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Application of a Weakly Non-Linear Analysis to the Analysis of Thermoacoustic Combustion Instabilities - new

D. Laera[1], S. M. Camporeale[1], G. Campa[2]
[1]Politecnico di Bari, Bari, Italy
[2]Ansaldo Energia, Genoa, Italy

The thermoacoustic combustion instabilities are complex phenomena that may occur in steady flow combustion systems that are aboard of, e.g., rocket engines or gas turbines. The phenomena involve the interaction of chemical reactions with fluid-dynamic and propagation of pressure waves in the combustion chamber. Combustion instabilities may lead to a stable condition (known as “limit-cycle”) ...

Loudspeaker Response Optimization with the Aid of Impulse Response

R. Balistreri [1],
[1] Klipsch Group, Inc., Indianapolis, IN, USA

COMSOL Multiphysics® simulation software is receiving a lot of attention in the loudspeaker industry thanks to the quality of the results it provides making it an essential tool to optimize geometries so that the best reproduction capabilities of the loudspeaker system are achieved. Setting up a loudspeaker simulation requires defining a geometry with moving diaphragm. This can be done ...

Design of Electroacoustic Absorbers Using PID Control

H. Lissek, R. Boulandet, and M. Maugard
Ecole Polytechnique Federale de Lausanne
Lausanne, Switzerland

An \"electroacoustic absorber\" is a loudspeaker, used as an absorber of sound, which acoustic impedance can be varied by electrical means. This can be achieved either by plugging passive shunt electric networks at the loudspeaker terminals (“shunt loudspeakers”) or by feeding back the loudspeaker with a voltage proportional to acoustic quantities, such as sound pressure and diaphragm normal ...

Numerical Simulation of Phonon Dispersion Relations for Phononic Crystals

G. Zhu[1], E.M. Dede[1]
[1]Toyota Research Institute of North America, Ann Arbor, MI, USA

In previous work, a two-dimensional (2D) model was carried out to simulate the phononic band structure of a phononic crystal with square lattice structure, but this model did not account for the out-of-plane phonon dispersions [1]. In fact, for 2D films used for coating materials, it is more interesting to understand their cross-plane properties. In this work, the phonon dispersion relation of ...

Simulation of an Ultrasonic Immersion Test for the Characterization of Anisotropic Materials

A. Castellano[1], P. Foti[1], A. Fraddosio[1], S. Marzano[1], M.D. Piccioni[1], D. Scardigno[1]
[1]DICAR, Politecnico di Bari, Bari, Italy

Introduction: Improving the capability of nondestructive evaluations requires the analysis of suitable models dealing with the physical and mechanical phenomena involved in the experiments. For example, ultrasonic tests may be a powerful, fast and effective method for nondestructive characterization of mechanical properties of materials. This requires the study of the related elastodynamic ...

Dynamic Characterization and Mechanical Simulation of Cantilevers for Electromechanical Vibration Energy Harvesting

N. Alcheick[1], H. Nesser[1], H. Debeda[1], C. Ayela[1], I. Dufour [1]
[1]Univ. Bordeaux, IMS Lab, Pessac, France

Energy harvesting from ambient vibrations has become an interesting topic for powering wireless sensor networks. Resonant microdevices based on MEMS have become of central importance at low frequency. The power produced at resonance is at least one order of magnitude larger than off frequency power since the largest strain is obtained at resonance. In order to obtain large strain for efficient ...

A FEM Study of Displacement Sensor Based on Magnetostrictive/Piezoelectric Composite Material

Qingwei Liu [1], Hangjie Mo [1]
[1] Shanghai Jiao Tong University, Shanghai, China

This paper studies the application of laminate magnetoelectric (ME) material in displacement sensor. We studied the L-L block composite thanks to designed structure by coupling displacement signal with the displacement potential of ME composite. A nonlinear approximation is adapted to modeling magnetostrictive phase and implemented in COMSOL Multiphysics® software. The simulation results ...

Sound Field Analysis of Monumental Structures by the Application of Diffusion Equation Model - new

Z. S. Gul[1], N. Xiang[2], M. Caliskan[3]
[1]Department of Architecture, Middle East Technical University, Ankara, Turkey
[2]School of Architecture, Rensselaer Polytechnic Institute, Troy, NY, USA
[3]Department of Mechanical Engineering, Middle East Technical University, Ankara, Turkey

Sound energy distribution patterns within enclosed spaces are the basic concerns of architectural acoustics. Energy decays are analyzed for major acoustical parameter estimations, while spatial energy distribution and flow vectors are indicative in the analysis of sound energy circulation and concentration zones. In this study the acoustical field of a real-size multi-domed monumental ...

Parametric Simulation of PZT Diameter to Hole Ratio for Optimized Membrane Displacement

A. Arevalo [1], D. Castro [1], D. Conchouso [1], I. G. Foulds [2]
[1] Computer, Electrical and Mathematical Sciences and Engineering (CEMSE), King Abdullah University of Science and Technology (KAUST), Saudi Arabia
[2] The University of British Columbia, School of Engineering, Okanagan Campus, Saudi Arabia

For our simulation we used the Piezoelectric Devices interface. The structure was set with (clamped) fix constraint boundaries to both ends. The bottom electrode was set to be the ground for the electrostatic physics and the top electrode was set to be a Terminal with potential of 10V. A parametric sweep study was set to change the geometry, the parameters to change was the hole diameter (Holed) ...

Design and Implementation of Multichannel Piezoelectric Acoustic Sensor

R. S. Hallikar [1], S. Munshi [1], M. U. Kumari[1], K. Padmaraju[2],
[1] R. V. College of Engineering, Bengaluru, Karnataka, India
[2] JNTU Kakinada, Kakinada, Andhra Pradesh, India

This paper concentrates on developing a self-contained cochlea whose performance is at par with natural hearing. The Artificial Basilar Membrane (ABM) design is done in such a manner so as to get a performance similar to the natural hearing. Finite element analysis was done with the help of COMSOL Multiphysics software. Two materials, Polyvinylidene fluoride (PVDF) and lead zirconate titanate ( ...