1. |
Nowak Z., Pęcherski R.B., Constitutive modelling of shear bands effect in ductile materials: formulation and computational aspects,
8th Wdzydzeanum Workshop on „FLUID – SOLID INTERACTION”, 2020-08-30/09-03, Wdzydze Kiszewskie (PL), pp.1-2, 2020 |  |
2. |
Postek E., Pęcherski R.B., Nowak Z., Viscoplasticity effect during impact of metallic foams,
CCAM & 3D-Printing, Collaborative Conference on Advanced Materials, 2019-08-26/08-30, St. Julian's (MT), pp.16-17, 2019 Streszczenie: In the last 20 years, a new rapidly developing method is applied to calculations of solid mechanics problems, [1]. It is a non-local method. The predecessors of the method that have been applied to crystals were developed in [2] and [3]. In the presentation, we show an application of the method for the evaluation of the viscoplasticity effects [4, 5] in the copper foams. The oxygen free high conductivity copper (OHFC) can be applied to produce the open-cell multifunctional structures, for example, heat exchangers, heat capacitors, using additive manufacturing [6]. We use the highly parallelized program Peridigm for the analysis, [7].
Figure 1(a) shows an exemplary impacting foam sample attacking with a velocity of 20 m/s an elastic block. The highest plastic strains are in the case of ideally elastic-plastic case (b). The equivalent plastic strains are higher when neglecting the strain rate hardening effects (d) than including both strain hardening and strain rate hardening effects (c). We provide dependences of the equivalent plastic strains on impact velocities and strain rate hardening exponents.
Literature;
1. S.A. Silling, Journal of Mechanics and Physics of Solids, 48, 175 (2000).
2. D. Rogula, Nonlocal theory of material media (Springer), 123 (1982).
3. A. Kunin, Elastic media with microstructure, one dimensional models (Springer), (1982).
4. J.A. Mitchell, A Nonlocal, Ordinary, State-Based Plasticity Model for Peridynamics (SANDIA ), (2011).
5. J.T. Foster, S.A. Silling, W.W. Chen, International Journal for Numerical Mechods in Engineering, 81,1242 (2010).
6. R.B. Pęcherski, M. Nowak, Z. Nowak, International Journal for Multiscale Computational Engineering, 15, 431 (2017).
7. M.L. Parks, D.J. Littlewood, J.A. Mitchell, S.A. Silling, Peridigm Users’ Guide (SANDIA), (2012). Słowa kluczowe: metallic foams, composites, impact loading, peridynamics, parallel computing Afiliacje autorów:
Postek E. | - | IPPT PAN | Pęcherski R.B. | - | IPPT PAN | Nowak Z. | - | IPPT PAN |
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3. |
Kowalewski Z.L., Nowak Z., Pęcherski R.B., Libura T., Identification of effects associated to dynamic testing using shpb or dict- experiment and numerical analysis,
DynaMAT, The 13th WORKSHOP on DYNAMIC BEHAVIOR OF MATERIALS AND ITS APPLICATIONS IN INDUSTRIAL PROCESSES, 2019-04-17/04-19, Nicosia (CY), pp.1-2, 2019 |  |
4. |
Nowak Z., Nowak M., Pęcherski R.B., On the energy absorbtion in open cell foams under dynamic loading,
DynaMAT, The 13th WORKSHOP on DYNAMIC BEHAVIOR OF MATERIALS AND ITS APPLICATIONS IN INDUSTRIAL PROCESSES, 2019-04-17/04-19, Nicosia (CY), pp.1-2, 2019 |  |
5. |
Pęcherski R.B., Rusinek A., Frąś T., Nowak M., Nowak Z., Energetyczny warunek plastyczności materiałów ortotropowych wykazujących asymetrię zakresu sprężystego,
OMIS 2019, XIII Konferencja Naukowa Odkształcalność Metali i Stopów, 2019-11-19/11-22, Łańcut (PL), pp.48-49, 2019 |  |
6. |
Nowak Z., Numerical simulation of crushing processes in metallic open-cell foam,
PCM-CMM, 4th Polish Congress of Mechanics, 23rd International Conference on Computer Methods in Mechanics, 2019-09-08/09-12, Kraków (PL), pp.1, 2019 |  |
7. |
Nowak Z., Nowak M., Pęcherski R.B., Propagation of compaction waves in the open-cell copper foams,
ESMC, 10th European Solid Mechanics Conference, 2018-07-02/07-06, Bologna (IT), pp.1, 2018 |  |
8. |
Widłaszewski J., Nowak M., Nowak Z., Kurp P.♦, Termomechaniczne kształtowanie profili rurowych wspomagane laserowo,
PLASTMET, 11 KONFERENCJA ZINTEGROWANE STUDIA PODSTAW DEFORMACJI PLASTYCZNEJ METALI, 2018-11-27/11-30, Łańcut (PL), pp.162-163, 2018 |  |
9. |
