scholarly journals Up-to-date mathematical models lines of development of information technologies in the field of numerical methods of structures strength calculations

2018 ◽  
Vol 44 ◽  
pp. 00060
Author(s):  
Vladimir Meleshko
Keyword(s):  
Finite Element ◽  
Numerical Methods ◽  
Mathematical Models ◽  
Information Technologies ◽  
Structural Mechanics ◽  
High Dimensionality ◽  
Finite Element Models ◽  
Systems Of Equations ◽  
Distinctive Features ◽  
Complex Program

In order to carry out reliable calculations of structures adequate to reality, in particular, for taking into account plastic resource, it is necessary to use complex program systems and build finite element models of high dimensionality. This work provides a comparison of different mathematical models, which can be used for numerical analysis. Consideration was given to basic variation principles and methods of calculating structural mechanics. Distinctive features of forming systems of equations of classical methods of structural mechanics and known numerical methods were demonstrated. Possible advantages of methods with respect to accuracy and rate of calculations were revealed. Consideration was given to possible improvements of existing mathematical models in elastoplastic domain. Possible directions of development in the field of engineering methods for calculating strength were proposed.

scholarly journals COMPARATIVE ANALYSIS OF THE PARAMETERS OF FINITE-ELEMENT MODELS OF SOILS OBTAINED BY NUMERICAL METHODS

2017 ◽  
pp. 23-31
Author(s):  
Vladimir Ivanovich Matselya ◽  
Igor Nikolaevich Seelev ◽  
Alexey Valentinovich Lekontsev ◽  
Robert Rafaelevich Khafizov ◽  
Pavel Viktorovich Yakovlev ◽  
...  
Keyword(s):  
Finite Element ◽  
Comparative Analysis ◽  
Numerical Methods ◽  
Small Deformation ◽  
Finite Element Models ◽  
Linear Elastic ◽  
Industrial Buildings ◽  
Test Models ◽  
Weak Points ◽  
Plaxis 3D

The popularity of numerical methods for modeling soil bases determines the increased demand for the accuracy of calculations. The choice of a model that meets the requirements of accuracy of calculations and minimization of costs is determined by comparative analysis of common soil models described in scientific literature and used in calculations of sediments and dynamic effects of buildings (finite element linear elastic, elastic, ideal-plastic, Mora - Coulomb with strengthening, elasto-plastic with strengthening at small deformation). The results have been obtained on test models using finite element method in the environment of PLAXIS 3D and SCAD Office programs. In order to compare results obtained, subject to requirements of the current regulatory documents, a comparative analysis of soils was carried out according to the model of Body of rules 22.13330.2011 "Foundations of buildings and structures". The analysis results were used for choosing an optimal model of soil bases of industrial buildings estimated in earthquake-proof design. It should be noted that the strong and weak points identified for each model justify the choice of the best model for each particular case.

Identifying Real Stiffness Properties of Structural Elements of Adapted Finite-Element Models of Buildings and Structures - Part 1: Problem Setting

2014 ◽  
Vol 670-671 ◽  
pp. 732-735 ◽  
Author(s):  
Pavel I. Novikov
Keyword(s):  
Finite Element ◽  
Mathematical Models ◽  
Dynamic Characteristics ◽  
Finite Element Models ◽  
Structural Elements ◽  
Reliable Analysis ◽  
Adaptive Procedures ◽  
Stiffness Properties ◽  
The Creation ◽  
Problem Setting

The distinctive paper is devoted to problem of identification the dynamic characteristics of mathematical models based on the measured dynamic characteristics of real constructions. It is describes a problem of discrepancy of measured and modeling eigen pairs. It is shown that the problem is systemic. The creation and verification processes of mathematical (finite element) models used in the design constructions need some work and adjustments. For a reliable analysis of the construction ways are suggested to overcome the identified gaps using adaptive procedures.

scholarly journals Mathematical Models Based on Transfer Functions to Estimate Tissue Temperature During RF Cardiac Ablation in Real Time

2012 ◽  
Vol 6 (1) ◽  
pp. 16-22
Author(s):  
Jose Alba-Martínez ◽  
Macarena Trujillo ◽  
Ramon Blasco-Gimenez ◽  
Enrique Berjano
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Finite Element ◽  
Mathematical Models ◽  
Dynamic System ◽  
Applied Voltage ◽  
Transfer Functions ◽  
Tissue Temperature ◽  
System Response ◽  
Finite Element Models

Radiofrequency cardiac ablation (RFCA) has been used to treat certain types of cardiac arrhythmias by producing a thermal lesion. Even though a tissue temperature higher than 50ºC is required to destroy the target, thermal mapping is not currently used during RFCA. Our aim was thus to develop mathematical models capable of estimating tissue temperature from tissue characteristics acquired or estimated at the beginning of the procedure (electrical conductivity, thermal conductivity, specific heat and density) and the applied voltage at any time. Biological tissue was considered as a system with an input (applied voltage) and output (tissue temperature), and so the mathematical models were based on transfer functions relating these variables. We used theoretical models based on finite element method to verify the mathematical models. Firstly, we solved finite element models to identify the transfer functions between the temperature at a depth of 4 mm and a constant applied voltage using a 7Fr and 4 mm electrode. The results showed that the relationships can be expressed as first-order transfer functions. Changes in electrical conductivity only affected the static gain of the system, while specific heat variations produced a change in the dynamic system response. In contrast, variations in thermal conductivity modified both the static gain and the dynamic system response. Finally, to assess the performance of the transfer functions obtained, we conducted a new set of computer simulations using a controlled temperature protocol and considering the temperature dependence of the thermal and electrical conductivities, i.e. conditions closer to those found in clinical use. The results showed that the difference between the values estimated from transfer functions and the temperatures obtained from finite element models was less than 4ºC, which suggests that the proposed method could be used to estimate tissue temperature in real time.

scholarly journals Comparison between finite element analysis and rheological models for chip formation

2020 ◽  
Vol 23 (2) ◽  
pp. 255-268
Author(s):  
Olga Liivapuu ◽  
Jüri Olt ◽  
Tanel Tärgla
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Numerical Methods ◽  
Chip Formation ◽  
Cutting Parameters ◽  
Finite Element Models ◽  
Empirical Methods ◽  
Element Analysis ◽  
Rheological Models ◽  
Selection Of

In the process of cutting, often the selection of cutting parameters is done considering empirical methods. This approach is more expensive and does not usually lead to the best solutions. Numerical methods for simulating the chip formation have been under development over the last thirty years. The aim of the present research is to compare models based on rheological properties of metals with 2D Finite Element Models of chip formation process.

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.

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