Simulation of Mechanical Behaviour of Materials Using Constant Boundary Elements - A Discussion on the Accuracy of Results for Beams

2020 ◽  
Vol 1013 ◽  
pp. 106-113
Author(s):  
P. Kirana Kumara
Keyword(s):  
Mechanical Behaviour ◽  
Smart Materials ◽  
Numerical Technique ◽  
Boundary Elements ◽  
Good Choice ◽  
Structural Member ◽  
Simulation Techniques ◽  
Accuracy Of Results ◽  
Phd Thesis ◽  
3D Problem

The Boundary Element Method (BEM) is one among the most popular simulation techniques employed to simulate mechanical behaviour of materials, including smart engineering materials. Although BEM is a quite well-established numerical technique, literature tells that the method may not be well suited to simulate structures where one or two of the dimensions is much smaller than the remaining dimension/s (for a 3D problem). Hence in this work, deflection of a cantilever beam is simulated using constant boundary elements to get a feel of the accuracy of the BEM when used to simulate such type of structures. Although the concept is not new, the study assumes significance because studies which list the results in detail are not readily found in the literature. In this study, the results are obtained for different mesh resolutions also. The results indicate that - as expected - constant boundary elements are not a good choice for simulating the mechanical behaviour of smart materials when the structural member to be simulated is thin. Although it is a known fact that constant boundary elements converge very slowly, the present study helps to get a clearer picture on the accuracy and the convergence rate that one can expect from constant boundary elements. This paper heavily borrows content from this author’s PhD thesis [1]. The geometry considered in this paper is a beam. One may also note that the author is publishing another paper [2] (“Simulation of Mechanical Behaviour of Materials using Constant Boundary Elements - A Discussion on the Accuracy of Results for Bars”) that is very similar to this paper except that the geometry considered in that paper is a bar.

Simulation of Mechanical Behaviour of Materials using Constant Boundary Elements - A Discussion on the Accuracy of Results for Bars

2020 ◽  
Vol 1013 ◽  
pp. 99-105
Author(s):  
P. Kirana Kumara
Keyword(s):  
Mechanical Behaviour ◽  
Smart Materials ◽  
Numerical Technique ◽  
Boundary Elements ◽  
Good Choice ◽  
Structural Member ◽  
Simulation Techniques ◽  
Accuracy Of Results ◽  
Phd Thesis ◽  
3D Problem

The Boundary Element Method (BEM) is one among the most popular simulation techniques employed to simulate mechanical behaviour of materials, including smart engineering materials. Although BEM is a quite well-established numerical technique, literature tells that the method may not be well suited to simulate structures where one or two of the dimensions is much smaller than the remaining dimension/s (for a 3D problem). Hence in this work, deflection of a cantilever beam is simulated using constant boundary elements to get a feel of the accuracy of the BEM when used to simulate such type of structures. Although the concept is not new, the study assumes significance because studies which list the results in detail are not readily found in the literature. In this study, the results are obtained for different mesh resolutions also. The results indicate that - as expected - constant boundary elements are not a good choice for simulating the mechanical behaviour of smart materials when the structural member to be simulated is thin. Although it is a known fact that constant boundary elements converge very slowly, the present study helps to get a clearer picture on the accuracy and the convergence rate that one can expect from constant boundary elements. This paper heavily borrows content from this author’s PhD thesis [1]. The geometry considered in this paper is a bar. One may also note that the author is publishing another paper [2] (“Simulation of Mechanical Behaviour of Materials using Constant Boundary Elements - A Discussion on the Accuracy of Results for Beams”) that is very similar to this paper except that the geometry considered in that paper is a beam.

scholarly journals A review on the modeling and simulations of solid-state diffusional phase transformations in metals and alloys

