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Pozycja Nośność graniczna cienkościennych słupów z centralnymi żebrami pośrednimi w ramach drugiego rzędu nieliniowego przybliżenia(Wydawnictwo Politechniki Łódzkiej, 1997) Kołakowski, Zbigniew; Teter, A.W pracy przeanalizowano interakcyjne wyboczenie cienkościennych słupów wzmocnionych żebrami pośrednimi. Żebra modelowano płytami. Przyjęto, że słupy są swobodnie podparte na obu końcach. Zastosowano drugi rząd nieliniowego przybliżenia asymptotycznej metody Byskowa i Hutchinsona [1] wykorzystując w obliczeniach numerycznych metodę macierzy przejścia. Analizę przeprowadzono dla różnych parametrów geometrycznych.Pozycja Global and local instability of thin-walled columns beyond the proportional limit(Wydawnictwo Politechniki Łódzkiej, 1997) Kołakowski, Zbigniew; Kowal-Michalska, KatarzynaThe problem of global and local stability in the inelastic range for thin-walled columns is examined on the basis of the defonnation theory and the incremental theory of plasticity. Columns of closed and open cross-sections built from rectangular isotropic plates are subjected to the loading changing from unifonn compression to pure bending. A solution of elastic buckling for a thin-walled orthotropic columns based on Koiter's asymptotic method is employed to investigate the elasto-plastic buckling mode of the colunm and to detennine the critical load. The study is based on the numerical method of the transition matrix. The results of numerical calculations are presented in diagramsPozycja Static Buckling of FML Columns in Elastic-Plastic Range.(Lodz University of Technology. Faculty of Mechanical Engineering. Department Division of Dynamics., 2016) Kołakowski, Zbigniew; Kowal-Michalska, KatarzynaThe paper deals with the elasto-plastic buckling of thin-walled Fiber Metal Laminates short columns/profiles subjected to axial uniform compression. Structures of open and hollow (closed) cross-sections are considered build of at plate walls. Multilayered FML walls are considered as built of alternating layers of aluminum and fiber-glass composite. Three elastic-plastic theories are employed for constitutive relations description of aluminum layers i.e. fully elastic material behavior, the J2-deformation theory of plasticity and the J2 flow theory later both with Ramberg-Osgood formula application, whereas composite layers are assumed elastic within whole loading range. Some exemplary results determined with the application of own analytical-numerical method based on the Koiter's theory, in the Byskov and Hutchinson formulation are enclosed in the form of tables and plots.Pozycja Local Buckling of Thin-Walled Column of Square Cross-Section Made of In-Plane Coupled Laminate.(Lodz University of Technology. Faculty of Mechanical Engineering. Department Division of Dynamics., 2016) Kołakowski, Zbigniew; Teter, Andrzej; Pasierbiewicz, DamianThe non–symmetric, general laminate exhibits different types of coupling between the extension, shearing, bending and twisting. For practical reasons, the in–plane coupled laminate is a particularly interesting. In this case, the coupling between shearing andextension takes place. Details calculations were performed for a short columns of square cross-section made of in–plane coupled and fully uncoupled laminate under uniform compression. Finite element method (FEM) and analytical–numerical method (ANM) were performed. In FEM analyses, the eigenbuckling problem has been solved using the Lanczos method, whereas the nonlinear buckling analysis were performed using the Newton– Raphson method and the Ritz method. In ANM analyses, the Koiter’s asymptotic theory is applied. The relationship between forces/moments and deformations/curvature were described using classical lamination theory (CLT). The coupling between in–plane shearing and extension has a significant influence on the behavior of thin–walled structures under compression.Pozycja Comparision of Numerical Results with Known Solutions of Buckling Problem of Pressured Shallow Spherical Shells.