dr inż. Szymon Nosewicz

 Zakład Informatyki i Nauk Obliczeniowych (ZIiNO) Pracownia Metod Obliczeniowych Mechaniki Nieliniowej (PMOMN) stanowisko: adiunkt telefon: (+48) 22 826 12 81 wew.: 289 pokój: 413 e-mail: snosew

##### Doktorat
2016-02-25Discrete element modeling of powder metallurgy processes
 promotor -- prof. dr hab. inż. Jerzy Rojek, IPPT
666

##### Ostatnie publikacje
1.Madan N., Rojek J., Nosewicz S., Convergence and stability analysis of the deformable discrete element method, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, ISSN: 0029-5981, DOI: 10.1002/nme.6014, pp.1-22, 2019

Streszczenie:

This work investigates numerical properties of the algorithm of the discrete element method employing deformable circular discs presented in an earlier authors' publication. The new formulation, called the deformable discrete element method (DDEM) enhances the standard discrete element method (DEM) by introducing an additional (global) deformation mode caused by the stresses in the particles induced by the contact forces. An accurate computation of the contact forces would require an iterative solution of the implicit relationship between the contact forces and particle displacements. In order to preserve efficiency of the DEM, the new formulation has been adapted to the explicit time integration. It has been shown that the explicit DDEM algorithm is conditionally stable and there are two restrictions on its stability. Except for the limitation of the time step as in the standard DEM, the stability in the DDEM is governed by the convergence criterion of the iterative solution of the contact forces. The convergence and stability limits have been determined analytically and numerically for selected regular and irregular configurations. It has also been found out that the critical time step in DDEM remains unchanged with respect to standard DEM.

Słowa kluczowe:

discrete element method; deformable particles; iterative solution; convergence criterion;explicit scheme; stability

Afiliacje autorów:

 Madan N. - IPPT PAN Rojek J. - IPPT PAN Nosewicz S. - IPPT PAN
40p.
2.Nosewicz S., Rojek J., Chmielewski M., Pietrzak K., Discrete Element Modeling of Intermetallic Matrix Composite Manufacturing by Powder Metallurgy, Materials, ISSN: 1996-1944, Vol.12, No.281, pp.1-18, 2019

Streszczenie:

This paper presents a numerical and experimental analysis of manufacturing of intermetallic ceramic composites by powder metallurgy techniques. The scope of the paper includes the formulation and development of an original numerical model of powder metallurgy of two-phase material within the framework of the discrete element method, simulations of powder metallurgy processes for different combinations of process parameters, and a verification of the numerical model based on own experimental results. Intermetallic-based composite NiAl–Al2O3 has been selected as representative material for experimental and numerical studies in this investigation. Special emphasis was given to the interactions between the intermetallic and ceramic particles by formulating the special model for adhesive contact bond. In order to properly represent a real microstructure of a two-phase sintered body, a discrete element specimen was generated using a special algorithm. Numerical validation showed the correct numerical representation of a sintered two-phase composite specimen. Finally, micromechanical analysis was performed to explain the macroscopic behavior of the sintered sample. The evolution of the coordination number, a number of equilibrium contacts, and the distribution of the cohesive neck size with respect to time are presented.

Słowa kluczowe:

powder metallurgy; sintering; discrete element method; modeling; intermetallic matrix composites

Afiliacje autorów:

 Nosewicz S. - IPPT PAN Rojek J. - IPPT PAN Chmielewski M. - Institute of Electronic Materials Technology (PL) Pietrzak K. - IPPT PAN
35p.
3.Nosewicz S., Rojek J., Wawrzyk K., Kowalczyk P., Maciejewski G., Maździarz M., Multiscale modeling of pressure-assisted sintering, COMPUTATIONAL MATERIALS SCIENCE, ISSN: 0927-0256, DOI: 10.1016/j.commatsci.2018.10.001, Vol.156, pp.385-395, 2019

Streszczenie:

This report presents the modeling of pressure-assisted sintering within the framework of a multiscale approach. Three individual numerical methods have been collectively applied to predict the behavior of a sintering body at three different scales. The appropriate solutions to connect each model/scale have been proposed. Molecular dynamics have been employed to evaluate the grain boundary diffusion coefficient at the atomistic scale. The obtained results of diffusive parameters have been transferred to the micromechanical model of sintering. Here, the discrete element method was used to represent the sintered material properties at the microscopic scale. Micromechanical based results have been validated by own experimental data of material density evolution, indicating the required coincidence. The transfer from micro- to the macroscopic model has been realized by determining the macroscopic viscous moduli from discrete element simulations and subsequently applying them to the continuum model of sintering. The numerical results from finite element simulations at the macroscopic scale have been compared with discrete element ones.

Słowa kluczowe:

Sintering; Multiscale modeling; Discrete element method; Molecular dynamics; Finite element method

Afiliacje autorów:

 Nosewicz S. - IPPT PAN Rojek J. - IPPT PAN Wawrzyk K. - IPPT PAN Kowalczyk P. - IPPT PAN Maciejewski G. - other affiliation Maździarz M. - IPPT PAN
30p.
4.Rojek J., Zubelewicz A., Madan N., Nosewicz S., The discrete element method with deformable particles, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, ISSN: 0029-5981, DOI: 10.1002/nme.5767, Vol.114, No.8, pp.828-860, 2018

Streszczenie:

This work presents a new original formulation of the discrete element method (DEM) with deformable cylindrical particles. Uniform stress and strain fields are assumed to be induced in the particles under the action of contact forces. Particle deformation obtained by strain integration is taken into account in the evaluation of interparticle contact forces. The deformability of a particle yields a nonlocal contact model, it leads to the formation of new contacts, it changes the distribution of contact forces in the particle assembly, and it affects the macroscopic response of the particulate material. A numerical algorithm for the deformable DEM (DDEM) has been developed and implemented in the DEM program DEMPack. The new formulation implies only small modifications of the standard DEM algorithm. The DDEM algorithm has been verified on simple examples of an unconfined uniaxial compression of a rectangular specimen discretized with regularly spaced equal bonded particles and a square specimen represented with an irregular configuration of nonuniform-sized bonded particles. The numerical results have been verified by a comparison with equivalent finite elementmethod results and available analytical solutions. The micro-macro relationships for elastic parameters have been obtained. The results have proved to have enhanced the modeling capabilities of the DDEM with respect to the standard DEM.

Słowa kluczowe:

average stress, deformable particles, discrete element method, elastic constants, micro-macro relationships, nonlocal contact model

Afiliacje autorów:

 Rojek J. - IPPT PAN Zubelewicz A. - University of New Mexico (US) Madan N. - IPPT PAN Nosewicz S. - IPPT PAN
40p.
5.Nosewicz S., Romelczyk-Baishya B., Lumelskyj D., Chmielewski M., Bazarnik P., Jarząbek D., Pietrzak K., Kaszyca K., Pakieła Z., Experimental and numerical studies of micro- and macromechanical properties of modified copper–silicon carbide composites, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, ISSN: 0020-7683, DOI: 10.1016/j.ijsolstr.2018.10.025, pp.1-14, 2018

Streszczenie:

The presented research investigation comprises the study of the mechanical properties of modified copper–silicon carbide composites at the micro- and macroscopic scale. The improvement of a copper–silicon carbide composite refers to the addition of a protective layer at the ceramic reinforcement in order to prevent the dissolution of silicon in the copper matrix. The macromechanical behaviour has been evaluated by the performance in a small punch test. The investigation has been carried out with samples with varying volume content of ceramic reinforcement and different protective layers of the silicon carbide particles. Moreover, the influence of temperature during the strength test has been studied. Next, the results have been referred to the interfacial bonding strength of Cu and SiC particles. SEM characterization of samples has been performed to link the composites’ microstructure with the mechanical behaviour. Finally, the experimental results of the small punch test have been predicted via a numerical approach. Finite element analysis has been employed to reproduce the response of the composite specimen during the test. Satisfactory agreement with the experimental curve has been obtained.

