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Vibration Analysis of a Carbon Nanotube Reinforced Uniform and Tapered Composite Beams

Babu Arumugam Ananda, Rajamohan Vasudevan, Bandaru Naresh, Sudhagar P. Edwin, Kumbhar Surajkumar G.

Archives of Acoustics

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2019

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Vol. 44, No. 2

309--320

EN

In this study, free and forced vibration responses of carbon nanotube reinforced uniform and tapered composite beams are investigated. The governing differential equations of motion of a carbon nanotube (CNT) reinforced uniform and tapered composite beams are presented in finite element formulation. The validity of the developed formulation is demonstrated by comparing the natural frequencies evaluated using present FEM with those of available in literature. Various parametric studies are also performed to investigate the effect of aspect ratio, percentage of CNT content, ply orientation, and boundary conditions on natural frequencies and mode shapes of a CNT reinforced composite beam. It was observed that the addition of carbon nanotube in fiber reinforced polymer composite (FRP) beam enhances the stiffness of the structure which consequently increases the natural frequencies and alters the mode shapes.

2

Control of a Finite Element Based Dynamic System

Marcsa D., Kuczmann M.

Przegląd Elektrotechniczny

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2015

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R. 91, nr 12

155-158

EN

This paper presents the formulation of the circuit-coupled finite element method embedded in closed loop control system. The controller checks the output of the dynamic system after each time step and controls the input (current or voltage) to reach the steady state faster. The analysed dynamic systems are a voltage fed solenoid with iron core, and a three phase switched reluctance motor. The results of the voltage driven solenoid are compared with the results from the analytical model. The control parameters for the proportional-integral-derivative controller were estimated using the step response of the solenoid. The controller of switched reluctance motor is a speed and position based control logic.

PL

W artykule zaprezentowano sformułowanie sprzężone obwodowo-elementowoskończeniowe wykorzystanoe w systemie sterowania z zamkniętą pętlą. Kontroler sprawdza wyjście z systemu dynamicznego po każdym kroku czasowym i steruje wejście (prąd lub napięcie) w celu szybszego dojścia do stanu ustalonego. Analizowane systemy dynamiczne są napięciowo zasilanymi solenoidami z rdzeniem żelaznym w połączeniu z trójfazowym przełączalnym silnikiem reluktancyjnym. Wyniki otrzymane dla układu napędowego porównane zostały z wynikami otrzymanymi w modelu analitycznym. Parametry sterowania sterownika różniczkowo-całkowego zostały estymowane za pomocą analizy skokowej odpowiedzi solenoidu. Sterownik silnika reluktancyjnego przełączalnego bazuje na logice sterowania szybkości i położenia.

3

Modeling of shell-beam transitions in the presence of finite rotations

Wagner W., Gruttmann F.

Computer Assisted Mechanics and Engineering Sciences

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2002

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Vol. 9, No. 3

405-418

EN

A finite element formulation for a transition element between shells and beam structures is described in this paper. The elements should allow changes between models in an `optimal' way without or with little disturbances which decrease rapidly due to the principle of Saint-Venant. Thus, the constraints are formulated in such a way that a transverse contraction within the coupling range is possible. The implementation of the coupling conditions is done with the Penalty Method or the Augmented Lagrange Method. The element formulation is derived for finite rotations. Same rotational formulations are used in beam and shell elements. Rotational increments up to an angle of 2pi are possible without singularities based on a multiplicative update procedure. It can be shown that the transition to rigid bodies can be derived with some modifications. Examples prove the reliability of the transition formulation. Here simple element tests and practical applications are shown.