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EN
This article presents the application of Chaboche nonlinear kinematic hardening model in simulations of uniaxial ratcheting. First, the symmetrical strain-controlled cyclic tension/compression tests for PA6 aluminum samples were done. Using the experimental stress–strain curve, initial material hardening parameters were determined by the ABAQUS software. The experimental curve was compared with the numerical one. For better fitting of both curves, the optimization procedure based on the least-square method was applied. Using the determined hardening parameters, numerical simulations of the ratcheting were done by the finite element analysis software. Numerical results were then compared with the experimental data obtained in the stress-controlled cyclic loading test.
EN
In order to characterise the material and damage behaviour of additively manufactured polyamide 12 (PA12) under quasi-static load and to implement it in a numerical model, experiments under quasi-static load as well as microstructural investigations were carried out. Selective laser sintering (SLS) was used as the manufacturing process. For the classification of the material behaviour, quasi-static cyclic tests with holding times as well as tensile tests were performed. X-ray refraction and computed tomography (CT) were used to investigate the damage behaviour. The Chaboche model, which has already been applied for metallic materials under thermomechanical loading, served as the basis for the selection of the numerical material model. The same procedure was used for the selection of the damage model, where the Gurson–Tvergaard–Needleman (GTN) model was chosen, which was already used for porous metallic materials. The Chaboche model shows very good agreement with experimental results. Furthermore, the coupling with the GTN model allows a very good modelling of the damage behaviour. Finally, it could be shown that the selected models are suitable to simulate the material and damage behaviour of 3D printed PA12.
PL
W artykule opisano podstawy nowoczesnego systemu dedykowanego pod wentylatory międzystopniowych chłodnic powietrza, rekuperatorów w obiegach turbozespołu gazowego oraz chłodniach wentylatorowych w obiegach parowych. System ten opiera się na numerycznych algorytmach, których zadaniem jest monitorowanie pracy oraz określenie stopnia degradacji najbardziej wytężonych elementów konstrukcji. Rozszerzeniem kompetencji jest dobór optymalnych warunków pracy, sprzężonych ściśle z aktualnymi parametrami obiegu turbozespołu gazowego. System wyposażony jest w autorskie procedury będące wynikiem długoletnich prac wykonywanych w IMP PAN w Gdańsku.
EN
In this papers I have been presented fundamental of news monitoring system dedicated by the fans of intercooler and recuperative heat exchangers from the cycle of gas turbine and cooling tower from cycle of steam turbine. This system based on the numerical algorithm. The goal of this algorithm is monitoring work and calculation level of damage highly loaded elements parts in machines. Extension of the competences it is selection of optimal boundary of works, which is precisely linked from actual parameters of thermodynamic cycle. System is used by authorial procedures as a result of many years worked in IMP PAN.
EN
During seismic events, the gravity loads may cause a reduction of the lateral stiffness of structures; inelastic deformations combined with horizontal loads (P-Δ effect) can bring to a state of dynamic instability that obviously influences building safety. Especially for flexible structures, the P-Δ effect amplifies structural deformations and resultants stresses, and thus may represent a source of sideway collapse. Since this type of collapse is the result of progressive accumulation of plastic deformation on structural components, the specific objective of this works is to study this effect on a three floor metallic frame (made of aluminium alloy). A non-linear finite element (FE) model of the frame has been developed to study the dynamic non-linear behaviour of the structure, and compare it with the experimental results obtained from a scaled model of the real structure. The FE model, where a simple isotropic hardening behaviour was assumed for the material, was not able to reproduce the real behaviour of the structure. Rather, the correct description of the cyclic plastic behaviour of the material was essential for the numerical analysis of the structure. The characterization of the non-linear behaviour of the material was made by cyclic tension–compression tests on material specimen, from which the coefficients of Chaboche's model were properly calibrated. In this way, the finite element model of the structure provided results in optimum agreement with the experimental ones, and was able to predict the lateral collapse very well.
EN
The main purpose of this paper is the parameters identification of the Perzyna and the Chaboche models for the aluminum alloy at elevated temperature. The additional purpose is comparison of the results for these viscoplastic models. The results have been verified by the numerical simulation of the laboratory tests. The material parameters have been calculated on the basis of the uniaxial tension test. The determination of the Perzyna model’s parameters has been made on the basis of the ideas presented in papers of Perzyna [14–16, 18]. Then the parameters identification of the Chaboche model has been performed using concept presented in [2, 5, 6]. The elastic and inelastic properties have been estimated using the non-linear approximation by the least-squares method in Marquardt-Levenberg variant [12, 13]. The correctness assessment of the performed approximation has been verified by correlation and determination coefficients.
