T. H. Hanley, H. T. D. Grigg, B. J. Gallacher
Newcastle University, Newcastle-Upon-Tyne, UK
Introducing a disorder into a finite periodic oscillatory system induces the presence of a 'trapped mode': a mode in which the displacement field is localised to the region of the disorder. A main inhibitor to MEMS resonators achieving a high quality (Q) factor is energy radiation through the support to the substrate. The trapped modes present a way to tune this to a minimal value. An initial ...
Castaings, M.1, Predoi, M.V.2, Hosten, B.1 1 Laboratoire Mécanique Physique, Univ. Bordeaux 1, UMR CNRS 5469, Talence, France
2 Catedra de Mecanica, Universitatea Politehnica Bucuresti, Bucuresti, Romania
Wave propagation in elastic waveguides is a problem of constant interest from the last decades. Several numerical approaches exist. The most intuitive uses time-marching routines that solve the equations of dynamic equilibrium and supply displacements of the structure nodes as time functions. This procedure is usually time and memory consuming due to huge number of temporal iterations required ...
B. Baumann1, B. Kost1, M. Wolff1,2, H. Groninga2, T. Blöß1, and S. Knickrehm1
1Hamburg University of Applied Sciences, Hamburg, Germany
2PAS-Tech GmbH, Zarrentin, Germany
First results in the automatic shape optimization of a photoacoustic sample cell are described. The aim is to maximize the sensor’s signal strength. The approach considers all shapes that can be represented by a number of axis-symmetrical truncated cones which are connected in a continuous way. In addition, the cell is subjected to certain constraints (e.g. the laser beam is not blocked during ...
Using COMSOL to Support a Cost-Effective, Non-Destructive Evaluation Approach for Predicting Bolt Failure in Highway Bridges
A. Elyea, B. Doubek, G. Hubbard, and D. Ozevin
Department of Civil Engineering
University of Illinois at Chicago
The development of a quantitative nondestructive evaluation method, as an alternative to visual inspection, for inspecting pre-tensioned bolts in fracture critical bridges is presented. In order to understand the ultrasonic behavior of a wide variety of bolt geometries used in bridges, numerical models of nine different bolt geometries were developed. The numerical models included the ...
ACOUSTICS@MBD CONSULTANTS, LLC, Westborough, MA, USA
There is a practical interest among composite materials manufacturers to high-speed accurate non-destructive evaluation (NDE) technology for voids inspection when these voids are natural components of such complex structures like resin insulated layer of double-sided copper-clad laminates. Model based design (MBD) of NDE system is one of principal solutions for voids inspection in such composites ...
D. Borelli and C. Schenone
DIPTEM, University of Genova, Genova, Italy
The present paper describes the results of a Finite Element Model used to analyze sound propagation in lined ducts. By means of a numerical model it was possible to predict the insertion loss inside rectangular lined ducts in a frequency range from 250 Hz to 4000 Hz. The model was validated by a comparison with experimental data obtained in accordance to ISO 11691 and ISO 7235 standards. The ...
Y. Jing, and N. Xiang
Graduate program of Architectural Acoustics, School of Architecture, Rensselaer Polytechnic Institute, Troy, NY, USA
This note proposes a modified boundary condition for the diffusion equation model to predict the reverberation times and sound pressure distributions in enclosures.While previous diffusion equation models usually only have good performances for a certain range of absorption surfaces, the modified diffusion model yields more satisfactory results for both low and high absorption surfaces.An example ...
L. Martinelli, and A. Lamberti
Universita di Bologna, Italy
Objective of this contribution is to show how to implement the Mild Slope Equations with COMSOL Multiphysics. These equations are commonly used to study the propagation of waves in harbors. Some interesting features are presented, namely the use of weak terms (used for the modelling of the source term); the evaluation of a smooth phase gradient from the complex dependent variable; a robust ...
K. Mcilhany, and J.C Hernandez
U.S. Naval Academy, Annapolis, MD, USA
Acoustic Imaging of hand movement is being studied with COMSOL and Matlab. A hardware implementation is being pursued that will be an array of 16x16 ultra-sonic speakers placed in a grid facing a similar grid of 16x16 microphones, operating at 40kHz. COMSOL is used to repeatedly calculate the diffraction pattern from a small scattering center, approximately 1.0cm in diameter. In conjunction ...
R. C. Thiagarajan
ATOA Scientific Technologies Private Limited
Ultrasonic acoustic waves usually encounter interfaces with significant impedance mismatch in practical medical or industrial imaging applications. A transparent interface can help to improve the performance of medical and industrial imaging and overall innovative applications. Similarly, a broadband total reflection interface can help to improve the architectural or transportation barrier ...