Analysis of Carbon Nano Tubes using Molecular Structural Mechanics Approach

2020 ◽  
Vol 12 (4) ◽  
Author(s):  
J. Jayapriya ◽  
D Muruganandam ◽  
B. Senthil Kumar
Keyword(s):  
Finite Element ◽  
Elastic Moduli ◽  
Structural Mechanics ◽  
Diameter Ratio ◽  
Finite Element Models ◽  
Fe Model ◽  
High Toughness ◽  
Young’S Moduli ◽  
Energy Equivalence ◽  
Carbon Nano Tubes

Carbon Nano Tubes (CNTs) have a nanostructure with length-to-diameter ratio greater than 1,000,000 exhibiting unusually high toughness and elastic-moduli. Young’s modulus of a single-walled CNT is estimated through Molecular Structural Mechanics Approach is being simulated as a frame-like-structure where primary bonds between successive atoms forms a beam. Properties for FE model are calculated from energy equivalence between molecular and structural mechanics. By validation, computed results match well with the literature. Finite element models such as armchair and zig-zag are established and Young’s-moduli are effectively predicted.

SEA model for structural acoustic coupling by means of periodic finite element models of the structural subsystems

2021 ◽  
Vol 263 (1) ◽  
pp. 5301-5309
Author(s):  
Luca Alimonti ◽  
Abderrazak Mejdi ◽  
Andrea Parrinello
Keyword(s):  
Finite Element ◽  
Numerical Approach ◽  
Unit Cell ◽  
Analytical Models ◽  
Finite Element Models ◽  
Fe Model ◽  
Acoustic Coupling ◽  
Representative Unit Cell ◽  
Definition Of ◽  
Acoustic Treatment

Statistical Energy Analysis (SEA) often relies on simplified analytical models to compute the parameters required to build the power balance equations of a coupled vibro-acoustic system. However, the vibro-acoustic of modern structural components, such as thick sandwich composites, ribbed panels, isogrids and metamaterials, is often too complex to be amenable to analytical developments without introducing further approximations. To overcome this limitation, a more general numerical approach is considered. It was shown in previous publications that, under the assumption that the structure is made of repetitions of a representative unit cell, a detailed Finite Element (FE) model of the unit cell can be used within a general and accurate numerical SEA framework. In this work, such framework is extended to account for structural-acoustic coupling. Resonant as well as non-resonant acoustic and structural paths are formulated. The effect of any acoustic treatment applied to coupling areas is considered by means of a Generalized Transfer Matrix (TM) approach. Moreover, the formulation employs a definition of pressure loads based on the wavenumber-frequency spectrum, hence allowing for general sources to be fully represented without simplifications. Validations cases are presented to show the effectiveness and generality of the approach.

Automated Finite Element Analysis of Tree Branches

2017 ◽  
Vol 17 (4) ◽  
Author(s):  
Zahra Shahbazi ◽  
Devon Keane ◽  
Domenick Avanzi ◽  
Lance S. Evans
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Biological Materials ◽  
Finite Element Models ◽  
Fe Model ◽  
Biological Applications ◽  
Efficient Tool ◽  
Element Analysis ◽  
New Process ◽  
Tree Branch

Finite element analysis (FEA) has been one of the successful tools in studying mechanical behavior of biological materials. There are many instances where creating FE models requires extensive time and effort. Such instances include finite element analysis of tree branches with complex geometries and varying mechanical properties. Once a FE model of a tree branch is created, the model is not applicable to another branch, and all the modeling steps must be repeated for each new branch with a different geometry and, in some cases, material. In this paper, we describe a new and novel program “Immediate-TREE” and its associated guided user interface (GUI). This program provides researchers a fast and efficient tool to create finite element analysis of a large variety of tree branches. Immediate-TREE automates the process of creating finite element models with the use of computer-generated Python files. Immediate-TREE uses tree branch data (geometry, mechanical, and material properties) and generates Python files. Files were then run in finite element analysis software (abaqus) to complete the analysis. Immediate-TREE is approximately 240 times faster than creating the same model directly in the FEA software (abaqus). This new process can be used with a large variety of biological applications including analyses of bones, teeth, as well as known biological materials.

Behavior of Sand Compaction Columns Installed in Cohesionless Deposits

2020 ◽  
Vol 14 (2) ◽  
Author(s):  
N. Aarthi
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Internal Friction ◽  
Critical Appraisal ◽  
Diameter Ratio ◽  
Composite Foundation ◽  
Stone Column ◽  
Fe Model ◽  
Angle Of Internal Friction ◽  
Settlement Behavior

A critical appraisal of the reviewed literature revealed that there are very limited studies avail-able on the strength characteristics focusing on the load-settlement behavior of sand compaction col-umns (SCCs) when installed in cohesionless deposits. The method, though contemporary to the reputed stone column technique, is not yet studied rigorously in the available past studies, more precisely on the load-bearing characteristics when compared to the latter. Therefore the present study focuses on studying the behavior of multiple column composite foundation supported by sand compaction columns installed in loose to medium dense sands on a lab-scale numerical model. The study is carried out using commercially available finite element (FE) code 3D PLAXIS. Spacing to diameter ratio (S/D) ranging from 1.5 to 3.5 and initial relative density (RD) from 30 to 60% was adopted to study the changes in the load-settlement behavior of the improved deposit. Extending the FE model to further parametric study, the effect of angle of internal friction of the column sand and diameter of the column on the bearing capacity and settlement characteristics were analysed with and without normalization. From the results obtained, it is found that, for the considered FE model, the improved deposit with 3D spacing between the SCCs behaves distinctly different from all other cases analyzed.

