Marcin Nowak, Ph.D., Eng.

Department of Mechanics of Materials (ZMM)
Thermoplasticity Laboratory (LT)
position: specialist
telephone: (+48) 22 826 12 81 ext.: 401
room: 236
e-mail: nowakm

Doctoral thesis
2015-03-26Analiza deformacji i zniszczenia struktur komórkowych w zastosowaniu do symulacji procesu infiltracji pianki korundowej ciekłym metalem 
supervisor -- Zdzisław Nowak, Ph.D., Dr. Habil., Eng., IPPT PAN
709
 
Recent publications
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
Abstract:

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

Keywords:

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

Affiliations:
Pęcherski R.B.-IPPT PAN
Nowak M.-IPPT PAN
Nowak Z.-IPPT PAN
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
Abstract:

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.

Keywords:

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

Affiliations:
Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.-IPPT PAN
Potoczek M.-other affiliation
Śliwa R.E.-other affiliation
3.Widłaszewski J., Nowak M., Nowak Z., Kurp P., Laser-assisted forming of thin-walled profiles, Metal Forming, ISSN: 0867-2628, Vol.XXVIII, No.3, pp.183-198, 2017
Abstract:

Forming processes assisted by localised laser heating are studied in recent years. Heating is used to make it possible or facilitate forming of materials, which exhibit such adverse properties as: brittleness, effects of high work-hardening or a high elastic springback. The hereby presented investigations concern the hybrid thermo-mechanical forming of thin-walled parts using local heating of the material by the laser beam. The research is aimed at forming of parts from materials used in the aviation industry, such as the nickel-base super-alloys Inconel 625, Inconel 718, and also martensitic superalloys AISI 410 and AISI 325. Preliminary investigations are conducted using X5CrNil8-10 (1.4301) stainless steel. Experimental study and numerical simulations cover the behaviour of thin beams 1 mm thick, subjected to mechanical load in the cantilever arrangement and heated by the CO2 laser beam moving from the free end of the sample towards its fixture. The possibility of obtaining large bending deformations relatively easily due to the application of laser beam is demonstrated experimentally. Experimentally verified finite element numerical simulations show the intense plastic flow of the material layer heated by the laser beam. It is accompanied by a shift of the cross-section neutral axis of the beam. Bending of thin-walled tubes in a specially designed device is studied in the next step. It allows introducing mechanical loading in a controlled manner, heating the material by a moving laser beam and forcing the required deformation according to the kinematic scheme of the device.

Keywords:

laser-assisted forming, finite element method, thin-walled structure

Affiliations:
Widłaszewski J.-IPPT PAN
Nowak M.-IPPT PAN
Nowak Z.-IPPT PAN
Kurp P.-Kielce University of Technology (PL)
4.Sumelka W., Nowak M., Non-normality and induced plastic anisotropy under fractional plastic flow rule: a numerical study, INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, ISSN: 0363-9061, DOI: 10.1002/nag.2421, Vol.40, pp.651-675, 2016
Abstract:

In this paper, an implementation of fractional plastic flow rule in the framework of implicit and explicit procedures is under consideration. The fractional plastic flow rule is obtained from a generalisation of the classical plastic flow rule utilising fractional calculus. The key feature of this new concept is that in general, the non-associative flow is obtained without necessity of additional potential assumption. If needed, the model can cover the anisotropy induced by plastic deformation. Illustrative examples showing the unusual flexibility of this model are also presented.

Keywords:

non-normality of plastic flow, fractional calculus, return mapping algorithm

Affiliations:
Sumelka W.-other affiliation
Nowak M.-IPPT PAN
5.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
Abstract:

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.

Keywords:

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

Affiliations:
Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Potoczek M.-other affiliation
Śliwa R.E.-other affiliation
6.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
Abstract:

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.

Keywords:

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

Affiliations:
Nowak M.-IPPT PAN
Nowak Z.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Potoczek M.-other affiliation
Śliwa R.E.-other affiliation
7.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
Abstract:

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.

Keywords:

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

Affiliations:
Pęcherski R.B.-IPPT PAN
Szeptyński P.-other affiliation
Nowak M.-IPPT PAN
8.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
Abstract:

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.

Keywords:

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

Affiliations:
Nowak M.-IPPT PAN
Ostrowska-Maciejewska J.-other affiliation
Pęcherski R.B.-IPPT PAN
Szeptyński P.-other affiliation
9.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
Abstract:

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.