Słowa kluczowe:

metal matrix composites; silicon carbide; metallic layers deposition; small punch; interface strength; finite element method

Afiliacje autorów:

 Nosewicz S. - IPPT PAN Romelczyk-Baishya B. - Warsaw University of Technology (PL) Lumelskyj D. - IPPT PAN Chmielewski M. - Institute of Electronic Materials Technology (PL) Bazarnik P. - Warsaw University of Technology (PL) Jarząbek D. - IPPT PAN Pietrzak K. - other affiliation Kaszyca K. - other affiliation Pakieła Z. - Warsaw University of Technology (PL)
35p.
6.Maździarz M., Rojek J., Nosewicz S., Molecular dynamics study of self-diffusion in stoichiometric B2-NiAl crystals, Philosophical Magazine, ISSN: 1478-6435, DOI: 10.1080/14786435.2018.1480838, Vol.98, No.24, pp.2257-2274, 2018

Streszczenie:

Self-diffusion parameters in stoichiometric B2-NiAl solid state crystals were estimated by molecular statics/dynamics simulations with the study of required simulation time to stabilise diffusivity results. An extrapolation procedure to improve the diffusion simulation results was proposed. Calculations of volume diffusivity for the B2 type NiAl in the 1224–1699 K temperature range were performed using the embedded-atom-model potential. The results obtained here are in much better agreement with the experimental results than the theoretical estimates obtained with other methods.

Słowa kluczowe:

NiAl; nickel–aluminium; diffusivity; molecular dynamics; molecular statics; embedded-atom method; sintering

Afiliacje autorów:

 Maździarz M. - IPPT PAN Rojek J. - IPPT PAN Nosewicz S. - IPPT PAN
30p.
7.Strojny-Nędza A., Pietrzak K., Gładki A., Nosewicz S., Jarząbek D.M., Chmielewski M., The effect of ceramic type reinforcement on structure and properties of Cu-Al2O3 composites, BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 0239-7528, DOI: 10.24425/124271, Vol.66, No.4, pp.553-560, 2018

Streszczenie:

The purpose of this paper is to elaborate on mechanical alloy
ing conditions for a composite powder consisting of copper a
nd brittle aluminium oxides. Detailed analysis of the Cu-Al2O3
powder mixture structure obtained in the mechanical alloyi
ng process allows for the
study of the homogenization phenomena and for obtaining gra
ins (in composite form) with a high degree of uniformity. The
Cu-5 vol.%Al2O3
composites were obtained by means of the spark plasma sinter
ing technique. The results presented herein were studied an
d discussed in
terms of the impact of using a different form of aluminium oxid
e powder and a different shape of copper powder on composite pr
operties.
Research methodology included microstructure analysis as
well as its relation to the strength of Cu-Al2O3
interfaces. It transpires from the
results presented below that the application of electrocor
undum as a reinforcement phase in composites decreases poro
sity in the ceramic
phase, thus improving thermal properties and interfacial s
trength.

Słowa kluczowe:

metal matrix composites, spark plasma sintering, thermal conductivity, interfacial strength

Afiliacje autorów:

 Strojny-Nędza A. - Institute of Electronic Materials Technology (PL) Pietrzak K. - other affiliation Gładki A. - Institute of Electronic Materials Technology (PL) Nosewicz S. - IPPT PAN Jarząbek D.M. - IPPT PAN Chmielewski M. - Institute of Electronic Materials Technology (PL)
25p.
8.Jóźwik I., Strojny-Nędza A., Chmielewski M., Pietrzak K., Kurpaska Ł., Nosewicz S., High resolution SEM characterization of nano-precipitates in ODS steels, MICROSCOPY RESEARCH AND TECHNIQUE, ISSN: 1059-910X, DOI: 10.1002/jemt.23004, Vol.81, No.5, pp.502-508, 2018

Streszczenie:

The performance of the present-day scanning electron microscopy (SEM) extends far beyond delivering electronic images of the surface topography. Oxide dispersion strengthened (ODS) steel is on of the most promising materials for the future nuclear fusion reactor because of its good radiation resistance, and higher operation temperature up to 750°C. The microstructure of ODS should not exceed tens of nm, therefore there is a strong need in a fast and reliable technique for their characterization. In this work, the results of low-kV SEM characterization of nanoprecipitates formed in the ODS matrix are presented. Application of highly sensitive photo-diode BSE detector in SEM imaging allowed for the registration of single nm-sized precipitates in the vicinity of the ODS alloys. The composition of the precipitates has been confirmed by TEM-EDS.

Słowa kluczowe:

ODS steels, scanning electron microscopy, spark plasma sintering

Afiliacje autorów:

 Jóźwik I. - Institute of Electronic Materials Technology (PL) Strojny-Nędza A. - Institute of Electronic Materials Technology (PL) Chmielewski M. - Institute of Electronic Materials Technology (PL) Pietrzak K. - other affiliation Kurpaska Ł. - National Centre for Nuclear Research (PL) Nosewicz S. - IPPT PAN
20p.
9.Chmielewski M., Pietrzak K., Teodorczyk M., Nosewicz S., Jarząbek D., Zybała R., Bazarnik P., Lewandowska M., Strojny-Nędza A., Effect of metallic coating on the properties of copper-silicon carbide composites, APPLIED SURFACE SCIENCE, ISSN: 0169-4332, DOI: 10.1016/j.apsusc.2016.12.130, Vol.421, pp.159-169, 2017

Streszczenie:

In the presented paper a coating of SiC particles with a metallic layer were used to prepare copper matrix composite materials. The role of the layer was to protect the silicon carbide from decomposition and dissolution of silicon in the copper matrix during the sintering process. The SiC particles were covered by chromium, tungsten and titanium using Plasma Vapour Deposition method. After powder mixing of components, the final densification process via Spark Plasma Sintering (SPS) method at temperature 950C was provided. The almost fully dense materials were obtained (> 97.5%). The microstructure of obtained composites was studied using scanning electron microscopy as well as transmission electron microscopy. The microstructural analysis of composites confirmed that regardless of the type of deposited material, there is no evidence for decomposition process of silicon carbide in copper. In order to measure the strength of the interface between ceramic particles and the metal matrix, the micro tensile tests have been performed. Furthermore, thermal diffusivity was measured with the use of the laser pulse technique. In the context of performed studies, the tungsten coating seems to be the most promising solution for heat sink application. Compared to pure composites without metallic layer, Cu-SiC with W coating indicate the higher tensile strength and thermal diffusitivy, irrespective of an amount of SiC reinforcement. The improvement of the composite properties is related to advantageous condition of Cu-SiC interface characterized by well homogenity and low porosity, as well as individual properties of the tungsten coating material.

Słowa kluczowe:

metal matrix composites, silicon carbide, metallic layers deposition, thermal conductovity, interface strength

Afiliacje autorów:

 Chmielewski M. - Institute of Electronic Materials Technology (PL) Pietrzak K. - other affiliation Teodorczyk M. - other affiliation Nosewicz S. - IPPT PAN Jarząbek D. - IPPT PAN Zybała R. - Warsaw University of Technology (PL) Bazarnik P. - Warsaw University of Technology (PL) Lewandowska M. - other affiliation Strojny-Nędza A. - Institute of Electronic Materials Technology (PL)
35p.
10.Nosewicz S., Rojek J., Chmielewski M., Pietrzak K., Discrete element modeling and experimental investigation of hot pressing of intermetallic NiAl powder, ADVANCED POWDER TECHNOLOGY, ISSN: 0921-8831, DOI: 10.1016/j.apt.2017.04.012, Vol.28, pp.1745-1759, 2017

Streszczenie:

This paper presents the numerical and experimental analysis of hot pressing of NiAl powder with an emphasis on the best possible representation of its main stages: initial powder compaction and pressure-assisted sintering. The numerical study has been performed within the discrete element framework. In the paper, an original viscoelastic model of hot pressing has been used. In order to ensure that the applied values of material parameters in numerical simulations are appropriate, the reference literature has been reviewed. It produced the relations and equations to estimate the values of all required sintering material parameters of the considered viscoelastic model. Numerical simulations have employed the geometrical model of the initial dense specimen generated by a special algorithm which uses the real grain distribution of powder. The numerical model has been calibrated and validated through simulations of the real process of hot pressing of intermetallic NiAl material. The kinetics of compaction, sintering and cooling stage indicated by the evolution of density, shrinkage and densification rate have been studied. The comparison of numerical and experimental results has shown a good performance of the developed numerical model.

