prof. dr hab. inż. Ryszard Pęcherski

Zakład Teorii Ośrodków Ciągłych i Nanostruktur (ZTOCiN)
Pracownia Fizyki Polimerów (PFP)
stanowisko: profesor zwyczajny
telefon: (+48) 22 826 12 81 wew.: 210
pokój: 234
e-mail: rpecher

Doktorat
1979Teoretyczny opis wpływu napromieniowania neutronami na właściwości lepkoplastyczne miękkiej stali 
promotor -- prof. dr hab. inż. Piotr Perzyna, IPPT PAN
320 
Habilitacja
1999Opis deformacji plastycznej metali z efektami mikropasm ścinania 
Profesura
2007-10-22Nadanie tytułu naukowego profesora
Promotor prac doktorskich
1.2017-06-30Stręk Anna  
(AGH)
Ocena właściwości wytrzymałościowych i funkcjonalnych materiałów komórkowych 
2.2013-10-23Szeptyński Paweł  
(AGH)
Opracowanie kryterium stanu granicznego dla materiałów anizotropowych wykazujących asymetrię zakresu sprężystego1063
 
3.2013-06-21Frąś Teresa  
(UL/AGH)
Modélisation de la surface d'écoulement des matériaux incluant l'anisotropie initiale et l'effet différentiel des contraintes, approche expérimentale et numérique662
 
4.2008-12-17Zając Bogusław Franciszek  
(PK)
Doświadczalno-analityczne określenie wytężenia polimerowej skleiny w belkach zespolonych 
5.2006-11-15Kordzikowski Piotr  
(PK)
Podstawy teorii wytężenia materiałów komórkowych w oparciu o energetyczne kryteria stanów granicznych 
6.2006-03-20Gawłowski Sebastian  
(PK)
Podejście statyczne do oceny nośności granicznej prętów cienkościennych otwartych 
7.2005-04-20Nalepka Kinga Teresa  
(PK)
Fizyczne podstawy energetycznego kryterium wytężenia dla materiałów anizotropowych na przykładzie monokryształu miedzi 

Ostatnie publikacje
1.Pęcherski R.B., Nowak M., Nowak Z., VIRTUAL METALLIC FOAMS. APPLICATION FOR DYNAMIC CRUSHING ANALYSIS, INTERNATIONAL JOURNAL FOR MULTISCALE COMPUTATIONAL ENGINEERING, ISSN: 1543-1649, Vol.15, No.5, pp.431-442, 2017

Streszczenie:

The subject of the study are the models based on digital microstructures, in particular open-cell metallic foams characterized with the skeleton formed of convex or re-entrant cells. Recently, the auxetic materials revealing negative Poisson’s ratio have attracted increasing attention in the context of modern materials applications. Up to date, the research of auxetics is mainly concentrating on the cell structure design and the analysis of quasi-static response. The dynamic properties of such materials are less known. Impact compressions of the two kind of foams under high-velocity are numerically analyzed. To simulate the deformation processes the finite element program ABAQUS is used. The computer tomography makes the basis for the formulation of computational model of virtual foam and the finite element discretization of the skeleton. For numerical simulations the constitutive elasto-viscoplasticity model is applied that defines the dynamic behavior of oxygen-free high conductivity (OFHC) Cu using the experimental data reported in the literature. The numerical predictions of crushing force for velocity 50 and 300 m/s are discussed

Słowa kluczowe:

compression test, open-cell copper, convex cell, re-entrant cell, virtual cellular materials, metallic foams, numerical simulation

Afiliacje autorów:

Pęcherski R.B.-IPPT PAN
Nowak M.-IPPT PAN
Nowak Z.-IPPT PAN
25p.
2.Nowak Z., Nowak M., Pęcherski R., Potoczek M., Śliwa R.E., Numerical Simulations of Mechanical Properties of Alumina Foams Based on Computed Tomography, JOURNAL OF MECHANICS OF MATERIALS AND STRUCTURES, ISSN: 1559-3959, DOI: 10.2140/jomms.2017.12.107, Vol.12, No.1, pp.107-121, 2017

Streszczenie:

The aim of this paper is to apply the results of microtomography of alumina foam to create a numerical model and perform numerical simulations of compression tests. The geometric characteristics of real foam samples are estimated from tomographic and scanning electron microscopy images. The performance of the reconstructed models is compared to experimental values of elastic moduli. A preliminary analysis of failure strength simulations under compression of alumina foam is also provided.

Słowa kluczowe:

Alumina open-cell foam, computed tomography microstructure, Young’s modulus, compressive strength of alumina foams

Afiliacje autorów:

Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.-IPPT PAN
Potoczek M.-other affiliation
Śliwa R.E.-other affiliation
20p.
3.Nowak Z., Nowak M., Pęcherski R.B., Potoczek M., Śliwa R.E., Mechanical properties of the ceramic open-cell foams of variable cell sizes, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.1515/amm-2015-0333, Vol.60, No.3, pp.1957-1963, 2015

Streszczenie:

The mechanical properties and numerical model of ceramic alumina open-cell foam, which is produced by the chemical method of gelcasting with different cell sizes (porosities) are presented. Geometric characteristics of real foam samples were estimated from tomographic and scanning electron microscopy images. Using this information, numerical foam model was proposed. A good agreement between the numerical model and the results elaborated from microtomography was obtained. To simulate the deformation processes the finite element program ABAQUS was used. The main goal of this computation was to obtain macroscopic force as a function of applied vertical displacement in compression test.

Słowa kluczowe:

mechanical properties of foams, alumina open-cell foam, Young modulus, strength of alumina foams

Afiliacje autorów:

Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Potoczek M.-other affiliation
Śliwa R.E.-other affiliation
30p.
4.Nalepka K.T., Sztwiertnia K., Nalepka P., Pęcherski R.B., The strength analysis of Cu/α−Al2O3 interfaces as a key for rational composite design, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.1515/amm-2015-0332, Vol.60, No.3, pp.1953-1956, 2015

Streszczenie:

Electron back-scattered diffraction (EBSD) studies carried out for the Cu/α−Al2O3 composites manufactured by pulsed laser deposition method and by the powder metallurgy enable to uncover a set of orientation relationships characteristic for materials of this type. The identified interfaces are categorized according to the bonding strength. Additionally, their microstructure is reproduced by molecular dynamic (MD) simulations. The obtained classification of the phase boundaries constitutes key information for effective composite design.

Słowa kluczowe:

EBSD, Cu/α−Al2O3 composites, PLD, bonding strength, molecular dynamics simulation

Afiliacje autorów:

Nalepka K.T.-other affiliation
Sztwiertnia K.-other affiliation
Nalepka P.-Agriculture University in Krakow (PL)
Pęcherski R.B.-other affiliation
30p.
5.Frąś T., Rusinek A., Pęcherski R.B., Bernier R., Jankowiak T., Analysis of friction influence on material deformation under biaxial compression state, TRIBOLOGY INTERNATIONAL, ISSN: 0301-679X, DOI: 10.1016/j.triboint.2014.06.019, Vol.80, pp.14-24, 2014

Streszczenie:

The biaxial compression test, based on the concept presented in [1] and on the technique of the channel-die test [2] and [3], is discussed as an experimental method allowing evolution of the friction conditions from the dry-film lubrication, by using MoS2 grease, to the dry conditions to be analysed. This article gives an outline of the experimental set-up, its validation and the technique of the test results analysis. The analysis of friction is based on the experimental data coupled with the numerical simulation of the performed tests and on the theoretical approach introduced in [4]. The Oxygen-Free High Conductivity (OFHC) copper in the ‘as-received’ state in contact with the 42CrMo4 steel are chosen as the materials used for the experimental investigation.

Słowa kluczowe:

Biaxial compression, Friction modelling, OFHC copper

Afiliacje autorów:

Frąś T.-other affiliation
Rusinek A.-National Engineering School of Metz (ENIM) (FR)
Pęcherski R.B.-other affiliation
Bernier R.-National Engineering School of Metz (ENIM) (FR)
Jankowiak T.-other affiliation
35p.
6.Frąś T., Nishida M., Rusinek A., Pęcherski R., Fukuda N., Description of the Yield State of Bioplastics on Examples of Starch-Based Plastics and PLA/PBAT Blends, ENGINEERING TRANSACTIONS (ROZPRAWY INŻYNIERSKIE), ISSN: 0867-888X, Vol.62, No.4, pp.329-354, 2014

Streszczenie:

The present work concerns the description of the yield state of biodegradable materials. As examples, biodegradable polymers are chosen – cornpole CRP-M2, starch fatty acid ester, and PLA/PBAT, poly(lactic acid) (PLA) blended with poly(butylene adipate/terephthalate) (PBAT) [1, 2]. These biodegradable, plant-derived bioplastics are a promising alternative to petroleum-based plastics. To describe the onset of plasticity in the bioplastics under discussion, Burzyński ’s hypothesis of material effort has been applied [3, 4]. The applied criteria account for the differential strength effect and for the shear correction resulting from the difference between experimental and theoretical values, obtained as a result of the Huber-Mises approach [5, 6]. In general, these properties of yield state are characteristic for polymers. The description of yield state for bioplastics is an issue that has hardly been investigated, which illustrates the novel nature of this paper in which this topic is discussed

Słowa kluczowe:

bioplastics, strength differential effect, shear correction, yield surface, Burzyński yield condition

Afiliacje autorów:

Frąś T.-IPPT PAN
Nishida M.-Nagoya Institute of Technology (JP)
Rusinek A.-National Engineering School of Metz (ENIM) (FR)
Pęcherski R.-IPPT PAN
Fukuda N.-Aichi Center for Industry and Science Technology (JP)
7p.
7.Rojek J., Lumelskyy D., Pęcherski R., Grosman F., Tkocz M., Chorzępa W., Forming limit curves for complex strain paths, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.2478/amm-2013-0042, Vol.58, pp.587-593, 2013

Streszczenie:

This paper presents results of experimental studies of forming limit curves (FLC) for sheet forming under complex strain paths. The Nakazima-type formability tests have been performed for the as-received steel blank and for the blank pre-strained by13%. Prestraining leads to abrupt change of strain path in the blank deformation influencing the forming limit curve. The experimental FLC of the pre-strained blank has been compared with the FLC constructed by transformation of the as-received FLC. Quite a good agreement has been found out. The concept of strain-path independent FLCs in polar coordinates has been verified. Two types of the polar diagrams have been considered, the first one with the strain-path angle and effective plastic strain as the polar coordinates, and the second one originally proposed in this work in which the thickness strain has been used instead of the effective plastic strain as one of the polar coordinates. The second transformation based on our own concept has given a better agreement between the transformed FLCs, which allows us to propose this type of polar diagrams as a new strain-path in dependent criterion to predict sheet failure in forming processes.