2018 ◽  
Vol 5 ◽  
pp. 10 ◽  
Author(s):  
Xueyan Liu ◽  
Hongwei Li ◽  
Mei Zhan
Keyword(s):  
Solid State ◽  
Phase Transformations ◽  
Numerical Technique ◽  
Metals And Alloys ◽  
Analytical Models ◽  
Theoretical Research ◽  
Current Status ◽  
Advantages And Disadvantages ◽  
Simulation Techniques ◽  
Molecular Dynamics Methods

Solid-state diffusional phase transformations are vital approaches for controlling of the material microstructure and thus tailoring the properties of metals and alloys. To exploit this mean to a full extent, much effort is paid on the reliable and efficient modeling and simulation of the phase transformations. This work gives an overview of the developments in theoretical research of solid-state diffusional phase transformations and the current status of various numerical simulation techniques such as empirical and analytical models, phase field, cellular automaton methods, Monte Carlo models and molecular dynamics methods. In terms of underlying assumptions, physical relevance, implementation and computational efficiency for the simulation of phase transformations, the advantages and disadvantages of each numerical technique are discussed. Finally, trends or future directions of the quantitative simulation of solid-state diffusional phase transformation are provided.

Mathematic Model of Liquidus Temperature in Quaternary Aluminum Phase Diagram

2015 ◽  
Vol 1095 ◽  
pp. 545-548
Author(s):  
Ke Qiu ◽  
Ri Chu Wang ◽  
Chao Qun Peng
Keyword(s):  
Liquidus Temperature ◽  
Quaternary System ◽  
Polynomial Regression ◽  
Numerical Technique ◽  
Mathematic Model ◽  
Solidification Temperature ◽  
Computational Approaches ◽  
Independent Variables ◽  
Regression Functions ◽  
Accuracy Of Results

A numerical technique for constructing liquidus temperature in quaternary system has been proposed. This technique offers accurate calculations of solidification temperature and demonstrates on the Al-Si-Mg-Fe system. The thermodynamic data is extracted by calling the TQ-interface (Thermodynamic Calculation Interface) and modeled using efficient computational approaches such as polynomial regression and interpolation. Si and Mg are treated as independent variables in regression functions, while Fe is treated as interpolated variable. The validated accuracy of results obtained through this method is compared with those calculated using Thermo-Calc. This technique is useful for quaternary systems.

Combining FEM and MD to simulate C60/PA-12 nanocomposites

2019 ◽  
Vol 10 (3) ◽  
pp. 380-392
Author(s):  
Georgios I. Giannopoulos ◽  
Stelios K. Georgantzinos ◽  
Androniki Tsiamaki ◽  
Nicolaos Anifantis
Keyword(s):  
Mechanical Behaviour ◽  
Numerical Scheme ◽  
Mechanical Performance ◽  
Numerical Technique ◽  
Computational Cost ◽  
Md Simulations ◽  
Unit Cell ◽  
Content Type ◽  
Polyamide 12 ◽  
Solid Element

Purpose The purpose of this paper is the computation of the elastic mechanical behaviour of the fullerene C60 reinforced polyamide-12 (PA-12) via a two-stage numerical technique which combines the molecular dynamics (MD) method and the finite element method (FEM). Design/methodology/approach At the first stage, the proposed numerical scheme utilizes MD to characterize the pure PA-12 as well as a very small cubic unit cell containing a C60 molecule, centrally positioned and surrounded by PA-12 molecular chains. At the second stage, a classical continuum mechanics (CM) analysis based on the FEM is adopted to approximate the elastic mechanical performance of the nanocomposite with significantly lower C60 mass concentrations. According to the computed elastic properties arisen by the MD simulations, an equivalent solid element with the same size as the unit cell is developed. Then, a CM micromechanical representative volume element (RVE) of the C60 reinforced PA-12 is modelled via FEM. The matrix phase of the RVE is discretized by using solid finite elements which represent the PA-12 mechanical behaviour predicted by MD, while the C60 neighbouring location is meshed with the equivalent solid element. Findings Several multiscale simulations are performed to study the effect of the nanofiller mass fraction on the mechanical properties of the C60 reinforced PA-12 composite. Comparisons with other corresponding experimental results are attempted, where possible, to test the performance of the proposed method. Originality/value The proposed numerical scheme allows accurate representation of atomistic interfacial effects between C60 and PA-12 and simultaneously offers a significantly lower computational cost compared with the MD-only method.

