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Nagroda Rektora PW PDF Print E-mail
Nagroda Zespołowa I st. Rektora PW za osiągnięcia naukowe w ra. 2015/2016 przyznana zespołowi:  S.Czarnecki, R.Czubacki, T. Lewińskim, T.Sokół, P.Wawruch dnia  2 X 2017 r. (Rektor PW: prof. Jan Szmidt)
 
On the Calibration of a Numerical Model for Concrete-to-Concrete Interface PDF Print E-mail
Sławomir Dudziak,  Wioletta Jackiewicz-Rek,  Zofia Kozyra, On the Calibration of a Numerical Model for Concrete-to-Concrete Interface, Materials 2021, 14(23), 7204;
online: https://doi.org/10.3390/ma14237204

Abstract
The study was devoted to the numerical modelling of concrete-to-concrete interfaces. Such an interface can be found in many modern composite structures, so proper characterisation of its behaviour is of great importance. A strategy for calibration of a model based on cohesive finite elements and the elastic-damage traction–separation constitutive law available by default in the Abaqus code was proposed. Moreover, the default interface material model was enhanced with the user-field-variables subroutine to include a real strength envelope for such interfaces. Afterwards, the modelling approach was validated with numerical simulation of the most popular tests for determining the strength characteristics of concrete-to-concrete interfaces: three-point bending beam with a notch, splitting bi-material cubic specimens, and slant-shear tests. The results of own pilot studies were used as well as those reported by other researchers. The performed simulations proved the accuracy of the proposed modelling strategy (the mean ratio of ultimate forces obtained with numerical models and from experiments was equal to 1.01). Furthermore, the presented examples allowed us to better understand the basic test methods for concrete interfaces and the observed mechanisms of failure during them.
 
The isotropic material design of in-plane loaded elastic-plastic plates PDF Print E-mail
S. Czarnecki, T. Lewiński, The isotropic material design of in-plane loaded elastic-plastic plates, Materials, 2021, 14(23), 7430;
online: https://www.mdpi.com/1996-1944/14/23/7430

Abstract
This paper puts forward a new version of the Isotropic Material Design method for the optimum design of structures made of an elasto-plastic material within the Hencky-Nadai-Ilyushin theory. This method provides the optimal layouts of the moduli of isotropy to make the overall compliance minimal. Thus, the bulk and shear moduli are the only design variables, both assumed as non-negative fields. The trace of the Hooke tensor represents the unit cost of the design. The yield condition is assumed to be independent of the design variables, to make the design process as simple as possible. By eliminating the design variables, the optimum design problem is reduced to the pair of the two mutually dual Linear Constrained Problems (LCP). The solution to the LCP stress-based problem directly determines the layout of the optimal moduli. A numerical method has been developed to construct approximate solutions, which paves the way for constructing the final layouts of the elastic moduli. Selected illustrative solutions are reported, corresponding to various data concerning the yield limit and the cost of the design. The yield condition introduced in this paper results in bounding the values of the optimal moduli in the places of possible stress concentration, such as reentrant corners.
 
95 lat Profesora Zbigniewa Kączkowskiego PDF Print E-mail
20160409 036 mm
Spotkanie z doktorantami

Prof. dr inż.  Zbigniew Kączkowski >> w dniu 10 kwietnia 2016 skończył 95 lat. Z okazji jubileuszu spotkał się ze swoimi doktorantami. Profesor wypromował 24 doktorantów (lista doktorantówpdf). Profesor Kączkowski pierwszego doktoranta wypromował w roku 1959, ostatniego w roku 1991.
Doktoranci przygotowali list png, który został odczytany i wręczony Jubilatowi.

Główna część spotkania poświęcona była omówieniu wszystkich 24 doktoratów. Profesor, jak zawsze, świetnie przygotowany wspominał doktoraty i doktorantów. Szczególnie gorąco wspominaliśmy doktorantów, którzy już nie żyją. Kilku doktorantów, ze względu na sędziwy wiek, nie mogło przyjechać. Franciszek Jarzyński, doktorat obroniony w roku 1964, w tym roku kończy 100 lat!
Jubileusz  zakończył się obietnicą kolejnego spotkania za 5 lat - na 100 lecie urodzin Profesora.
Zbigniew Kacprzyk
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In-Depth Verification of a Numerical Model for an Axisymmetric RC Dome PDF Print E-mail
Przemysław Czumaj, Sławomir Dudziak, Zbigniew Kacprzyk, In-Depth Verification of a Numerical Model for an Axisymmetric RC Dome, Symmetry 2021, 13(11), 2152;
online: https://doi.org/10.3390/sym13112152

Abstract
The designers of civil engineering structures often have to face the problem of the reliability of complex computational analyses performed most often with the Finite Element Method (FEM). Any assessment of reliability of such analyses is difficult and can only be approximate. The present paper puts forward a new method of verification and validation of the structural analyses upon an illustrative example of a dome strengthened by circumferential ribs along the upper and lower edges. Four computational systems were used, namely Abaqus, Autodesk Robot, Dlubal RFEM, and FEAS. Different models were also analyzed—two-dimensional (2D) and three-dimensional (3D) ones using continuum, bar, and shell finite elements. The results of the static (with two kinds of load—self-weight and load distributed along the upper ring) and modal analyses are presented. A detailed comparison between the systems’ and models’ predictions was made. In general, the spatial models predicted a less stiff behavior of the analyzed dome than the planar models. The good agreement between different models and systems was obtained for the first natural frequency with axisymmetric eigenmodes (except from the Autodesk Robot system). The presented approach to the verification of complex shell–bar models can be effectively applied by structural designers.
 
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