Słowa kluczowe:

Powder metallurgy; Hot pressing; Sintering; Simulation; Discrete element method; Nickel aluminide

Afiliacje autorów:

 Nosewicz S. - IPPT PAN Rojek J. - IPPT PAN Chmielewski M. - Institute of Electronic Materials Technology (PL) Pietrzak K. - IPPT PAN
30p.
11.Nosewicz S., Rojek J., Chmielewski M., Pietrzak K., Lumelskyj D., Application of the Hertz formulation in the discrete element model of pressure-assisted sintering, GRANULAR MATTER, ISSN: 1434-5021, DOI: 10.1007/s10035-016-0699-9, Vol.19, No.1, pp.16-1-8, 2017

Streszczenie:

This paper presents the numerical modelling of initial powder compaction and pressure-assisted sintering performed by original viscoelastic discrete element model. The research is focused on the influence of the type of the model representing an elastic part of interparticle force. Two elastic contact models—linear and nonlinear Hertz model—have been implemented and used to analyse interaction of NiAl powder particles during compaction and sintering process. Numerical models have been validated using own experimental results. Microscopic effects (particle penetration) and macroscopic changes (relative density) have been compared. It has been shown that although both models represent properly macroscopic behaviour of the material at the sintering process, the Hertz model produces the results closer to the real experimental ones during the initial compaction stage. Evaluation of macroscopic quantities enables implementation of the discrete element model in the framework of the multiscale modelling framework which is currently developed for sintering processes.

Słowa kluczowe:

Powder metallurgy, Sintering, Initial compaction, Elasticity, Discrete element method

Afiliacje autorów:

 Nosewicz S. - IPPT PAN Rojek J. - IPPT PAN Chmielewski M. - Institute of Electronic Materials Technology (PL) Pietrzak K. - IPPT PAN Lumelskyj D. - IPPT PAN
30p.
12.Chmielewski M., Pietrzak K., Strojny-Nędza A., Jarząbek D., Nosewicz S., Investigations of interface properties in copper-silicon carbide composites, ARCHIVES OF METALLURGY AND MATERIALS, ISSN: 1733-3490, DOI: 10.1515/amm-2017-0200, Vol.62, No.2B, pp.1315-1318, 2017

Streszczenie:

This paper analyses the technological aspects of the interface formation in the copper-silicon carbide composite and its effect on the material’s microstructure and properties. Cu-SiC composites with two different volume content of ceramic reinforcement were fabricated by hot pressing (HP) and spark plasma sintering (SPS) technique. In order to protect SiC surface from its decomposition, the powder was coated with a thin tungsten layer using plasma vapour deposition (PVD) method. Microstructural analyses provided by scanning electron microscopy revealed the significant differences at metal-ceramic interface. Adhesion force and fracture strength of the interface between SiC particles and copper matrix were measured. Thermal conductivity of composites was determined using laser flash method. The obtained results are discussed with reference to changes in the area of metal-ceramic boundary.

Słowa kluczowe:

copper matrix composites, silicon carbide, interface, thermal conductivity, adhesion

Afiliacje autorów:

 Chmielewski M. - Institute of Electronic Materials Technology (PL) Pietrzak K. - other affiliation Strojny-Nędza A. - Institute of Electronic Materials Technology (PL) Jarząbek D. - IPPT PAN Nosewicz S. - IPPT PAN
30p.
13.Maździarz M., Rojek J., Nosewicz S., Estimation of micromechanical NiAl sintering model parameters from the molecular simulations, INTERNATIONAL JOURNAL FOR MULTISCALE COMPUTATIONAL ENGINEERING, ISSN: 1543-1649, DOI: 10.1615/IntJMultCompEng.2017020289 , Vol.15, No.4, pp.343-358, 2017

Streszczenie:

Molecular statics/dynamics estimation of constitutive parameters for a micromechanical NiAl sintering model is reported in this paper. The parameters include temperature-dependent diffusion coefficients, surface energy, and linear thermal expansion. These parameters define material behavior during sintering and are used in the sintering particle model implemented in the discrete element model. The investigated material, the NiAl intermetallic, belongs to novel materials characterized by advantageous mechanical properties. Various machine elements are manufactured from a pure NiAl powder or from powder mixtures containing the NiAl using the sintering technology. It is well known that sintering is governed by diffusion. Therefore diffusive properties are important parameters of the micromechanical model of sintering. Numerical estimation of the model parameters by simulations at the lower scale is a powerful tool alternative to experimental methods. Molecular statics and dynamics models for NiAl have been created using the embedded atom model potential. Numerical simulations have allowed us to estimate the volume, surface, and grain-boundary diffusivity for the B2-type NiAl in the 1573 to 1673 K temperature range. Dependence of the diffusion coefficients on temperature has been determined and validity of the Arrhenius-type temperature dependency has been assessed. The parameters evaluated numerically have been compared with available experimental data as well as with theoretical predictions obtained with other methods. Many of the results presented in this paper have a pioneer character and are not known in the literature.

Słowa kluczowe:

NiAl, sintering, diffusivity, molecular dynamics, molecular statics, nanoparticles

Afiliacje autorów:

 Maździarz M. - IPPT PAN Rojek J. - IPPT PAN Nosewicz S. - IPPT PAN
25p.
14.Rojek J., Nosewicz S., Chmielewski M., Micro-macro relationships from discrete element simulations of sintering, INTERNATIONAL JOURNAL FOR MULTISCALE COMPUTATIONAL ENGINEERING, ISSN: 1543-1649, DOI: 10.1615/IntJMultCompEng.2017020322, Vol.15, No.4, pp.323-342, 2017

Streszczenie:

A two-scale modeling framework for sintering processes has been presented. Formulation of the micromechanical model of sintering developed in the discrete element method and basic relationships in the macroscopic model of sintering have been briefly reviewed. The methodology to determine macroscopic quantities–stress, strains, and constitutive viscous properties-from the discrete element simulations has been presented. This methodology has been applied to modeling of NiAl sintering. First, the discrete element model (DEM) has been calibrated by fitting the numerical densification curve to the experimental data. The DEM model with calibrated parameters has been used in simulations specially conceived to give macroscopic viscous moduli of the sintered material. Using the averaging procedures macroscopic stresses and strains have been calculated. Strain rates have been obtained differentiating the strain curves with respect to time. Finally, the viscous constitutive properties of the sintered material have been determined. The dependence of the shear and volumetric viscous moduli on the relative density (or equivalently) on the porosity has been obtained. It has been found that the numerical simulations predict a similar dependence as that assumed in the phenomenological macroscopic models. Thus, the validity of the micro-macro relationships obtained from the discrete element simulations of powder sintering has been confirmed. The proposed methodology allows us to use the discrete element model in the framework of multiscale modeling of sintering.

