Modelling biomacromolecular assemblies with continuum mechanics

2015 ◽  
Vol 43 (2) ◽  
pp. 186-192 ◽  
Author(s):  
Benjamin Hanson ◽  
Robin Richardson ◽  
Robin Oliver ◽  
Daniel J. Read ◽  
Oliver Harlen ◽  
...  
Keyword(s):  
Finite Element ◽  
Molecular Motor ◽  
Md Simulations ◽  
Thermal Fluctuations ◽  
Theoretical Background ◽  
Thermal Agitation ◽  
Element Analysis ◽  
Biomolecular Dynamics ◽  
Modelling Methods ◽  
Element Algorithm

We have developed a continuum mechanical description of proteins using a finite element algorithm which has been generalized to include thermal fluctuations and which is therefore known as fluctuating finite element analysis (FFEA). Whereas conventional molecular dynamics (MD) simulations provide a trajectory in which each individual atomic position fluctuates, a FFEA trajectory shows how the overall shape of the protein changes due to thermal agitation. We describe the theoretical background to FFEA, its relationship to more established biomolecular modelling methods and provide examples of its application to the mesoscale biomolecular dynamics of the molecular motor dynein.

scholarly journals Dynamic Analysis of Folded Low Shells by Using Finite Element Analysis

2020 ◽  
pp. 94-103
Author(s):  
Emmanuel E. T. Olodo ◽  
Georges Adjibola A. Ale ◽  
Edmond Codjo Adjovi ◽  
Antoine Vianou
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Variational Principle ◽  
Harmonic Analysis ◽  
Forced Vibrations ◽  
Internal Damping ◽  
Element Analysis ◽  
Dynamic Stresses ◽  
Element Algorithm ◽  
Calculation Code

Aims: This work is devoted to the development of a finite element algorithm for solving problem in forced vibrations of folded low shells. Methodology: The differential equations for harmonic analysis are obtained from the Lagrange variational principle. Description of the dynamic behavior is made by the structure discretization into a system of curvilinear iso-parametric finite elements used in modal analysis. The method is implemented by a calculation code on a square-plane folded shell model withnumber of crease edges in both directions k=l=3. Results: Displacement amplitudesare obtained by decomposition into vibration eigenforms. The maximum values of dynamic stresses are determined taking into account the shell's support conditions.The results of the harmonic analysis show thatimprovement in frequency characteristics and reduction of stresses in the folded shell depend on the constructive and internal damping of the structureand the increase in the number of fold edges k and l in both directions for examplebecause this contributes to decrease in the forced vibration amplitudes.

Stress Analysis of Pipe Support Attachments: A Comparison of Analytical Methods and Finite Element Analysis for Circular and Non-Circular Attachments

2013 ◽  
Author(s):  
Anindya Bhattacharya
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Analysis ◽  
Analytical Methods ◽  
Theoretical Background ◽  
Fe Analysis ◽  
Design Parameters ◽  
Post Processing ◽  
Element Analysis ◽  
Custom Made

Despite the availability of special purpose FE codes with post processing facilities as per rules of ASME SEC VIII Division 2, use of simple analytical methods like ring loading around a circumference or more complex methods like Welding Research council bulletins 107 and 297, will continue to be used in the industry for a significant period of time for stress analysis of pipe support attachments. The reasons are few: not all engineering companies have such custom made FE codes, lack of trained personnel to work with general purpose FE codes, ease of implementation of the available methods and their successful design history, cost and time issues with FE analysis etc. In this paper these available methods will be reviewed based on their theoretical background, their range of applicability w.r.t the typical design parameters and their comparison with FE analysis. More recent analytical methods based on mathematically accurate space curves of intersections for circular attachments will also be discussed. This study will include both circular as well as non-circular attachments. This paper will highlight the strengths and weaknesses of the conventionally used methods especially with respect to their mathematical limitations to make an analyst aware of the potential over conservatism and under conservatism of these analytical methods. Finite element analysis models will be discussed in detail specifically in relation to elements used, element parameters, boundary conditions and post processing.

Development of Offshore Structural Analysis Software X-SEA Coupled With FAST

2019 ◽  
Author(s):  
Ki-Du Kim ◽  
Sorrasak Vachirapanyakun ◽  
Pasin Plodpradit ◽  
Van Nguyen Dinh ◽  
Jin-Ho Park
Keyword(s):  
Finite Element ◽  
Offshore Structures ◽  
Theoretical Background ◽  
Imperial College ◽  
Coupled Analysis ◽  
Current Version ◽  
Analysis Software ◽  
Element Analysis ◽  
Finite Element Program ◽  
Element Program

Abstract Coupled analysis of offshore structures is currently challenging. The 3D finite element analysis software X-SEA coupled with FAST 8 program is therefore developed and discussed in this paper. The current version of X-SEA includes the results of extensive research and development based on finite element program XFINAS, which was originally developed in Imperial College London. The solution of the X-SEA ranges from the simple static to highly advanced dynamic analysis applied to the offshore structures. GID is used as pre- and post processor of X-SEA. The brief theoretical background of X-SEA software is summarized. Numerical examples of offshore monopile, wind turbine jackets, pile super element and fatigue analysis verified with SACS software in terms of reactions, displacements and member forces are investigated.

