Department of Structural Mechanics and Computer Aided Engineering
The emergence of auxetic material as a result of optimal isotropic design PDF Print E-mail
The emergence of auxetic material as a result of optimal isotropic design
S. Czarnecki, P. Wawruch
czar wawPhys. Status Solidi B, 1–11 (2015) / DOI 10.1002/pssb.201451733
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Using both mathematical and numerical methods, the optimal distributions of material characterized by the Young modulus and Poisson ratio (as well as other moduli of isotropy) maximizing the overall stiffness of an inhomogeneous isotropic elastic 3D body transmitting a given surface loading to a given support are constructed. The overall stiffness of the body is defined as the inverse of the work of external forces on displacements, called here the compliance of the structure. The isoperimetric condition bounds the integral of the trace of the Hooke tensor. It is proved that isotropic composite materials forming the bodies of extremely high stiffness exhibit negative Poisson ratio in large subdomains, which points at the significance of the auxetic material in modern structural design. The obtained results show that the whole range of possible variation of the Poisson ratio is used, from −1 to 1/2, which proves usefulness of the auxetic materials.

Theoretical Foundations of Civil Engineering, Polish-Ukrainian Transactions, 2014 PDF Print E-mail
tfoce 2014Uderzenie punktu materialnego w belkę, Jemielita G., Kozyra Z., Theoretical Foundations of Civil Engineering, Polish-Ukrainian Transactions. Ed. by W. Szcześniak, pp. 51-58, Warsaw 2014.
Streszczenie: W pracy wyznaczono prędkość masy i prędkość punktów materialnych belki w trakcie zderzenia.  Wyznaczono też przemieszczenia dynamiczne belki przy zderzeniu elastycznym i nieelastycznym w zależności od przemieszczenia statycznego.

Izotropowe kompozyty periodyczne - homogenizacja struktur I rzedu, Łukasiak T., Theoretical Foundations of Civil Engineering, Polish-Ukrainian Transactions. Ed. by W. Szcześniak, pp. 77-84, Warsaw 2014.
Streszczenie:  Materiały kompozytowe w 2D charakteryzuja się z reguły ortotropowymi cechami. Interesującymi, nie tylko z teoretycznego punktu widzenia, są takie kompozyty których makro-właściwości są izotropowe np. stal posiadająca wewnętrzną mikro-strukturę traktowana jest makroskopowo jako ciało izotropowe. W pracy przedstawiono homogenizację kompozytów wykorzystując metodę elementów skończonych.

Parametric Modeling of Space Frame Structures, Kacprzyk Z., Ostapska–Łuczkowska K., Theoretical Foundations of Civil Engineering, Polish-Ukrainian Transactions. Ed. by W. Szcześniak, pp. 167-172, Warsaw 2014.
Abstract: The subject of this paper is a study of different mathematical models of curves and surfaces applied in CAD systems with an aim to identify best modelling approach for a certain design problems. The study is supported by practical examples performed with the use of commercial software. Examples show how modelling approach differs or should differ for different space frames types. For better model efficiency, irrelevant elements are neglected in certain models.
XXIII R-S-P Seminar, Theoretical Foundation of Civil Engineering (23RSP) (TFoCE 2014) PDF Print E-mail
tfoce 2014XXIII R-S-P Seminar, Theoretical Foundation of Civil Engineering (23RSP) (TFoCE 2014)
Edited by Marian Drusa, Ruzica R. Nikolic and Marian Marschalko, Procedia Engineering, Volume 91, Pages 1-492 (2014)

Isogeometric Analysis as a New FEM Formulation - Simple Problems of Steady State Thermal Analysis, Zbigniew Kacprzyk, Katarzyna Ostapska-Łuczkowska, Pages 87-92, doi:10.1016/j.proeng.2014.12.018
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Abstract: The subject of this article concerns Isogeometric Analysis as a new formulation within Finite Element Method. Motivation for this new approach was presented together with theoretical foundations of the method. The main subject of the paper is numerical implementation of the method in the Matlab environment. Special focus was put on the new concept of element and new geometry data interpretation in terms of analysis. Object oriented programming was utilized to produce more universal tool for future investigations. Several examples for Poisson's partial differential equation solution were presented. The h-refinement was utilized to show method convergence. Steady state thermal analysis was performed with temperatures and heat flux as boundary conditions. Quick geometry data transfer and mesh refinement from Rhino software with Grasshopper plug-in was also prepared and described in the paper. Finally, authors' conclusions concerning new method were presented and comparison between FEM and IGA was made on the basis of the studied examples.
Keywords: Isogeometric Analysis (IGA); Finite Element Method (FEM); B-spline; NURBS; T-spline; CAD; Computer Aided Engineering ;