Słowa kluczowe:

sheet forming, formability, forming limit curve, complex strain-path

Afiliacje autorów:

Rojek J.-IPPT PAN
Lumelskyy D.-IPPT PAN
Pęcherski R.-IPPT PAN
Grosman F.-Silesian University of Technology (PL)
Tkocz M.-other affiliation
Chorzępa W.-Kirchhoff Polska Sp. z o.o. (PL)
20p.
8.Nowak M., Nowak Z., Pęcherski R.B., Potoczek M., Śliwa R.E., On the reconstruction method of ceramic foam structures and the methodology of Young modulus determination, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.2478/amm-2013-0154, Vol.58, No.4, pp.1219-1222, 2013

Streszczenie:

In the present paper a finite element model was used to investigate the mechanical properties such as Young’s modulus of open-cell ceramic foam. Finite element discretization was derived from real foam specimen by computer tomography images. The generated 3D geometry of the ceramic foam was used to simulate deformation process under compression. The own numerical procedure was developed to control finite element mesh density by changing the element size. Several numerical simulations of compression test have been carried out using commercial finite element code ABAQUS. The size of the ceramic specimen and the density of finite element mesh were examined. The influence of type and size of finite element on the value of Young’s modulus was studied, as well. The obtained numerical results have been compared with the results of experimental investigations carried out by Ortega [11]. It is shown that numerical results are in close agreement with experiment. It appears also that the dependency of Young’s modulus of ceramic foam on density of finite element mesh cannot be ignored.

Słowa kluczowe:

foams, 3D image analysis, cellular ceramics, FE modeling, porous alumina, mechanical properties

Afiliacje autorów:

Nowak M.-IPPT PAN
Nowak Z.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Potoczek M.-other affiliation
Śliwa R.E.-other affiliation
20p.
9.Ostrowska-Maciejewska J., Szeptyński P., Pęcherski R.B., Mathematical foundations of limit criterion for anisotropic materials, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.2478/amm-2013-0155, Vol.58, No.4, pp.1223-1235, 2013

Streszczenie:

In the paper a new proposition of limit state criteria for anisotropic solids exhibiting different strengths at tension and compression is presented. The proposition is based on the concept of energetically orthogonal decompositions of stress state introduced by Rychlewski. The concept of stress state dependent parameters describing the influence of certain stress modes on the total measure of material effort was firstly presented by Burzynski. The both concepts are reviewed in the paper. General formulation of a new limit criterion as well as its specification for certain elastic symmetries is given. It is compared with some of the other known limit criteria for anisotropic solids. General methodology of acquiring necessary data for the criterion specification is presented. The ideas of energetic and limit state orthogonality are discussed - their application in representation of the quadratic forms of energy and limit state criterion as a sum of square terms is shown

Słowa kluczowe:

anisotropy, strength hypothesis, material effort, yield condition, plastic potential, strength differential effect, elasticity, plasticity

Afiliacje autorów:

Ostrowska-Maciejewska J.-IPPT PAN
Szeptyński P.-other affiliation
Pęcherski R.B.-IPPT PAN
20p.
10.Lumelskyy D., Marczewska I., Rojek J., Pęcherski R., Grosman F., Tkocz M., Effect of friction on failure location in sheet metal formability tests, COMPUTER METHODS IN MATERIALS SCIENCE / INFORMATYKA W TECHNOLOGII MATERIAŁÓW, ISSN: 1641-8581, Vol.13, No.1, pp.43-48, 2013

Streszczenie:

This paper presents numerical investigations of the influence of friction on sheet deformation in Nakazima type formability tests. Numerical simulations have been performed using the authors’ own explicit dynamic finite element program. Numerical results have been compared with experimental data. Location of fracture was of major interest in this work. The studies confirmed that the fracture location near the center of the specimen as required by the standards can be obtained for low values of the friction coefficient. Numerical simulation combined with the inverse analysis has been used to estimate a real value of the friction coefficient in the Nakazima formability test.

Słowa kluczowe:

formability test, explicit FE method, friction, fracture location

Afiliacje autorów:

Lumelskyy D.-IPPT PAN
Marczewska I.-IPPT PAN
Rojek J.-IPPT PAN
Pęcherski R.-IPPT PAN
Grosman F.-Silesian University of Technology (PL)
Tkocz M.-other affiliation
10p.
11.Lumelskyy D., Marczewska I., Rojek J., Pęcherski R., Grosman F., Tkocz M., Wpływ tarcia na lokalizację pękania w próbach tłoczności Nakazimy, PRACE NAUKOWE POLITECHNIKI WARSZAWSKIEJ, SERIA: MECHANIKA, ISSN: 0137-2335, Vol.253, pp.57-62, 2013

Streszczenie:

W artykule przedstawiono analizę numeryczną wpływu tarcia na rozkład odkształceń uzyskanych w próbach tłoczności przeprowadzonych metodą Nakazimy. Symulacje numeryczne zostały przeprowadzone w autorskim programie opartym na metodzie elementów skończonych z jawnym całkowaniem ruchu względem czasu. Wyniki numeryczne porównano z danymi eksperymentalnymi. Główną uwagę zwrócono na lokalizację miejsca pęknięcia. Badania potwierdziły, że miejsce pęknięcia w pobliżu środka próbki, zgodnie z wymaganiami norm, można uzyskać przy małych wartościach współczynnika tarcia. Symulacja numeryczna, w połączeniu z analizą odwrotną, została wykorzystana do oszacowania rzeczywistej wartości współczynnika tarcia w przeprowadzonych próbach tłoczności metodą Nakazimy.

Słowa kluczowe:

próba tłoczności Nakazimy, wpływ tarcia, lokalizacja pękania, symulacje numeryczne MES, analiza odwrotna

Afiliacje autorów:

Lumelskyy D.-IPPT PAN
Marczewska I.-IPPT PAN
Rojek J.-IPPT PAN
Pęcherski R.-IPPT PAN
Grosman F.-Silesian University of Technology (PL)
Tkocz M.-other affiliation
12.Lumelskyy D., Rojek J., Pęcherski R., Grosman F., Tkocz M., Numerical simulation of formability tests of pre-deformed steel blanks, ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1016/j.acme.2012.04.010, Vol.12, No.2, pp.133-141, 2012

Streszczenie:

This paper presents the results of numerical simulations of the formability tests carried out for a pre-stretched 1 mm thick DC04 steel sheet. Simulation consisted of the subsequent stages as follows: uniaxial stretching of the sheet, unloading and stress relaxation, cutting specimens out of the pre-stretched sheet and bulging the blank with a hemispherical punch. Numerical modeling has been verified by comparison of the simulation results with the experimental ones. Good concordance of the results indicates correct performance of the numerical model and possibility to use it in further theoretical studies.

Słowa kluczowe:

Sheet forming, Formability, Forming limit diagram, Pre-stretching, Numerical simulation

Afiliacje autorów:

Lumelskyy D.-IPPT PAN
Rojek J.-IPPT PAN
Pęcherski R.-IPPT PAN
Grosman F.-Silesian University of Technology (PL)
Tkocz M.-other affiliation
15p.
13.Ostrowska-Maciejewska J., Pęcherski R.B., Szeptyński P., Limit Condition for Anisotropic Materials with Asymmetric Elastic Range, ENGINEERING TRANSACTIONS (ROZPRAWY INŻYNIERSKIE), ISSN: 0867-888X, Vol.60, No.2, pp.125-138, 2012

Streszczenie:

In the paper a new proposition of an energy-based hypothesis of material effort is introduced. It is based on the concept of influence functions introduced by Burzyński [3] and on the concept of decomposition of elastic energy density introduced by Rychlewski [18]. A new proposition enables description of a wide class of linearly elastic materials of arbitrary symmetry exhibiting strength differential effect.

Słowa kluczowe:

linear elasticity, anisotropy, material effort hypotheses, limit state criteria

Afiliacje autorów:

Ostrowska-Maciejewska J.-other affiliation
Pęcherski R.B.-IPPT PAN
Szeptyński P.-other affiliation
7p.
14.Szeptyński P., Pęcherski R.B., Propozycja nowego kryterium plastyczności dla blach ortotropowych z uwzględnieniem asymetrii zakresu sprężystego, RUDY I METALE NIEŻELAZNE, ISSN: 0035-9696, Vol.R57, No.4, pp.243-249, 2012

Streszczenie:

W artykule przedstawiono propozycję nowego kryterium plastyczności dla blach ortotropowych wykazujących różnicę wytrzymałości przy rozciąganiu i ściskaniu. Nowe kryterium bazuje na energetycznym warunku stanu granicznego dla materiałów anizotropowych zaproponowanym przez Rychlewskiego [2] i łączy się z wprowadzoną przez Burzyńskiego [3] koncepcją zależnych od charakteru stanu naprężenia funkcji określających udział poszczególnych składników rozkładu głównego gęstości energii sprężystej w całkowitej mierze wytężenia materiału. Podano specyfikację kryterium dla wszystkich płaskich symetrii sprężystych. Zaprezentowano ogólną metodę pozyskiwania danych niezbędnych do wyznaczenia parametrów kryterium na podstawie wyników prostych prób wytrzymałościowych - rozciągania, ściskania i ścinania. Wskazano na szczególne konsekwencje w opisie deformacji plastycznej blach w przypadku przyjęcia prawa płynięcia plastycznego stowarzyszonego z zaprezentowanym warunkiem plastyczności.

Słowa kluczowe:

blachy walcowane, anizotropia, asymetria zakresu sprężystego, kryterium plastyczności, hipotezy wytężenia

Afiliacje autorów:

Szeptyński P.-other affiliation
Pęcherski R.B.-IPPT PAN
7p.
15.Lumelskyy D., Rojek J., Pęcherski R., Grosman F., Tkocz M., Numeryczna symulacja doświadczalnych prób tłoczności wstępnie wyprężonych blach ze stali DC04, HUTNIK - WIADOMOŚCI HUTNICZE, ISSN: 1230-3534, Vol.79, No.1, pp.14-18, 2012

Streszczenie:

W pracy przedstawiono wyniki symulacji numerycznej próby tłoczności wstępnie wyprężonej blachy ze stali DC04 o grubości 1 mm. Symulacja obejmowała kolejno następujące etapy: wyprężanie blachy, odciążenie, wycięcie wykrojki z blachy wyprężonej oraz próbę wybrzuszania półkulistym stemplem. Wyniki numeryczne porównano z wynikami doświadczalnymi. Uzyskana zgodność wyników wskazuje na prawidłowe działanie modelu numerycznego oraz możliwość wykorzystania go do dalszych badań teoretycznych.