Out-of-Plane Bending Moment-Induced Hotspot Stress Evaluation Using Advanced Numerical Technique

2018 ◽  
Author(s):  
Jae-bin Lee ◽  
Weoncheol Koo ◽  
Joonmo Choung
Keyword(s):  
Numerical Technique ◽  
Bending Moment ◽  
Stress Distributions ◽  
Empirical Formulas ◽  
Element Analysis ◽  
Simulation Techniques ◽  
Analysis Technique ◽  
Out Of Plane ◽  
Plane Bending ◽  
Hotspot Stress

There have been various studies to predict out-of-plane bending (OPB) moment-induced stresses in mooring chain links. Recently, the BV guideline as one of the deliverables from OPB JIP reported empirical formulas to predict the nominal OPB moment-induced stress with suitable concentration factors (SCFs) so that prediction of the OPB moment-induced hotspot stresses can be available. A non-linear finite element analysis technique has been developed to more accurately estimate the OPB moment-induced hotspot stress. There has been no choice but to apply prescribed rotation to generate the OPB moment in this numerical technique (existing approach). Pointing out some disadvantages in the BV guideline and existing approach, an advanced numerical was proposed to simulate more realistic tension-induced OPB mechanism. In the present paper, basic differences were presented in terms of numerical simulation techniques, nominal OPB moments, and hotspot OPB stresses. In order to show differences of the stress distributions and the hotspot OPB stresses between existing and advanced approaches, a benchmark chain link model was constructed in which the nominal diameter was 107mm. From the comparison of stress distributions in straight parts of the link, significant differences were found between the existing and advanced approaches. The existing approach more developed the compressive stresses due to the prescribed rotation-induced OPB moment than the advanced approach. This also led to more increased hotspot OPB moments.

A Locally Refined Finite Element Approach for Journal-Bearing System Analysis

2005 ◽  
Author(s):  
S. W. Xiong ◽  
Q. Jane Wang ◽  
W. K. Liu ◽  
Chih Lin ◽  
D. Zhu ◽  
...  
Keyword(s):  
System Analysis ◽  
Journal Bearing ◽  
Numerical Technique ◽  
Point Contact ◽  
Contact Problems ◽  
Journal Bearings ◽  
Mixed Lubrication ◽  
Special Technique ◽  
Simulation Techniques ◽  
Refined Meshes

The effect of roughness should be taken into consideration in the lubrication and geometric design of heavy-duty machine elements. Deterministic simulation techniques have been developed for the investigation of point-contact mixed-lubrication problems. Such approaches should also been extended to deterministic mixed lubrication solutions for journal-bearing conformal-contact systems. However, journal-bearing mixed lubrication involves a much larger area of surface interaction as compared to point contact problems. It is difficult to use similar micro/nano scale meshes directly to journal bearings under the current computer capability. It is a great challenge to develop a new deterministic numerical technique for the mixed lubrication of journal bearing systems with the consideration of the effect of surface roughness design. This paper presents a special technique for deterministic analyses of journal-bearings in mixed lubrication conditions, in which the coarse mesh is used to determine the elastic deformation of the journal bearing, whilst locally refined meshes are used for the effect of roughness. Journal-bearing systems in heavy machinery are often subject to dynamic loading. Therefore, a transient refinement scheme is also introduced.

scholarly journals Magneto-mechanical characterization of magnetorheological elastomers

2019 ◽  
Vol 30 (17) ◽  
pp. 2534-2543 ◽  
Author(s):  
Alberto Bellelli ◽  
Andrea Spaggiari
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Analysis Of Variance ◽  
Compression Test ◽  
Mechanical Behaviour ◽  
Smart Materials ◽  
Mechanical Response ◽  
Ferromagnetic Material ◽  
Bending Test ◽  
Magnetorheological Elastomers