Keywords:

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

Affiliations:
Potoczek M.-other affiliation
Śliwa R.E.-other affiliation
Pęcherski R.B.-IPPT PAN
Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
10.Nowak M., Usprawnienie programów numerycznych w języku Pascal dla mikrokomputerów IBM XT/AT, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.10, pp.1-244, 1989
11.Nowak M., Niektóre algorytmy algebry liniowej w języku Pascal, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.22, pp.1-228, 1986

List of chapters in recent monographs
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

Conference abstracts
1.Nowak Z., Nowak M., Widłaszewski J., Kurp P., Experimental and numerical investigation on laser-assisted bending of pre-loaded metal plate, CMM-2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), No.MS13, pp.37-38, 2017
Abstract:

The laser forming technique has an important disadvantage, which is the limitation of plastic deformation generated by a single laser beam pass. In order to increase the plastic deformation one has to repeat the process several times or use the alternative method. To increase the plastic deformation it is possible to add external forces during the laser forming process. In this paper, we investigate the influence of external pre-loads on the laser bending of steel plate. The pre-loads investigated generate bending towards the laser beam. The thermal, elastic-plastic analysis is performed using the commercial nonlinear finite element analysis package ABAQUS. The focus of the paper is to identify how this pattern of the pre-load influence the final bend angle of the plate.

Keywords:

laser forming, force-assisted laser bending, thermo-mechanical simulations, FEA

Affiliations:
Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Widłaszewski J.-IPPT PAN
Kurp P.-Kielce University of Technology (PL)
2.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
Abstract:

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.

Keywords:

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

Affiliations:
Pęcherski R.B.-IPPT PAN
Nowak M.-IPPT PAN
3.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
Abstract:

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.

Keywords:

numeryczna rekonstrukcja, struktury otwartokomórkowe, pianki metaliczne, mikrotomografia komputerowa

Affiliations:
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Nowak Z.-IPPT PAN
Frąś L.J.-IPPT PAN
4.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
Abstract:

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.

Keywords:

dynamiczna analiza, procesy zgniatania, pianki metaliczne, struktury otwarokomórkowe

Affiliations:
Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
5.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
Abstract:

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.

Keywords:

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

Affiliations:
Pęcherski R.B.-IPPT PAN
Nowak M.-IPPT PAN
Frąś L.J. -IPPT PAN
6.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
Abstract:

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.

Keywords:

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

Affiliations:
Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Potoczek M.-other affiliation
Śliwa R.E.-other affiliation
7.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
Abstract:

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.

Keywords:

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

Affiliations:
Pęcherski R.B.-IPPT PAN
Nowak M.-IPPT PAN
Nowak Z.-IPPT PAN
8.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
Abstract:

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.

Keywords:

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

Affiliations:
Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
9.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
Abstract:

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.

Keywords:

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

Affiliations:
Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
10.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
Abstract:

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.

Keywords:

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

Affiliations:
Nowak M.-IPPT PAN
Nowak Z.-IPPT PAN
Pęcherski R.B.-IPPT PAN
11.Nowak M., Application of periodic unit cell for modeling of porous materials, 8th Workshop on Dynamic Behaviour of Materials and Its Applications in Industrial Processes, 2014-06-25/06-27, Warszawa (PL), pp.47-48, 2014
12.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
Abstract:

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.

Keywords:

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

Affiliations:
Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Potoczek M.-other affiliation
Śliwa R.E.-other affiliation
13.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
Abstract:

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.

Keywords:

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

Affiliations:
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
14.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
Abstract:

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

Keywords:

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

Affiliations:
Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
15.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
Abstract:

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.

Keywords:

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

Affiliations:
Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Potoczek M.-other affiliation
Śliwa R.E.-other affiliation
16.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
Abstract:

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.

Keywords:

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

Affiliations:
Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
17.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
Abstract:

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.

Keywords:

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 %

Affiliations:
Nowak Z.-IPPT PAN
Nowak M.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Potoczek M.-other affiliation
Śliwa R.E.-other affiliation
18.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
Abstract:

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.

Keywords:

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

Affiliations:
Nowak M.-IPPT PAN
Nowak Z.-IPPT PAN
Pęcherski R.B.-IPPT PAN
Potoczek M.-other affiliation
Śliwa R.E.-other affiliation
19.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
20.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
21.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
22.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
23.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
24.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