Experimental Correlation of Dynamic Finite Element Models

1995 ◽  
Author(s):  
Raymond E. Martin ◽  
David M. O’Brien
Keyword(s):  
Finite Element ◽  
Finite Element Models ◽  
Fe Model ◽  
Dynamic Finite Element ◽  
Aircraft Landing ◽  
Modal Model ◽  
Analytical Development ◽  
Structure Correlation ◽  
Operational Data ◽  
Wheel Brake

Abstract Finite element models used in the dynamic analysis of structures benefit from correlation with experimental data at each step in the analytical development. The steps Aircraft Landing Systems has followed in obtaining both modal and operational data for the validation of aircraft wheel, brake, and strut FEA models are discussed in this paper. These steps include the creation of a valid experimental modal model for major components in the structure, correlation of the modal results to tie FE model results, testing of sub-assemblies, and collecting data from dynamometer tests of the system and their correlation to the assembled FE model of the system. Various procedures are described which have been developed and adapted by Aircraft Landing Systems and which enable practical correlation to frequencies as high as 2000 Hz. The application of the procedures are demonstrated with examples from recent testing.

Structural Response of Timber-Concrete Composite Beams Predicted by Finite Element Models and Manual Calculations

2014 ◽  
Vol 17 (11) ◽  
pp. 1601-1621 ◽  
Author(s):  
Nima Khorsandnia ◽  
Hamid Valipour ◽  
Keith Crews
Keyword(s):  
Finite Element ◽  
Axial Stress ◽  
Damage Model ◽  
Structural Response ◽  
General Purpose ◽  
Finite Element Models ◽  
Fe Model ◽  
Loading Capacity ◽  
Model Predictions ◽  
Ultimate Loading Capacity

This paper presents the structural response of timber-concrete composite (TCC) beams predicted by finite element models (i.e. continuum-based and 1D frame) and manual calculations. Details of constitutive laws adopted for modelling timber and concrete are provided and application of the Hashin damage model in conjunction with continuum-based FE for capturing failure of timber under bi-axial stress state is discussed. A simplified strategy for modelling the TCC connection is proposed in which the connection is modelled by a nonlinear spring and the full load-slip behaviour of each TCC connection is expressed with a formula that can be directly implemented in the general purpose FE codes and used for nonlinear analysis of TCC beams. The developed FE models are verified by examples taken from the literature. Furthermore, the load-displacement response and ultimate loading capacity of the TCC beams are determined according to Eurocode 5 method and compared with FE model predictions.

scholarly journals Feasibility Study on Tension Estimation Technique for Hanger Cables Using the FE Model-Based System Identification Method

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Kyu-Sik Park ◽  
Taek-Ryong Seong ◽  
Myung-Hyun Noh
Keyword(s):  
Finite Element ◽  
System Identification ◽  
Boundary Conditions ◽  
Natural Frequency ◽  
Inverse Analysis ◽  
Finite Element Models ◽  
Fe Model ◽  
Identification Methods ◽  
System Identification Method ◽  
Model Based

Hanger cables in suspension bridges are partly constrained by horizontal clamps. So, existing tension estimation methods based on a single cable model are prone to higher errors as the cable gets shorter, making it more sensitive to flexural rigidity. Therefore, inverse analysis and system identification methods based on finite element models are suggested recently. In this paper, the applicability of system identification methods is investigated using the hanger cables of Gwang-An bridge. The test results show that the inverse analysis and systemic identification methods based on finite element models are more reliable than the existing string theory and linear regression method for calculating the tension in terms of natural frequency errors. However, the estimation error of tension can be varied according to the accuracy of finite element model in model based methods. In particular, the boundary conditions affect the results more profoundly when the cable gets shorter. Therefore, it is important to identify the boundary conditions through experiment if it is possible. The FE model-based tension estimation method using system identification method can take various boundary conditions into account. Also, since it is not sensitive to the number of natural frequency inputs, the availability of this system is high.