Nowak Z., Nowak M., Widłaszewski J., Kurp P.♦, Symulacje numeryczne laserowo wspomaganego gięcia materiałów wykorzystywanych w przemyśle lotniczym,
PLASTMET, 11 KONFERENCJA ZINTEGROWANE STUDIA PODSTAW DEFORMACJI PLASTYCZNEJ METALI, 2018-11-27/11-30, Łańcut (PL), pp.97-98, 2018 |  |
10. |
Postek E., Pęcherski R.B., Nowak Z., Perydynamiczna symulacja procesów zgniatania otwartokomórkowych pianek miedzianych,
PLASTMET, 11 KONFERENCJA ZINTEGROWANE STUDIA PODSTAW DEFORMACJI PLASTYCZNEJ METALI, 2018-11-27/11-30, Łańcut (PL), pp.120-121, 2018 Streszczenie: W ciągu ostatnich dwudziestu lat opracowano nową metodę bezsiatkową znaną jako perydynamika [1]. Metoda ta posługuje się zrównoleglonym kodem obliczeniowym [2]. Przedmiotem badań jest deformacja miedzianej pianki o strukturze otwartokomórkowej poddanej dynamicznemu ściskaniu, Rys. 1.
Model komputerowy szkieletu pianki otrzymano wykorzystując koncepcję materiału wirtualnego przedstawioną w pracy [3]. W zależności od potrzeb wymiary struktury szkieletu pianki można skalować. Materiałem pianki jest miedź beztlenowa o wysokiej przewodności cieplnej (OFHC), wykorzystywana do wytwarzania wielofunkcyjnych struktur komórkowych takich jak wymienniki lub kondensatory cieplne, itp. W obliczeniach zastosowano lepkoplastyczny model materiału szkieletu pianki, a symulacje przeprowadzono dla różnych prędkości uderzenia. Rezultaty metody perydynamiki porównano z obliczeniami MES podobnych problemów ściskania dynamicznego pianki. Obliczenia wykonano w ICM Uniwersytetu Warszawskiego na komputerze CRAY XC-40 oraz na klastrze HP w centrum TASK w Gdańsku. Słowa kluczowe: Obciążenia uderzeniowe, pianka metaliczna, perydynamika Afiliacje autorów:
Postek E. | - | IPPT PAN | Pęcherski R.B. | - | IPPT PAN | Nowak Z. | - | IPPT PAN |
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11. |
Libura T., Nowak Z., Kowalewski Z.L., Widłaszewski J., Behaviour of inconel 718 aerospace alloy thin sheets under in-plane tension-compression,
SME, XXVIII Symposium On Experimental Mechanics of Solids in memory of prof. Jacek Stupnicki, 2018-10-17/10-20, Jachranka (PL), pp.42-42, 2018 |  |
12. |
Postek E., Nowak Z., Pęcherski R.B., Impact resistance of crushable foam skeleton,
SolMech 2018, 41st SOLID MECHANICS CONFERENCE, 2018-08-27/08-31, Warszawa (PL), pp.1-2, 2018 Streszczenie: The analyses of the modern cellular materials due to complexity of their internal structure require efficient computer methods and codes. The new method that has been developed mostly in the last 10 years is peridynamics [1, 2]. The developments resulted in highly parallelized code [3] that we use in our analysis. The subject of the study are alumina foams produced by gelcasting method. The results of microtomography of alumina foams are used to create the numerical model reconstructing the structure of foam skeleton. The numerical simulations of failure strength under compression for alumina foams are performed. The calculations with use of the numerical model are time consuming. Therefore, the simplified method of the assessment of failure strength is proposed. The 3D model of the foam structure is created. The detailed description of the model generation is presented in Nowak et al. [5]. The numerical models of real Al2O3 foam with porosity 96 %, and discussion of theirs mechanical properties have been presented. The method of the assessment of failure strength of real alumina foam produced by the gelcasting is proposed. We attempt to present the mechanism of damaging of a crushable foam under impact. Słowa kluczowe: foams, damage, impact, peridynamics Afiliacje autorów:
Postek E. | - | IPPT PAN | Nowak Z. | - | IPPT PAN | Pęcherski R.B. | - | IPPT PAN |
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13. |
Nowak Z., Nowak M., Widłaszewski J., Kurp P.♦, Experimental and numerical investigation on laser-assisted bending of pre-loaded inconel 718 beams,
SolMech 2018, 41st SOLID MECHANICS CONFERENCE, 2018-08-27/08-31, Warszawa (PL), pp.282-283, 2018 |  |
14. |
Pawłowski P., Pęcherski R.B., Nowak M., Nowak Z., Skłodowski M., Application of the Concept of Virtual Material for the Design of Additive Manufacturing Processes of Open Cell Foams,
