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1

A new method for identification of cyclic plasticity model parameters

Suchocki Cyprian, Kowalewski Zbigniew

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 2

art. no. e69, 1--14

EN

In this study, a new method for determining the material parameters of cyclic plasticity is presented. The method can be applied to evaluate the model parameters from any loading histories measured experimentally. The experimental data require basic processing only to be utilized. The method can be applied to calibrate the parameters of different elastoplastic models such as the Chaboche-Rousselier (Ch–R) constitutive equation or other model formulations which use different rules of isotropic hardening. The developed method was utilized to evaluate the material parameters of copper for a selected group of constitutive models. It is shown that among the considered model formulations a very good description of the mechanical properties of copper is achieved for the Ch-R model with two Voce terms used for simulating the isotropic hardening and two backstress variables utilized for capturing the kinematic hardening behavior. Furthermore, it is demonstrated that a model calibrated using the cyclic tension/compression data is able to properly capture the material response in torsion. Similarly, when the constitutive parameters are determined using the cyclic torsion data the model is able to properly reproduce the material behavior in tension/compression. It is concluded that for the considered type of constitutive equations the material parameters can be identified from a single mechanical test. The proposed methodology was validated using the relations derived analytically.

2

Material parameter identification for clinching process simulation using neural network metamodels

Nguyen Duc Vinh, Lin Pai-Chen, Nguyen Minh Chien, Wu Yang-Jiu, Tran Hoang Son, Tran Xuan Van

Annals of Computer Science and Information Systems

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2022

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Vol. 33

183--188

EN

Clinching is a mechanical joining method in which two sheet workpieces are clamped and locked together using a punch and a die. Process parameters for such joint elements are often designed based on numeric simulation. Before this step, the identification of good material parameters is crucial to get validated computational results. In this paper, neural network metamodels are used for this specific task as a means to deal with large computation time. The identified material parameters reduce significantly the error between computational results and experimental results.

3

Novel curve fitting method based on constrained optimization for the modelling of human brain aneurysms using Mooney–Rivlin hyperelastic materials in the entire range of deformations til rupture

Tóth Brigitta K., Lengyel András

Acta of Bioengineering and Biomechanics

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2022

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Vol. 24, no. 2

95--108

EN

Brain aneurysms often prove fatal if ruptured, therefore, understanding their mechanical behaviour in the coupled system of vessels and blood flow can significantly help preventive surgical treatment. The purpose of this work was to analyse measurement data and to determine material parameters for the hyperelastic Mooney–Rivlin model for model building and numerical simulations of aneurysms. Methods: A total of 88 human brain aneurysm specimens of 41 patients obtained from surgery were processed in this work based on the tests performed by the authors in a previous project. A novel algorithm was proposed and applied in this work to fit stress–stretch ratio curves for multiple measurement data using constrained optimization with hard conditions to comply with known mechanical behaviour. Results: The method produced parameters of stretch ratio–stress curves for a number of groups of the specimens representing the average as well as the extreme stresses, separately for male and female subsamples. Stretch range both in compression and in tension up to rupture was covered and material stability for the entire range was also verified. Conclusions: The fitted curves with recommended range of validity are directly applicable to numerical finite element or coupled simulations of aneurysms supporting preventive medical treatment or decision making.

4

Effect of foam’s heterogeneity on the behaviour of sandwich panels

Chuda-Kowalska Monika

Civil and Environmental Engineering Reports

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2019

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Vol. 29, no. 4

97--111

EN

This study aimed to develop a knowledge about material parameters identification of the foam core and numerical modelling of the sandwich panels to accurately predict the behaviour of this kind of structures. The polyisocyanurate foam (PIR) with low density used in sandwich panels dedicated to civil engineering is examined in the paper. A series of experiments (tensile, compression and bending tests) were carried out to identify its mechanical parameters. To determine the heterogeneity of analysed foam a Digital Image Correlation (DIC) technique, named Aramis, is applied in the paper. The results obtained from FE analyses are compared with the experimental results on full-size plates carried out by the author and proper conclusions are drawn.

