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1
Content available Effective algorithm for structural optimization subjected to fatigue damage and random excitation
Sága M., Vaško M., Ságová Z., Handrik M.
Zeszyty Naukowe. Transport / Politechnika Śląska
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2018
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z. 99
149--161
EN
The aim of the paper is to present the computationally timeconsuming task of simulating the process of randomly oscillating thin-shell structures to realize an optimal design with limitations in terms of fatigue damage. The most important aim here is to design an effective optimization algorithm and choose an appropriate approach for the evaluation of multiaxial fatigue damage in the context of the random and non-proportional character of stress in the structure when considering the standard finite element model. The authors propose their own optimization algorithm, which is described in the present study and, on the basis of tests, has proven to be suitable for the aforementioned technical problems. The proposition of algorithms for calculating the accumulation of fatigue damage in non-proportional and multiaxial stresses (especially in terms of the application of rainflow analysis by decomposition of the equivalent stress, as determined by the appropriate “fatigue” criterion) is very important in such computational processes. The entire computational process was implemented in MATLAB with the “Discret_Opt_Fat” main control program. The article presents the theoretical basis for the presented complex problem solution, its algorithmization and the technical application.
2
Content available Parallel and distributed implementation of optimization algorithms in fe analyses
Handrik M., Vasko M., Kopas P.
Zeszyty Naukowe. Transport / Politechnika Śląska
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2012
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z. 76
67--74
EN
The aim of this paper is analysis of optimization algorithms in terms of their possible solutions in parallelization and distributed computing systems. Main goal is using of evolutionary algorithms and implementation of parallel algorithms. As the software platform for application of distributed optimization algorithms is using software package BOINC. For evaluation of the objective function is used FEM program ADINA.
PL
Artykuł analizuje algorytmy optymalizacyjne pod kątem ich możliwości obliczeń równoległych oraz rozproszonych systemów obliczeniowych. Ukierunkowany jest przede wszystkim na algorytmy ewolucyjne oraz ich implementację równoległą. Jako platforma softwarowa do zastosowania rozproszonego systemu obliczeniowego algorytmu zostało zastosowane oprogramowanie pośredniczące BOINC. W celu oceny funkcji docelowej został zastosowany w MES program ADINA.
3
Content available remote The Analysis of the Eigenfrequencies of Ductile Cast Iron with the Spheroidal Shape of Graphite
Vavro J., Handrik M., Vavro J. J., Vavrova A.
Machine Dynamics Research
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2010
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Vol. 34, No. 4
110-117
EN
The given work is focused on the analysis of the eigenfreqencies and natural shapes as well as it is connected with stress distribution in the frequency area referring to the ductile cast iron with the spheroidal shape of graphite. The analysis was made with help of finite element method (FEM) in the software system ADINA.v.8.6.2.
4
Content available remote Structure Analysis and Fatigue Life Prediction of the Large Scale Handling Device
Vaško M., Handrik M., Sága M., Kopas P., Vaško A.
Machine Dynamics Research
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2010
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Vol. 34, No. 4
102-109
EN
The goal of the paper was to present predictions of the fatigue lifetime of the large scale welded construction. The structural modelling and the stress-strain analysis were realised using finite element method. To determine the fatigue damage or the residual lifetime the "von Mises" equivalent stress was compared with normal stress from classical S-N (Wohler) curve (Fig. 5). The results were compared with reality, i.e. with measuring on real equipment. Distribution of the critical points confirmed consensus between both approaches (computational and experimental).
5
Content available remote Some Notes on Analysis of Bending and Torsion Combined Loading
Jakubovičová L., Sága M., Kopas P., Handrik M., Vaško M.
Machine Dynamics Research
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2010
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Vol. 34, No. 3
97-105
EN
The purpose of this paper is to present procedure of stress and strain distribution analyses at the testing sample. Experimental device is designed for combined bending - torque loading. Structural design of the equipment allows loading by constant turn of the clamping parts. The stress and strain magnitude in test sample depends on the shape and material sample. To obtain the exact solution of the stress and strain values is generally very difficult and therefore for their specification was used FE method and experimental measurement using optical system ARAMIS.
6
Content available remote Computational Simulations of Stress Distribution in Surrounding of Graphite Particles
Kopas P., Handrik M., Jakubovičová L., Sága M.
Machine Dynamics Research
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2010
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Vol. 34, No. 3
115-123
EN
The goal of the paper has been to present a computational simulation of the stress distribution in the surrounding of graphite particles. There were designed four algorithms for creation fields with random shape of graphite particles. Based on quantitative and qualitative evaluating of these algorithms it can be seen that the only appropriate field generation procedure with graphite particles is algorithm call "diffusion of carbon". Main objective of statistical processing of analysis result is determination of the 99.8% quantile stress concentration function for one or more graphite particles.
7
Content available remote Finite displacements in reciprocity-based FE formulation
Kompiš V., Novák P., Handrik M.
Computer Assisted Mechanics and Engineering Sciences
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2002
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Vol. 9, No. 4
469-480
EN
In this paper, Trefftz polynomials are used for the development of FEM based on the reciprocity relations. Such reciprocity principles are known from the Boundary Element formulations, however, using the Trefftz polynomials in the reciprocity relations instead of the fundamental solutions yields the non-singular integral equations for the evaluation of corresponding sub-domain (element) relations. A weak form satisfaction of the equilibrium is used for the inter-domain connectivity relations. For linear problems, the element stiffness matrices are defined in the boundary integral equation form. In non-linear problems the total Lagrangian formulation leads to the evaluation of the boundary integrals over the original (related) domain evaluated only once during the solution and to the volume integrals containing the non-linear terms. Also, Trefftz polynomials can be used in the post-processing phase of the FEM computations for small strain problems. By using the Trefftz polynomials as local interpolators, smooth fields of the secondary variables (strains, stresses, etc.) can be found in the whole domain (if it is homogeneous). This approach considerably increases the accuracy of the evaluated fields while maintaining the same rate of convergence as that of the primary fields. Stress smoothing for large displacements will be the aim of further research. Considering the examples of simple tension, pure bending and tension of fully clamped rectangular plate (2D stress/strain problems) for large strain-large rotation problems, the use of the initial stiffness, the Newton-Raphson procedure, and the incremental Newton-Raphson procedure will be discussed.
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