prof. dr hab. Kazimierz Sobczyk


Doktorat
1966Rozpraszanie fal sprężystych na powierzchniach określonych stochastycznie 
promotor -- prof. dr hab. inż. Sylwester Kaliski, IPPT PAN
113 
Profesura
1983Nadanie tytułu naukowego profesora
Inne
1991Członek korespondent Polskiej Akademii Nauk
2007Członek rzeczywisty Polskiej Akademii Nauk

Promotor prac doktorskich
1.1997Trębicki Jerzy  Stochastyczna analiza układów drgających o zimnej strukturze 
2.1987Kazimierczyk Piotr  Identyfikacja parametryczna układów dynamicznych opisywanych stochastycznymi dyfuzyjnymi procesami Markowa 
3.1984Kotulski Zbigniew  Funkcjonały charakterystyczne stochastycznych procesów falowych 
4.1979Gambin Barbara  Fale sprężyste w półprzestrzeni stochastycznie niejednorodnej 
5.1979Karwowski Andrzej  Wariacyjna metoda analizy konstrukcji sprężystych z losowymi własnościami 

Ostatnie publikacje
1.Sobczyk K., Hołobut P., Information-theoretic approach to dynamics of stochastic systems, PROBABILISTIC ENGINEERING MECHANICS, ISSN: 0266-8920, DOI: 10.1016/j.probengmech.2011.05.007, Vol.27, No.1, pp.47-56, 2012

Streszczenie:

In the paper we show how some basic informational quality measures (e.g. the Shannon entropy and the relative entropy/Kullback-Leibler divergence) defined for stochastic dynamical systems change in time and how they depend on the system properties and intensity of random disturbances. First, the Liouvillian systems (when randomness is present in the initial states only) are discussed and then various (linear and nonlinear) systems with random external excitations are treated in detail. Both, general and specific systems are considered, including numerical and graphical illustrations.

Słowa kluczowe:

stochastic dynamics, information, entropy, relative entropy, information gain, non-Gaussian prediction, maximum entropy approximation

Afiliacje autorów:

Sobczyk K.-IPPT PAN
Hołobut P.-IPPT PAN
30p.
2.Sobczyk K., Perros K., Papadimitriou C., Fatigue reliability of multidimensional vibratory degrading systems under random loading, JOURNAL OF ENGINEERING MECHANICS-ASCE, ISSN: 0733-9399, DOI: 10.1061/(ASCE)EM.1943-7889.0000052, Vol.136, No.2, pp.179-188, 2010

Streszczenie:

In this paper, the basic methodology for the fatigue reliability assessment of randomly vibrating multidegree-of-freedom systems is presented within the coupled response-degradation model. The fatigue process in the system components is quantified by the fatigue crack growth equations which—via the stress range—are coupled with the system response. Simultaneously, the system dynamics is affected by fatigue process via its stiffness degradation so that it provides the actual stress values to the fatigue growth equation. In addition to the general coupled response-degradation analysis, its special case of noncoupled fatigue crack growth is treated as well for the wide-band stationary applied stress by the use of its first four spectral moments and the approximate, empirically motivated, Dirlik’s probability distribution for the stress range. Both, the general analysis and the illustrating exemplary problems elaborated in the paper provide the route to the fatigue reliability estimation in complex–hierarchical vibratory systems under random loading.

Słowa kluczowe:

Fatigue, Crack growth, Random vibration, System reliability, Stiffness degradation

Afiliacje autorów:

Sobczyk K.-IPPT PAN
Perros K.-University of Thessaly (GR)
Papadimitriou C.-University of Thessaly (GR)
32p.
3.Gaidai O., Naess A., Sobczyk K., The effect of fatigue-induced crack propagation on the stochastic dynamics of nonlinear structure, PROBABILISTIC ENGINEERING MECHANICS, ISSN: 0266-8920, Vol.23, No.4, pp.438-443, 2008
4.Sobczyk K., Morphological complexity of material microstructures: From stochastic models to fracture estimation, PROBABILISTIC ENGINEERING MECHANICS, ISSN: 0266-8920, Vol.23, No.4, pp.444-455, 2008
5.Sobczyk K., Trębicki J., Movchan A.B., Characterization of random microstructural stresses and fracture estimation, EUROPEAN JOURNAL OF MECHANICS A-SOLIDS, ISSN: 0997-7538, DOI: 10.1016/j.euromechsol.2006.12.001, Vol.26, pp.573-591, 2007

Streszczenie:

In this paper, the analytical approach to quantitative characterization of random microstructural residual stress field in brittle elastic materials is presented. The analysis consists of two parts. First, we expound the basic features of random microstructural stresses and show how the eigenstrain approach (of “classical” micromechanics) can be extended to the situations where randomness of the initial eigenstrains has to be taken into account. The second part of the paper deals with the effects of random microstresses on crack growth phenomena. The stress intensity induced by random dilatant transformation eigenstrains and by thermally-induced random microstresses are treated in detail, including numerical and graphical illustrations of specific crack problems

Słowa kluczowe:

Random residual microstresses, Random eigenstrain model, Stress intensity factor, Toughening effect, Thermal microstresses

Afiliacje autorów:

Sobczyk K.-IPPT PAN
Trębicki J.-IPPT PAN
Movchan A.B.-other affiliation
6.Hołobut P., Sobczyk K., Random hydrogen - induced stresses and effects on cracking, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.59, No.6, pp.1-21, 2007

Streszczenie:

The paper presents a method for quantitative characterization of random hydrogen-induced stresses. The method is based on randomized diffusion-elasticity equations. Also a stochastic parametric model, suitable for representing relevant empirical data, is outlined. The general considerations are illustrated by two particular examples. The first one concerns the effect of random hydrogen concentration on material failure time in a half-space, whereas the second one shows its effect on the Mode-I stress intensity factor for a crack in a circular cylinder.

