scholarly journals DESIGN OPTIMIZATION OF A CIVIL STRUCTURE USING NUMERICAL SIMULATIONS

2020 ◽  
Vol 10 (2) ◽  
pp. 5-13
Author(s):  
Florian VLĂDULESCU
Keyword(s):  
Geometric Model ◽  
Input Parameter ◽  
Element Model ◽  
Design Parameters ◽  
Fe Model ◽  
Shell Elements ◽  
Optimization Study ◽  
Input Parameters ◽  
Parametric Relationships

This optimization study aims to determine the effect of each input parameter on the output parameters, how the input parameters can interact with each other and also it is emphasized the determination of the values for the input parameters that optimize the responses. In this study, the objective is to obtain an optimal configuration for a resistance structure specific to a telecommunications tower. For this purpose, a variable geometric model using design parameters is created, based on which a 3D finite element model (FEM) is obtained, which is used in the optimization study. The FE model is updated automatically for each version of geometric model and is made using beam and shell elements. Design of Experiments (DOE) methodology allows for using a mathematical model that predicts how input parameters interact to create output responses in an optimization process. Parameters’ correlation and monitoring allow for identifying important parameters and the correlation matrix and sensitivity graphs also help understanding the parametric relationships. Variation limits for design parameters are defined and these parameters can have integer or fractional values.

scholarly journals A Methodology for Optimal Design of Transmission Lines to Protection against Lightning Surges in Presence of Arresters

2020 ◽  
Vol 9 (1) ◽  
pp. 105-110
Author(s):  
R. Shariatinasab ◽  
R. Azimi
Keyword(s):  
Transmission Lines ◽  
Geometric Model ◽  
Design Parameters ◽  
Target Number ◽  
Planning Stage ◽  
Shielding Failure ◽  
Surge Arresters ◽  
The Monte Carlo Method ◽  
Optimal Value

In this paper, a methodology for determination of the optimal value of protection design parameters, i.e. tower footing resistance, insulation strength, and surge arresters’ rating in the planning stage of transmission lines (TLs) is presented. This method calculates the shielding failure flashover rate (SFFOR) of TLs, based on Electro-geometric model (EGM) of TLs, and the back flashover rate (BFR) of TLs, based on the Monte Carlo method, in which the accuracy of the proposed methodology has been verified by comparing the resultant results with those obtained with the use of the IEEE FLASH program. The proposed method can be directly used to achieve the minimum lightning flashover rate (LFOR) of TLs by the minimum investment cost. Also, it can be used, indirectly, for determination of the appropriate value of the footing resistance, insulation strength and arresters’ rating to satisfy any target number of LFOR that might be specified by the utilities or standards.

scholarly journals Formulation of the membership function and determination of the input of fuzzy loads in the structural fuzzy analyzing problem

2007 ◽  
Vol 29 (2) ◽  
pp. 117-126
Author(s):  
Nguyen Van Pho
Keyword(s):  
Membership Function ◽  
Input Parameter ◽  
Design Standards ◽  
Input Parameters ◽  
Triangular Membership Function ◽  
Probabilistic Density Function ◽  
Fuzzy Parameters ◽  
Selection Of ◽  
The Membership Function

The fuzzy analyzing process consists of different steps. In this paper, the author considers only the method for formulation of the membership function of fuzzy loads acting on the structure. Based on the membership function of fuzzy loads, the combinations of deterministic of the regression analyzing process will be determined. The membership function of fuzzy loads is selected by the triangular membership function. It is in conformity with the concept on selection of loads in the design standards. The combination of inputs for the analyzing process will be determined, based on the number of present times of the value of input parameters (including the deterministic parameters, fuzzy parameters and the random ones) in the schema of analysis. The number of present times of input parameters is either proportional to value of the corresponding membership function or to the value of the probabilistic density function. A method for determining the appropriate combination of deterministic inputs so that each input parameter will present only one time in each combination is proposed. To illustrate the proposed method, an example on the determination of input combinations of tornado's velocity in Vietnam is presented.

Analysis of the Worst Mistuning Patterns in Bladed Disk Assemblies

2003 ◽  
Vol 125 (4) ◽  
pp. 623-631 ◽  
Author(s):  
E. P. Petrov ◽  
D. J. Ewins
Keyword(s):  
Finite Element ◽  
Large Scale ◽  
Optimization Problem ◽  
Element Model ◽  
Design Parameters ◽  
Finite Element Models ◽  
Bladed Disks ◽  
Bladed Disk ◽  
The Many

The problem of determining the worst mistuning patterns is formulated and solved as an optimization problem. Maximum resonant amplitudes searched across the many nodes of a large-scale finite element model of a mistuned bladed disk and across all the excitation frequencies in a given range are combined into an objective function. Individual blade mistuning is controlled by varying design parameters, whose variation range is constrained by manufacture tolerances. Detailed realistic finite element models, which have so far only been used for analyzing tuned bladed disks, are used for calculation of the forced resonant response of mistuned assemblies and for determination of its sensitivity coefficients with respect to mistuning variation. Results of the optimum search of mistuning patterns for some practical bladed disks are analyzed and reveal higher worst cases than those found in previous studies.