Słowa kluczowe:

blacha wstępnie wyprężona, próby tłoczności, symulacja numeryczna

Afiliacje autorów:

Lumelskyy D.-IPPT PAN
Rojek J.-IPPT PAN
Pęcherski R.-IPPT PAN
Grosman F.-Silesian University of Technology (PL)
Tkocz M.-other affiliation
6p.
16.Vadillo G., Fernandez-Saez J., Pęcherski R.B., Some applications of Burzyński yield condition in metal plasticity, MATERIALS AND DESIGN, ISSN: 0261-3069, DOI: 10.1016/j.matdes.2010.08.013, Vol.32, pp.628-635, 2011

Streszczenie:

The classical J2 plasticity theory is widely used to describe the plastic response of metallic materials. However, this theory does not provide satisfactory predictions for materials which exhibit pressure-sensitive yielding or plastic dilatancy. Another difficulty is the so-called strength differential effect (SD), leading to the asymmetry of the elaasstic range. The Burzyński yield condition, proposed in 1928, can be used to overcome some of these problems. In this paper an implicit integration of the elasto-plastic constitutive equations for the paraboloid case of Burzyński yield condition is frmulated. Also, the tangent operator consistent with the integration algorithm was developed and is presented. The proposed model was implemented in a commercial FE code and different kinds of tests reported in the literature were simulated. The comparison between the numerical and experimental results shows that the plasticity theory with the paraboloid case of Burzyński's yield condition describes adequately the strength diffrential effect, which is present in many kinds of materials significant for recent applications.

Słowa kluczowe:

metal matrix, mechanical, plastic behaviour, Burzyński paraboloid yield condition, strength differential effect

Afiliacje autorów:

Vadillo G.-University Carlos III of Madrid (ES)
Fernandez-Saez J.-University Carlos III of Madrid (ES)
Pęcherski R.B.-IPPT PAN
30p.
17.Frąś T., Nowak Z., Perzyna P., Pęcherski R.B., Identification of the model describing viscoplastic behaviour of high strength metals, INVERSE PROBLEMS IN SCIENCE AND ENGINEERING, ISSN: 1741-5977, DOI: 10.1080/17415977.2010.531474, Vol.19, No.1, pp.17-30, 2011

Streszczenie:

Ultrafine grained (UFG) and nanocrystalline metals (nc-metals) are studied. Experimental investigations of the behaviour of such materials under quasistatic as well as dynamic loading conditions related with microscopic observations show that in many cases the dominant mechanism of plastic strain is a multiscale development of shear deformation modes. The comprehensive discussion of these phenomena in UFG and nc-metals is given in M.A. Meyers, A. Mishra and D.J. Benson [Mechanical properties of nanocrystalline materials, Progr. Mater. Sci. 51 (2006), pp. 427–556], where it has been shown that the deformation mode of nanocrystalline materials changes as the grain size decreases into the ultrafine region. For smaller grain sizes (d < 300 nm) shear band development occurs immediately after the onset of plastic flow. Significant strain-rate dependence of the flow stress, particularly at high strain rates, was also emphasized. Our objective is to identify the parameters of Perzyna constitutive model, a new description of viscoplastic deformation, which accounts for the observed shear banding. The viscoplasticity model proposed earlier by Perzyna [Fundamental problems in viscoplasticity, Adv. Mech. 9 (1966), pp. 243–377] was extended in order to describe the shear banding contribution in Z. Nowak, P. Perzyna, R.B. Pecherski [Description of viscoplastic fow accounting for shear banding, Arch. Metall. Mater. 52 (2007), pp. 217–222]. The shear banding contribution function, which was introduced formerly by Pe¸cherski [Modelling of large plastic deformation produced by micro-shear banding, Arch. Mech. 44 (1992), pp. 563–584] and applied in continuum plasticity accounting for shear banding in R.B. Pecherski [Macroscopic measure of the rate of deformation produced by micro-shear banding, Arch. Mech. 49 (1997), pp. 385–401] plays pivotal role in the viscoplasticity model. The derived constitutive equations were identified and verified with the application of experimental data provided in the article by D. Jia, K.T. Ramesh and E. Ma [Effects of nanocrystalline and ultrafne grain sizes on constitutive behavior and shear bands in iron, Acta Mat. 51 (2003), pp. 3495–3509], where quasistatic and dynamic compression tests with UFG and nanocrystalline iron specimens of a wide range of mean grain size were reported. Numerical simulation of the compression of the prismatic specimen was made by the ABAQUS FEM program with UMAT subroutine. Comparison with experimental results proved the validity of the
identified parameters and the possibilities of the application of the proposed description for other high strength metals.

Słowa kluczowe:

Ultra fine grained metals, nanocrystalline metals, viscoplastic deformation, shear banding, shear banding contribution function, numerical simulation of compression test, identification of the model parameters

Afiliacje autorów:

Frąś T.-IPPT PAN
Nowak Z.-IPPT PAN
Perzyna P.-IPPT PAN
Pęcherski R.B.-IPPT PAN
20p.
18.Pęcherski R.B., Szeptyński P., Nowak M., An extension of Burzyński hypothesis of material effort accounting for the third invariant of shear tensor, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, Vol.56, No.2, pp.503-508, 2011

Streszczenie:

The aim of the paper is to propose an extension of the Burzyński hypothesis of material effort to account for the influence of the third invariant of stress tensor deviator. In the proposed formulation the contribution of the density of elastic energy of distortion in material effort is controlled by Lode angle. The resulted yield condtion is analyzed and possible applications and comparison with the results known in the literature are discussed.

Słowa kluczowe:

Burzyński yield condition, strength differential effect, pressure sensitivity, Lode angle, third invariant of stress tensor deviator

Afiliacje autorów:

Pęcherski R.B.-IPPT PAN
Szeptyński P.-other affiliation
Nowak M.-IPPT PAN
20p.
19.Nowak M., Ostrowska-Maciejewska J., Pęcherski R.B., Szeptyński P., Yield criterion accounting for the third invariant of stress tensor deviator. Part I. Proposition of the yield criterion based on the concept of influence functions, ENGINEERING TRANSACTIONS (ROZPRAWY INŻYNIERSKIE), ISSN: 0867-888X, Vol.59, No.4, pp.273-281, 2011

Streszczenie:

In the paper a new proposition of an energy-based hypothesis of material effort is introduced. It is based on the concept of influence functions introduced by Burzyński [3] and on the concept of decomposition of elastic energy density introduced by Rychlewski [18]. A new proposition enables description of a wide class of linearly elastic materials of arbitrary symmetry exhibiting strength differential effect.

Słowa kluczowe:

linear elasticity, anisotropy, material effort hypotheses, limit state criteria

Afiliacje autorów:

Nowak M.-IPPT PAN
Ostrowska-Maciejewska J.-other affiliation
Pęcherski R.B.-IPPT PAN
Szeptyński P.-other affiliation
7p.
20.Potoczek M., Śliwa R.E., Pęcherski R.B., Nowak Z., Nowak M., Modelowanie struktury geometrycznej i wytrzymałości na ściskanie pianek ceramicznych przeznaczonych do infiltracji ciekłymi metalami, RUDY I METALE NIEŻELAZNE, ISSN: 0035-9696, Vol.R56, No.11, pp.594-598, 2011

Streszczenie:

Kompozyty metalowo-ceramiczne o strukturze infiltrowanej charakteryzują się unikatową przestrzenną strukturą wzajemnie przenikających się szkieletów fazy metalicznej i fazy ceramicznej. Najczęstszym sposobem wytwarzania tego typu kompozytów jest infiltracja roztopionego metalu do porowatej kształtki ceramicznej. W niniejszej pracy zastosowano piankowe kształtki korundowe (alfa-Al2O3), wytworzone nową metodą otrzymywania ceramiki porowatej, którą jest żelowanie spienionej zawiesiny (ang. gelcasting of foams). W projektowaniu właściwości mechanicznych pianek ceramicznych przeznaczonych do infiltracji roztopionym metalem, a także w badaniach właściwości mechanicznych kompozytów w postaci pianki ceramicznej infiltrowanej metalem powstaje potrzeba odtworzenia struktury ceramicznej szkieletu kompozytu.

Słowa kluczowe:

Kompozyty metalowo-ceramiczne, pianki ceramiczne, modelowanie, symulacje MES

Afiliacje autorów:

Potoczek M.-other affiliation
Śliwa R.E.-other affiliation
Pęcherski R.B.-IPPT PAN
Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
7p.
21.Nowacki W.K., Nowak Z., Perzyna P., Pęcherski R.B., Effect of strain rate on ductile fracture. A new methodology, JOURNAL OF THEORETICAL AND APPLIED MECHANICS, ISSN: 1429-2955, Vol.48, No.4, pp.1003-1026, 2010

Streszczenie:

The aim of our study is to discuss a new methodology to account for the effect of strain rate on ductile fracture phenomena. Theory of inelastic materials accounting for the effects of microshear bands and microdamage is presented. The influence of microshear bands is explained by means of a function describing the instantaneous contribution of shear banding in the total rate of plastic deformation. The experimental investigations of the effect of strain rate on ductile fracture with use of the results of a dynamic double shear test of DH-36 steel with thermographic observations are reported. The registration of temperature evolution during the deformation process can provide additional data for the identification of the shear banding contribution function and the onset of ductile fracture.

Słowa kluczowe:

Effect of strain rate, ductile fracture, dynamic double shear test, DH-36 steel, thermographic observation

Afiliacje autorów:

Nowacki W.K.-IPPT PAN
Nowak Z.-IPPT PAN
Perzyna P.-IPPT PAN
Pęcherski R.B.-IPPT PAN
9p.
22.Frąś T., Kowalewski Z.L., Pęcherski R.B., Rusinek A., Applications of Burzyński failure criteria - I. Isotropic materials with asymmetry of elastic range, ENGINEERING TRANSACTIONS (ROZPRAWY INŻYNIERSKIE), ISSN: 0867-888X, Vol.58, pp.1-10, 2010

Streszczenie:

The main idea of energy-based hypothesis of material effort proposed by Burzyński is briefly presented and the resulting failure criteria are discussed. Some examples, based on the own studies, which depict applications of these criteria are discussed and visualisations of limit surfaces in the space of principal stresses are presented.

Słowa kluczowe:

Burzyński yield condition, yield surface, strength differential effect, energy-based yield criteria

Afiliacje autorów:

Frąś T.-IPPT PAN
Kowalewski Z.L.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Rusinek A.-National Engineering School of Metz (ENIM) (FR)
6p.
23.Nalepka K.T., Pęcherski R.B., The strength of the interfacial bond in the ceramic matrix composites Al2O3–Ni, MECHANICS AND CONTROL, ISSN: 2083-6759, Vol.29, No.3, pp.132-137, 2010

Streszczenie:

Using the results of High Resolution Transmission Electron Microscopy studies on epitaxial layers fcc metal/corundum we have proposed atomistic model of the interfacial structure of the Al2O3-Ni composite.

Słowa kluczowe:

High Resolution Transmission Electron Microscopy, epitaxial layers, fcc meta/corundum, CTIP+EAM model, strength of the interface

Afiliacje autorów:

Nalepka K.T.-IPPT PAN
Pęcherski R.B.-IPPT PAN
6p.
24.Kordzikowski P., Pęcherski R., Assessment of the material strength of anisotropic materials with asymmetry of the elastic range, MECHANICS AND CONTROL, ISSN: 2083-6759, Vol.29, No.2, pp.57-62, 2010

Streszczenie:

The aim of the paper is to apply the energy-based criterion of limit elastic states for the assessment of the material effort of anisotropic materials. The linear elastic anisotropic materials in the plane state of stress are considered. The theory of elastic eigen states determined by the symmetry of the Hooke elastic tensors (stiffness and compliance tensors) and the energy-based criterion of elastic limit states for anisotropic materials is used according to the theory proposed by Jan Rychlewski. Experimental data for paperboard and the results of atomic calculations were applied. The common feature of aforementioned materials is the strength differential effect related to the asymmetry of the elastic range. Often, to determine the degree of this asymmetry one uses the ratio of the experimentally measured limit of elasticity (yield) in compression to the limit of elasticity in tension. Also, the failure criterion of P.S. Theocaris is mentioned within the discussion of the possibility of the extension of the criterion proposed by Rychlewski for anisotropic materials revealing asymmetry of elastic range anfd the related strength differential effect.