Finite Element Simulation of Crack Compliance Experiments to Measure Residual Stresses in Thick-Walled Cylinders

2003 ◽  
Vol 125 (3) ◽  
pp. 305-308 ◽  
Author(s):  
R. R. de Swardt
Keyword(s):  
Finite Element ◽  
Hoop Stress ◽  
High Strength ◽  
Finite Element Models ◽  
Fe Model ◽  
Element Simulation ◽  
Highly Nonlinear ◽  
Strain Stress ◽  
Reverse Yielding ◽  
Stress States

A comparative study to map the residual strain/stress states through the walls of autofrettaged thick-walled high-strength steel cylinders has been conducted with neutron diffraction, Sachs boring, and the compliance methods. Test samples with different wall thickness ratios were prepared to have significant amounts of reverse yielding due to the Bauschinger effect. In an effort to explain observed differences in the hoop stress results, the crack compliance experiment was simulated with finite elements. Several residual stress fields were introduced in the finite element models. A theoretical finite element (FE) model, which is capable of accurately modeling the highly nonlinear reverse yielding of the material, was able to accurately predict the crack compliance strain measurements.

Identifying Real Stiffness Properties of Structural Elements of Adapted Finite-Element Models of Buildings and Structures - Part 2: Computational-Experimental Methodology

2014 ◽  
Vol 670-671 ◽  
pp. 736-741 ◽  
Author(s):  
Alexander M. Belostotskiy ◽  
Pavel I. Novikov
Keyword(s):  
Finite Element ◽  
Experimental Methodology ◽  
Finite Element Models ◽  
Fe Model ◽  
Wave Method ◽  
Model Adaptation ◽  
Structural Elements ◽  
Defect Identification ◽  
Stiffness Properties ◽  
Standing Wave Method

The distinctive paper is devoted to new defect identification methodology based on dynamic characteristics of real construction. The methodology is founded on mathematically formalized procedure of FE-model adaptation by measured and calculated eigen pairs of dynamic system. Main steps of the methodology are described. Application of the methodology together with standing wave method might allow to identify deviations of stiffness parameters of a real construction facility.

Analysis of Composite Bolted Connection Joints Under Out of Plane Loading

2020 ◽  
Author(s):  
Hassan A. Mahmoud ◽  
Mostafa Shazly ◽  
Yehia Bahei-El-Din ◽  
Emad El-Kashif
Keyword(s):  
Finite Element ◽  
Areal Density ◽  
Finite Element Models ◽  
Fe Model ◽  
Stacking Sequence ◽  
Bolted Connection ◽  
Structural Applications ◽  
Edge Distance ◽  
Out Of Plane ◽  
Bolt Diameter

Abstract The use of composite joints has been increased in recent years in structural applications such as aircraft, civil engineering structure, ship structure, wind energy sector, and automotive industry. In this paper, the behaviour of composite bolted connection joints under out of plane loading is investigated. A parametric study was conducted to study the joint stiffness variation with various geometric parameters, which include the edge distance, bolt diameter, plate width, and the laminate stacking sequence. The experimental work was conducted on GFRP tension clips (L-angle) joint specimens manufactured by the vacuum infusion technique. In the present work, two types of laminates were used, unidirectional laminates [0°]5 with an areal density of 1050 gm/m2, triaxial laminates [−45°/+45°/0°]5 with an areal density of 1200 g/m2. A 3D finite element (FE) model was developed to study the effect of joint parameters on its stiffness. Finite element models were constructed, and the experimental results were used to validate the finite element models. The analysis concluded that the failure load increases when the edge distance to bolt diameter ratio (E/D) increases and the triaxial stacking sequence is better than unidirectional. The (E/D) ratio, the (W/D) ratio and stacking sequence were found to be very significant parameters.

Characterization of Material Behavior of the Fused Deposition Modeling Processed Parts

2017 ◽  
Author(s):  
Madhukar Somireddy ◽  
Aleksander Czekanski
Keyword(s):  
Finite Element ◽  
Elastic Moduli ◽  
Fused Deposition Modeling ◽  
Material Behavior ◽  
Constitutive Law ◽  
Finite Element Models ◽  
Strength Parameters ◽  
Fused Deposition ◽  
Deposition Modeling

In the present research, one of the additive manufacturing techniques, fused deposition modeling (FDM) fabricated parts are considered for investigation of their material behavior. The FDM process is a layer upon layer deposition of a material to build three dimensional parts and such parts behave as laminated composite structures. Each layer of the part acts as a unidirectional fiber reinforced lamina, which is treated as an orthotropic material. The mesostructure of a part fabricated via fused deposition modeling process is accounted for in the investigation of its mechanical behavior. The finite element (FE) procedure for characterization of a material constitutive law for the FDM processed parts is presented. In the analysis, the mesostructure of the part obtained via FDM process is replicated in the finite element models. Finite element models of tensile specimens are developed with mesostructure that would be obtained from FDM process, then uniaxial tensile test simulations are conducted. The elastic moduli of a lamina are calculated from the linear analysis and the strength parameters are obtained from the nonlinear finite element analysis. The present work provides a FE methodology to find elastic moduli and strength parameters of a FDM processed part by accounting its mesostructure in the analysis.

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