Afiliacje autorów:

Hołobut P.-IPPT PAN
Sobczyk K.-IPPT PAN
7.Trębicki J., Sobczyk K., On nonlinear stochastic vibratory systems with stiffness degradation, ACTA MECHANICA, ISSN: 0001-5970, DOI: 10.1007/s00707-007-0545-6, Vol.195, pp.203-214, 2007

Streszczenie:

In the paper a coupled response–degradation problem for a nonlinear vibrating system is analyzed. The analysis allows to account for the effect of stiffness degradation (during the vibration process) on the response and, in the same time, gives the actual stress values for estimation of damage accumulating in the system. The paper constitutes an extension of the approach (a sequential characterization of the degradation random process) presented in [4] to vibrating systems with nonlinear restoring term.

Afiliacje autorów:

Trębicki J.-IPPT PAN
Sobczyk K.-IPPT PAN
8.Sobczyk K., Losowość, złożoność, prognozowalność: próby zrozumienia, NAUKA, ISSN: 1231-8515, Vol.2, pp.45-64, 2006
9.Sobczyk K., Stochastic dynamics and reliability of degrading systems, BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 0239-7528, Vol.54, No.1, pp.125-138, 2006

Streszczenie:

In this paper the basic methodology of the coupled response-degradation modelling of stochastic dynamical systems is presented along with the effective analysis of selected problems. First, the general formulation of the problems of stochastic dynamics coupled with the evolution of deterioration process is given. Then some specific degrading oscillatory systems under random excitation are analyzed with a special attention on the systems with fatigue-induced stiffness degradation. Both, the general discussion and the analysis of selected exemplary problems indicate how the reliability of deteriorating stochastic dynamical systems can be assessed

Słowa kluczowe:

stochastic dynamics, fatigue induced stiffness degradation, hysteretic systems, systems with varying/random structure

Afiliacje autorów:

Sobczyk K.-IPPT PAN
10.Sobczyk K., Zjawiska losowe: w poszukiwaniu ukrytego porządku, Academia, Magazyn Polskiej Akademii Nauk, ISSN: 1733-8662, Vol.3, pp.7, 2006
11.Papadimitriou C., Haralampidis Y., Sobczyk K., Optimal experiment design in stochastic structural dynamics, PROBABILISTIC ENGINEERING MECHANICS, ISSN: 0266-8920, DOI: 10.1016/j.probengmech.2004.06.002, Vol.20, No.1, pp.68-78, 2005

Streszczenie:

This paper provides a methodology for optimal prediction of the response of randomly vibrating structures using information from a limited number of measurements. The objective is to optimize the locations of sensors for the purpose of making the most accurate predictions of the response at unmeasured locations in structural systems. The kriging method is used to find the response predictions and the corresponding mean-square errors at unmeasured locations. The mean-square errors in the predictions depend on the locations of sensors and the correlation characteristics of the response evaluated from the model of dynamics and the characteristics of the excitation. The response predictions depend also on the information contained in measurements. The optimal sensor locations are selected to minimize the total mean-square error of the response predictions at unmeasured points. This leads to a complicated non-convex optimization problem in which multiple local and global optima may exist. A hybrid optimization method based on evolution strategies is used to determine a global minimum. The optimal experimental design method presented in the paper is illustrated by designing the optimal sensor locations for an elastic beam and a plate subjected to a class of random stationary loads.

Słowa kluczowe:

Structures, Random vibrations, Sensor locations, Kriging, Evolution strategies

Afiliacje autorów:

Papadimitriou C.-University of Thessaly (GR)
Haralampidis Y.-University of Thessaly (GR)
Sobczyk K.-IPPT PAN
12.Kacprzyk J., Malinowski K., Marecki J., Pohorecki R., Sobczyk K., Weryński A., Włosiński W., Woliński W., Strategia nauk technicznych do roku 2020 - propozycje (ekspertyza), NAUKA, ISSN: 1231-8515, Vol.2, pp.129-162, 2005
13.Sobczyk K., Information Dynamics. Premises, Challenges and Results, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.2, pp.1-32, 2000
14.Kotulski Z., Sobczyk K., Non-local Description of Pollution Transport in Random Medium, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.34, pp.1-22, 1992
15.Sobczyk K., O identyfikacji układów, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.26, pp.1-28, 1986
16.Sobczyk K., Fale sprężyste w dyskretnym ośrodku stochastycznym (Praca habilitacyjna), Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.5, pp.1-76, 1974
17.Sobczyk K., O stochastycznym opisie ośrodka porowatego, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.22, pp.1-13, 1969
18.Sobczyk K., Pole termosprężyste w półprzestrzeni ograniczonej powierzchnią nierówną, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.29, pp.1-18, 1967

Lista rozdziałów w ostatnich monografiach
1.
11
Sobczyk K., Polskie i światowe osiągnięcia nauki: Nauki Techniczne, rozdział: Mechanika stochastyczna: Geneza, modele, zastosowania, Fundacja im. Wojciecha Świętosławskiego, 2, pp.429-462, 2010
2.
172
Sobczyk K., Mechanics of the 21st Century, Proceedings of the 21st International Congress of Theoretical and Applied Mechanics, Warsaw, Poland, 15-21 August 2004, rozdział: Stochastic Dynamics of Engineering Systems, Springer, Gutkowski W., Kowalewski T.A. (Eds.), pp.19-60, 2005