Dynamics of Multi-body Mechanical Systems with Unilateral Constraints and Impacts, Artur Zbiciak, Zofia Kozyra, Pages 112-117, doi:10.1016/j.proeng.2014.12.024
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Abstract: The paper deals with mathematical description and computer simulation of multi-body dynamical systems with constraints imposed on displacements and velocities. Such mechanical systems contain a finite number of material points, whose motion is limited by unilateral constraints. The mathematical description of the problem, concerning the interaction between material points and unilateral constraints, is presented. The dynamic problem was defined in order to evaluate accelerations of elements and reactions of constraints. Moreover, the impact problem was formulated. The solution of the impact problem determines non-continuous change in velocities of elements and impulses of constraints' reactions.
Keywords: dynamics; non-smooth mechanics; multi-body systems; unilateral constraints; impact; contact; non-linear vibrations ;

Traditional Design versus BIM Based Design, Ireneusz Czmoch, Adam Pękala, Pages 210-215, doi:10.1016/j.proeng.2014.12.048
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Abstract:The paper shortly presents the history and development of the traditional design in civil engineering. Next, the idea of Building Information Modelling (BIM) and its practical benefits are described. Main part of the paper is devoted to discussion about what kind of difficulties we may encounter during the implementation of the BIM technology and how they are related to the potential benefits. Case study presents the existing design prepared in BIM technology.
Keywords: traditional design; civil engineering; CAD; BIM

Building Information Modelling – 4D Modelling Technology on the Example of the Reconstruction Stairwell, Zbigniew Kacprzyk, Tomasz Kępa, Pages 226-231, doi:10.1016/j.proeng.2014.12.051
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Abstract: Building Information Modelling (BIM) is a process that involves creating, generating, managing and using a digital representations of physical and functional characteristics of building. The use of the term 4D is intended to refer to the fourth dimension: time, i.e. 4D is 3D + schedule (time). The role of 4D BIM is to add a new dimension to 3D CAD or solid modelling—that is, 4D BIM adds a fourth dimension of Time to the 3D Space of CAD solid modelling on computer. In the paper show the project entirely made using 4D BIM
Keywords: Building Information Modelling (BIM); 3D design; CAD; architectural engineering and construction (AEC) software
Złota Kreda PDF Print E-mail

Złota Kreda
A note on optimal design of multiphase elastic structures PDF Print E-mail
structural optimizationA note on optimal design of multiphase elastic structures
N. Briggs, A. Cherkaev, G. Dzierżanowski
Structural and Multidisciplinary Optimization: Volume 51, Issue 3 (2015), Page 749-755,
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The paper describes the first exact results in optimal design of three-phase elastic structures. Two isotropic materials, the "strong" and the "weak" one, are laid out with void in a given two-dimensional domain so that the compliance plus weight of a structure is minimized. As in the classical two-phase problem, the optimal layout of three phases is also determined on two levels: macro- and microscopic. On the macrolevel, the design domain is divided into several subdomains. Some are filled with pure phases, and others with their mixtures (composites). The main aim of the paper is to discuss the non-uniqueness of the optimal macroscopic multiphase distribution. This phenomenon does not occur in the two-phase problem, and in the three-phase design it arises only when the moduli of material isotropy of "strong" and "weak" phases are in certain relation.
Optymalizacja topologiczna konstrukcji inżynierskich. PDF Print E-mail
Projekt badawczy Narodowego Centrum Nauki pt.:
Optymalizacja topologiczna konstrukcji inżynierskich. Ujęcie syntetyzujące metody: projektowania anizotropii z wolnego wyboru, projektowania materiałów niejednorodnych oraz metodę siatek typu Michella,
Kierownik: prof. dr hab. inż. Tomasz Lewiński,
Politechnika Warszawska; Wydział Inżynierii Lądowej,
środki przyznane: 772 040 zł,
zajął 5. miejsce spośród 188 projektów złożonych w ramach konkursu: OPUS, Panel ST 8 (data ogłoszenia: 16 IX 2013 r.). Do drugiego etapu zakwalifikowano 47 wniosków; do finansowania skierowano 32 wnioski.

Projekt ten będzie wykonywany w ramach umowy:
zawartej w dniu 15 lipca 2014 r. pomiędzy
NCN a Politechniką Warszawską.
Nr projektu: 2013/11/B/ST8/04436
Okres realizacji: 15.07.2014-14.07. 2017, przedłużony aneksem do 14.12.2017.
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