Słowa kluczowe:

strength differential effect, Rychlewski criterion, anisotropic materials, asymmetruy of elastic range

Afiliacje autorów:

Kordzikowski P.-other affiliation
Pęcherski R.-other affiliation
6p.
25.Frąś T., Pęcherski R., Applications of the Burzyński hypothesis of material effort for isotropic solids, MECHANICS AND CONTROL, ISSN: 2083-6759, Vol.29, No.2, pp.45-50, 2010

Streszczenie:

The paper contains a short presentation of main idea of energy-based hypothesis of material effort proposed by Burzyński with discussion of the resulting failure criteria. Some examples illustrating applications of these criteria are discussed and visualisations of limit surfaces in the space of principal stresses are presented.

Słowa kluczowe:

Burzyński yield condition, yield surface, strength differential effect, energy-based yield criteria

Afiliacje autorów:

Frąś T.-IPPT PAN
Pęcherski R.-other affiliation
6p.
26.Klepaczko J.R., Rusinek A., Rodriguez-Martinez J.A., Pęcherski R.B., Arias A., Modelling of thermo-viscoplastic behavior of DH-36 and Weldox 460-E structural steels at wide ranges of strain rates and temperatures, comparison of constitutive relations for impact problems, MECHANICS OF MATERIALS, ISSN: 0167-6636, Vol.41, No.5, pp.599-621, 2009

Streszczenie:

In this paper, the thermo-viscoplastic behaviour of DH-36 and Weldox-460-E steels is analyzed at wide ranges of strain rates and temperature. These materials are commonly used for naval applications. Thus, the may be subjected to a wide range of exploitation temperature and at the same time to high strain rates due to accidental impact or explosion. The thermo-viscoplastic behaviour of these materials has been modeled by application of RK (Rusinek-Klepaczko) constitutive relation. The comparison with other models well known in the literature has been studied.

Słowa kluczowe:

constitutive modelling, thermo-viscoplasticity, DH-36 steel, Weldox-460-E steel, impact processes, FE numerical simulations, perforation process

Afiliacje autorów:

Klepaczko J.R.-IPPT PAN
Rusinek A.-National Engineering School of Metz (ENIM) (FR)
Rodriguez-Martinez J.A.-other affiliation
Pęcherski R.B.-IPPT PAN
Arias A.-other affiliation
32p.
27.Rusinek A., Rodriguez-Martinez J.A., Klepaczko J.R., Pęcherski R.B., Analysis of thermo-visco-plastic behaviour of six high strength steels, MATERIALS AND DESIGN, ISSN: 0261-3069, DOI: 10.1016/j.matdes.2008.07.034, Vol.30, No.5, pp.1748-1761, 2009

Streszczenie:

In this paper the thermo-visco-plastic behaviour of six high strength steels is analyzed in a wide range of strain rates and temperature. The steels belong to two well-known versions of steels: three ferritic steels: HSLA-65, DH-36 and Wedox 460-E and three austenitic steels: Nitronic-50, Uranus B66 and Al-6XN.
Micro-mechanism of plastic deformation in the case of ferritic steels is dominated by dislocation's gliding. In the case of austenitic steels the twinning appears that modifies the material's plastic properties. In the present paper the RK (Rusinek-Klepaczko) constitutive relation is evaluated for modelling of the plastic behaviour of six steels which represent these two different deformation mechanisms.

Słowa kluczowe:

ferritic steels, austenitic steels, RK Rusinek - Klepaczko model, dislocation glide, twining, thermo-visco-plasticity

Afiliacje autorów:

Rusinek A.-National Engineering School of Metz (ENIM) (FR)
Rodriguez-Martinez J.A.-other affiliation
Klepaczko J.R.-IPPT PAN
Pęcherski R.B.-IPPT PAN
27p.
28.Rodriguez-Martinez J.A., Rusinek A., Klepaczko J.R., Pęcherski R.B., Extension of R-K constitutive relation to phase transformation phenomena, MATERIALS AND DESIGN, ISSN: 0261-3069, Vol.30, No.7, pp.2513-2520, 2009

Streszczenie:

In this paper an extension of the Rusinek-Klepaczko (RK) constitutive relation is presented. The new formulation proposed, allows defining the phase transformation effect observed on macroscopic scale using a phenomenological approach. The key point is to introduce in the original formulation of RK model a new stress component based on evolution of martensite, which takes into account strain, strain rate and temperature effects. Analytical predictions of the xtended constitutive relation are compared with experimental results for 301Ln2B steel.

Słowa kluczowe:

RK model, phase transformation, austenitic steel

Afiliacje autorów:

Rodriguez-Martinez J.A.-other affiliation
Rusinek A.-National Engineering School of Metz (ENIM) (FR)
Klepaczko J.R.-IPPT PAN
Pęcherski R.B.-IPPT PAN
27p.
29.Kowalczyk-Gajewska K., Pęcherski R.B., Phenomenological description of the effect of micro-shear banding in micromechanical modelling of polycrystal plasticity, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, Vol.54, pp.717-730, 2009

Streszczenie:

The rigid-plastic crystal plasticity model accounting for the effect of micro-shear banding mechanism on the reduction of the global strain hardening rate is presented. The instantaneous contribution of micro-shear bands in the rate of plastic deformation is described by means of the constitutive function that depends on the type of strain path specified by the current direction of strain rate tensor. The capabilities of the model are explored by studying the strain-stress behavior of polycrystalline material together with the crystallographic texture evolution in the polycrystalline element

Słowa kluczowe:

Crystallographic texture, Anisotropic material, Crystal plasticity, Polycrystalline material, Micro-shear banding

Afiliacje autorów:

Kowalczyk-Gajewska K.-IPPT PAN
Pęcherski R.B.-IPPT PAN
20p.
30.Pęcherski R.B., Burzyński field criterion vis-a-vis the related studiem reported in the literature, ENGINEERING TRANSACTIONS (ROZPRAWY INŻYNIERSKIE), ISSN: 0867-888X, Vol.56, pp.317-327, 2008

Streszczenie:

The paper is written in accompaniment of the publication of English translation of W. Burzyński's paper [1], which deals with the yield criterion for materials revealing the sensitivity of yield strength to pressure derived by W. Burzyński during preparation of his doctor thesis in 1927 [2]. More recently the dependence of yield strength on pressure is related to the so-called strength differential (SD) effect, i.e. asymmetry of elastic range, cf. e.g. [3,4]. Therefore, the original Burzyński's energy-based approach in the literature is reported and his main achievement in ths field concerning the recent studies is discussed.

Słowa kluczowe:

Burzyński yield condition, strength differential effect, asymmetry of elastic range, hypotheses of material effort

Afiliacje autorów:

Pęcherski R.B.-IPPT PAN
31.Kowalczyk-Gajewska K., Mróz Z., Pęcherski R.B., Micromechanical modelling of polycrystalline materials under non-proportional deformation paths, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, Vol.52, pp.181-192, 2007

Streszczenie:

The rigid-plastic crystal plasticity model with single yield surface of 2n-degree is applied to simulate the polycrystalline behaviour and the crystallographic texture development under non-proportional deformation paths. The role of two controlling parameters: the amplitude and frequency for the processes of tension or compression assisted by cyclic torsion of thin-walled tubes made of copper is analysed. The effect of micro-shear bands on the reduction of global hardening rate is described by means of the contribution function of shear banding in the rate of plastic deformation. The conclusions drawn from the study can find also application in the extension of the analysis for high strength and hard deformable materials.

Słowa kluczowe:

micromechanics, modelling of materials, rigid-plastic solids, crystal plasticity, texture, cyclic torsion, non-proportional deformation path, micro-shear bands

Afiliacje autorów:

Kowalczyk-Gajewska K.-IPPT PAN
Mróz Z.-IPPT PAN
Pęcherski R.B.-IPPT PAN
32.Nowak Z., Perzyna P., Pęcherski R.B., Description of viscoplastic flow accounting for shear banding, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, Vol.52, No.2, pp.217-222, 2007

Streszczenie:

The subject of the study is concerned with ultra fine grained (ufg) and nanocrystalline metals (nc-metals). Experimental investigations of the behaviour of such materials under quasistatic as well as dynamic loading conditions related with microscopic observations show that in many cases the dominant mechanism of plastic strain is multiscale development of shear deformation modes – called shear banding. The comprehensive discussion of these phenomena in ufg and nc-metals is given in [1], [2] and [3], where it has been shown that the deformation mode of nanocrystalline materials changes as the grain size decreases into the ultrafine region. For smaller grain sizes (d < 300 nm) shear band development occurs immediately after the onset of plastic flow. Significant strain-rate dependence of the flow stress, particularly at high strain rates was also emphasized. Our objective is to propose a new description of viscoplastic deformation, which accounts for the observed shear banding. Viscoplasticity model proposed earlier by P e r z y n a [4], [5] was extended in order to describe the shear banding contribution. The shear banding contribution function, which was introduced formerly by P ę c h e r s k i [6], [7] and applied in continuum plasticity accounting for shear banding in [8] and [9] as well as in [10] and [11] plays pivotal role in the viscoplasticity model. The derived constitutive equations were identified and verified with application of experimental data provided in paper [2], where quasistatic and dynamic compression tests of ufg and nanocrystalline iron specimens of a wide range of mean grain size were reported. The possibilities of the application of the proposed description for other ufg and nc-metals are discussed.