5

Analiza statystyczna parametrów materiałowych zacisków hamulcowych

Bednarz J.

Autobusy : technika, eksploatacja, systemy transportowe

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2018

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R. 19, nr 6

359--362, CD

PL

W trakcie produkcji wielkoseryjnej części samochodowych zakłada się, że parametry materiałowe wytworzonych elementów są dokładnie takie same. W rzeczywistości nie jest to jednak prawda. W artykule przedstawiono analizę statystyczną parametrów materiałowych zacisków hamulcowych. Przedstawiono analizę statyczną własności materiału dla następujących parametrów materiałowych: gęstość materiału, zawartość procentowa glinu w stopie, zawartość procentowa żelaza w stopie, zawartość procentowa krzemu w stopie, zawartość procentowa magnezu w stopie.

EN

During the mass production of automotive parts, it is assumed that the dynamic parameters of generated elements are exactly the same. In fact, this is not true. The article presents statistical analysis of material parameters of brake calipers. Statistical analysis of material properties for the following material parameters is presented: material density, percentage of aluminum in the alloy, percentage of iron in the alloy, percentage of silicon in the alloy, percentage of magnesium in the alloy.

6

Podsumowanie badań laboratoryjnych piaskowca pod kątem analizy wyrywania kotwy

Gontarz J., Podgórski J., Kalita M., Siegmund M.

Budownictwo i Architektura

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2017

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Vol. 16, nr 3

113--123

PL

W pracy przedstawiono wyniki badań mechanicznych dwóch rodzajów piaskowca pochodzącego z dwóch kopalń kamienia w Polsce. Wykonano badania ściskania próbek sześciennych, trójpunktowego zginania belek, zginania belek z nacięciami i badanie wytrzymałości na rozciąganie przy zginaniu oraz przy ściskaniu metodą kwazi-brazylijską. Na podstawie przeprowadzonych badań wyznaczono wartości wytrzymałości na ściskanie, wytrzymałości na rozciąganie, moduły Younga i współczynniki Poissona. Z testu zginania naciętych belek wyznaczono krytyczny mnożnik intensywności naprężeń w pierwszej modzie pękania oraz krytyczną energię pękania. Wyznaczone wartości docelowo mają służyć jako parametry modeli komputerowych używanych w symulacjach badania mającego na celu wyrywanie fragmentu skała za pomocą zakotwionej w niej kotwy samopodcinającej.

EN

The paper presents the results of mechanical laboratory tests of two types of sandstone, white and gray, obtained from two stone quarries in Poland. Compression tests of cubic samples, three-point bending tests, bending of notched beams and quasi-Brazilian test were performed. Basing on these tests, the values of compressive strength, tensile strength, Young’s modulus and Poisson’s ratio were determined. From the bending test of notched beams, a critical stress intensity factor in mode I and critical energy release rate was determined. These values are intended to be used as parameters of numerical (FEM) model to simulate the pull-out test of an anchor pulled out from the rock surface.

7

Ocena wpływu budowy geologicznej na wyniki numerycznego modelowania przemieszczeń ścian i dna wykopu w świetle danych pomiarowych ze stacji A14 I linii metra w Warszawie

Popielski P., Kasprzak A., Smoliński B.

Przegląd Geologiczny

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2016

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Vol. 64, nr 4

230--237

EN

The paper shows a comprehensive analysis of the displacement of anchored diaphragm wall on the example of the trench of the A14 Świętokrzyska station of underground line I in Warsaw. Based on the collected information and technical documentation the 2D numerical models were generated in ZSoil2014v.14.10 (Z_SOILPC 2014v.14.10; Zace Services; Lausanne2015). According to available documentation, sophisticated soil and water conditions were taken into accountin the analysis. Based on the calculations the character of displacements at different steps of trench digging were discussed. In the conclusion, the influence of variability of geological and geotechnical conditions was evaluated.

