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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 ...

Towards Rotordynamic Analysis with COMSOL Multiphysics

M. Karlsson[1]
[1]ÅF, Stockholm, Sweden

In this paper a pre-study on using COMSOL Multiphysics for rotordynamic analysis is presented. It is concluded that it is possible to use COMSOL Multiphysics to perform rotordynamical analysis. However, there are no standard environment for rotordynamics, hence the user has to extend the structural model with the rotordynamics effect such as gyroscopic effect and rotordynamical coefficients. By ...

Optimization of an Acoustic Waveguide for Professional Audio Applications

M. Cobianchi[1] and R. Magalotti[1]
[1] B&C Speakers S.p.a., Bagno a Ripoli, FI, Italia

In modern live sound reinforcement there is a growing use of line sources, obtained through the stacking of many loudspeakers with properly controlled wavefront shape. Thus the use of waveguides is mandatory in order to modify the shape and size of the wavefront exiting from professional compression drivers. With the help of COMSOL Multiphysics®, we have designed a waveguide featuring an ...

Design of Ultrasonic MEMS Temperature Sensor Using COMSOL Multiphysics® Software

S. K. Kamilla [1], G. Parag [1], H. Tripathy [1], P. Pattanaik [1],
[1] Semiconductor Research Lab, ITER, Siksha 'O' Anusandhan University, Bhubaneswar, Odisha, India

The attempt has taken to miniaturized size of non contact temperature sensor by using ultrasonic trans-receiver. The piezoelectric material is used in both transmitter and receiver ends for this ultrasonic Micro-Electronics Mechanical Systems (MEMS) based temperature sensing device. Prior to fabrication of ultrasonic MEMS device, design and simulation are extensively used to avoid wastage of ...

Simulação de um Sistema de Levitação Acústica para Manipulação de Partículas em Ar

M. A. B. Andrade [1], N. Pérez [2], J. C. Adamowski [3],
[1] Instituto de Física, Universidade de São Paulo, São Paulo, SP, Brasil
[2] Centro Universitario de Paysandú, Universidad de la República, Paysandú, Uruguai
[3] Departamento de Engenharia Mecatrônica e Sistemas Mecânicos, Escola Politécnica, Universidade de São Paulo, São Paulo, SP, Brasil

Este trabalho apresenta a simulação numérica de um sistema de levitação acústica para manipulação de partículas em ar. O sistema de levitação consiste de dois transdutores de ultrassom e um refletor de face plana. Através da simulação é calculado o potencial da força de radiação acústica que atua numa esfera. Os resultados da simulação são verificados experimentalmente através da comparação da ...

Analysis of High-Frequency Thermoacoustic Instabilities in Lean, Premixed Gas Turbine Combustors

F. Berger [1], T. Hummel [1], P. Romero [1], M. Schulze [1], B. Schuermans [2], T. Sattelmayer [1],
[1] Lehrstuhl für Thermodynamik, TU München, Germany
[2] GE Power, Switzerland

Modern gas turbine systems for power generation are prone develop so-called thermosacoustic instabilities in the combustion chamber. Physically, these instabilities emerge as large amplitude pressure oscillations within the combustor, which are caused by constructive feedback interactions between the flame and the combustor's natural acoustic modes. The oscillations disturb the combustion ...

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 ...

Phase Decomposition for Loudspeaker Analysis

R. Christensen [1],
[1] GN ReSound A/S, Copenhagen, Denmark

The vibration of an electrodynamic loudspeaker driver causes a resulting sound pressure. For simple pistonic vibration, there is a simple relationship between the vibration and the sound pressure. For complex vibration patterns, however, different parts of the vibrating surface contribute differently to the sound pressure, depending on the position in which the sound pressure is evaluated. A ...

Numerical Vibration Analysis of Impacted CFRP Specimens Using COMSOL Multiphysics® Software

P. Jatzlau [1], F. Seybold [1], C. Grosse [1],
[1] Technical University of Munich, Chair of Non-destructive Testing, Munich, Germany

The vibration behavior of carbon fiber reinforced composites (CFRP) specimens with impact damage is presented in order to evaluate if an before/after modal analysis can be used as a non-destructive testing method to detect delaminations. The impact damage is modeled by decreasing the stiffness in the described area of delamination. As detailed experimental data exists for the modeled structure, ...

Lamb Waves in Fluid-Loaded Plates

T. Kaufmann[1], F. Kassubek[1], D. Pape [1], M. Lenner[1]
[1]ABB Corporate Research, Baden-Dättwil, Switzerland

Lamb waves are elastic waves propagating in free solid plates. In the case of plates loaded with a fluid, the equations describing these waves have to be modified to include the effects of the fluid. In our work we have tackled this problem using COMSOL Multiphysics®. We have used the two-dimensional plane strain model of the solid mechanics interface to calculate the eigenmodes of the coupled ...