Słowa kluczowe:

Viscoplastic flow, shear banding, micro-shear bands, nanocrystalline metals, nc-metals, ultra fine grain (ufg) metals

Afiliacje autorów:

Nowak Z.-IPPT PAN
Perzyna P.-IPPT PAN
Pęcherski R.B.-IPPT PAN
33.Mróz Z., Kowalczyk-Gajewska K., Maciejewski J., Pęcherski R.B., Tensile or compressive plastic deformation of cylinders assisted by cyclic torsion, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.58, No.6, pp.497-527, 2006

Streszczenie:

Technological metal forming processes of extrusion, forging and rolling with imposed cyclic torsion or shear deformation have been recently studied in view of their advantages with respect to monotonic loading processes, cf. Bochniak and Korbel [2–4]. The present work is aimed to analyze such process in the case of simple tension or compression of a cylindrical tube with imposed cyclic torsional deformation. The material element response is assumed to be rigid-perfectly plastic or elastic-perfectly plastic. For these models, the analytical solutions can be provided for the steady cyclic responses and the effect of two process parameters, namely the ratio of shear and axial strain rates η and the amplitude of shear strain γm , can be clearly demonstrated. Three different regimes of cyclic response can be visualized in the plane η, γm. The cyclic response of a cylinder under combined axial compression and cyclic torsion is predicted by considering a simplified model of a set of concentric tubes and neglecting their radial stress interaction. The axial force and torsional moment are then specified by averaging the responses of consecutive tubes. The cyclic response diagrams for the cylinder are then generated in terms of axial force and torsional moment related to axial deformation and angle of twist

Słowa kluczowe:

cyclic torsion, plastic deformation of cylinders, elastic-perfectly plastic model, rigid-perfectly plastic model, analytical solutions of cyclic response of a cylinder

Afiliacje autorów:

Mróz Z.-IPPT PAN
Kowalczyk-Gajewska K.-IPPT PAN
Maciejewski J.-IPPT PAN
Pęcherski R.B.-IPPT PAN
34.Pieczyska E.A., Pęcherski R.B., Gadaj S.P., Nowacki W.K., Nowak Z., Matyjewski M., Experimental and theoretical investigations of glass fibre reinforced composite subjected to uniaxial compression for a wide spectrum of strain rates, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.58, pp.273-291, 2006

Streszczenie:

Results of static and dynamic compression tests for two types of glass fibrereinforced polypropylene composites are presented. Stress-strain curves showing the influence of the strain rate on the composite mechanical properties have been obtained.
A three-dimensional description of the material behavior during the deformation has been developed. The material constitutive parameters have been calculated.
Specification of the parameters and description of the methods used for their identification have been worked out. The results are discussed in terms of the deformation processes and the material non-homogeneity.

Słowa kluczowe:

static and dynamic compression tests, glass fibrereinforced polypropylene composites, Stress-strain curves, constitutive model, three-dimensional description

Afiliacje autorów:

Pieczyska E.A.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Gadaj S.P.-other affiliation
Nowacki W.K.-IPPT PAN
Nowak Z.-IPPT PAN
Matyjewski M.-other affiliation
35.Kowalczyk-Gajewska K., Gambin W., Pęcherski R.B., Ostrowska-Maciejewska J., Modelling of crystallographic texture development in metals accounting for micro-shearbands, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, Vol.50, No.3, pp.575-593, 2005

Streszczenie:

The rigid-plastic model for the single grain is developed in which the velocity gradient is split into two parts connected with crystallographic slip and micro-shear bands respectively. For crystallographic slip the regularized Schmid law proposed by Gambin is used. For the micro-shear bands the model developed by Pęcherski, which accounts for the contribution of this mechanism in the rate of plastic deformation by means of a function fms is applied. Different constitutive equations for the plastic spin due to two considered mechanisms of plastic deformation are used. The present model is applied to simulate crystallographic texture evolution in the polycrystalline element.

Słowa kluczowe:

crystallographic texture, modelling of texture, micro-shear bands, regularized Schnid law, plastic spin

Afiliacje autorów:

Kowalczyk-Gajewska K.-IPPT PAN
Gambin W.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Ostrowska-Maciejewska J.-other affiliation
36.Pęcherski R.B., Nalepka K.T., Nowak Z., Próba modelowania mechanicznych własności nanometali, INŻYNIERIA MATERIAŁOWA, ISSN: 0208-6247, Vol.4, pp.170-174, 2005

Streszczenie:

W pracy przedyskutowano aktualne problemy modelowania własności mechanicznych metali o strukturze nanometrycznej. Omówiono możliwości opisu deformacji sprężysto-plastycznej i lepkoplastycznej materiałów o bimodalnym rozkładzie ziarn. Przedstawiono wyniki badań sprężystych własności nanoziarn oraz identyfikacji ich spręzystych stanów granicznych z zastosowaniem kwantowo-mechanicznych obliczeń z pierwszych zasad (ab initio) na przykładzie idealnego kryształu miedzi. Wskazano na możliwości dalszych badań zmierzających do opracowania przesłanek potrzebnych do projektowania nanomateriałów.

Słowa kluczowe:

nanometale, obliczenia ab initio, kryształ miedzi, modelowanie własnosci mechanicznych, sprężyste stany graniczne

Afiliacje autorów:

Pęcherski R.B.-IPPT PAN
Nalepka K.T.-IPPT PAN
Nowak Z.-IPPT PAN
37.Pęcherski R.B., Opis deformacji plastycznej metali z efektami mikropasm ścinania (Praca habilitacyjna), Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.2, pp.1-125, 1998
38.Perzyna P., Pęcherski R.B., Analiza wpływu prędkości odkształcenia na zniszczenie plastyczne metali, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.62, pp.1-27, 1979
39.Pęcherski R., Teoretyczny opis wpływu napromieniowania neutronami na właściwości lepkoplastyczne miękkiej stali (Praca doktorska), Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.53, pp.1-129, 1978

Lista ostatnich monografii
1.
86
Ostrowska-Maciejewska J., Pęcherski R.B., Anizotropia sprężysta i wytężenie cienkich warstw i powłok, IMIM PAN (Kraków), IPPT PAN (Warszawa), pp.1-173, 2006
Lista rozdziałów w ostatnich monografiach
1.
335
Pęcherski R.B., Nalepka K.T., Frąś T., Nowak M., Constitutive Relations under Impact Loadings. Experiments, Theoretical and Numerical Aspects, rozdział: Inelastic Flow and Failure of Metallic Solids. Material Effort: Study Across Scales, Springer, CISM, Udine, T. Łodygowski, A. Rusinek (Eds.), 552, pp.245-285, 2014
2.
211
Pęcherski R.B., Nowacki W.K., Nowak Z., Perzyna P., Workshop in Memory of Prof. J.R. Klepaczko: Dynamic Behaviour of Materials, rozdział: Effect of strain rate on ductile fracture. A new methodology, LPMM, Metz, Rusinek A., Chevrier P. (Eds.), pp.65-73, 2009

Prace konferencyjne
1.Pęcherski R.B., Kowalczyk-Gajewska K., Nowak Z., Opis udziału pasm ścinania w płynięciu plastycznym polikrystalicznych metali z uwzględnieniem wpływu zmiany drogi odkształcenia, Niejednorodności odkształcenia w procesach przeróbki plastycznej i rekrystalizacji, Seminarium poświęcone 70. rocznicy urodzin Profesora Z. Jasieńskiego, 2005-01-21/01-21, Kraków (PL), pp.191-202, 2005

Abstrakty konferencyjne
1.Kowalewski Z.L., Nowak Z., Pęcherski R.B., Investigations of Tantalum at Direct Impact Compression Tests on Miniaturized Specimens, PLASTICITY 2017, INTERNATIONAL CONFERENCE ON PLASTICITY, DAMAGE, AND FRACTURE 2017, 2017-01-03/01-09, Puerto Vallarta (MX), pp.100-102, 2017

Streszczenie:

In the paper the results of experimental and numerical investigations concerning an influence of strain rate on mechanical properties of pure tantalum are presented. Experiments were carried out using Direct Impact Compression Test (DICT) technique (Malinowski et al. [2007]). The Perzyna elasto-viscoplasticity theory (Perzyna [1966]) was applied to predict the dynamic compression yield strength of the tested material at strain rates from 1.0 x10-3 s−1 to 0.5 x106 s−1.

Afiliacje autorów:

Kowalewski Z.L.-IPPT PAN
Nowak Z.-IPPT PAN
Pęcherski R.B.-IPPT PAN
2.Nowak Z., Kowalewski Z.L., Pęcherski R.B., A numerical solution of longitudinal wave propagation in a miniaturized specimens of tantalum at direct impact compression test, DYMAT, 10th Workshop, 2016-08-24/08-26, Poznań (PL), pp.69-71, 2016

Streszczenie:

The results of experimental and numerical investigations concerning an influence of strain rate on mechanical properties of pure tantalum are presented. Experiments were carried out using Direct Impact Compression Test (DICT) technique. The miniaturization concept of the experimental setup for the dimensions of specimen (diameter dS = 1.5 mm and thickness lS = 0.50 mm), Hopkinson transmitter bar diameter (dH = 3.0 mm) and the striker (diameter dI = 11.5 mm and the length lI =12 mm), together with application of a novel optical arrangement for measurement of striker velocity, enabled compression tests to be executed at strain rates from 1.0 x103 s−1 to 0.5 x106 s−1. The Perzyna elasto-viscoplasticity theory is applied to predict the dynamic compression yield strength of the tested material at different strain rates. In the course of specimens deformation by means of the DICT technique, it was observed that the peak force obtained from the strain gauge mounted on the transmitter Hopkinson bar was lower than the peak force obtained within the framework of the uniaxial stress wave analysis. An explanation of this discrepancy is provided due to the analysis of the localization of deformation in the tested specimens considered as three-dimensional body subjected to high strain rate loading and the resulting stress wave attenuation as it propagates within the specimen.

Słowa kluczowe:

direct impact test, numerical simulations, tantalum

Afiliacje autorów:

Nowak Z.-IPPT PAN
Kowalewski Z.L.-IPPT PAN
Pęcherski R.B.-IPPT PAN
3.Pęcherski R.B., Nalepka K.T., Nalepka P., Sztwiertnia K., Kret S., Ustrzycka A., Assessment of the strength of nanocomposites based on interface bonding analysis, ICTAM XXIV, 24th International Congress of Theoretical and Applied Mechanics, 2016-08-21/08-26, Montréal (CA), pp.2384-2385, 2016

Streszczenie:

Recent investigations reveal that interface bonding strength is dependent on the relative orientation of crystallites of the both phases [2]. The experimental, theoretical and computational investigations confirm this observation in the case of Cu/Al2O3 system, [3], [4]. It is shown that the statistical distribution of the values of interface strength for different relative orientations of bonded phases should be included in the phenomenological model of the damage initiation in nanocomposites. The novelty of the presented study is the combination of different experimental techniques: HRTEM, EBSD and molecular dynamics simulations with phenomenological theory of damage development in nanocomposites due to debonding at the interphase boundary [5], [6], [7]. A class of new models with the yield condition determined by one of quadric surfaces, in particular paraboloid or ellipsoid one is considered and the comparison with popular Gurson approach is discussed, [8].

Słowa kluczowe:

nanocompistes, strength, interface, bonding, HRTEM, EBSD, molecular dynamics

Afiliacje autorów:

Pęcherski R.B.-IPPT PAN
Nalepka K.T.-IPPT PAN
Nalepka P.-Agriculture University in Krakow (PL)
Sztwiertnia K.-other affiliation
Kret S.-Institute of Physics, Polish Academy of Sciences (PL)
Ustrzycka A.-IPPT PAN
4.Nalepka P., Nalepka K.T., Pęcherski R.B., Analysis of deformation mechanisms in Cu /Al2O3 interfaces with the use of HRTEM images , SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P243, pp.1-2, 2016

Streszczenie:

The composition of metal with ceramics is applied to many devices, structural elements of machines as well as their equipment. Therefore, evaluating the strength of interfaces of this type becomes an important scientific issue of fundamental character. Numerous attempts are made to solve the posed problem, both experimental and theoretical ones. The presented approach enables local, more precise determining the mechanical properties of interfaces. The basis of conducted calculations is the geometry of the interface strongly preferred by the considered system of materials. It is defined by the mutual orientation of crystallites of two phases and the position of the plane boundary. The combination of two advanced research methods: electron back-scatter diffraction (EBSD) and high resolution transmission electron microscopy (HRTEM) enables identification of this crucial characteristics. The second of them additionally reveals a representative microstructure of the interface in the form of a projection. We reconstruct it in three dimensions by means of molecular dynamics (MD) simulations. In this way, we identify deformation mechanisms that enable the formation of the bonding between the metallic phase and ceramic one.

