Przemysław Sadowski, Ph.D., Eng.

Department of Mechanics of Materials (ZMM)
Materials Modeling Group (ZeMM)
position: assistant professor
telephone: (+48) 22 826 12 81 ext.: 453
room: 140
e-mail: psad

Doctoral thesis
2009-02-26Modelowanie przepływu ciepła przez powierzchnię kontaktu ciał chropowatych w procesach przeróbki plastycznej 
supervisor -- Prof. Stanisław Stupkiewicz, Ph.D., Dr. Habil., Eng., IPPT PAN
627
 
Recent publications
1.Sadowski P., Kowalczyk-Gajewska K., Stupkiewicz S., Consistent treatment and automation of the incremental Mori–Tanaka scheme for elasto-plastic composites, COMPUTATIONAL MECHANICS, ISSN: 0178-7675, DOI: 10.1007/s00466-017-1418-z, pp.1-19, 2017
Sadowski P., Kowalczyk-Gajewska K., Stupkiewicz S., Consistent treatment and automation of the incremental Mori–Tanaka scheme for elasto-plastic composites, COMPUTATIONAL MECHANICS, ISSN: 0178-7675, DOI: 10.1007/s00466-017-1418-z, pp.1-19, 2017

Abstract:
A consistent algorithmic treatment of the incremental Mori–Tanaka (MT) model for elasto-plastic composites is proposed. The aim is to develop a computationally efficient and robust micromechanical constitutive model suitable for large-scale finite-element computations. The resulting overall computational scheme is a doubly-nested iteration-subiteration scheme. The Newton method is used to solve the nonlinear equations at each level involved. Exact linearization is thus performed at each level so that a quadratic convergence rate can be achieved. To this end, the automatic differentiation (AD) technique is used, and the corresponding AD-based formulation is provided. Excellent overall performance of the present MT scheme in threedimensional finite-element computations is illustrated.

Keywords:
Mori–Tanaka method, Composite materials, Elasto-plasticity, Finite element method, Automatic differentiation

2.Sadowski P., Kowalczyk-Gajewska K., Stupkiewicz S., Response discontinuities in the solution of the incremental Mori–Tanaka scheme for elasto-plastic composites, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.69, No.1, pp.3-27, 2017
Sadowski P., Kowalczyk-Gajewska K., Stupkiewicz S., Response discontinuities in the solution of the incremental Mori–Tanaka scheme for elasto-plastic composites, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.69, No.1, pp.3-27, 2017

Abstract:
The incremental Mori–Tanaka model of elasto-plastic composites is discussed, and the corresponding finite-step formulation is shown to lead to discontinuities in the overall response at the instant of elastic-to-plastic transition in the matrix. Specifically, two situations may be encountered: the incremental equations may have two solutions or no solution. In the former situation, switching between the two solutions is associated with a jump in the overall stress. Response discontinuities are studied in detail for a special case of proportional deviatoric loading. The discontinuities constitute an undesirable feature of the incremental Mori–Tanaka scheme that apparently has not been discussed in the literature so far. Remedies to the related problems are briefly discussed.

Keywords:
mean-field homogenization, Mori–Tanaka method, incremental scheme, composite materials, elasto-plasticity

3.Stupkiewicz S., Lengiewicz J., Sadowski P., Kucharski S., Finite deformation effects in soft elastohydrodynamic lubrication problems, TRIBOLOGY INTERNATIONAL, ISSN: 0301-679X, DOI: 10.1016/j.triboint.2015.03.016, Vol.93, pp.511-522, 2016
Stupkiewicz S., Lengiewicz J., Sadowski P., Kucharski S., Finite deformation effects in soft elastohydrodynamic lubrication problems, TRIBOLOGY INTERNATIONAL, ISSN: 0301-679X, DOI: 10.1016/j.triboint.2015.03.016, Vol.93, pp.511-522, 2016

Abstract:
Soft elastohydrodynamic lubrication regime is typical for many elastomeric and biological contacts. As one or both contacting bodies are then highly compliant, relatively low contact pressures may lead to large deformations which are neglected in the classical EHL theory. In the paper, the related finite-deformation effects are studied for two representative soft-EHL problems. To this end, a fully-coupled nonlinear formulation has been developed which combines finite-strain elasticity for the solid and the Reynolds equation for the fluid, both treated using the finite element method with full account of all elastohydrodynamic couplings. Results of friction measurements are also reported and compared to theoretical predictions for lubricated contact of a rubber ball sliding against a steel disc under high loads.