PL
Celem pracy jest adaptacja lepkoplastycznego modelu Chaboche'a do opisu nieliniowych właściwości specjalnych struktur granulowanych. Nowatorskie, w stosunku do poprzednich prac autorów, jest uwzględnienie w modelu, poza dotychczas rozważanym wzmocnieniem izotropowym, także kinematycznego wzmocnienia materiału. Specjalne struktury granulowane umożliwiają uzyskanie zmiennych właściwości fizycznych poprzez umieszczenie luźnego materiału granulowanego w miękkiej i szczelnej powłoce, w której wytwarza się podciśnienie. Stopień podciśnienia wpływa w zasadniczy sposób na globalne właściwości struktur, umożliwiając aktywną kontrolę takich niepożądanych zjawisk, jak drgania czy hałas.
EN
Present work deals with special granular structures. They consist of loose grains placed in a hermetic space with underpressure. The response of the material on compression and traction is discussed. Different underpressure values and strain rates are taken into consideration. The Chaboche's model is selected to capture main features of considered structures. Numerical method is applied to estimate material's parameters. In a final part of the paper the verification process of numerical and experimental data is presented.
PL
W pracy przedstawiono numeryczną metodę identyfikacji parametrów materiałowych lepkoplastycznego modelu Chaboche'a. Jako materiał modelowy przyjęto specjalne struktury granulowane. Specjalne struktury granulowane budowane są na bazie materiałów sypkich umieszczanych w szczelnej osnowie, w której generuje się podciśnienie. W pracy wspomniano istniejące metody analityczne umożliwiające identyfikację lepkoplastycznego modelu Chaboche'a oraz podkreślono zalety nowo proponowanej metody numerycznej.
EN
In the paper an original numerical method of Chaboche's model parameters identification is presented. As an exemplary material, special granular structures are selected. Special granular structures are composed basing on loose materials encapsulated in a hermetic space with underpressure. Controlling the range of internal pressure (the vacuum range) it is possible to effectively change the global physical features of a granular matter. It is particularly interesting to apply such structures in semi-active damping of vibrations or noise. In this paper existing analytical methods of the viscoplastic Chaboche's model parameters identification are mentioned. The advantages of the new, numerical methodology is underlined.
EN
The paper presents three methods of damage parameters identification in viscous flow conditions. Constitutive relations including damage are used according to the Chaboche and Lemaitre concept. The authors propose also their own modifications of identification algorithm. All algorithms are compared in the identification process for aluminum alloys.
PL
Tematyka pracy poświęcona jest omówieniu metody estymacji parametrów materiałowych wybranego lepkoplastycznego modelu konstytutywnego. Pomimo faktu, że obiektem modelowania są struktury, zbudowane z luźnego materiału sypkiego, otoczonego zamkniętą plastomerową osnową, w której wytwarzane jest podciśnienie zewnętrzne, prezentowana metoda identyfikacji modelu jest uniwersalna.
EN
Procedure of material constants values estimation, taking into consideration results of rheological tests, without the necessity of carrying out more complex experiments, will be the topic of the paper.
10
Content available remote The elasto- viscoplastic Chaboche model
EN
The elasto-viseoplastie constitutive equations of the Chaboehe model [I] have been developed and modified many times. The aim of the present paper is to present the existing Chaboche model variants and describe its scientific and engineering applications. A compact review of literature on these applications is given, focussed on publications offering a wider and more comprehensive view of the elasto-viscoplastic Chaboche model. The article is an introduction to a comprehensive investigation of the elasto-viscoplastic Chaboche model.
EN
A new "smart structure", based on granular materials encapsulated in an elastic envelope, is proposed and investigated in the paper. Fundamental mechanical properties of the specially prepared granular testing specimens are described by the viscoplastic constitutive Chaboche's model. The experimental results of uniaxial tests are presented and applied to the identification of parameters of the Chaboche's law. The proposed procedure of material parameters estimation is based on evolutionary algorithms, solving corresponding optimization problem. The efficiency of the approach and the quality of the results are discussed.
EN
The aim of the paper is to present the development and numerical application of the elasto-viscoplastic Chaboche model. The detailed description of several variants of Chaboche model. The detailed description of several variants of Chaboche model is given, with the material parameters specified. The dynamic analysis of the circular steel plate, compared with the experiments, illustrates the practical application of the described model. For the sake of introducing the Chaboche model into the commercial program MSC.Marc system the user-defined subroutine UVSCPL has been applied.
PL
Celem artykułu jest prezentacja rozwoju i numerycznej aplikacji sprężysto-lepkoplastycznego modelu Chaboche'a. Przedstawione są szczegółowe opisy kilku wariantów modelu wraz z parametrami materiałowymi. Dynamiczna analiza kołowej płyty stalowej, która jest porównywana z wynikami eksperymentalnymi, ilustruje praktyczne zastosowanie opisywanego modelu. Do wprowadzenia modelu Chaboche'a do komercyjnego programu MSC.Marc użyta jest procedura UVSCPL.
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