Słowa kluczowe:

nanocomposites, deformation in interface, HRTEM

Afiliacje autorów:

Nalepka P.-Agriculture University in Krakow (PL)
Nalepka K.T.-IPPT PAN
Pęcherski R.B.-IPPT PAN
5.Frąś L.J., Jarząbek D., Dziekoński C., Pęcherski R.B., Viscoplastic deformation of magnethoreological solids, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P244, pp.1-2, 2016

Streszczenie:

The microsized (~10µm) ferroelements build the structure of magenthoreological (MR) fluid. This two phase material in neutral state behaves as a fluid but in magnetic field becomes a solid and has properties of elasto-viscoplastic material. This is due to the skeleton made by ferrolements connected into braids. The aim of the paper is to identify the physical mechanisms of deformation of such a structure with use of own set up for in situ microscopic observations.

Słowa kluczowe:

magnethoreological solids, viscoplasticity, ferroelements, compression test, shear banding

Afiliacje autorów:

Frąś L.J.-IPPT PAN
Jarząbek D.-IPPT PAN
Dziekoński C.-IPPT PAN
Pęcherski R.B.-IPPT PAN
6.Pęcherski R.B., Nowak M., Application of X-ray micro-computed tomography for numerical simulation of auxetic foam fabrication, ESMC 2015, 9th European Solid Mechanics Conference, 2015-07-06/07-10, Leganés-Madrid (ES), Vol.1, pp.#1248-1-2, 2015

Streszczenie:

The design of new multifunctional foams as well as metal-ceramic and polymer-ceramic composites of ceramic foam structure, which can be applied as lightweight wear resistant elements, fire resistant or fire retardant parts, piezoelectric actuators etc., requires the solution of the following questions:
- in what way to fabricate polyurethane, metallic or ceramic foams and preforms of assumed skeleton structure,
- how to produce tomograms, i.e. 3D virtual volume reconstructions of real foam structure [1],
- how to elaborate methods of numerical simulations of fabrication processes of auxetic foams with use of the tomograms.
Depending on manufacturing method the cells obtain convex or concave shape. The materials with convex cell structure reveal positive Poisson's ratio. The complex structure of the foam related with reentrant cells produce the oposite effect - the negative Poisson's ratio is observed and such foams become auxetic. The aim of the presented study is to tackle the third question related with numerical simulation of fabrication processes of auxetic foams.

Słowa kluczowe:

auxetic foam, micro-tomography, negative Poisson’s ratio, numerical simulation, metallic foam, open-cell foam, fabrication

Afiliacje autorów:

Pęcherski R.B.-IPPT PAN
Nowak M.-IPPT PAN
7.Nowak M., Pęcherski R.B., Nowak Z., Frąś L.J., Numeryczna rekonstrukcja struktury pianek otwartokomórkowych z wykorzystaniem tomografii komuterowej, OMIS'2015, XI Konferencja Odkształcalność Metali i Stopów, 2015-11-17/11-20, Łańcut (PL), pp.61-62, 2015

Streszczenie:

Przedmiotem badań niniejszej pracy jest numeryczna rekonstrukcja struktur rzeczywistych pianek otwartokomórkowych w celu wygenerowania reprezentatywnego elementu objetości. Analizowane są dwa rodzaje pianek (ceramiczna i polimerowa), których porowatość wynosi odpowiednio 90% i 94%. Oba rodzaje pianek zostały przebadane z użyciem mikrotomografu komputerowego. Uzyskane dane zostały zaimportowane do programu ScanIP, przy pomocy którego przeprowadzono cyfrową obróbkę uzyskanych obrazów oraz wydzielono fazę reprezentującą szkielet pianki.

Słowa kluczowe:

numeryczna rekonstrukcja, struktury otwartokomórkowe, pianki metaliczne, mikrotomografia komputerowa

Afiliacje autorów:

Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Nowak Z.-IPPT PAN
Frąś L.J.-IPPT PAN
8.Nowak Z., Nowak M., Pęcherski R.B., Numeryczna analiza dynamicznych procesów ściskania metalicznych pianek otwartokomórkowych, OMIS'2015, XI Konferencja Odkształcalność Metali i Stopów, 2015-11-17/11-20, Łańcut (PL), pp.59-60, 2015

Streszczenie:

W pracy dokonano analizy wielkości sił zgniatania, energii dyssypacji oraz sposobów deformowania się dwóch typów metalicznych pianek otwartokomórkowych sciskanych dynamicznie z różnymi prędkościami. Zbadano pianki o strukturze wypukłej oraz o komórkach wklęsłych, które charakteryzują się ujemnym wspołczynnikiem Poissona.

Słowa kluczowe:

dynamiczna analiza, procesy zgniatania, pianki metaliczne, struktury otwarokomórkowe

Afiliacje autorów:

Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
9.Frąś L.J., Konowrocki R., Pęcherski R.B., Niesprężyste deformacje materiałów magnetoreologicznych. Doświadczalna wizualizacja i model fizyczny, OMIS'2015, XI Konferencja Odkształcalność Metali i Stopów, 2015-11-17/11-20, Łańcut (PL), pp.13-14, 2015

Streszczenie:

Magnetorheological materials are commonly used in technical devices because of specific behaviour in magnetic field. The magnetoactive particles are immersed in the carried fluid. The material becomes solid under the influence of magnetic field. The structure of solid material consists of the chains of the particles lying along the direction of magnetic field and the material under the stress is deforming as a solid body. The present studies are focused on the microscopic and phenomenological models of non-newtonian fluid. However, the mechanisms of deformation in solidified material under magnetic field require further investigations. The aim of the paper is to present the experimental visualization of the rearrangements of the particles in the activated by magnetic field chains. Basing on microscopic observations, the hypothesis is formulated that the mechanism of micro-shear banding is responsible for inelastic deformation of magnetorheological material. The discussed physical model makes the basis of the material description within the framework of the Perzyna viscoplasticity theory.

Słowa kluczowe:

magnetorheological fluid, magnetorheological gel, Perzyna viscoplastic model

Afiliacje autorów:

Frąś L.J.-IPPT PAN
Konowrocki R.-IPPT PAN
Pęcherski R.B.-IPPT PAN
10.Frąś L.J., Pęcherski R.B., Viscoplasticity of magnetorheological materials - theoretical description and experimental investigations, PCM-CMM 2015, 3rd Polish Congress of Mechanics and 21st Computer Methods in Mechanics, 2015-09-08/09-11, Gdańsk (PL), pp.673-674, 2015

Streszczenie:

The extension of viscoplasticity Perzyna's model for the field of magnetorheological materials is proposed. The model is adopted to identify the mechanisms of microscopic rearrangement of ferroelements producing visible increase of material stiffness, in particular increase of shear modulus. The project of laboratory test stand is presented. It is based on Split Hopkinson Pressure Bar set-up equipped with container for magnetorheological fluid and coil to control it.

Słowa kluczowe:

magnetorheological fluid, magnetorheological gel, Pezryna viscoplasticity model, Split Hopkinson Pressure Bar

Afiliacje autorów:

Frąś L.J.-IPPT PAN
Pęcherski R.B.-IPPT PAN
11.Pęcherski R.B., Nowak M., Frąś L.J. , Numerical simulations of auxetic metallic foam fabrication process, PCM-CMM 2015, 3rd Polish Congress of Mechanics and 21st Computer Methods in Mechanics, 2015-09-08/09-11, Gdańsk (PL), pp.857-858, 2015

Streszczenie:

The subject of te study are metallic open-cell foams. In particular, the foam of Cu skeleton is considered. To simulate the deformation process of such a material the finite element program ABAQUS is used. The tomogram reconstructing the 3D virtual volume of a real foam structure with the use of computed tomography is applied to formulate the finite element model of the convex open-cell foam cube of the edge of 800 voxels created with application of ABAQUS/CAE. The initial cube of convex open-cell skeleton is subjected to three-axial compression applied as uniform displacements normal to the surface of cube faces in order to simulate numerically auxetic foam fabrication process.

Słowa kluczowe:

auxetic foam, micro-tomography, tomograms, negative Poisson's ration, numerical simulation, metallic foam, open-cell foam, foam fabrication

Afiliacje autorów:

Pęcherski R.B.-IPPT PAN
Nowak M.-IPPT PAN
Frąś L.J. -IPPT PAN
12.Nowak Z., Nowak M., Pęcherski R.B., Potoczek M., Śliwa R.E., Numerical simulations of mechanical properties of alumina foams based on computer tomography, PCM-CMM 2015, 3rd Polish Congress of Mechanics and 21st Computer Methods in Mechanics, 2015-09-08/09-11, Gdańsk (PL), pp.853-854, 2015

Streszczenie:

The aim of the paper is to apply the results of microtomography of alumina foam to create the numerical model and perform the numerical simulations of compression tests. The geometric characteristics of real foam samples are estimated from tomographic and scanning electron microscopy images. The performance of the reconstructed models is compared to experimental values of elastic moduli.

Słowa kluczowe:

Alumina open-cell foam, the computed tomography microstructure, Young modulus, the compressive strength of alumina foams

Afiliacje autorów:

Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Potoczek M.-other affiliation
Śliwa R.E.-other affiliation
13.Pęcherski R.B., Nowak M., Nowak Z., Numerical simulation of dynamic processes in metal foams. I. virtual metallic foam, PETER 2015, Annual International Workshop on Dynamic Behaviour of Structures and Materials, Interaction and Friction Across the Strain Rates, 2015-08-26/08-28, London (GB), Vol.1, pp.19-20, 2015

Streszczenie:

The design of new multifunctional foams requires the solution of the following questions: in what way to fabricate metallic foams of assumed skeleton structure, how to produce tomograms, i.e. 3D virtual foam reconstructions of real foam structure [1], how to elaborate methods of numerical simulations of assumed processes in auxetic foams with use of the tomograms. Depending on manufacturing method the cells obtain convex or concave shape. The materials with convex cell structure reveal positive value of Poisson’s ratio, that is if a sample is stretching, then its cross-section is getting thinner. The complex structure of the foam related with reentrant cells produces the opposite effect during stretching of a sample, i.e. its cross-section is increasing. Then the negative Poisson’s ratio is observed and such foams become auxetic. The aim of the study is to study the third question. The motivation is given in [2], where it has been stressed that numerical simulations predicting a new material’s behaviour reduce laboratory costs and accelerates the trial and error procedure.