Keywords:
Soft-EHL problem, Finite deformation, Finite element method, Monolithic scheme

4.Sadowski P., Kowalczyk-Gajewska K., Stupkiewicz S., Classical estimates of the effective thermoelastic properties of copper–graphene composites, COMPOSITES PART B-ENGINEERING, ISSN: 1359-8368, DOI: 10.1016/j.compositesb.2015.06.007, Vol.80, pp.278-290, 2015
Sadowski P., Kowalczyk-Gajewska K., Stupkiewicz S., Classical estimates of the effective thermoelastic properties of copper–graphene composites, COMPOSITES PART B-ENGINEERING, ISSN: 1359-8368, DOI: 10.1016/j.compositesb.2015.06.007, Vol.80, pp.278-290, 2015

Abstract:
Significant research effort is concentrated worldwide on development of graphene-based metal-matrix composites with enhanced thermomechanical properties. In this work, we apply two classical micromechanical mean-field theories to estimate the effective thermoelastic properties that can be achieved in practice for a copper–graphene composite. In the modelling, graphene is treated as an anisotropic material, and the effect of its out-of-plane properties, which are less recognized than the in-plane properties, is studied in detail. To address the severe difficulties in processing of graphene-based metal-matrix composites, the copper–graphene composite is here assumed to additionally contain, due to imperfect processing, particles of graphite and voids. It is shown quantitatively that the related imperfections may significantly reduce the expected enhancement of the effective properties. The present predictions are also compared to the experimental data available in the literature.

Keywords:
Metal-matrix composites (MMCs), Mechanical properties, Thermal properties, Micro-mechanics, Graphene

5.Sadowski P., Stupkiewicz S., Combined effect of friction and macroscopic deformation on asperity flattening, TRIBOLOGY INTERNATIONAL, ISSN: 0301-679X, DOI: 10.1016/j.triboint.2010.04.011, Vol.43, pp.1735-1741, 2010
Sadowski P., Stupkiewicz S., Combined effect of friction and macroscopic deformation on asperity flattening, TRIBOLOGY INTERNATIONAL, ISSN: 0301-679X, DOI: 10.1016/j.triboint.2010.04.011, Vol.43, pp.1735-1741, 2010

Abstract:
The combined effect of friction and macroscopic plastic deformation on asperity flattening is studied. Crushing of a periodic array of wedge-like asperities is formulated as a rigid-viscoplastic periodic indentation problem with superimposed macroscopic deformation. A micromechanical framework is developed and the corresponding boundary value problem is solved using the finite element method. An anomalous regime of asperity flattening is predicted at low flattening rates, in which the effect of friction on asperity flattening is opposite to that observed in the absence of macroscopic deformation and also at high flattening rates. An incremental elastoplastic analysis confirms this finding.

Keywords:
Asperity flattening, Real contact area, Surface layer, Metal forming

6.Sadowski P., Stupkiewicz S., A model of thermal contact conductance at high real contact area fractions, WEAR, ISSN: 0043-1648, Vol.268, pp.77-85, 2010
Sadowski P., Stupkiewicz S., A model of thermal contact conductance at high real contact area fractions, WEAR, ISSN: 0043-1648, Vol.268, pp.77-85, 2010

Abstract:
Thermal contact conductance (TCC) is studied in the whole range of real contact area fractions between zero and unity. For this purpose, a two-scale model is developed in which the effective (macroscopic) TCC coefficient is obtained from the solution of the heat conduction problem at the scale of asperities. Additional thermal resistance at the real contact spots is included in the model. The model is applied for several real 3D roughness topographies for which the effective TCC coefficient is determined as a function of the real contact area fraction and the local TCC coefficient at real contact spots. An analytical function is found which approximates this relationship in the whole range of parameters, and a characteristic length-scale parameter is introduced which characterizes the effective TCC properties of a rough surface.

Keywords:
Roughness topography, Real contact area, Thermal contact conductance, Characteristic length


List of chapters in recent monographs
1.
133
Stupkiewicz S., Sadowski P., Analysis and simulation of contact problems, Lecture notes in applied and computational mechanics, rozdział: Micromechanical analysis of deformation and temperature inhomogeneities within rough contact layers, Springer, Wriggers P., Nackenhorst U. (Eds.), 27, pp.325-332, 2006

Conference abstracts
1.Sadowski P., Kowalczyk-Gajewska K., Stupkiewicz S., Micromechanical modelling of elasto-plastic composites: efficient and robust finite-element implementation of Mori-Tanaka model, CNM, 5th Conference on Nano- and Micromechanics, 2017-07-04/07-06, Wrocław (PL), No.O-08, pp.31-33, 2017
Sadowski P., Kowalczyk-Gajewska K., Stupkiewicz S., Micromechanical modelling of elasto-plastic composites: efficient and robust finite-element implementation of Mori-Tanaka model, CNM, 5th Conference on Nano- and Micromechanics, 2017-07-04/07-06, Wrocław (PL), No.O-08, pp.31-33, 2017

Keywords:
Mean-field homogenization, Mori-Tanaka method, Composite materials, Finite element method

2.Sadowski P., Kowalczyk-Gajewska K., Stupkiewicz S., Efficient algorithmic treatment of the incremental Mori–Tanaka scheme for elasto-plastic composites, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P070, pp.1-2, 2016
3.Lengiewicz J., Sadowski P., Stupkiewicz S., Finite element modelling of elastohydrodynamic lubrication in the finite deformation regime, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.43-44, 2014
4.Sadowski P., Stupkiewicz S., Estimation of the effective properties of composites with inclusions of diverse shapes and properties, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.139-140, 2014
5.Sadowski P., Kucharski S., Lengiewicz J., Stupkiewicz S., Soft elastohydrodynamic lubrication problems in the finite deformation regime: experimental testing and modelling, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.323-324, 2014