Słowa kluczowe:

discrete element method, sintering, simulation, micro-macro relationships, multiscale modeling

Afiliacje autorów:

 Rojek J. - IPPT PAN Nosewicz S. - IPPT PAN Chmielewski M. - Institute of Electronic Materials Technology (PL)
25p.
15.Chmielewski M., Pietrzak K., Strojny-Nędza A., Kaszyca K., Zybala R., Bazarnik P., Lewandowska M., Nosewicz S., Microstructure and thermal properties of Cu-SiC composite materials depending on the sintering technique, SCIENCE OF SINTERING, ISSN: 0350-820X, DOI: 10.2298/SOS1701011C, Vol.49, pp.11-22, 2017

Streszczenie:

The presented paper investigates the relationship between the microstructure and thermal properties of copper–silicon carbide composites obtained through hot pressing (HP) and spark plasma sintering (SPS) techniques. The microstructural analysis showed a better densification in the case of composites sintered in the SPS process. TEM investigations revealed the presence of silicon in the area of metallic matrix in the region close to metal ceramic boundary. It is the product of silicon dissolving process in copper occurring at an elevated temperature. The Cu-SiC interface is significantly defected in composites obtained through the hot pressing method, which has a major influence on the thermal conductivity of materials.

Słowa kluczowe:

Metal matrix composites; Silicon carbide; Interface; Spark plasma sintering; Thermal conductivity.

Afiliacje autorów:

 Chmielewski M. - Institute of Electronic Materials Technology (PL) Pietrzak K. - other affiliation Strojny-Nędza A. - Institute of Electronic Materials Technology (PL) Kaszyca K. - other affiliation Zybala R. - Warsaw University of Technology (PL) Bazarnik P. - Warsaw University of Technology (PL) Lewandowska M. - other affiliation Nosewicz S. - IPPT PAN
25p.
16.Chmielewski M., Nosewicz S., Kurpaska Ł., Romelczyk B., Evolution of material properties during the sintering process of Cr-Re-Al2O3 composites, COMPOSITES PART B-ENGINEERING, ISSN: 1359-8368, DOI: 10.1016/j.compositesb.2016.04.065, Vol.98, pp.88-96, 2016

Streszczenie:

This paper constitutes an analysis of the effect of heat treatment time on the properties of Cr-Re-Al2O3 composite materials. It was found that as a result of sintering, rhenium is dissolved in chromium to create chromium-rhenium solid solution. This process is time-dependent, therefore as the time extends, the structure of material becomes homogenous, which improves its mechanical properties. Within the frame of herein presented studies, a series of technological tests have been carried out for a constant sintering temperature (1450°C) and pressure (30 MPa), with the use of a variable holding time in the maximum temperature. As a result, changes in the structure of Crsingle bondRe matrix have been determined and the resulting changes in the properties of composite. Based on those tests, optimal conditions of the sintering process have been determined from the point of view of obtaining a homogenous structure and the most beneficial properties of Cr-Re-Al2O3 composites.

Słowa kluczowe:

Metal-matrix composites (MMCs), Mechanical properties, Mechanical testing, Sintering

Afiliacje autorów:

 Chmielewski M. - Institute of Electronic Materials Technology (PL) Nosewicz S. - IPPT PAN Kurpaska Ł. - National Centre for Nuclear Research (PL) Romelczyk B. - Warsaw University of Technology (PL)
45p.
17.Chmielewski M., Nosewicz S., Jakubowska D., Lewandowska M., Mizera J., Rojek J., Bazarnik P., The influence of sintering time on the microstructural properties of chromium-rhenium matrix composites, International Journal of Refractory Metals and Hard Materials, ISSN: 0263-4368, DOI: 10.1016/j.ijrmhm.2016.05.017, Vol.59, pp.78-86, 2016

Streszczenie:

This paper comprises the results of studies of the changes in the structure of Cr-Re-Al2O3 metal matrix depending on heat treatment time in sintering temperature. The density of material with the following composition: 95%(75%Cr-25%Al2O3)+5%Re was increased using the technique of sintering under pressure (30MPa) at the temperature of 1450°C. As a result, materials characterized by a high relative density (< 97% of theoretical density) were obtained. Next, they were subjected to structural tests including scanning and transmission electron microscopy as well as X-ray diffraction. Changes in the phase composition, grains size and parameters of crystallographic structure depending on heat treatment time were analysed. It was found that during sintering rhenium is dissolved in the chromium matrix and Cr-Re solid solution is formed. When sintering time is extended to 120 min, the matrix of the composite becomes completely homogenous, which results in an increased strength of the composite.

Słowa kluczowe:

Metal matrix composites, Rhenium, Hot pressing, Microstructure analysis, XRD

Afiliacje autorów:

 Chmielewski M. - Institute of Electronic Materials Technology (PL) Nosewicz S. - IPPT PAN Jakubowska D. - other affiliation Lewandowska M. - other affiliation Mizera J. - Warsaw University of Technology (PL) Rojek J. - IPPT PAN Bazarnik P. - Warsaw University of Technology (PL)
35p.
18.Jurczak K., Rojek J., Nosewicz S., Lumelskyy D., Bochenek K., Chmielewski M., Pietrzak K., Modelowanie wstępnego prasowania proszków metodą elementów dyskretnych, HUTNIK - WIADOMOŚCI HUTNICZE, ISSN: 1230-3534, DOI: 10.15199/24.2016.1.1, Vol.83, No.1, pp.3-7, 2016

Streszczenie:

W niniejszym artykule zaprezentowano wyniki modelowania zagęszczania proszku stanowiącego wstępny etap procesu prasowania na gorąco. Modelowanie numeryczne zrealizowano metodą elementów dyskretnych z wykorzystaniem kulistych cząstek. Analizę skoncentrowano na badaniu mechanizmów zagęszczania proszku przy ciśnieniu do 50 MPa oraz poszukiwaniu modeli odpowiednich przy zastosowanych warunkach realizacji procesu. Symulacje numeryczne wykonano wykorzystując dwa modele oddziaływania cząstek proszku: sprężysty model Hertza-Mindlina-Deresiewicza oraz plastyczny model Storåkersa. Wyniki numeryczne zostały porównane z wynikami laboratoryjnymi prasowania proszku NiAl. Otrzymano dużą zgodność wyników eksperymentalnych i numerycznych.

This paper presents the results of discrete element simulation of powder compaction which is the initial stage in the hot pressing process. Numerical simulation has been performed by discrete element method with using spherical particles. The research has been focused on densification mechanisms under pressure 50 MPa and models appropriate for these conditions. Numerical simulations have been carried out for two contact models: elastic Hertz-Mindlin-Deresiewicz and plastic - Storåkers. Numerical results and results from laboratory test of the uniaxial pressing of NiAl powder have been compared. The obtained results of numerical simulation and laboratory tests showing a good agreement.

Słowa kluczowe:

metoda elementów dyskretnych, prasowanie proszków, materiały intermetaliczne, discrete element method, powder compaction, intermetallics

Afiliacje autorów:

 Jurczak K. - IPPT PAN Rojek J. - IPPT PAN Nosewicz S. - IPPT PAN Lumelskyy D. - IPPT PAN Bochenek K. - IPPT PAN Chmielewski M. - Institute of Electronic Materials Technology (PL) Pietrzak K. - other affiliation
7p.
19.Rojek J., Nosewicz S., Jurczak K., Chmielewski M., Bochenek K., Pietrzak K., Discrete element simulation of powder compaction in cold uniaxial pressing with low pressure, Computational Particle Mechanics, ISSN: 2196-4378, DOI: 10.1007/s40571-015-0093-0, Vol.3, pp.513-524, 2016

Streszczenie:

This paper presents numerical studies of powder compaction in cold uniaxial pressing. The powder compaction in this work is considered as an initial stage of a hot pressing process so it is realized with relatively low pressure (up to 50 MPa). Hence the attention has been focused on the densification mechanisms at this range of pressure and models suitable for these conditions. The discrete element method employing spherical particles has been used in the numerical studies. Numerical simulations have been performed for two different contact models—the elastic Hertz–Mindlin–Deresiewicz model and the plastic Storåkers model. Numerical results have been compared with the results of laboratory tests of the die compaction of the NiAl powder. Comparisons have shown that the discrete element method is capable to represent properly the densification mechanisms by the particle rearrangement and particle deformation.