8

Material parameters of antimonides and amorphous materials for modelling the mid-infrared lasers

Piskorski Ł., Sarzała R. P.

Optica Applicata

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2016

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Vol. 46, nr 2

227--240

EN

The proper modelling of semiconductor device operation with full complexity of many interrelated physical phenomena taking place within its volume is possible only when the material parameters which appear in each part of the self-consistent model are known. Therefore, it is necessary to include in calculations the material composition, temperature, carrier concentration, and wavelength dependences in electrical, thermal, recombination and optical models. In this work we present a complete set of material parameters which we obtained basing mostly on the experimental data found in several dozen publications. To refine the number of equations, we restrict the material list to those which are typically used in edge-emitting lasers and vertical-cavity surface-emitting lasers designed for mid-infrared emission.

9

Computer aided diagnostic of risky state in human pelvic bone

John A., Wysota P.

Journal of Achievements in Materials and Manufacturing Engineering

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2011

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Vol. 49, nr 2

313--322

EN

Purpose: of this paper is to raise the issue of recognition of dangerous states in human pelvic bone. These states can lead to damages of bone. Design/methodology/approach: consist of using the images from quantitative computed tomography (QCT). On the base of obtained data the numerical model of pelvic bone was created. Very important stage it was determination the values of material parameters. In the paper two methods were described. The first method directly basis on the data from radiology. In regard to difficulties with tomography data the second method was applied - the numerical simulations. The computer program was developed to obtain distribution of material parameters in numerical model of pelvic bone on the base of decreasing of bone mass. Findings: of the paper is that when decreasing of bone mass occurs in whole bone the stresses grow up continuously at the time. When decreasing of bone mass appears in individual region only the stresses decrease at the beginning and next increase while the bone mass still decrease. It could be one of the reason of lack of the symptoms in primary stage of osteoporosis. Research limitations/implications: are connected with accessibility of data from QCT. During QCT the bone system as well as density phantom are X-rayed simultaneously. On the base of standard density coming from the phantom the calibration curve is drown. Practical implications: it is the proposed procedure which facilitate the detection of risky state in pelvic bone. Originality/value: of researches consist in complex approach to problem of osteoporosis in human pelvic bone and applying the numerical simulations to create the numerical model of pelvic bone with osteoporotical changes.

10

Goldmann applanation tonometry - not as good as gold

Śródka W.

Acta of Bioengineering and Biomechanics

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2010

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Vol. 12, no. 2

39-47

EN

A thesis that linear mechanics does not apply to the analysis of cornea load during Goldmann applanation tonometry measurement and that the concept of surface tension in the lacrimal fluid is an ineffective attempt at circumventing the associated problems is put forward. The fundamental problem emerging during numerically simulated measurement of pressure on the eyeball, whose dimensions are considered to be calibrated, stems from the fact that the flattening of the cornea at the nominal intraocular pressure leads to a critical state in which the shell loses stability. The consequences are far-reaching. The Goldmann tonometer performs well at low intraocular pressure, but above the nominal pressure its readings are always understated. The cause of the error is not the tonometer itself (its readings can be even very accurate). It is shell “solution” called Imbert–Fick law which is faulty.

11

Identyfikacja stałych materiałowych do obliczeń metodą elementów skończonych

Czabanowski R.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Nauki Techniczne

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2009

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Z. 13

112--117

PL

W artykule przedstawiono badania eksperymentalne mające na celu wyznaczenie stałych materiałowych niezbędnych do obliczeń metodą elementów skończonych elementów i podzespołów wykonanych z hiperelastycznych elastomerów.

EN

The paper discusses experimental tests carried out to determine material parameters of highly elastic elastomers for FEM calculates of part and units made up rubber-like materials.