WCCM 2018, 13th World Congress on Computational Mechanics, 2018-07-22/07-27, Nowy Jork (US), pp.584-584, 2018 |  |
15. |
Nowak Z., Nowak M., Pęcherski R.B., Wiśniewski K., Widłaszewski J., Kurp P.♦, Computational Modelling of Thermoplastic Behaviour of Inconel 718 in Application to Laser-Assisted Bending of Thin-Walled Alloy Tubes,
WCCM2018, 13th World Congress on Computational Mechanics, 2018-07-22/07-27, Nowy Jork (US), pp.1, 2018 |  |
16. |
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), pp.MS13-37-38, 2017 Streszczenie: 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. Słowa kluczowe: laser forming, force-assisted laser bending, thermo-mechanical simulations, FEA Afiliacje autorów:
Nowak Z. | - | IPPT PAN | Nowak M. | - | IPPT PAN | Widłaszewski J. | - | IPPT PAN | Kurp P. | - | Kielce University of Technology (PL) |
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17. |
Pęcherski R.B., Nowak Z., Nowak M., Natonik K.J.♦, Potoczek M.♦, Śliwa R.E.♦, Problems of virtual cellular materials: representative volume element and energy-based assessment of failure strength,
DBM, 11th Workshop Dynamic Behaviour of Materials and its Applications in Industrial Processes, 2017-08-23/08-25, Guimarães (PT), pp.12-13, 2017 Streszczenie: Three kinds of cellular materials are considered. Depending on geometry and physical properties of the skeleton, these are metallic cellular materials with convex or reentrant open cell structure. To the third group belong alumina foams produced by gel casting method. Finite element computations are used to analyse mechanical properties of a material volume. Such an analysis is usually related with big computational costs. Therefore, it is important to keep the size of the considered cellular material volume as small as possible. On the other hand, the validity of the continuum model requires the proper size of the RVE. The aim of the study is to estimate the sufficient size of representative volume element (RVE) in order to assess the validity of the elastic model of the considered cellular material. An array of cubes of virtual cellular material is used to compute the particular deformation modes providing elastic moduli, Young modulus E, shear modulus G and bulk modulus K as well as the resulting Poisson's ratio. Also the results of the microtomography of alumina foams are used to create the „virtual cellular material” i.e. the numerical model reconstructing the structure of real foam skeleton. The numerical simulations of compression test are performed. The results are compared with experimental data of elastic moduli and failure strength. The numerical simulations of failure strength under compression for alumina foams are performed. The calculations with use of the numerical model are time consuming. Therefore, the simplified method of the assessment of failure strength is proposed. It is based on the energy-based hypothesis on the equivalence of of elastic moduli and the resulting equivalence of the values of failure strength of real alumina foam and the cellular material with regular structure (e.g. fcc type). The justification of the hypothesis based on experimental data of compression of alumina foam are discussed and the range of validity as regards porosity values is studied. Słowa kluczowe: virtual cellular materials, convex skeleton, reentrant skeleton. representative volume element, numerical simulations Afiliacje autorów:
Pęcherski R.B. | - | IPPT PAN | Nowak Z. | - | IPPT PAN | Nowak M. | - | IPPT PAN | Natonik K.J. | - | inna afiliacja | Potoczek M. | - | Rzeszów University of Technology (PL) | Śliwa R.E. | - | Rzeszów University of Technology (PL) |
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18. |
Nowak Z., Nowak M., Pęcherski R.B., Dynamic compression strength of copper open-cell foams,