Słowa kluczowe:

Discrete element method, Simulation, Powder compaction, Cold uniaxial pressing

Afiliacje autorów:

 Rojek J. - IPPT PAN Nosewicz S. - IPPT PAN Jurczak K. - IPPT PAN Chmielewski M. - Institute of Electronic Materials Technology (PL) Bochenek K. - IPPT PAN Pietrzak K. - other affiliation
20.Chmielewski M., Nosewicz S., Rojek J., Pietrzak K., Mackiewicz S., Romelczyk B., A study of densification and microstructure evolution during hot pressing of NiAl/Al2O3 composite, Advanced Composite Materials, ISSN: 0924-3046, DOI: 10.1080/09243046.2013.879408, Vol.24, No.1, pp.57-66, 2015

Streszczenie:

Evolution of the density and the microstructure during hot pressing of NiAl/Al2O3 composite has been investigated in the present paper. In particular, the effect of the process parameters, viz. compacting pressure, sintering temperature and sintering time, on the evolution of the density of the intermetallic–ceramic composite has been studied. Evolution of the density has been related to microstructure changing. Porosity, pore structures and grains rearrangement have been analysed in microscopic observations.

Słowa kluczowe:

hot pressing, sintering, intermetallic–ceramic composite, density evolution, microstructure

Afiliacje autorów:

 Chmielewski M. - Institute of Electronic Materials Technology (PL) Nosewicz S. - IPPT PAN Rojek J. - IPPT PAN Pietrzak K. - other affiliation Mackiewicz S. - IPPT PAN Romelczyk B. - Warsaw University of Technology (PL)
20p.
21.Rojek J., Nosewicz S., Pietrzak K., Chmielewski M., Evaluation of macroscopic stresses in discrete element models of sintering processes, COMPUTER METHODS IN MATERIALS SCIENCE / INFORMATYKA W TECHNOLOGII MATERIAŁÓW, ISSN: 1641-8581, Vol.15, No.1, pp.219-255, 2015

Streszczenie:

This paper presents investigation of macroscopic stresses in powder metallurgy process modelled with the discrete element method. The discrete element model belongs to the class of micromechanical models. In the DEM model the material is represented by an assembly of particles interacting by contact forces and the method is formulated in terms of forces and displacements. In order to evaluate macroscopic stresses a special upscaling procedure is necessary. The paper presents basic formulation of the discrete element method with special attention for the contact interaction models for powder compaction and sintering. A method to evaluate macroscopic stresses based on the two level averaging is presented. The discrete element model of sintering is verified using own experimental results. Macroscopic stresses are calculated for the whole process including loading, heating, sintering, cooling and unloading. It has been found out that the macroscopic stresses are consistent with changing process parameters. The procedure is suitable for multiscale modelling of sintering.

Słowa kluczowe:

sintering, modeling, discrete element method, macroscopic stresses

Afiliacje autorów:

 Rojek J. - IPPT PAN Nosewicz S. - IPPT PAN Pietrzak K. - other affiliation Chmielewski M. - Institute of Electronic Materials Technology (PL)
12p.
22.Nosewicz S., Rojek J., Mackiewicz S., Chmielewski M., Pietrzak K., Romelczyk B., The influence of hot pressing conditions on mechanical properties of nickel aluminide/alumina composite, Journal of Composite Materials, ISSN: 0021-9983, DOI: 10.1177/0021998313511652, Vol.48, No.29, pp.3577-3589, 2014

Streszczenie:

The influence of hot pressing conditions on mechanical properties of nickel aluminide/alumina composite has been investigated in the present paper. In particular, effect of the process parameters, viz. compacting pressure, sintering temperature and sintering time on the evolution of density, elastic constants and tensile strength properties of the intermetallic-ceramic composite has been studied. Elastic constants, the Young's modulus and Poisson's ratio, have been evaluated using an ultrasonic testing method, and the tensile strength has been determined by a Brazilian-type splitting test. Microscopic observations of microstructure evolution complemented the experimental procedure. Experimental results have been confronted with theoretical models showing a good agreement between the data compared.

Słowa kluczowe:

Hot pressing, sintering, intermetallic-ceramic composite, elastic properties, Brazilian test, tensile strength, ultrasonic method

Afiliacje autorów:

 Nosewicz S. - IPPT PAN Rojek J. - IPPT PAN Mackiewicz S. - IPPT PAN Chmielewski M. - Institute of Electronic Materials Technology (PL) Pietrzak K. - other affiliation Romelczyk B. - Warsaw University of Technology (PL)
30p.
23.Chmielewski M., Nosewicz S., Pietrzak K., Rojek J., Strojny-Nędza A., Mackiewicz S., Dutkiewicz J., Sintering Behavior and Mechanical Properties of NiAl, Al2O3, and NiAl-Al2O3 Composites, Journal of Materials Engineering and Performance, ISSN: 1059-9495, DOI: 10.1007/s11665-014-1189-z, Vol.23, No.11, pp.3875-3886, 2014

Streszczenie:

It is commonly known that the properties of sintered materials are strongly related to technological conditions of the densification process. This paper shows the sintering behavior of a NiAl-Al2O3 composite, and its individual components sintered separately. Each kind of material was processed via the powder metallurgy route (hot pressing). The progress of sintering at different stages of the process was tested. Changes in the microstructure were examined using scanning and transmission electron microscopy. Metal-ceramics interface was clean and no additional phases were detected. Correlation between the microstructure, density, and mechanical properties of the sintered materials was analyzed. The values of elastic constants of NiAl/Al2O3 were close to intermetallic ones due to the volume content of the NiAl phase particularly at low densities, where small alumina particles had no impact on the composite’s stiffness. The influence of the external pressure of 30 MPa seemed crucial for obtaining satisfactory stiffness for three kinds of the studied materials which were characterized by a high dense microstructure with a low number of isolated spherical pores.

Słowa kluczowe:

ceramics, composites, electron, intermetallic, metallic matrix, microscopy, powder metallurgy, sintering, structural

Afiliacje autorów:

 Chmielewski M. - Institute of Electronic Materials Technology (PL) Nosewicz S. - IPPT PAN Pietrzak K. - other affiliation Rojek J. - IPPT PAN Strojny-Nędza A. - Institute of Electronic Materials Technology (PL) Mackiewicz S. - IPPT PAN Dutkiewicz J. - Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
20p.
24.Nosewicz S., Rojek J., Pietrzak K., Chmielewski M., Viscoelastic discrete element model of powder sintering, POWDER TECHNOLOGY, ISSN: 0032-5910, DOI: 10.1016/j.powtec.2013.05.020, Vol.246, pp.157-168, 2013

Streszczenie:

This paper presents an original viscoelastic model of powder sintering developed within the discrete element framework. The viscous model used by other authors has been enriched by adding a spring connected in series to the viscous rheological element. In this way elastic and viscous effects in the particle interaction during sintering are treated using the Maxwell viscoelasticity. The new numerical model has been verified through simulation of simple problems of free sintering and sintering under pressure. Sintering processes have been treated as isothermic. In order to accelerate the analysis an algorithmic mass scaling has been used allowing to use larger time steps in the explicit time integration scheme. The results obtained using the new model are consistent with the standard viscous model. At the same time, a much better efficiency of the new model in comparison to the standard viscous one has been found because the critical time steps required by the viscoelastic model are much larger than those required by the viscous model. The new model has been applied to the simulation of real process of sintering of NiAl powder. The kinetics of sintering indicated by the evolution of density has been studied. The comparison of numerical and experimental results has shown a good performance of the developed numerical model.

