Integration of active vibration control methods with finite element models of smart laminated composite structures

Vibration control problems can be directly and systematically solved in a single analysis stage using commercial finite element programs. Integration of control methods into the finite element solutions (ICFES) can be achieved in ANSYS. In this work, first, the direct velocity feedback (DVF) control is tested on a 3-DOF mechanical system under a step input. The simulation results obtained by the ICFES are compared with the analytical results obtained by the Laplace transform method. Then, active control of free and forced vibrations in a smart laminated composite structure (SLCS) with two different lay-ups is studied numerically and experimentally. The SLCS consists of a symmetric laminated glass-epoxy composite beam with [0/90](s) and [451-45](s) lay-ups and a piezoelectric actuator. For the vibration suppression, the DVF control tested on a mechanical system is applied to the SLCS. In addition, displacement feedback (DF) control is studied. Experiments are conducted to verify the natural frequencies and the closed loop time responses. Analytical results for the mechanical system and experimental results for the SLCS match well to the corresponding results obtained using the ICFES technique. (C) 2009 Elsevier Ltd. All rights reserved

Analysis of end point vibrations of a two-link manipulator by integrated CAD/CAE procedures

in this work, the effect of flexibility on the trajectory of a planar two-link manipulator is studied using integrated computer-aided design/analysis (CAD/CAE) procedures. The solid models and finite element models of the parts of the manipulator are created by using the CAD/CAE software I-DEAS. The assembly is defined, and knowing the payload and the end point trajectory, the velocities and accelerations of the parts, joint forces and driving torques are calculated using the rigid body dynamics. All the time dependent nodal forces acting on the parts including distributed gravity and inertia forces are created in files with the I-DEAS program file format. The finite element vibration analysis of the parts is performed by I-DEAS. The end point vibrations and the deviations from the rigid-body trajectory are analyzed for different types of end point acceleration curves. A circular trajectory is considered as an example. It is observed that the precision of the manipulator can be increased by testing different end point acceleration curves without changing the trajectory and the duration of the end point work. The procedure explained in this work can be used for this purpose successfully. (C) 2004 Elsevier B.V. All rights reserved

Comparison of Dynamic Performance of Piezoelectric Sensors With Different Characteristic

Günümüzde piezoelektrik malzemeler algılayıcı veya uyarıcı olarak mühendislik uygulamalarında sıklıkla kullanılmaktadır. En yaygın kullanılan piezoelektrik malzeme kurşun-zirkonyumtitanyum (PZT) piezo seramiktir. Piezo seramikler karakteristik özelliklerine göre yumuşak ve sert olarak iki ana sınıfa ayrılırlar ve PZT-2, PZT-4, PZT-5A, PZT-5H, PZT-8 olarak isimlendirilirler. Bu çalışmada, akıllı bir kirişte farklı karakteristikti piezoelektrik algılayıcının dinamik cevapları sonlu elemanlar yöntemi kullanılarak ANSYS/Workbench programında incelenmiştir. Akıllı kiriş, alüminyum kiriş ile bir piezoelektrik algılayıcı ve bir piezoelektrik uyarıcıdan oluşmuştur. Akıllı kirişte hem uç noktasına tekil kuvvet, hem uyarıcıya voltaj, darbe ve adım girdiler şeklinde uygulanmıştır. Algılayıcı ve yer değiştirme sinyalleri dinamik analiz yapılarak elde edilmiştir. Akıllı kirişin piezoelektrik algılayıcı konumu ve karakteristiğine göre farklı dinamik cevaplar verdiği gözlemlenmiştir.Nowadays, piezoelectric materials have been widely used as a sensor or an actuator in engineering applications. The most commonly used piezoelectric material is lead-zirconatetitanium (PZT) ceramic. According to the characteristics, piezo ceramics are classified into two main classes, soft PZTs and hard PZTs, and they are called as PZT-2, PZT-4, PZT-5A, PZT-5H, PZT-8. In this work, dynamic responses of a piezoelectric sensor with different characteristics of a smart beam were investigated by using the finite element method in ANSYS/Workbench program. The smart beam was composed of an aluminum beam and a PZT sensor and a PZT actuator. Both a single force to the end point and a voltage to the actuator were applied in the smart beam in the form of impulse and step inputs. Sensor and displacement signals were obtained by performing the dynamic analysis. It was observed that the smart beam has varied dynamic responses via the location and characteristic of piezoelectric sensor

Implementation of Active and Passive Vibration Control of Flexible Smart Composite Manipulators with Genetic Algorithm

Endpoint vibrations of flexible manipulators (FM) are suppressed using active or passive control techniques. Suppressing vibrations increases the dynamic performance of the FM in engineering applications. In this study, a model extraction approach is proposed for vibration suppression of single-link flexible smart and composite manipulators. Active and passive control (APC) of residual vibrations is studied theoretically and experimentally. The smart manipulator consists of patching a piezoelectric (PZT) actuator to an aluminum and composite link. The finite element (FE) model of smart manipulators, including revolute joint and PZT actuator, is created in ANSYS. The motion profile and actuator voltage are the inputs, the tip displacement is the output. Then, the state-space (SS) mathematical models of the smart manipulators are extracted from the FE models by using the inputs and outputs. The open-loop and closed-loop simulations are performed using the extracted mathematical models in MATLAB. Passive control is achieved by the motion profiles, while active control is achieved by the PZT actuators. The PD controller with the displacement feedback is used to create the actuation voltages. For the optimized APC, the PD gains are optimized with a genetic algorithm by using the integral of the squared error and integral of absolute magnitude of the error fitness functions. Residual vibrations of smart manipulators are successfully reduced by the optimized APC. To verify the simulation results, open-loop and closed-loop experiments are carried out. The SS mathematical model successfully predicts the dynamic performance of FSM for various motion profiles, according to experimental results