Słowa kluczowe:

Metallic open-cell foam with the convex or concave cells, the foam of OFHC Cu skeleton, the foam structure with use of computer tomography images, numerical simulation of dynamic processes in metal foams

Afiliacje autorów:

Pęcherski R.B.-IPPT PAN
Nowak M.-IPPT PAN
Nowak Z.-IPPT PAN
14.Nowak Z., Nowak M., Pęcherski R.B., Numerical simulation of the dynamic processes in metal foams. Part II. Compression tests of open cell copper foams, PETER 2015, Annual International Workshop on Dynamic Behaviour of Structures and Materials, Interaction and Friction Across the Strain Rates, 2015-08-26/08-28, London (GB), Vol.1, pp.21-22, 2015

Streszczenie:

Metallic cellular materials have been widely acknowledged for their multifunctional applications related also with energy absorption capability in addition to their light weight. In recent years, the auxetic materials revealing negative Poisson’s ratio have attracted much attention. Up to date, the research of auxetics is mainly concentrating on the cell design and the static response, although the auxetic materials also demonstrate potential for energy absorption, fracture retardant, and high-velocity impacts resistance. In the paper, a comparative study is reported on the high-velocity impact responses of two type metallic cellular foams, that is, convex open cell foam and auxetic foam. The material of the skeleton of the virtual foam is assumed to be isotropic and elastic-plastic. For numerical simulations the constitutive relation is applied which defines the behaviour of oxygen-free high conductivity copper (OFHC) using the experimental data reported in Nemat-Nasser and Li (1998) and Rusinek at al. (2010). The impact limits and absorption energy of the two foams are obtained by means of explicit nonlinear finite element simulations using ABAQUS. It has been found that the auxetic foam is superior to the convex cell foam in impact resistance because of the material concentration at the impacted area due to the negative Poisson’s ratio effect.

Słowa kluczowe:

Open-cell foams, the impact resistance of convex and auxetic copper (OFHC) foams

Afiliacje autorów:

Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
15.Lumelskyy D., Rojek J., Pęcherski R.B., Grosman F., Tkocz M., Numerical study of an effect of friction in Nakazima formability test, 8th Workshop on Dynamic Behaviour of Materials and Its Applications in Industrial Processes, 2014-06-25/06-27, Warszawa (PL), pp.45-46, 2014

Streszczenie:

This paper presents numerical investigations of the influence of friction in the contact between sheet and a punch on sheet deformation in Nakazima type formabilitybtests. The Nakazima test [1] is one of the most comonnly used tests to study experimentally formability of metal sheets. It consits in stretching of a sheet specimen by means of a hemispherical punch until fracture occurs.
The aim of this study has been to numerically identify frictional conditions in a selected case of the Nakazima test and study numerically effect of change of friction on strain path and forming limit curve. (FLC). Numerical simulations have been performed assuming the data corresponding to own lboratory tests carried out for the steel grade HC380LA 1.5 mm thick.

Słowa kluczowe:

formabilty of metal sheets, Nakazima test, numerical simulation, friction effects

Afiliacje autorów:

Lumelskyy D.-IPPT PAN
Rojek J.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Grosman F.-Silesian University of Technology (PL)
Tkocz M.-other affiliation
16.Nowak Z., Nowak M., Pęcherski R.B., Numerical simulation of metal forming processes with application of modified elastic-plastic model, 8th Workshop on Dynamic Behaviour of Materials and Its Applications in Industrial Processes, 2014-06-25/06-27, Warszawa (PL), pp.51-52, 2014

Streszczenie:

Finite element method is an efficient numerical tool to analyse problems of the sheet metal forming processes including cup drawing and stamping. Proper description of material properties is crucial for accurate analysis. In particular, the anisotropy and asymmetry of elastic range, related with strength differential effect (SDE), of considered materials play an important role in finite element simulation. The paper presents a new yield criterion for the transversal isotropy of metal sheets under plane stress conditions which is an extension of the isotropic yield function proposed by Burzyński (1928) (Studium nad hipotezami Burzyński’s doctoral dissertation ”Study on material effort hypotheses”, Engng. Trans., 2009, t. 57, nr 3–4, s. 185–215) . One additional coefficient has been introduced in order to allow a better representation of plastic behavior of metal sheets. The proposed yield condition includes the influence of first invariant of the stress tensor and also the strength differential effect. The system of equations describing the sheet metal forming process is solved by algorithm using the return mapping procedure. Plane stress constraint is incorporated into the Newton-Raphson iteration loop. The proposed algorithm is verified by performing a numerical test using shell elements in commercial FEM software ABAQUS/EXPLICIT with a developed VUMAT subroutine.

Słowa kluczowe:

the strength differential effect, a new yield criterion for the transversal isotropy of metal sheets, numerical simulations of cup deep drawing process

Afiliacje autorów:

Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
17.Nowak M., Nowak Z., Pęcherski R.B., Energy-based multisurface limit criteria in application for modelling and simulation of metal forming processes, 8th Workshop on Dynamic Behaviour of Materials and Its Applications in Industrial Processes, 2014-06-25/06-27, Warszawa (PL), pp.53-54, 2014

Streszczenie:

Metallic materials are usually used in engineering applications in the as received state. In such a case, developing in in the course of manufacturing processes texture induces anisotropy of mechanical properties and produces often the so-called strength differential effect (SDE).The precise description of elastic properties and formulation of limit criterion requires application of the formalism used typically for anisotropic solids. It is a complex and difficult task related with
proper experimental characterisation of all material parameters. In some cases, however, a simple model of isotropic solid revealing possible strength differential effect and certain correction for the limit strength in shear can be proposed. It is in accord with the observation that developing texture influences mostly shear strength of metallic solids.

Słowa kluczowe:

A simple model of isotropic solid, strength differential effect, the limit strength in shear

Afiliacje autorów:

Nowak M.-IPPT PAN
Nowak Z.-IPPT PAN
Pęcherski R.B.-IPPT PAN
18.Lumelskyy D., Rojek J., Pęcherski R., Grosman F., Tkocz M., Influence of friction on strain distribution in Nakazima formability test of circular specimen, AutoMetForm/SFU 2014, New Materials for Vehicle Components, 2014-11-03/11-05, Freiburg (DE), pp.214-217, 2014

Streszczenie:

This paper presents experimental and numerical investigations of the influence of friction on sheet deformation in Nakazima type formability tests. Numerical simulations have been performed using the authors own explicit dynamic finite element program. Strain distribution obtained in numerical analyses has been compared with experimental data. Location of fracture was of major interest in this specimen as required by the standards can be obtained for low value of the friction coefficient. With the increase of the friction coefficient the fracture is displaced further from the center.

Słowa kluczowe:

formability of metal sheets, Nakazima test, numerical simulation, friction effect, failure location

Afiliacje autorów:

Lumelskyy D.-IPPT PAN
Rojek J.-IPPT PAN
Pęcherski R.-IPPT PAN
Grosman F.-Silesian University of Technology (PL)
Tkocz M.-other affiliation
19.Nowak Z., Nowak M., Pęcherski R.B., Potoczek M., Śliwa R.E., Własności mechaniczne pianek ceramicznych o komórkach otwartych i różnej porowatości, IX Seminarium Naukowe ZINTEGROWANE STUDIA PODSTAW DEFORMACJI PLASTYCZNEJ METALI PLASTMET, 2014-11-25/11-28, Łańcut (PL), pp.1-2, 2014

Streszczenie:

W pracy określono własności mechaniczne i przedstawiono model numeryczny ceramicznej pianki korundowej, otrzymanej metodą żelowania spienionej zawiesiny (gelcasting). Metoda ta pozwala wytwarzać pianki zawierające kmórki o różnej wielkości, a w konsekwencji otrzymywać pianki o różnej porowatości. Wielkości charakteryzujące geometrię rzeczywistych pianek ustalono z wykorzystaniem obrazów tomograficznych 3D oraz obrazów z mikroskopu skaningowego. Informacje te wykorzystano przy opracowaniu modelu numerycznego badanej pianki. Symulacje numeryczne procesów deformacji przeprowadzono z zastosowaniem programu elementow skończonych ABAQUS.

Słowa kluczowe:

pianki ceramiczne, metoda żelowania, porowatość, symulacje numeryczne procesów deformacji tomografia komputerowa, mikroskopia skaningowa

Afiliacje autorów:

Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Potoczek M.-other affiliation
Śliwa R.E.-other affiliation
20.Nalepka K.T., Pęcherski R.B., Plastic flow and failure of solids. Modelling across scales, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.25-26, 2014

Streszczenie:

The aim of the presentation is to discuss the classical problems of elastic limit criteria from the perspective of basic quantum mechanical approach [1]. In the case of metallic solids the multiscale mechanisms of plastic deformation and failure are analyzed [2]. In particular, the role of shear banding responsible for plastic flow is elucidated [3].

Słowa kluczowe:

elastic limit criteria, metal/ceramic interface, copper/saphire nanocomposites, PLD, HRTEM, EBSD

Afiliacje autorów:

Nalepka K.T.-IPPT PAN
Pęcherski R.B.-IPPT PAN
21.Lumelskyy D., Rojek J., Pęcherski R., Grosman F., Tkocz M., Numerical investigation of influence of friction on strain distribution and forming limit curve in Nakazima formability test, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.45-46, 2014

Streszczenie:

This paper presents numerical investigations of the influence of friction in the contact between sheet and a punch on sheet deformation in Nakazima type formability tests. The Nakazima test [1] is one of the most commonly used tests to study experimentally formability of metal sheets. It consists in stretching of a sheet specimen by means of a hemispherical punch until occurrence of fracture.

Słowa kluczowe:

formability, Nakazima test, influence of friction, numerical simulations, deformation of metal sheets

Afiliacje autorów:

Lumelskyy D.-IPPT PAN
Rojek J.-IPPT PAN
Pęcherski R.-IPPT PAN
Grosman F.-Silesian University of Technology (PL)
Tkocz M.-other affiliation
22.Nowak Z., Grosman F., Lumelskyy D., Nowak M., Pęcherski R.B., Rojek J., Tkocz M., Metal cup deep drawing processes – numerical simulation and experimental verification, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.47-48, 2014

Streszczenie:

Finite element method is an efficient numerical tool to analyse problems of the sheet metal forming processes in particular cup drawing and stamping. Proper description of material properties is crucial for accurate analysis. In particular, the anisotropy and asymmetry of elastic range, which is related with strength differential effect (SDE), of considered materials play an important role in finite element simulation. For metal forming analysis with use of traditional models many experimental tests are usually needed to obtain the adequate description of anisotropic behaviour of metal sheets. Therefore, the search for new models, which are based on simplified description of the effects of anisotropy and SDE requiring less experimental tests seems to be justified.
The paper presents the application of a new yield criterion for the transversal isotropy of metal sheets under plane stress conditions. The proposed criterion is based on the study of yield criteria accounting for SDE and anisotropy nade by W. Burzyński [1]. The system of equations describing the sheet metal forming process is solved by the algorithm using the return mapping procedure. Plane stress constraint is incorporated into the Newton-Raphson iteration loop. The proposed algorithm is verified by performing the numerical calculations using shell elements of the commercial FEM sftware ABAQUS/EXPLICIT with own VUMAT subroutine.