Słowa kluczowe:

Powder sintering, Simulation, Discrete element method, Viscoelastic model

Afiliacje autorów:

 Nosewicz S. - IPPT PAN Rojek J. - IPPT PAN Pietrzak K. - other affiliation Chmielewski M. - Institute of Electronic Materials Technology (PL)
35p.
25.Rojek J., Nosewicz S., Pietrzak K., Chmielewski M., Simulation of Powder Sintering Using a Discrete Element Model, ACTA MECHANICA ET AUTOMATICA, ISSN: 1898-4088, DOI: 10.2478/ama-2013-0030, Vol.7, pp.175-179, 2013

Streszczenie:

This paper presents numerical simulation of powder sintering. The numerical model introduced in this work employs the discrete element method which assumes that material can be modelled by a large assembly of discrete elements (particles) of spherical shape interacting among one another. Modelling of sintering requires introduction of the cohesive interaction among particles representing interparticle sintering forces. Numerical studies of sintering have been combined with experimental studies which provided data for calibration and validation of the model. In the laboratory tests evolution of microstructure and density during sintering have been studied. Comparison of numerical and experimental results shows a good performance of the numerical model developed

Słowa kluczowe:

Powder Sintering, Simulation, Discrete Element Method

Afiliacje autorów:

 Rojek J. - IPPT PAN Nosewicz S. - IPPT PAN Pietrzak K. - other affiliation Chmielewski M. - Institute of Electronic Materials Technology (PL)
7p.
26.Nosewicz S., Rojek J., Numeryczne modelowanie naprężeń rezydualnych w spiekanych materiałach kompozytowych, PRZEGLĄD MECHANICZNY, ISSN: 0033-2259, Vol.10, pp.30-34, 2013

Streszczenie:

Sintering process is one of the major method of manufacture technology of composite materials with intermetallic matrix reinforced by ceramic particles. In the final stage of sintering, during cooling of material, the microcracks may occur due to appearance of significant residual stress at the grain boundaries, which leads to progressive degradation of the material. This paper presents numerical modeling of micro- and macroscopic stress during and after sintering process composite materials. The original thermo-viscoelastic model of discrete elements have been performed. Numerical simulations have been carried out on the example of the NiAl-Al2O3 composite. The obtained results confirm correct and efficient performance of the proposed numerical model.

Słowa kluczowe:

sintering, composite, residual stresses, discrete element method

Afiliacje autorów:

 Nosewicz S. - IPPT PAN Rojek J. - IPPT PAN
5p.
27.Nosewicz S., Rojek J., Numeryczne modelowanie naprężeń występujących w trakcie oraz po procesie metalurgii proszków materiałów kompozytowych, PRACE NAUKOWE POLITECHNIKI WARSZAWSKIEJ, SERIA: MECHANIKA, ISSN: 0137-2335, Vol.253, pp.13-18, 2013

Streszczenie:

W technologii metalurgii proszków spiekanie, wraz z chłodzeniem, jest jednym z kluczowych etapów wytwarzania materiałów kompozytowych na osnowie metalicznej, podczas którego może dochodzić do pękania materiału na skutek występujących na granicach faz naprężeń rezydualnych. Prezentowana praca przedstawia wyniki modelowania numerycznego naprężeń mikro- oraz makroskopowych występujących w trakcie oraz po procesie metalurgii proszków materiałów kompozytowych. Do analizy procesów metalurgii proszków został użyty oryginalny termo-lepkosprężysty model elementów dyskretnych. Symulacje numeryczne zostały przeprowadzone na przykładzie kompozytu NiAl-Al2O3. Uzyskane wyniki potwierdzają poprawne oraz efektywne działanie zaproponowanego modelu numerycznego.

Słowa kluczowe:

metoda elementów dyskretnych, symulacje numeryczne, spiekanie, metalurgia proszków, naprężenia rezydualne

Afiliacje autorów:

 Nosewicz S. - IPPT PAN Rojek J. - IPPT PAN
28.Nosewicz Sz., Rojek J., Pietrzak K., Chmielewski M., Kaliński D., Modelowanie procesu spiekania materiałów dwufazowych metodą elementów dyskretnych, RUDY I METALE NIEŻELAZNE, ISSN: 0035-9696, Vol.57, No.9, pp.599-603, 2012

Streszczenie:

W niniejszym artykule zostały przedstawione nowe wyniki modelowania procesu spiekania metodą elementów dyskretnych. W sformułowaniu teoretycznym dla części sprężystej zastosowano model kontaktu Hertza w celu lepszego odwzorowania oddziaływania elementów kulistych w trakcie prasowania. Sformułowanie i implementację modelu rozszerzono na przypadek spiekania materiałów dwufazowych. Na podstawie badań literaturowych wyznaczono parametry materiałowe procesu, które zostały następnie zweryfikowane za pomocą wyników eksperymentalnych. Wyniki numeryczne ewolucji gęstości próbki porównano z wynikami doświadczalnymi otrzymując dużą zgodność.

Słowa kluczowe:

materiały dwufazowe, metalurgia proszków, spiekanie, metoda elementów dyskretnych

Afiliacje autorów:

 Nosewicz Sz. - IPPT PAN Rojek J. - IPPT PAN Pietrzak K. - IPPT PAN Chmielewski M. - Institute of Electronic Materials Technology (PL) Kaliński D. - other affiliation
7p.
29.Rojek J., Pietrzak K., Chmielewski M., Kaliński D., Nosewicz S., Discrete Element Simulation of Powder Sintering, COMPUTER METHODS IN MATERIALS SCIENCE / INFORMATYKA W TECHNOLOGII MATERIAŁÓW, ISSN: 1641-8581, Vol.11, No.1, pp.68-73, 2011

Streszczenie:

This paper presents numerical modelling of powder sintering. The numerical model introduced in this work employs the discrete element method which assumes that material can be modelled by a large assembly of discrete elements (particles) of spherical shape interacting among one another. Modelling of sintering requires introduction of the cohesive interaction among particles representing inter-particle sintering forces. Numerical studies of sintering have been supplemented with experimental studies which provided data for calibration and validation of the model. In the laboratory tests evolution of microstructure and density during sintering have been studied. Comparison of numerical and experimental results shows a good performance of the numerical model developed.

Słowa kluczowe:

powder sintering, powder metallurgy, simulation, discrete element method

Afiliacje autorów:

 Rojek J. - IPPT PAN Pietrzak K. - IPPT PAN Chmielewski M. - Institute of Electronic Materials Technology (PL) Kaliński D. - other affiliation Nosewicz S. - IPPT PAN
5p.
30.Nosewicz S., Rojek J., Modelowanie spiekania proszków metodą elementów dyskretnych, PRACE NAUKOWE POLITECHNIKI WARSZAWSKIEJ, SERIA: MECHANIKA, ISSN: 0137-2335, Vol.238, pp.7-12, 2011

##### Lista ostatnich monografii
 1.512 Nosewicz S., Discrete element modeling of powder metallurgy processes, IPPT Reports on Fundamental Technological Research, 5, pp.1-183, 2016

##### Prace konferencyjne
1.Rojek J., Zubelewicz A., Madan N., Nosewicz S., New formulation of the discrete element method, CMM 2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), DOI: 10.1063/1.5019043, Vol.1922, pp.030009-1-8, 201815p.
2.Wawrzyk K., Kowalczyk P., Nosewicz S., Rojek J., A constitutive model and numerical simulation of sintering processes at macroscopic level, CMM 2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), DOI: 10.1063/1.5019045, Vol.1922, pp.030011-1-7, 201815p.
3.Rojek J., Nosewicz S., Maździarz M., Kowalczyk P., Wawrzyk K., Lumelskyj D., Modeling of a Sintering Process at Various Scales, Procedia Engineering, ISSN: 1877-7058, DOI: 10.1016/j.proeng.2017.02.210, Vol.177, pp.263-270, 2017

Streszczenie:

This paper presents modeling of a sintering process at various scales. Sintering is a powder metallurgy process consisting in consolidation of powder materials at elevated temperature but below the melting point. Sintering models at the atomistic, microscopic and macroscopic scales have been presented. Sintering is a process governed by diffusion therefore the atomistic modeling using the molecular dynamics has been focused on investigation of the diffusion process. The micromechanical model has been developed within the framework of the discrete element method. It allows us to consider microstructure and its changes during sintering. The macroscopic model is based on the continuum phenomenological approach. It combines elastic, thermal and viscous creep deformation. The methodology to determine macroscopic quantities: stress, strains and constitutive viscous properties from the discrete element simulations has been presented. Possibilities of the developed models have been demonstrated by applying them to simulation of sintering of the intermetallic NiAl powder. Own experimental results have been used to calibrate and validate numerical models.