(Lodz University of Technology. Faculty of Mechanical Engineering. Department Division of Dynamics., 2016) Lykhachova, Olga; Kołakowski, ZbigniewBuckling problem of pressured shallow spherical shells is studied numerically for two types of finite elements: axisymmetric and non–axisymmetric. A very good correspondence of obtained results and known solutions is revealed in the case of clamed and hinged spherical segments for both types of finite elements. The comparison of results also shows that using non–axisymmetric finite element lets one get full pre– and post–buckling equilibrium path in the range of relative deflections w=h.Pozycja Static and dynamic interactive buckling regarding axial extension mode of thin-walled channel(Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej, 2010) Kołakowski, ZbigniewThe present paper deals with an influence of the axial extension mode on static and dynamic interactive buckling of a thin-walled channel with imperfections subjected to uniform compression when the shear lag phenomenon and distortional deformations are taken into account. A plate model is adopted for the channel. The structure is assumed to be simply supported at the ends. Equations of motion of component plates were obtained from Hamilton's principle taking into account all components of inertia forces. In the frame of first order nonlinear approximation, the dynamic problem of modal interactive buckling is solved by the transition matrix using the perturbation method and Godunov's orthogonalization.Pozycja Static and dynamic interactive buckling of composite columns.(Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej, 2009) Kołakowski, ZbigniewThe static and dynamic problem of interaction of global buckling modes in compressed columns with complex open and closed cross-sections was considered in the paper. The columns made of laminate composites were assumed to be simply supported at both loaded ends. A plate model was adopted in the analysis. The equations of motion of individual pla- tes (Schokker et al., 1996; Sridharan and Benito, 1984) were obtained from Hamilton’s Principle, taking into account all components of iner- tia forces (Teter and Kołakowski, 2005). Within the frame of the first order nonlinear approximation, the dynamic problem of modal interac- tive buckling was solved by the transition matrix using a perturbation method. Distortions of cross-sections and the shear-lag phenomenon were taken into consideration in the problem solution. A modification of the quasi-bifurcation dynamic Kleiber-Kotula-Saran criterion (Kleiber et al., 1987) was proposed. A comparison of the proposed modification to the Budiansky-Hutchinson criterion (Budiansky and Hutchinson, 1966; Hutchinson and Budiansky, 1966) was presented for a rectangular pulse loading.Pozycja Some aspects of the axial extension mode in an elastic thin-walled beam-column.(Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej, 2012) Kołakowski, ZbigniewThe present paper deals with the influence of the axial extension mode on static and dynamic interactive buckling of a thin-walled beam-column with imperfections subjected to uniform compression when the shear lag phenomenon and distortional deformations are taken into account. A plate model (2D) is adopted for the beam-column. One- and two-dimensional models of the elements are compared, too. The structure is assumed to be simply supported at the ends. Equations of motion of the component plates are obtained from Hamilton’s Principle, taking into account all components of inertia forces. Within the frame of the first order nonlinear approximation, the dynamic problem of modal interactive buckling is solved by the transition matrix using the perturbation method and Godunov’s orthogonalization.Pozycja Free and forced oscillations of Timoshenko beam made of viscoelastic material.(Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej, 2011) Manevich, A.; Kołakowski, ZbigniewDynamics of Timoshenko's beam made of a viscoelastic material is studied. Dimensionless equations of motion are obtained, depending only on two parameters, one of which relates to the shear flexibility and the second – to the viscous internal friction. Advantages of the proposed equations are illustrated by solutions to the free and forced oscillation problems for the simplest case of hinged-hinged beams. The influence of the beam shear flexibility and viscous internal friction on the natural frequencies and the dynamic amplification factor is studied.Pozycja Damping behaviour of thin-walled composite columns under impact in-plane loading(Politechnika Łódzka. Katedra Wytrzymałości Materiałów i Konstrukcji., 2012) Teter, A.; Kołakowski, ZbigniewIn this paper the analysis of the damping behaviour of thin-walled composite columns with open stiffened cross-sections subjected to in-plane pulse loading is described. The pulse loading of a rectangular shape is concerned. The discussed problem of the dynamic interactive buckling is solved by the analytical-numerical method (ANM) using the Koiter’s perturbations method. A critical value of the dynamic load factors is determined according to the Budiansky-Hutchinson’s criterion for different value of the viscous damping ratio. The detailed calculations confirm that small damping does not affect the dynamic response of the thin-walled composite columns under the impact in-plane loading.