This work analyses the properties and the magneto-mechanical characteristics of magnetorheological elastomers, a class of smart materials not yet broadly investigated. First, set of several samples of this material was manufactured, each one characterized by a different percentage of ferromagnetic material inside the viscoelastic matrix. The specimens were manufactured in order to create isotropic and anisotropic configurations, respectively, with randomly dispersed ferromagnetic particles or with an aligned distribution, obtained through and external magnetic field. Then, the mechanical behaviour of each sample was analysed by conducting a compression test, both with and without an external magnetic field. Moreover, a three-point bending test was also performed on the same specimens. Stiffness, deformation at maximum stress and specific energy dissipated were calculated based on the experimental data. The results were analysed considering the mechanical responses, and an analysis of variance was carried out in order to assess the statistical influence of each variable. The experimental results highlighted a strong correlation between the percentage of ferromagnetic material in each sample and its mechanical behaviour. The anisotropicity of the material, aligned in columnar structures, also affects the stiffness measured in the compression test, while the external magnetic field’s main contribution is to reduce the samples’ maximum deformation. Using analysis of variance results as guidelines, we built a simple phenomenological model which produces quite reliable predictions regarding the mechanical response of the magnetorheological elastomers under compressive stress.

Design of Actuation for Bistable Structures Using Smart Materials

2008 ◽  
Vol 54 ◽  
pp. 287-292
Author(s):  
Paul Cazottes ◽  
A. Fernandes ◽  
Joel Pouget ◽  
Moustapha Hafez
Keyword(s):  
Smart Materials ◽  
Shape Change ◽  
Significant Loss ◽  
Good Choice ◽  
Power Efficient ◽  
Mechanical Study ◽  
Interesting Approach ◽  
Bistable Structure ◽  
Surface Deflection ◽  
Bistable Structures

Several smart materials such as shape memory alloys (SMA) and electroactive polymers (EAP) have good properties in small scales and are often a good choice for tiny surface deflection applications. However they need continuous powering to keep their shape change, leading to a significant loss of energy. An interesting approach is to associate a smart material with a bistable element, which provides two stable positions without power. This action requires some energy to snap from one position to the other one. This association gives a very power-efficient solution. In this paper, we present a mechanical study on the actuation of a bistable structure, using a distributed torque actuation that is very suitable for smart materials. We provide an approach to optimize the actuation location, this allow to use less powerful and more compact actuators.

Image Analysis of Intramembrane Particles in Freeze-Fractured Biomembranes Using Computer Simulation Techniques

1975 ◽  
Vol 33 ◽  
pp. 214-215
Author(s):  
D.J. Benefiel ◽  
R.S. Weinstein
Keyword(s):  
Membrane Proteins ◽  
Freeze Fracture ◽  
Integral Membrane Proteins ◽  
Systematic Evaluation ◽  
Intramembrane Particles ◽  
Modeling Methods ◽  
Simulation Techniques ◽  
Freeze Fracture Electron Microscopy ◽  
Fracture Electron ◽  
Computer Simulation Techniques

Intramembrane particles (IMP or MAP) are components of most biomembranes. They are visualized by freeze-fracture electron microscopy, and they probably represent replicas of integral membrane proteins. The presence of MAP in biomembranes has been extensively investigated but their detailed ultrastructure has been largely ignored. In this study, we have attempted to lay groundwork for a systematic evaluation of MAP ultrastructure. Using mathematical modeling methods, we have simulated the electron optical appearances of idealized globular proteins as they might be expected to appear in replicas under defined conditions. By comparing these images with the apearances of MAPs in replicas, we have attempted to evaluate dimensional and shape distortions that may be introduced by the freeze-fracture technique and further to deduce the actual shapes of integral membrane proteins from their freezefracture images.

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