Modelling an orthopaedic knee prosthesis as a layered elastic system part 2: Finite element analysis

1995 ◽  
Vol 30 (3) ◽  
pp. 195-203 ◽  
Author(s):  
M P Whelan ◽  
J E Mottershead ◽  
P D Edwards ◽  
E G Little
Keyword(s):  
Finite Element ◽  
Knee Prosthesis ◽  
Three Dimensional ◽  
Contact Problems ◽  
Element Analysis ◽  
Contact Algorithm ◽  
Benchmark Tests ◽  
System Part ◽  
Displacement Constraints ◽  
Element Algorithm

This study deals with the development of a specialized finite element algorithm suitable for a non-linear contact stress analysis of a model of a plastic tibial plateau of a typical unicondylar knee prosthesis. The principle feature of the contact algorithm is the use of Lagrange multiplier methods for the application of displacement constraints to surface Gauss points of a contacting body to prevent mesh overlap. This allows the effective modelling of two- and three-dimensional contact problems, with or without friction, using higher order elements. Through the selection of suitable benchmark tests, the performance and accuracy of the algorithm was assessed prior to the model analysis. Good agreement was obtained between the finite element results for the contact model and existing theoretical and experimental data. It was found that the Hertzian theory failed to accurately predict localized stresses at the contact interface when the indenter was much stiffer than the model.

scholarly journals Mechanical and thermal stress analysis of hybrid ceramic and lithium disilicate based ceramic CAD-CAM inlays using 3-D finite element analysis

2021 ◽  
Vol 24 (3) ◽  
Author(s):  
Sameh Mahmoud Nabih ◽  
Nady Ibrahim Mohamed Ibrahim ◽  
Ahmed Ramadan Elmanakhly
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Analysis ◽  
Lithium Disilicate ◽  
Ceramic Materials ◽  
Thermal Fluctuations ◽  
Element Analysis ◽  
Tooth Structure ◽  
Cad Cam ◽  
Hybrid Ceramic

Objectives: The aim of this study was to analyze mechanical and thermal stresses of hybrid ceramic and lithium disilicate based ceramic of CAD/CAM inlays using 3D Finite element analysis. Material and Methods: A three dimensions finite element model of permanent maxillary premolar designed according to standard anatomy with class II cavity preparation for inlay restored with two different ceramic materials:- 1- Hybrid ceramic (Vita Enamic), 2- Lithium disilicate based ceramic (IPS e.max CAD). Totally six runs were performed on the model as: One loading case for each restorative material was tested in stress analysis; seven points of loading with 140N vertically applied at palatal cusp tip and cusp slop, marginal ridges and central fossa while the models base was fixed as a boundary condition in the two cases. Two thermal analysis cases were performed for each restoration material by applying 5ºC and 55ºC on the crown surface including the restoration surface. Results: The results of all structures were separated from the rest of the model to analyze the magnitude of stress in each component. For each group, maximum stresses on restorative materials, cement, enamel, and dentin were evaluated separately. Both ceramic materials generated similar stress distribution patterns for all groups when a total occlusal load of 140 N was applied. Conclusion: Thermal fluctuations of temperature have a great influence on the stresses induced on both restoration and tooth structure. IPS e.max CAD produced more favorable stresses on the tooth structure than Vita Enamic.   KEYWORDS Ceramics; Finite element analysis; IPS e.max CAD; Lithium disilicate;  Vita Enamic.

Stresses in Nozzle Shell Junctions due to External Loads: A Comparative Study

2013 ◽  
Author(s):  
Dipak K. Chandiramani ◽  
Suresh K. Nawandar ◽  
Shyam Gopalakrishnan
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Theoretical Background ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Section Viii ◽  
Division 2 ◽  
External Loads ◽  
Element Method

Various methods have been in use for the determination of stresses at the nozzle-shell junction due to external loads and moments. Some methods evaluate stress in the cylindrical or spherical shell (e.g. WRC 107 now WRC 537) while others evaluate stresses in cylindrical shells and nozzles (e.g. WRC 297). ASME Section VIII Division. 2 specifies use of WRC 107/WRC 297 or Finite Element Analysis (FEA) for determination of stresses at shell-nozzle junctions with external loads and moments on the nozzle. Each method could yield a different result for the same loading condition and geometry and this has been recognized in comparisons made in WRC 297 with WRC 107 and FEA. Further, customized FEA software are also available for this analysis. There still seems to be some confusion in users of these methods regarding selection of method for optimization of design. Users not familiar with Finite Element Method prefer to use calculations based on WRC 107/297. Hang-Sung Lee, et.al. have recently (PVP 2011 – 57407) analyzed nozzle shell junctions using the Finite Element Method, compared their results with calculations to WRC 297 and made recommendations. The work presented in this paper is not an attempt to compare individual stresses obtained by classical versus analytical methods. Instead, an attempt has been made to consolidate the results obtained by the various methods into charts to enable a user to make a preliminary assessment to ascertain under what geometrical conditions the calculations made by each of the above methods would result in overall Code acceptable stresses without the results being either overly conservative or un-conservative. This is particularly relevant to the geometries which use the graphs and charts which have been extrapolated without rigorous theoretical background in the WRC Bulletin 537. The Finite Element Method has been used as the referee method.

On the Prediction of Fusion Rate of Ice by Finite Element Analysis

1981 ◽  
Vol 103 (4) ◽  
pp. 727-732 ◽  
Author(s):  
T. R. Hsu ◽  
G. Pizey
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fresh Water ◽  
Close Agreement ◽  
Fusion Rate ◽  
Ambient Conditions ◽  
Element Analysis ◽  
Complicated Geometries ◽  
Multi Phase ◽  
Element Algorithm

A finite element algorithm including phase change is presented for the prediction of the rate of freezing of fresh water under general ambient conditions. This method has shown to be highly versatile in dealing with multi-phase materials of complicated geometries. Experiments were performed to verify the code prediction on the fusion of fresh water and a case with oil inclusion. Close agreement was observed between the predicted and measured values.

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