Analysis of the Worst Mistuning Patterns in Bladed Disc Assemblies

2001 ◽  
Author(s):  
E. P. Petrov ◽  
D. J. Ewins
Keyword(s):  
Finite Element ◽  
Large Scale ◽  
Optimization Problem ◽  
Element Model ◽  
Design Parameters ◽  
Finite Element Models ◽  
Resonant Response ◽  
Variation Range ◽  
The Many

In the paper, the problem of determining of the worst mistuning patterns is formulated and solved as an optimization problem. Maximum resonant amplitudes searched across the many nodes of a large-scale finite element model of a mistuned bladed disc and across all the excitation frequencies in a given range are combined into an objective function. Individual blade mistuning is controlled by varying design parameters, whose variation range is constrained by manufacture tolerances. Detailed realistic finite element models, which have so far only been used for analysing tuned bladed discs, are used for calculation of the forced resonant response of mistuned assemblies and for determination of its sensitivity coefficients with respect to mistuning variation. Results of the optimum search of mistuning patterns for some practical bladed discs are analysed and reveal higher worst cases than those found in previous studies.

scholarly journals Establishment of a three-dimensional finite element model of severe kyphotic deformity secondary to ankylosing spondylitis

2017 ◽  
Vol 45 (2) ◽  
pp. 639-646 ◽  
Author(s):  
Aikeremujiang Muheremu ◽  
Hui Li ◽  
Junyi Ma ◽  
Yong Ma ◽  
Yuan Ma
Keyword(s):  
Finite Element ◽  
Ankylosing Spondylitis ◽  
Geometric Model ◽  
Three Dimensional ◽  
Element Model ◽  
Biomechanical Analysis ◽  
Surface Model ◽  
Fe Model ◽  
Digital Platform ◽  
Posterior Spine

Objective To establish a three-dimensional (3D) finite element (FE) model of ankylosing spondylitis (AS) kyphosis that is a digital platform for further studies. Methods A 30-year-old man with AS kyphosis underwent computed tomography transverse scanning from T1 to the sacrococcyx. The images were imported into Mimics® 17.0 software to establish a 3D model of the posterior spine, which was then imported into Studio Geomagic 2013 software. Posterior spine convex geometry was established on the 3D geometric model for subsequent optimization of image processing. Unigraphics NX 8.5 produced the spinal kyphosis surface model. Modeled calcification of ligaments and partial resection of useless sacral bone were added. The model was imported into ANSYS 15.0 FE analysis software. Ligaments were added. Parameters were set to generate a 3D FE model of AS. Results and Conclusion A 3D FE model of AS was successfully established, providing a reliable digital platform for subsequent biomechanical analysis.

Influence of Process Parameters on Electrode Wear in Electrical Discharge Machining Cylindrical Shaped Parts

2020 ◽  
Vol 853 ◽  
pp. 24-28
Author(s):  
Nguyen Van Cuong ◽  
Le Hong Ky ◽  
Tran Thi Hong ◽  
Tran Thanh Hoang ◽  
Manh Cuong Nguyen ◽  
...  
Keyword(s):  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Input Parameter ◽  
Electrode Wear ◽  
Influence Of Process Parameters ◽  
Optimization Study ◽  
Input Parameters ◽  
Pulse On Time ◽  
Pulse Off Time ◽  
Off Time

This paper introduces an optimization study on electrode wear when electrical discharge machining (EDM) cylindrical shaped parts made from 90CrSi. In the study, the experiments were performed and analyzed by using Taguchi method. The input parameters of the experiments were the pulse on time, the pulse off time, the current, and the server voltage. The effect of input parameters on the electrode wear were evaluated by analyzing variance. Also, the optimum values of the input parameter were proposed for getting the minimum electrode wear.

scholarly journals On sensitivity analysis of unsteady responses for FEM models of beams

2020 ◽  
Vol S-I (2) ◽  
pp. 103-109
Author(s):  
M. Mironov ◽  
Keyword(s):  
Cross Sections ◽  
Quality Criteria ◽  
Element Model ◽  
Optimality Criteria ◽  
Design Parameters ◽  
Fe Model ◽  
Vibration Frequencies ◽  
Various Boundary Conditions ◽  
Analytical Derivatives ◽  
Analytical Expressions