Słowa kluczowe:

sintering, modeling, discrete element method, diffusion, molecular dynamics, macroscopic model

Afiliacje autorów:

 Rojek J. - IPPT PAN Nosewicz S. - IPPT PAN Maździarz M. - IPPT PAN Kowalczyk P. - IPPT PAN Wawrzyk K. - IPPT PAN Lumelskyj D. - IPPT PAN
15p.

##### Abstrakty konferencyjne
1.Rojek J., Madan N., Nosewicz S., Zubelewicz A., The deformable discrete element method, 6th European Conference on Computational Mechanics (ECCM 6), 7th European Conference on Computational Fluid Dynamics (ECFD 7), 2018-06-11/06-15, Glasgow (GB), pp.1, 2018

Słowa kluczowe:

Discrete Element Method, Deformable Particles, Nonlocal Contact Model, Poisson's Effect

Afiliacje autorów:

 Rojek J. - IPPT PAN Madan N. - IPPT PAN Nosewicz S. - IPPT PAN Zubelewicz A. - University of New Mexico (US)
2.Nosewicz S., Rojek J., Wawrzyk K., Kowalczyk P., Maciejewski G., Maździarz M., Multiscale modeling of sintering process of mixture of two-phase powder, 8th KMM-VIN Industrial Workshop: Modelling of composite materials and composite coatings, 2018-10-09/10-10, Freiburg (DE), pp.1-1, 2018
3.Wawrzyk K., Kowalczyk P., Rojek J., Nosewicz S., A numerical model of sintering processes at macroscopic level, SolMech 2018, 41st SOLID MECHANICS CONFERENCE, 2018-08-27/08-31, Warszawa (PL), pp.298-299, 2018

Streszczenie:

This paper presents modelling of double-phase powder sintering processes at the macroscopic level. In particular, its constitutive formulation, numerical implementation and numerical simulations are described. Numerical tests were carried out for a cylindrical specimen under uniaxial pressure and are compared against the microscopic model results. The model has been developed within the framework of a MUSINT project which is carried on in Institute of Fundamental Technological Research, Warsaw, Poland. The overall objective of the MUSINT (Multiscale numerical modelling of sintering processes) is development of numerical models allowing us to analyse at various scales manufacturing processes employing sintering as the main technological stage.

Słowa kluczowe:

finite element method, sintering, multiscale modelling, double-phase composite

Afiliacje autorów:

 Wawrzyk K. - IPPT PAN Kowalczyk P. - IPPT PAN Rojek J. - IPPT PAN Nosewicz S. - IPPT PAN
4.Madan N., Rojek J., Zubelewicz A., Nosewicz S., Convergence limit of a deformable discrete element model, SolMech 2018, 41st SOLID MECHANICS CONFERENCE, 2018-08-27/08-31, Warszawa (PL), pp.204-205, 2018
5.Nosewicz S., Rojek J., Maciejewski G., Maździarz M., Chmielewski M., Two-scale modelling of powder sintering, SolMech 2018, 41st SOLID MECHANICS CONFERENCE, 2018-08-27/08-31, Warszawa (PL), pp.210-211, 2018
6.Rojek J., Zubelewicz A., Madan N., Nosewicz S., Lumelskyj D., A novel treatment for the deformability of discrete elements, SolMech 2018, 41st SOLID MECHANICS CONFERENCE, 2018-08-27/08-31, Warszawa (PL), pp.202-203, 2018
7.Wawrzyk K., Nosewicz S., Rojek J., Kowalczyk P., A constitutive model and numerical simulation of sintering processes at macroscopic level, CMM 2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), pp.MS02-13-MS02-14, 2017

Streszczenie:

This document presents modelling of single-phase powder sintering processes at the macroscopic level. In particular, its constitutive formulation, numerical implementation and numerical test are described. Numerical tests were carried out for a cylindrical specimen under hydrostatic and uniaxial pressure. Results of macroscopic analysis are compared against the microscopic model results.

Słowa kluczowe:

sintering porcesses, numerical analysis, multiscale modelling

Afiliacje autorów:

 Wawrzyk K. - IPPT PAN Nosewicz S. - IPPT PAN Rojek J. - IPPT PAN Kowalczyk P. - IPPT PAN
8.Rojek J., Zubelewicz A., Madan N., Nosewicz S., New formulation of the discrete element method, CMM 2017, 22nd International Conference on Computer Methods in Mechanics, 2017-09-13/09-16, Lublin (PL), pp.MS13-27-MS13-28, 2017

Streszczenie:

This work presents a new original formulation of the discrete element method based on the soft contact approach. The standard DEM has been enhanced by introduction of the additional (global) deformation mode caused by the stresses in the particles induced by the contact forces. Uniform stresses and strains are assumed for each particle. The stresses are calculated from the contact forces. The strains are obtained using an inverse constitutive relationship. The strains allow us to obtain deformed particle shapes. The deformed shapes (ellipses) are taken into account in contact detection and evaluation of the contact forces. The numerical example shows that a particle deformation changes the particle interaction and the distribution of forces in the discrete element assembly.

Słowa kluczowe:

discrete element method; deformable particles; soft contact

Afiliacje autorów:

 Rojek J. - IPPT PAN Zubelewicz A. - University of New Mexico (US) Madan N. - IPPT PAN Nosewicz S. - IPPT PAN
9.Maździarz M., Rojek J., Nosewicz S., Molecular dynamics study of self-diffusion in stoichiometric B2-NiAl, CMN2017, Congress on Numerical Methods in Engineering, 2017-07-03/07-05, Valencia (ES), pp.1373, 2017
10.Rojek J., Nosewicz S., Maździarz M., Kowalczyk P., Wawrzyk K., Multiscale modelling of powder sintering processes, COMPLAS 2017, XIV International Conference on Computational Plasticity. Fundamentals and Applications, 2017-09-05/09-07, Barcelona (ES), pp.1, 2017
11.Chmielewski M., Pietrzak K., Strojny-Nędza A., Kaszyca K., Nosewicz S., Jarząbek D., The effect of nickel coating on the properties of Cu-SiC composites, EUROMAT 2017, European Congress and Exhibition on Advanced Materials and Processes, 2017-09-17/09-22, Thessaloniki (GR), pp.1, 2017
12.Nosewicz S., Rojek J., Maździarz M., Kowalczyk P., Wawrzyk K., Chmielewski M., Pietrzak K., Multiscale modeling of pressure-assisted sintering process, EUROMAT 2017, European Congress and Exhibition on Advanced Materials and Processes, 2017-09-17/09-22, Thessaloniki (GR), pp.1, 2017
13.Rojek J., Lumelskyj D., Nosewicz S., Romelczyk B., An elastoplastic contact model for spherical discrete elements, ICCCM 2017, International Conference on Computational Contact Mechanics, 2017-07-05/07-07, Lecce (IT), pp.1, 2017
14.Rojek J., Nosewicz S., Maździarz M., Kowalczyk P., Wawrzyk K., Modelling of sintering at atomistic, microscopic and macroscopic scales, Komplastech 2017, XXIV International Conference on Computer Methods in Materials Technology, 2017-01-15/01-18, Zakopane (PL), pp.126-128, 2017
15.Rojek J., Nosewicz S., Lumelskyj D., Romelczyk B., Bochenek K., Chmielewski M., Simulation of low-pressure powder compaction using an elastoplastic discrete element model, PARTICLES 2017, V International Conference on Particle-Based Methods. Fundamentals and Applications., 2017-09-26/09-28, Hannover (DE), pp.1, 2017
16.Maździarz M., Rojek J., Nosewicz S., Estimation of micromechanical NiAl sintering model parameters from the Atomistic Simulations, VII International Conference on Coupled Problems in Science and Engineering, 2017-06-12/06-14, Rhodes Island (GR), pp.1, 2017
17.Rojek J., Nosewicz S., Chmielewski M., Coupling micro- and macroscopic levels in a sintering model, VII International Conference on Coupled Problems in Science and Engineering, 2017-06-12/06-14, Rhodes Island (GR), pp.1, 2017
18.Rojek J., Nosewicz S., Development of a multiscale model of powder sintering, 5th KMM-VIN Industrial Workshop: Multi-scale and multi-physics materials modeling for advanced industries, 2016-01-26/01-27, Madryt (ES), pp.1, 2016
19.Rojek J., Jurczak K., Nosewicz S., Lumelskyj D., Chmielewski M., Contact models for discrete element simulation of the power compaction in a hot pressing process, CMIS 2016, Contact Mechanics International Symposium, 2016-05-11/05-16, Warszawa (PL), pp.28-29, 2016
20.Maździarz M., Rojek J., Nosewicz S., Molecular dynamics/statics simulation of Ni-Al nanoparticles sintering, ECCOMAS 2016, European Congress on Computational Methods in Applied Sciences and Engineering, 2016-06-05/06-10, Hersonissos (GR), pp.1, 2016