DBM, 11th Workshop Dynamic Behaviour of Materials and its Applications in Industrial Processes, 2017-08-23/08-25, Guimarães (PT), pp.8-9, 2017 Streszczenie: Metal foams in view of their structural strength and mechanical energy absorption capability under high speed impact can be utilized as energy absorbers. It is important to understand the propagation of compaction waves in the foams. Most commercially available metal foams are made of aluminium, nickel, copper, and metal alloys. Two kinds of foams exist, namely the open-cell and the closed-cell foams. Typically, the pore density of uncompressed open-cell foams varies between 5 to 100 PPI (pores per inch), while the porosity is in the range from 70% to 95%. Literature provides several examples of metal foams solutions for energy absorption applications, dealing with both experimental, numerical and analytical studies. The subject of the study are the models based on digital micro-structures, in particular open cell metallic foams characterized with the skeleton formed of convex or re-entrant cells. The re-entrant materials revealing negative Poisson's ratio have attracted increasing attention in the context of modern materials applications, [3]. The goal of the presented investigations is to study the impact limits and absorption energy of these two kind of open cell metallic foams. To simulate the deformation processes the finite element program ABAQUS is used. The computer tomography made the basis for the formulation of computational model of the foam and the finite element discretization of the skeleton. From each reconstructed volume, a representative cubic volume element was extracted. For numerical simulations the constitutive elasto-viscoplasticity model is applied that defines the dynamic behaviour of oxygen-free high conductivity (OFHC) Cu using the experimental data reported in the literature. The chosen material model for the numerical simulation is the Cowper-Symonds model. The model is able to predict the mechanical behaviour of the materials under different loading conditions and it is implemented in many FEM codes in order to investigate and describe problems such as ballistic impacts or problems in which the strain-rates component are relevant. In numerical simulations the bottom displacements in the impact direction are fixed and initial velocity V0 on the top surface and general contact (steel wall-Cu foam and selfcontact Cu foam) with the friction coefficient 0.35 is assumed. The numerical predictions of axial force (crushing force) within the wide range of velocity: from 50 to 300 m/s are discussed. The shock state variables derived from Hugoniot relation and the conservation laws are used for comparison with FEM simulations. Słowa kluczowe: copper open-cell foams, compaction waves, shock waves, crushing force, elasto-viscoplasticity model Afiliacje autorów:
Nowak Z. | - | IPPT PAN | Nowak M. | - | IPPT PAN | Pęcherski R.B. | - | IPPT PAN |
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19. |
Pęcherski R.B., Nowak Z., Application of virtual cellular material concept for the simulations of dynamic loading processes,
MatCel'2017 & DynMatCel'2017, Cellular Materials: Structural Behaviour, Modelling and Characterisation, 2017-09-25/09-27, Aveiro (PT), pp.54-54, 2017 Streszczenie: The subject of the study is the models based on digital microstructure, in particular open-cell metallic materials with the skeleton of convex or re-entrant cells. Recently, the auxetic materials have attracted increasing attention in the context of modern materials applications. The dynamic properties of such materials are less known. Impact compressions of the two kind of cellular materials under high-velocity are numerically analysed, [1]. To simulate the deformation processes the finite element program ABAQUS is used. The computer tomography makes the basis for the formulation of computational model and finite element discretization of the skeleton of virtual cellular material. For numerical simulations the constitutive elasto-viscoplasticity equations are applied that describe the dynamic behaviour of OFHC Cu. The numerical predictions of compression kinematics of the skeleton and crushing force for velocity 50 and 300 m/s are discussed. The results of computations are completed with the analysis of shock wave propagation. Słowa kluczowe: virtual cellular material, dynamic loading, crushing force, auxetic material, OFHC Cu, shock vaves Afiliacje autorów:
Pęcherski R.B. | - | IPPT PAN | Nowak Z. | - | IPPT PAN |
