computationally for the cut-out borne structure via a linear isoparametric finite element model of the composite structure in association with cubic-order of displacement kinematics. Also, a coupled code is prepared in MATLAB environment by joining the higher-order formulation and the simulation model (ABAQUS) to achieve the generic form to investigate the influential cut-out parameter (shape, size and position) on their eigenvalues. Further, a series of experimentations are carried out using the cut-out borne composite panel and compared with the computational frequency, including the experimental properties. Finally, the key behavior is surveyed through different kinds of numerical examples for various design constraint parameters including the cut-out relevant factors (shape, position and orientation) to show the subsequent inclusiveness of the proposed model.

Computational Modal Analyses of a Steel Nuclear Containment Vessel

2014 ◽  
Vol 490-491 ◽  
pp. 625-628
Author(s):  
Chun Lai Tian ◽  
Lin Yang ◽  
Rui Chang Zhao
Keyword(s):  
Finite Element ◽  
Shell Element ◽  
Element Model ◽  
Element Analysis ◽  
Software Cost ◽  
Containment Vessel ◽  
Nuclear Containment ◽  
Computational Analyses ◽  
Deformation Area ◽  
The Finite Element Model

In order to obtain frequencies and modal shapes of a nuclear containment vessel, the computational analyses have been carried out through free structure finite element analysis software. The finite element model of the vessel is built with shell element and solved by the type of the dynamics frequency solver. Results show that mainly deformation area is on the vessels cylindrical shell and the maximum displacements occur at its center. Compared with the design validation values, the frequencies obtained are a little lower. It may be because that the model built here is a completely vessel shell without any hatches or attachments. It is provided that a reliable method of computational structural analyses for the nuclear containment without commercial software cost.

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