Słowa kluczowe:

Sintering, Powder Material, Ni-Al, Molecular Dynamics, Molecular Statics

Afiliacje autorów:

 Maździarz M. - IPPT PAN Rojek J. - IPPT PAN Nosewicz S. - IPPT PAN
21.Rojek J., Kowalczyk P., Nosewicz S., Jurczak K., Wawrzyk K., Micro-macro relationships from discrete element simulations of sintering, ECCOMAS 2016, European Congress on Computational Methods in Applied Sciences and Engineering, 2016-06-05/06-10, Hersonissos (GR), pp.1, 2016

Słowa kluczowe:

sintering, discrete element method, multi-scale modeling

Afiliacje autorów:

 Rojek J. - IPPT PAN Kowalczyk P. - IPPT PAN Nosewicz S. - IPPT PAN Jurczak K. - IPPT PAN Wawrzyk K. - IPPT PAN
22.Nosewicz S., Jurczak K., Rojek J., Chmielewski M., Pietrzak K., Application of contact interaction of Hertz model to viscoelastic discrete element model of sintering, ISNNM, 14th International Symposium on Novel and Nano Materials, 2016-07-03/07-08, Budapeszt (HU), pp.119, 2016
23.Jurczak K., Rojek J., Nosewicz S., Lumelskyy D., Bochenek K., Chmielewski M., Pietrzak K., Modelowanie wstępnego prasowania proszków metodą elementów dyskretnych, KomPlasTech 2016, XXIII Konferencja Informatyka w Technologii Metali, 2016-01-17/01-20, Wisła (PL), pp.68, 2016

Streszczenie:

W niniejszym artykule zaprezentowano wyniki modelowania, zagęszczania proszku stanowiącego wstępny etap procesu prasowania na gorąco, metodą elementów dyskretnych opisaną w [1]. Modelowanie numeryczne zrealizowano metodą elementów dyskretnych, z wykorzystaniem kulistych cząstek. Badania skoncentrowano na mechanizmach zagęszczania proszku przy ciśnieniu 50 MPa oraz modelach odpowiednich przy zastosowanych warunkach procesu. Numeryczne symulacje wykonano z wykorzystaniem dwóch modeli: pierwszy - elastyczny Hertz-Mindlin-Deresiewicz, drugi - plastyczny Storakers, opisanych w pracy [2]. Wyniki symulacji numerycznych zostały porównane z wynikami laboratoryjnymi zagęszczania proszku NiAl w matrycy. W rezultacie otrzymano dużą zgodność wyników eksperymentalnych i numerycznych.

Słowa kluczowe:

metoda elementów dyskretnych, modelowanie, zagęszczanie proszków, prasowanie

Afiliacje autorów:

 Jurczak K. - IPPT PAN Rojek J. - IPPT PAN Nosewicz S. - IPPT PAN Lumelskyy D. - IPPT PAN Bochenek K. - IPPT PAN Chmielewski M. - Institute of Electronic Materials Technology (PL) Pietrzak K. - other affiliation
24.Rojek J., Nosewicz S., Maździarz M., Kowalczyk P., Wawrzyk K., Modelling of powder sintering at various scales, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P193, pp.1-2, 2016

Słowa kluczowe:

sintering, multiscale modelling

Afiliacje autorów:

 Rojek J. - IPPT PAN Nosewicz S. - IPPT PAN Maździarz M. - IPPT PAN Kowalczyk P. - IPPT PAN Wawrzyk K. - IPPT PAN
25.Nosewicz S., Rojek J., Pietrzak K., Chmielewski M., Discrete element modelling of hot pressing process, EUROMAT 2015, European Congress and Exhibition on Advanced Materials and Processes, 2015-09-20/09-24, Warszawa (PL), pp.1, 2015
26.Rojek J., Nosewicz S., Jurczak K., Viscoelastic cohesive contact formulation for discrete element model of powder sintering, ICCCM 2015, IV International Conference on Computational Contact Mechanics, 2015-05-27/05-29, Hannover (DE), pp.1-2, 2015

Słowa kluczowe:

cohesive contact, discrete element method, viscoelasticity, sintering

Afiliacje autorów:

 Rojek J. - IPPT PAN Nosewicz S. - IPPT PAN Jurczak K. - IPPT PAN
27.Nosewicz S., Rojek J., Pietrzak K., Chmielewski M., Numerical modeling of stresses in composites manufactured by powder metallurgy, ICMM3, 3rd International Conference on Material Modelling incorporating 13th European Mechanics of Materials Conference, 2013-09-08/09-11, Warszawa (PL), pp.133, 2013
28.Rojek J., Nosewicz S., Pietrzak K., Chmielewski M., Discrete element modelling of powder metallurgy processes, Particles 2013, III International Conference on Particle-based Methods, 2013-09-18/09-20, Stuttgart (DE), pp.1, 2013
29.Rojek J., Nosewicz S., Pietrzak K., Chmielewski M., Simulation of powder sintering using a discrete element method, VII International Symposium on Mechanics of Materials and Structures, 2013-06-03/06-06, Augustów (PL), pp.59-60, 2013
30.Rojek J., Nosewicz Sz., Pietrzak K., Chmielewski M., Kaliński D., Discrete element simulation of powder metallurgy manufacturing process of metal-ceramic composites, ECCOMAX 2012, 6th European Congress on Computational Methods in Applied Sciences and Engineering, 2012-09-10/09-14, Wiedeń (AT), pp.1-2, 2012
31.Nosewicz Sz., Rojek J., Pietrzak K., Chmielewski M., Kaliński D., Kačianauskas R., Discrete Element Modelling of Solid State Sintering Process of Metal-Ceramic Composite, SolMech 2012, 38th Solid Mechanics Conference, 2012-08-27/08-31, Warszawa (PL), pp.172-173, 2012
32.Rojek J., Nosewicz S., Pietrzak K., Chmielewski M., Kaliński D., Modelling of powder sintering using the discrete element method, CMM 2011, 19th International Conference on Computer Methods in Mechanics, 2011-05-09/05-12, Warszawa (PL), pp.241-1-2, 2011