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20. |
Nowak Z., Pęcherski R.B., Maj P.♦, Niestabilność plastycznego płynięcia w stopie Inconel 718. Badania doświadczalne Serrated flow in Inconel 718 alloy. Experimental investigations,
OMIS'2017, XII Konferencja NAukowa ODKSZTAŁCALNOŚĆ METALI I STOPÓW, 2017-11-21/11-24, Łańcut (PL), pp.47-48, 2017 Streszczenie: Badania doświadczalne efektu Portevin - Le Chatelier w Inconelu 718 przeprowadzono na płaskich próbkach. Do pomiarów zastosowano metodę cyfrowej korelacji obrazu (DIC), która jest efektywna i praktyczna dzięki bezkontaktowym pomiarom i dużej dokładności w ustalaniu charakterystycznych cech przestrzenno-czasowych deformacji próbki. Określenie takich cech zlokalizowanych pasm ścinania jest konieczne do zaproponowania modelu konstytutywnego dla metali wykazujących ten typ plastycznej niestabilności. Opracowany model konstytutywny pozwoli na numeryczne symulacje w pełnej skali 3D fizycznych testów z użyciem programu ABAQUS. Głównym celem pracy jest przedstawienie możliwości wykorzystania pomiarów uzyskanych techniką cyfrowej korelacji obrazu do wykrywania i charakteryzowania przestrzenno-czasowych cech efektu PLC w dostępnym komercyjnie stopie Inconel 718.
An experimental investigation of the Portevin–Le Chatelier effect in the Inconel 718 alloy is undertaken in this study through flat specimen geometries. Measurements based on digital image correlation (DIC) is an effective and practical optical technique due to the advantages of easy operation, non-contact, full field optical measurement, high accuracy and high computational efficiency for investigating the PLC effect and its spatio-temporal characteristics. The localization band characteristics are required to develop the constitutive relations for metals exhibiting this type of plastic instability, based on available material tests. The constitutive model can be used in full-scale 3D numerical simulations of the physical tests using the explicit solver of the finite element code ABAQUS. The objective of this paper is to show how DIC techniques are readily able to detect and characterize spatio-temporal features of the PLC behaviour of a commercial available Inconel 718 alloy. Słowa kluczowe: stop Inconel 718, efekt Portevin-Le Chatelier, cyfrowa korelacja obrazu, Inconel 718 alloy, Portevin-Le Chatelier effect, Digital Image Correlation (DIC) Afiliacje autorów:
Nowak Z. | - | IPPT PAN | Pęcherski R.B. | - | IPPT PAN | Maj P. | - | Warsaw University of Technology (PL) |
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21. |
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 |
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22. |
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 |
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23. |
Poniżnik Z., Nowak Z., Basista M., Numerical modeling of fracture toughness of metal-ceramic interpenetrating phase composites with account of material microstructure,
SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P198, pp.1-2, 2016 Streszczenie: The motivation for research on interpenetrating phase composites and possible applications of these novel materials were given in [1]. A rationale behind designing an IPC is to achieve a highly durable material that would combine the most desirable properties of the constituent phases: the high hardness and wear resistance of ceramic and improved fracture toughness and thermal conductivity due to the metal content. The interpenetrating metal-ceramic composites may have remarkable applicability in different sectors of industry, e.g. automotive and aerospace. They should, thus, be carefully investigated in terms of processing routes, material properties and modeling of material response to service conditions. A 3D FEM model in ABAQUS of the fracture parameters and crack growth in bi-continuous metal-ceramic composites with interpenetrating microstructure (IPC) is proposed. The crack is modeled using the extended finite element method (XFEM) [4]. The J-integral and fracture toughness KIc are determined for a real IPC microstructure obtained from micro-CT images. The fracture parameters (i.e. fracture toughness KIc, J integral, crack opening displacement) are key mechanical characteristics of IPC composites because of the brittleness of the ceramic phase. The main effects occurring in metal-ceramic IPC during fracture are described (cf. [2], [3]). Słowa kluczowe: Ceramic-metal composites, interpenetrating microstructure, fracture toughness, crack growth, numerical modeling, XFEM Afiliacje autorów:
