Institute of Fundamental Technological Research
Polish Academy of Sciences

Staff

Jędrzej Dobrzański, MSc

Department of Mechanics of Materials (ZMM)
Materials Modeling Group (ZeMM)
position: Specialist
PhD student
telephone: (+48) 22 826 12 81 ext.: 430
room: 238
e-mail:
ORCID: 0000-0001-9687-7496

Recent publications
1.  Dobrzański J., Wojtacki K., Stupkiewicz S., Lamination-based efficient treatment of weak discontinuities for non-conforming finite element meshes, COMPUTERS AND STRUCTURES, ISSN: 0045-7949, DOI: 10.1016/j.compstruc.2023.107209, Vol.291, No.107209, pp.1-14, 2024

Abstract:
When modelling discontinuities (interfaces) using the finite element method, the standard approach is to use a conforming finite-element mesh in which the mesh matches the interfaces. However, this natural approach can prove cumbersome if the geometry is complex, in particular in 3D. In this work, we develop an efficient technique for a non-conforming finite-element treatment of weak discontinuities by using laminated microstructures. The approach is inspired by the so-called composite voxel technique that has been developed for FFT-based spectral solvers in computational homogenization. The idea behind the method is rather simple. Each finite element that is cut by an interface is treated as a simple laminate with the volume fraction of the phases and the lamination orientation determined in terms of the actual geometrical arrangement of the interface within the element. The approach is illustrated by several computational examples relevant to the micromechanics of heterogeneous materials. Elastic and elastic-plastic materials at small and finite strain are considered in the examples. The performance of the proposed method is compared to two alternative, simple methods showing that the new approach is in most cases superior to them while maintaining the simplicity.

Keywords:
Finite element method,Interface,Weak discontinuity,Laminate,Homogenization,Elasticity,Plasticity

Affiliations:
Dobrzański J. - IPPT PAN
Wojtacki K. - IPPT PAN
Stupkiewicz S. - IPPT PAN
2.  Dobrzański J., Kawa M., Bearing capacity of eccentrically loaded strip footing on spatially variable cohesive soil, Studia Geotechnica et Mechanica, ISSN: 2083-831X, DOI: 10.2478/sgem-2021-0035, Vol.43, No.4, pp.425-437, 2021

Abstract:
The study considers the bearing capacity of eccentrically loaded strip footing on spatially variable, purely cohesive soil. The problem is solved using the random finite element method. The anisotropic random field of cohesion is generated using the Fourier series method, and individual problems within performed Monte Carlo simulations (MCSs) are solved using the Abaqus finite element code. The analysis includes eight different variants of the fluctuation scales and six values of load eccentricity. For each of these 48 cases, 1000 MCSs are performed and the probabilistic characteristics of the obtained values are calculated. The results of the analysis indicate that the mean value of the bearing capacity decreases linearly with eccentricity, which is consistent with Meyerhof's theory. However, the decrease in standard deviation and increase in the coefficient of variation of the bearing capacity observed are non-linear, which is particularly evident for small eccentricities. For one chosen variant of fluctuation scales, a reliability analysis investigating the influence of eccentricity on reliability index is performed. The results of the analysis conducted show that the value of the reliability index can be significantly influenced even by small eccentricities. This indicates the need to consider at least random eccentricities in future studies regarding probabilistic modelling of foundation bearing capacity.

Keywords:
random field, scale of fluctuation, eccentric load, cohesive soil, probabilistic analysis

Affiliations:
Dobrzański J. - IPPT PAN
Kawa M. - Wroclaw University of Science and Technology (PL)

Conference abstracts
1.  Dobrzański J., Wojtacki K., Stupkiewicz S., Lamination-Based Efficient Treatment of Weak Discontinuities for Non-Conforming Finite-Element Meshes, IUTAM Symposium, IUTAM Symposium on Enhancing Material Performance by Exploiting Instabilities and Damage Evolution, 2022-06-05/06-10, Warszawa (PL), DOI: 10.24423/iutam2022warsaw, No.P035, pp.49-49, 2022

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