Słowa kluczowe:

metal sheet forming, metal cup deep drawing, FE numerical simulations, strength differential effect, anisotropy and asymmetry of elastic range, transversal isotropy

Afiliacje autorów:

Nowak Z.-IPPT PAN
Grosman F.-Silesian University of Technology (PL)
Lumelskyy D.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Rojek J.-IPPT PAN
Tkocz M.-other affiliation
23.Nowak Z., Nowak M., Pęcherski R.B., A plane stress elastic-plastic analysis of sheet metal cup deep drawing processes, SSTA, 10th Jubilee Conference on Shell Structures - Theory and Applications, 2013-10-16/10-18, Gdańsk (PL), pp.129-132, 2013

Streszczenie:

The paper presents a new yield criterion for the transversal isotropy of metal sheets under plane-stress conditions which is an extension of the isotropic yield function proposed by Burzynski (Burzynski W. 1928). Studium nad hipotezami Burzynski's doctoral dissertation

Słowa kluczowe:

elastic-plastic analysis, transversal isotropy, metal sheets, deep drawing process, FE simulations, Burzyński yield condition, strength differential effect

Afiliacje autorów:

Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
24.Nowak Z., Nowak M., Pęcherski R.B., Potoczek M., Śliwa R.E., Numerical characterization and estimation of elastic properties of ceramic foams, 7th International Workshop on Dynamic Behaviour of Materials and its Applications in Industrial Processes, 2013-05-08/05-10, Madryt (ES), pp.41-42, 2013

Streszczenie:

In this work a numerical model of real foam with different cell sizes is presented and its applications are discussed. Geometric characteristics of real foam samples were estimated from tomographic and scanning electron microscopy images. Using this information, numerical foam model was proposed. The examples of generated numerically structures are shown. A good agreement between numerical model and the results elaborated from microtomography was obtained.

Słowa kluczowe:

Alumina open-cell foam, foam with different cell sizes, numerical foam model based on tomographic and scanning electron microscopy images

Afiliacje autorów:

Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Potoczek M.-other affiliation
Śliwa R.E.-other affiliation
25.Nowak Z., Nowak M., Pęcherski R.B., Numerical analysis of the cup deep drawing process with use of new yield condition for plane stress states, CMM 2013, 20th International Conference on Computer Methods in Mechanics, 2013-08-27/08-31, Poznań (PL), No.MS07, pp.9-10, 2013

Streszczenie:

The elastoplastic constitutive equations for materials under plane stress condition with new yield criterion have been proposed. This yield condition accounts for the effect of strength differential effect. The system of equations of sheet metal forming process is solved by algorithm using the return mapping procedure. Plane stress constrain is incorporated into the Newton-Raphson iteration loop. The proposed algorithm is verified by performing numerical tests using shell elements in commercial FEM software ABAQUS/EXPLICIT with developed VUMAT subroutine. It is shown that the proposed approach provides the satisfactory prediction of material behaviour, at least in the cases when the anisotropy effects are not so advanced.

Słowa kluczowe:

anisotropic behaviour of metal sheets, strength differential effect, explicit finite element analysis, plane stress

Afiliacje autorów:

Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
26.Nowak Z., Nowak M., Pęcherski R.B., Potoczek M., Śliwa R.E., The Compressive Strength of Ceramic Open-Cell Foams with the Variability of Cell Sizes, ICMM3, 3rd International Conference on Material Modelling incorporating 13th European Mechanics of Materials Conference, 2013-09-08/09-11, Warszawa (PL), pp.315-316, 2013

Streszczenie:

New aeronautic materials are obtained by liquid metal infiltration into a ceramic foam, called a preform. Ceramic preforms are produced by a new method of manufacturing of porous ceramics foams known as gelcasting. Porous ceramics fabricated by this method is characterized by a continuous network of spherical cells interconnected by circular windows. The open porosity due to the presence of windows creates good hydro-dynamical properties for liquid metals infiltration. For better understanding mechanical properties of such composites a numerical model of ceramic foam is needed, see e. g. ref. [1-4]. Geometry of ceramic foams can be generated in two steps. First, the coordinates of the center point of the spherical bubbles and its diameter are produced by PYTHON scripts. The diameters of spherical bubbles were estimated from microtomography and scanning electron microscopy images. On the other hand, the coordinates of the center points are determined in such a way that the bubbles have to intersect with each other. Finally, the intersecting bubbles are subtracted from the bulk block of any shape. Using this information, numerical foam model was proposed and good agreement between numerical model and real foam structure from microtomography was obtained. In this work we present a numerical model of real foam of alumina with different cell sizes and discuss its mechanical properties using several examples. The numerical simulations of uniaxial compression test have been performed. As a result the compressive strength of the investigated foams with porosities changing from 60 to 95 % were determined.

Słowa kluczowe:

Porous ceramics foams produced by gelcasting, open-cell ceramic foam, the numerical simulations of uniaxial compression test, the compressive strength of alumina foams with porosities changing from 60 to 95 %

Afiliacje autorów:

Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Potoczek M.-other affiliation
Śliwa R.E.-other affiliation
27.Nowak M., Nowak Z., Pęcherski R.B., Potoczek M., Śliwa R.E., Ocena mechanicznych właściwości ceramicznej pianki poddanej procesowi infiltracji, OMIS 2013, X Jubileuszowa Konferencja ODKSZTAŁCALNOŚĆ METALI I STOPÓW, 2013-11-26/11-29, Łańcut (PL), pp.1-2, 2013

Streszczenie:

Celem pracy jest ocena granicznych ciśnień oraz temperatury procesu, dla których proces infiltracji zachodzi bez uszkodzenia pianki w skali makroskopowej. W pracy przedstawiono numeryczny model procesu wypełniania ceramicznej preformy o otwartej strukturze porów. W procesie wypełniania preformy ciekłym metalem lokalny wzrost naprężeń i kruchość materiału powodują pękanie części elementów pianki. Opracowano model numeryczny tego procesu, który zaimplementowano w programie ABAQUS. Dla określenia stanu naprężenia w piance użyto sprzężonej metody CEL (ang. the coupled Eulerian-Lagrangian method) w programie Abaqus/Explicit.

Słowa kluczowe:

Proces infiltracji ceramicznych pianek ciekłym metalem, ocena granicznych ciśnień oraz temperatury procesu

Afiliacje autorów:

Nowak M.-IPPT PAN
Nowak Z.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Potoczek M.-other affiliation
Śliwa R.E.-other affiliation
28.Rojek J., Lumelskyy D., Grosman F., Tkocz M., Pęcherski R., Chorzępa W., Graniczne krzywe tłoczności przy zmiennych ścieżkach odkształcenia, PLASMET/2012, VIII Seminarium Naukowe Zintegrowane Studia Podstaw Deformacji Plastycznej Metali, 2012-11-20/11-23, Łańcut (PL), pp.x1-x3, 2012
29.Frąś T., Luckner J., Nowak M., Nowak Z., Pęcherski R., Analiza procesu formowania blach z uwzględnieniem różnicy wytrzymałości przy ściskaniu i rozciąganiu, PLASMET/2012, VIII Seminarium Naukowe Zintegrowane Studia Podstaw Deformacji Plastycznej Metali, 2012-11-20/11-23, Łańcut (PL), pp.1-3, 2012
30.Frąś T., Luckner J., Nowak M., Nowak Z., Pęcherski R., Rusinek A., Stręk A., Zastosowanie kryteriów granicznych Burzyńskiego I. Metale i kompozyty metaliczno-ceramiczne II. Pianki metaliczne, PLASMET/2012, VIII Seminarium Naukowe Zintegrowane Studia Podstaw Deformacji Plastycznej Metali, 2012-11-20/11-23, Łańcut (PL), pp.1-4, 2012
31.Nowak M., Nowak Z., Pęcherski R., Potoczek M., Śliwa R.E., Opracowanie metody rekonstrukcji struktury geometrycznej i sposobu wyznaczania modułu Younga pianek ceramicznych, PLASMET/2012, VIII Seminarium Naukowe Zintegrowane Studia Podstaw Deformacji Plastycznej Metali, 2012-11-20/11-23, Łańcut (PL), pp.1-3, 2012
32.Ostrowska-Maciejewska J., Pęcherski R., Szeptyński P., Matematyczne podstawy warunku granicznego dla materiałów anizotropowych, PLASMET/2012, VIII Seminarium Naukowe Zintegrowane Studia Podstaw Deformacji Plastycznej Metali, 2012-11-20/11-23, Łańcut (PL), pp.1-3, 2012
33.Lumelskyy D., Rojek J., Pęcherski R., Grosman F., Tkocz M., Numerical Studies of Formability of Pre-Stretched Steel Sheet, SolMech 2012, 38th Solid Mechanics Conference, 2012-08-27/08-31, Warszawa (PL), pp.172-173, 2012
34.Frąś T., Pęcherski R., Rusinek A., Experimental investigations of the influence of moderate strains and strain rates on the yield surface of OFHC copper, SolMech 2012, 38th Solid Mechanics Conference, 2012-08-27/08-31, Warszawa (PL), pp.122-123, 2012
35.Nowak Z., Frąś T., Nowak M., Pęcherski R.B., Analysis of the forming Processes Accounting for Asymmetry of Elastic Range, SolMech 2012, 38th Solid Mechanics Conference, 2012-08-27/08-31, Warszawa (PL), pp.92-93, 2012
36.Nowak M., Nowak Z., Pęcherski R., Potoczek M., Śliwa R.E., On the Geometry and Compressive Strength of Ceramic Foams, SolMech 2012, 38th Solid Mechanics Conference, 2012-08-27/08-31, Warszawa (PL), pp.174-175, 2012
37.Szeptyński P., Ostrowska-Maciejewska J., Pęcherski R.B., Extension of The Rychlewski Limit State Criterion Accounting For The Asymmetry of Elastic Range, SolMech 2012, 38th Solid Mechanics Conference, 2012-08-27/08-31, Warszawa (PL), pp.106-107, 2012
38.Nowak M., Luckner J., Nowak Z., Pęcherski R., Numerical simulation of the forming processes accounting for asymmetry of elastic range and initial anisotropy, CMM 2011, 19th International Conference on Computer Methods in Mechanics, 2011-05-09/05-12, Warszawa (PL), pp.383-1-2, 2011
39.Kowalczyk-Gajewska K., Pęcherski R.B., Micromechanical modeling of polycrystalline materials, Plasticity 2006, 12th International Symposium on Plasticity and Its Current Applications, 2006-07-17/07-22, Halifax (CA), Vol.CD ROM, pp.556-558, 2006
40.Kowalczyk-Gajewska K., Mróz Z., Pęcherski R.B., Micromechanical modeling of polycrystalline materials under non-proportional deformation paths, SolMech 2006, 35th Solid Mechanics Conference, 2006-09-04/09-08, Kraków (PL), pp.213-214, 2006