This paper discusses optimal design of structures in terms of various quality criteria with limitations for the parameters of dynamic stress-strain state (steady, unsteady, spectral). Efficiency of the methods based on the compliance with indirect optimality criteria, in particular, on the Kuhn-Tucker conditions, considerably depends on fast and accurate calculations of derivatives for the parameters of state in terms of design parameters, which is achieved by obtaining the analytical expressions. Introduction of these expressions to the optimization of FEM-based models is only possible if structural design parameters and the parameters of stiffness matrix and element masses are linked explicitly. The purpose of this work is to finalize and verify the methods for obtaining analytical derivatives of design parameters as functions of vibration frequencies, forced harmonic vibration frequencies and natural vibration frequencies of finite-element model with subsequent transition to completely analytical (not subtractive) differentiation of unsteady and spectral responses of design parameters. For an FE model of beam with a large number (one hundred) of finite elements, this study obtained and verified, for various boundary conditions and loading scenarios, the distributions of sensitivity coefficients for steady dynamic parameters in terms of design parameters, i.e. cross-sections of elements.

Mine conveyor belt fire classification

2021 ◽  
pp. 073490412110563
Author(s):  
Manuel J Barros-Daza ◽  
Kray D Luxbacher ◽  
Brian Y Lattimer ◽  
Jonathan L Hodges
Keyword(s):  
Input Parameter ◽  
Conveyor Belt ◽  
Classification Model ◽  
Design Parameters ◽  
Air Velocity ◽  
Conveyor Belts ◽  
Artificial Neural ◽  
Mine Roof ◽  
Test Scenarios

This article presents a conveyor belt fire classification model that allows for the determination of the most effective firefighting strategy. In addition, the effect of belt design parameters on the fire classification was determined. A methodology that involves the use of numerical simulations and artificial neural networks was implemented. An approach previously proposed for modeling fires over conveyor belts was used. With the objective of obtaining some required modeling input parameter and verifying the capacity of this approach to get realistic results, computational fluid dynamics model calibration and validation were carried out using experimental test results available in the literature. Results indicated that scenarios with belt positions closer to the mine roof and greater tunnel heights require a higher longitudinal air velocity to be attacked directly. Furthermore, the belt fire classification model provided by the artificial neural network had an accuracy around 95% when test scenarios were classified.

scholarly journals TO THE QUESTION OF THE DETERMINATION OF GEOMETRIC CHARACTERISTICS OF THE SECTION OF CORRUGATED BEAMS WITH TRAPEZOIDAL WEBS BASED ON THE SIMULATION RESULTS

2019 ◽  
Vol 15 (1) ◽  
pp. 29-40
Author(s):  
Tatiana Dmitrieva ◽  
Khukhuudei Ulambaya
Keyword(s):  
Finite Element ◽  
Software Package ◽  
Element Model ◽  
Shell Elements ◽  
Geometric Characteristics ◽  
Corrugated Webs ◽  
Trapezoidal Profile ◽  
Shell Finite Element ◽  
Made In

An algorithm for calculating the geometric characteristics of steel I-beams with plate corrugated webs of arbitrary type is proposed. The algorithm is implemented using the I-beam with plate trapezoid webs as an example. The determination of reduced area and moments of inertia in the axes of the cross section of the trapezoidal profile based on the finite element modeling of the beam with shell elements in calculations for bending and axial compression in the “ANSYS 14.5” software package is described. The verification procedure has been performed for a shell finite element model using the example of an I-beam with a standard flat web. A table has been compiled of geometric characteristics of rod corrugated elements of a trapezoidal profile in order to realize their finite element calculation using a rod diagram. An example of the calculation of a flat frame with a horizontal corrugated element, made in software package “LIRA-SAPR” using a flat rod diagram is given.

A Critical Analysis on the Cyclic Fatigue Testing of Rotary Endodontic Instrument

2013 ◽  
Vol 431 ◽  
pp. 82-87
Author(s):  
Chow Shing Shin ◽  
Q.M. Chang ◽  
Chun Pin Lin
Keyword(s):  
Finite Element ◽  
Fatigue Testing ◽  
Geometric Model ◽  
Element Model ◽  
Cyclic Fatigue ◽  
Simplified Model ◽  
Curvature Radius ◽  
Fe Model ◽  
Extra Effort ◽  
Angular Extent

Cyclic fatigue of rotary endodontic instruments has been tested using different techniques while the results were normally compared in terms of a canal curvature radiusRand an angular extent of instrument insertionθ. In this work, the effects of canal geometry and analysis method have been investigated by finite element (FE) analysis. A highly simplified FE model has been proposed and verified experimentally. Results from a detailed finite element (FE) model and a simple geometric model are discussed in the light of the simplified model results. It was found that the commonly used (R,θ) alone cannot quantify the severity of bending. The diameters and taper development of the canal and the instrument also played important roles. The simple geometric model can give unacceptable errors and cannot only be employed forensically. The detailed finite element model is much more resource consuming than the current simplified model and the extra effort is not worthwhile if only the bending strain is needed for correlation and prediction of instrument fatigue life.

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