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CONTENTS
Volume 5, Number 5, September 2009
 

Abstract
The present work is an alternative methodology in order to balance a nonlinear highly flexible rotor by using neural networks. This procedure was developed aiming at improving the performance of classical balancing methods, which are developed in the context of linearity between acting forces and resulting displacements and are not well adapted to these situations. In this paper a fully experimental procedure using neural networks is implemented for dealing with the adaptive balancing of nonlinear rotors. The nonlinearity results from the large displacements measured due to the high flexibility of the foundation. A neural network based meta-model was developed to represent the system. The initialization of the learning procedure of the network is performed by using the influence coefficient method and the adaptive balancing strategy is prone to converge rapidly to a satisfactory solution. The methodology is tested successfully experimentally.

Key Words
adaptive balancing; rotating machinery; neural networks; meta-modeling; nonlinear rotor.

Address
M. Villafane Saldarriaga; Mechanical Systems Laboratory, School of Mechanical Engineering, Federal University of Uberlandia,38400-902 Uberlandia, Brazil
J. Mahfoud; Laboratoire de Mecanique des Contacts et des Structures, UMR CNRS 5259, Institut National des Sciences Appliquees de Lyon, France
V. Steffen Jr.; Mechanical Systems Laboratory, School of Mechanical Engineering, Federal University of Uberlandia,38400-902 Uberlandia, Brazil
J. Der Hagopian; Laboratoire de Mecanique des Contacts et des Structures, UMR CNRS 5259, Institut National des Sciences Appliquees de Lyon, France

Abstract
This paper presents the development of a new Adaptive Tuned Dynamic Vibration Absorber (ATDVA) working with magnetorheological elastomers (MREs). The MRE materials were fabricated by mixing carbonyl iron particles with silicone rubber and cured under a strong magnetic field. An ATDVA prototype using MRE as an adaptable spring was designed and manufactured. The MRE ATDVA worked in a shear mode and the magnetic field was generated by a magnetic circuit and controlled through a DC power supply. The dynamic performances or the system transmissibility at various magnetic fields of the absorber were measured by using a vibration testing system. Experimental results indicated that this absorber can change its natural frequency from 35Hz to 90Hz, 150% of its basic natural frequency. A real time control logic is proposed to evaluate the control effect. The simulation results indicate that the control effect of MRE ATDVA can be improved significantly.

Key Words
tuned dynamic vibration absorber; magnetorheological elastomers; transmissibility; vibration control efficiency.

Address
X. Z. Zhang and W. H. Li; School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong,
NSW 2522, Australia

Abstract
In the present analysis, the spline finite strip with higher-order shear deformation is formulated for the static analysis of piezoelectric composite plates. The proposed method incorporates Reddy

Key Words
piezoelectric composite plate; spline finite strip method; Reddy

Address
G. Akhras and W. C. Li; Department of Civil Engineering, Royal Military College of Canada, P.O. Box 17000, STN Forces, Kingston, Ontario, K7K 7B4, Canada

Abstract
Based on the theory of piezoelasticity, an analytical solution for a typical multilayer piezoelectric composite cantilever is obtained by the Airy function method. The piezoelectric cantilever may consist of any number of layers. Moreover, the material and thickness for different layers may be different. The solution obtained in the present paper is concise and can be easily applied for the bending analysis of multilayer piezoelectric actuators considering the effect of bonding layers and electrodes. At last, a comprehensive parametric study is conducted to show the influence of electromechanical coupling (EMC), the number of piezoelectric layers, the elastic modulus of elastic layer and the thickness ratio on the bending behavior of actuators. Some interesting results for the design of multilayer piezoelectric actuators are presented.

Key Words
piezoelectric material; piezoelectric composite; multilayer; actuators.

Address
H. J. Xiang and Z. F. Shi; School of Civil Engineering, Beijing Jiaotong University, 100044, Beijing, P. R. China

Abstract
Superelastic Shape Memory Alloys (SMAs) are gaining acceptance for use as reinforcing bars in concrete structures. The seismic behaviour of concrete frames reinforced with SMAs is being assessed in this study. Two eight-storey concrete frames, one of which is reinforced with regular steel and the other with SMAs at the plastic hinge regions of beams and regular steel elsewhere, are designed and analyzed using 10 different ground motion records. Both frames are located in the highly seismic region of Western Canada and are designed and detailed according to current seismic design standards. The validation of a finite element (FE) program that was conducted previously at the element level is extended to the structure level in this paper using the results of a shake table test of a three-storey moment resisting steel RC frame. The ten accelerograms that are chosen for analyzing the designed RC frames are scaled based on the spectral ordinate at the fundamental periods of the frames. The behaviour of both frames under scaled seismic excitations is compared in terms of maximum inter-storey drift, top-storey drift, inter-storey residual drift, and residual top-storey drift. The results show that SMA-RC frames are able to recover most of its post-yield deformation, even after a strong earthquake.

Key Words
concrete frame; shape memory alloy; superelasticity; finite element analysis; residual drift; seismic damage.

Address
M. Shahria Alam, Moncef Nehdi* and Maged A. Youssef; Department of Civil and Environmental Engineering, The University of Western Ontario London, Ontario, N6A 5B9, Canada

Abstract


Key Words


Address
Hakan Ersoy; Akdeniz University, Mechanical Engineering Department, Division of Mechanics, Turkey
Lutfiye Ozpolat; Akdeniz University, Civil Engineering Department, Division of Mechanics, Turkey
Omer Civalek; Akdeniz University, Civil Engineering Department, Division of Mechanics, Turkey
Baki Ozturk; Ni de University Civil Engineering Department, Division of Mechanics, Turkey


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