Poniżnik Z. | - | IPPT PAN | Nowak Z. | - | IPPT PAN | Basista M. | - | IPPT PAN |
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24. |
Poniżnik Z., Nowak Z., Basista M., Numerical modeling of crack growth in interpenetrating metal-ceramic composites,
ICDM2, 2nd International Conference on Damage Mechanics, 2015-07-08/07-11, Troyes (FR), pp.41, 2015 Streszczenie: A 3D FEM model for crack growth in bi‐continuous metal‐ceramic composites with interpenetrating microstructure (IPC) is proposed. The results for the load‐displacements relationship in a plastically deformable reinforcing fibre computed by means of different material models will be shown. The J‐integral and fracture toughness will be determined for a simplified IPC microstructure with reinforcing ligaments modeled as axisymmetric fibres, and for real IPC microstructure obtained from micro‐CT images Słowa kluczowe: interpenetrating phase composites, bi‐continuous composites, metal‐ceramic composites, crack bridging, crack growth, fracture toughness, finite element method Afiliacje autorów:
Poniżnik Z. | - | IPPT PAN | Nowak Z. | - | IPPT PAN | Basista M. | - | IPPT PAN |
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25. |
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 |
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26. |
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 |
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27. |
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. | - | Rzeszów University of Technology (PL) | Śliwa R.E. | - | Rzeszów University of Technology (PL) |
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28. |
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 |
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29. |
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 |
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30. |
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 |
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31. |
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 |
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32. |
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. | - | Rzeszów University of Technology (PL) | Śliwa R.E. | - | Rzeszów University of Technology (PL) |
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33. |
Nowak Z., Grosman F.♦, Lumelskyj 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) | Lumelskyj D. | - | IPPT PAN | Nowak M. | - | IPPT PAN | Pęcherski R.B. | - | IPPT PAN | Rojek J. | - | IPPT PAN | Tkocz M. | - | Silesian University of Technology (PL) |
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34. |
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. | - | Rzeszów University of Technology (PL) | Śliwa R.E. | - | Rzeszów University of Technology (PL) |
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35. |
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 |
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36. |
Perzyna P., Nowak Z., The description of the behaviour of the ultrafine-grained titanium by the constitutive model of elasto-viscoplasticity,
CMM 2013, 20th International Conference on Computer Methods in Mechanics, 2013-08-27/08-31, Poznań (PL), No.TS03, pp.23-24, 2013 Streszczenie: The main objective of the present paper is the description of the behaviour of the ultrafine-grained (UFG) titanium by the constitutive model of elasto-viscoplasticity with the development of the identification procedure. We intend to utilize the constitutive model of the thermodynamical theory of elasto-viscoplasticity for description of nanocrystalline metals presented by Perzyna (2010)[1]. The identification procedure is based on experimental observation data obtained by Jia et al. (2001)[4] for ultrafine-grained titanium and by Wang et al. (2007) [5] for nanostructured titanium. Hexagonal close-packed (hcp) ultrafine-grained titanium processed by sever plastic deformation (SPD) has gained wide interest due to its excellent mechanical properties and potential applications as biomedical implants. Słowa kluczowe: Elasto-viscoplasticity, ultrafine-grained titanium, uniaxial compression Afiliacje autorów:
Perzyna P. | - | IPPT PAN | Nowak Z. | - | IPPT PAN |
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37. |
Poniżnik Z., Basista M., Nowak Z., Modeling of effective elastic constants and fracture toughness in metal-ceramic composites with interpenetrating microstructure,
ICF13, 13th International Conference on Fracture, 2013-06-16/06-21, Beijing (CN), No.S12-009, pp.81, 2013 Streszczenie: The paper is focused on modeling of the overall elastic properties and crack toughening mechanism by bridging in metal-ceramic interpenetrating phase composites (IPC). The Tuchinskii-Feng analytical model (Feng 2004) especially devised for IPC microstructures is further developed. Numerical FEM models of the effective elastic constants are implemented for the simplified 3-D cross microstructure and real microstructures based on micro-CT scans. The energy release rate increase due to crack bridging (Mataga 1989) is modeled numerically. The stress-displacement relationships in the reinforcing fibers undergoing large strains and delamination from the matrix materials are obtained and then applied as material models for the bridging reinforcements in compact-tension test specimen of the fracture toughness determination. The J integral for this specimen is calculated by FEM (Abaqus) with reinforcing ligaments modeled as truss and cohesive elements. The growth of a bridged crack is also modeled numerically. Słowa kluczowe: Effective elastic constants, Fracture toughness, Crack toughening, Crack bridging, Metal-ceramic composites, FEM Afiliacje autorów:
Poniżnik Z. | - | IPPT PAN | Basista M. | - | IPPT PAN | Nowak Z. | - | IPPT PAN |
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38. |
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. | - | Rzeszów University of Technology (PL) | Śliwa R.E. | - | Rzeszów University of Technology (PL) |
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39. |
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. | - | Rzeszów University of Technology (PL) | Śliwa R.E. | - | Rzeszów University of Technology (PL) |
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40. |
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 |
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41. |
Frąś T., Luckner J., Nowak M., Nowak Z., Pęcherski R.B., 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 |  |
42. |
Frąś T., Luckner J., Nowak M., Nowak Z., Pęcherski R.B., 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 |  |
43. |
Nowak M., Nowak Z., Pęcherski R.B., 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 |  |
44. |
Kowalewski Z.L., Nowak Z., Moćko W., Direct impact compression test of tantalum – experimental investigation and model identification,
SolMech 2012, 38th Solid Mechanics Conference, 2012-08-27/08-31, Warszawa (PL), pp.128-129, 2012 |  |
45. |
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 |  |
46. |
Nowak M., Nowak Z., Pęcherski R.B., 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 |  |
47. |
Nowak Z., Perzyna P., The Identification Procedure for the Constitutive Model of Elasto-Viscoplasticity Describing the Behaviour of Nanocrystalline Titanium,
SolMech 2012, 38th Solid Mechanics Conference, 2012-08-27/08-31, Warszawa (PL), pp.94-95, 2012 |  |
48. |
Nowak M., Luckner J., Nowak Z., Pęcherski R.B., 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 |  |
49. |
Nowak Z., Perzyna P., The identification procedure for the constitutive model of elasto–viscoplasticity with microdamage and dynamic grain growth mechanisms describing the behaviour of nanocrystalline iron,
CMM 2011, 19th International Conference on Computer Methods in Mechanics, 2011-05-09/05-12, Warszawa (PL), pp.385-1-2, 2011 |  |