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Use of an active element for dynamic control of a thin-walled laminated beam with kinematic excitation

Gawryluk Jarosław, Mitura Andrzej, Teter Andrzej

Archive of Mechanical Engineering

2019

Vol. LXVI, nr 3

379--387

The paper describes the dynamics of a composite cantilever beam with an active element. The vibrations of the kinematically excited beam are controlled with the use of a Macro Fiber Composite actuator. A proportional control algorithm is considered. During the analysis, actuator is powered by a time-varying voltage signal that is changed proportionally to the beam deflection. The MFC element control system with the implemented algorithm allowed for changing the stiffness of the tested structure. This is confirmed by the numerical and experimental results. Resonance curves for the beam with and without control are determined. The results show a very good agreement in qualitative terms.

Comparison of the theoretical load carrying capacity with the experimental data for some thin-walled plates and beams with intermediate stiffeners.

Teter Andrzej, Kołakowski Zbigniew

Archive of Mechanical Engineering

2001

Vol. 48, nr 1

29-54

In the present paper, an analysis of lower bound estimation of the load carrying capacity of structures with intermediate stiffeners is undertaken. Thin-walled structures with intermediate stiffeners in the elastic range, being under axial compression and a bending moment, are examined on the basis of the Byskov and Hutchinson's method and the co-operation between all the walls of the considered structures is shown. The structures are assumed to be simply supported at the ends. The study is based on the numerical method of the transition matrix, using Godunov's orthogonalization. Instead of the finite strip method, the exact transition matrix method is used in this case. In the presented method for lower bound estimation of the load carrying capacity of structures, it is postulated that the reduced local critical load should be determined taking into account the global pre-critical bending within the first order non-linear approximation to the theory of the interactive buckling of the structure. The results are compared to those obtained from the design code and the data reported by other authors. The present paper is the continuation of papers, where the interactive buckling of thin-walled beam columns with central intermediate stiffeners in the first and the second order approximation was considered. The most important advantage of this method is that it enables us to describe a complete range of behaviour of thin-walled structures from all global (flexural, flexural-torsional, lateral, distortional and their combinations) to local stability. In the solution obtained, the effects of interaction of modes, the transformation of buckling modes with an increase in load, the shear lag phanomenon and also the effect of cross-sectional distortion are included.

W prezentowanej pracy wyznaczono teoretyczne wartości nośności granicznej dla cienkościennych dźwigarów i płyt z centralnymi, wzdłużnymi żebrami pośrednimi obciążonych osiową siłą ściskającą i stałym momentem gnącym. Nieliniowe zagadnienie stateczności rozwiązano stosując teorię Byskova i Hutchinsona wykorzystując w obliczeniach numeryczną metodę macierzy przejścia. W prezentowanej metodzie oszacowania współczynników redukcji sztywności wzdłużnej postuluje się wyznaczenie zredukowanego lokalnego obciążenia krytycznego z uwzględnieniem globalnego do krytycznego zginania w ramach pierwszego nieliniowego rzędu przybliżenia teorii interakcyjnego wyboczenia konstrukcji. Otrzymane wyniki porównano z wynikami opublikowanymi przez innych autorów oraz z wartościami obliczonymi wg obowiązujących norm.