Study of Dual-Laser-Generated Surface Acoustic Waves Interacting with Multiangled Surface Breaking Cracks by Finite Element Method

2010 ◽  
Vol 49 (4) ◽  
pp. 046603 ◽  
Author(s):  
Chenyin Ni ◽  
Yifei Shi ◽  
Zhonghua Shen ◽  
Jian Lu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Dual Laser ◽  
Element Method

Ladder Type of Leaky Surface Acoustic Waves Filters on Substrate of Lithium Niobate

2021 ◽  
Vol 23 (3) ◽  
pp. 139-147
Author(s):  
A.S. Koigerov ◽  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Acoustic Waves ◽  
Communication Systems ◽  
Surface Acoustic Waves ◽  
Bandpass Filters ◽  
The Finite Element Method ◽  
Frequency Responses ◽  
Method Of Extraction ◽  
Element Method

High requirements on the electrical parameters of the filters are made in wireless radio communication systems. A number of tasks require bandpass filters with relative bandwidths of 8-12 %. In this case, the filter must have insertion losses of not more than 10 dB, have a rejection is not worse than 40 dB, unevenness in the bandwidth of not more than 1 dB. In addition, the amplitude frequency responses of the filter must have steep slopes due to the closely spaced frequency bands of neighboring communication systems. Due to its small size and other advantages, ladder resonator filters on surface acoustic waves are widely used in communication systems. To realize the high requirements of this type of filters, it is necessary not only to select all the topology parameters of the individual resonators included in the filter very accurately, but also to have a good computational theory and the necessary material parameters for the selected model at the design stage. Purpose: to show on the example of comparison of calculated and experimental frequency responses of ladder filters the validity of the method of extraction of the necessary parameters obtained for an infinite periodic structure by the finite element method for calculating of finite structures of real inter digital transducer and reflective gratings. Results: the method of extraction of parameters necessary for calculation by the method of connected modes on the basis of P-matrices is offered. The technique is based on the analysis of infinite periodic electrodes by the finite element method. Bandpass filters with a relative bandwidth 8-12 % on a piezosubstrate 49° YX LiNbO3 were designed and manufactured based on the proposed theory. It is shown that for this material, the calculation must take into account the direct radiation of bulk acoustic waves, since the design of ladder type filters, the radiation falls into the projected bandwidth of the filters. These calculations are confirmed by the results of experiments.

ANALYSIS OF SAW EXCITATION AND PROPAGATION UNDER PERIODIC METALLIC GRATING STRUCTURES

2000 ◽  
Vol 10 (03) ◽  
pp. 685-734 ◽  
Author(s):  
KEN-YA HASHIMOTO ◽  
TATSUYA OMORI ◽  
MASATSUNE YAMAGUCHI
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Field Analysis ◽  
The Finite Element Method ◽  
Numerical Techniques ◽  
Metallic Grating ◽  
Propagation Properties ◽  
Element Method

This paper reviews numerical techniques used for the analysis of excitation and propagation properties of surface acoustic waves (SAWs) under periodic metallic grating structures. First, the finite element method (FEM), the boundary element method (BEM) and the spectral domain analysis (SDA) are compared for the SAW field analysis. Then it is shown how skillfully excitation and propagation properties are characterized by using the FEM/SDA technique. Extended FEM/SDA theories are also detailed for the analysis of multi-finger grating structures.

scholarly journals Partition of Unity Finite Element Method applied to exterior problems with Perfectly Matched Layers

Acta Acustica ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 16
Author(s):  
Christophe Langlois ◽  
Jean-Daniel Chazot ◽  
Emmanuel Perrey-Debain ◽  
Benoit Nennig
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Acoustic Waves ◽  
Degrees Of Freedom ◽  
Partition Of Unity ◽  
Local Approximation ◽  
Computational Domain ◽  
Perfectly Matched Layers ◽  
Exterior Problems ◽  
Element Method

The Partition of Unity Finite Element Method (PUFEM) is now a well established and efficient method used in computational acoustics to tackle short-wave problems. This method is an extension of the classical finite element method whereby enrichment functions are used in the approximation basis in order to enhance the convergence of the method whilst maintaining a relatively low number of degrees of freedom. For exterior problems, the computational domain must be artificially truncated and special treatments must be followed in order to avoid or reduce spurious reflections. In recent papers, different Non-Reflecting Boundary Conditions (NRBCs) have been used in conjunction with the PUFEM. An alternative is to use the Perfectly Match Layer (PML) concept which consists in adding a computational sponge layer which prevents reflections from the boundary. In contrast with other NRBCs, the PML is not case specific and can be applied to a variety of configurations. The aim of this work is to show the applicability of PML combined with PUFEM for solving the propagation of acoustic waves in unbounded media. Performances of the PUFEM-PML are shown for different configurations ranging from guided waves in ducts, radiation in free space and half-space problems. In all cases, the method is shown to provide acceptable results for most applications, similar to that of local approximation of NRBCs.

scholarly journals Study of Acoustic Waves in a Teaching Classroom using Finite Element Method

2021 ◽  
pp. 65-75
Author(s):  
C. A. Wilson Bárcenas ◽  
J. M. Horta Rangel ◽  
M. A. Pérez Lara y Hernández ◽  
J. B. Hernández Zaragoza ◽  
M. L. Pérez Rea ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Acoustic Waves ◽  
Continuous Medium ◽  
The Finite Element Method ◽  
Computational Tools ◽  
Internal Surfaces ◽  
Engineering Department ◽  
Acoustic Physics ◽  
Element Method

Aims: To understand the behavior of acoustic waves in a specific classroom in order to get a configuration of panels and ceilings configuration to improve reception and clarity of internal sounds. This was possible by the modification of the properties of the enclosure, sush as the absorption coefficients of internal surfaces. The analysis was carried out through the implementation of a model by using Finite Element Method. Study Design: The acoustic behavior that enclosure for academic use require is discussed, indicating that it is common to find deficiencies in the acoustic architecture of enclosures, and the risks that this causes to cognitive and academic development, as a consequence of low understanding. Place and Duration of Study: Graduate Engineering Department, Universidad Autónoma de Querétaro, between August 2020 and June 2021. Methodology: The problem is solved by applying the finite element method. This implies that the essential concepts for the understanding of this subject are reviewed, such as; acoustic physics, mechanics of the continuous medium and finite element method. Results: After multiple analized scenarios, it was observed that while there is an absorption greater than the surface, the material of the panel or ceiling is not relevant. On the other hand, the size and surface where is located the panels turned out to be more relevant parameters. Conclusion: Considering the proposed alternatives, an increase in the Sound Pressure Level and a uniform distribution can be observed. The use of computational tools help to understand the behavior and distribution of acoustic waves in the classroom, which can provide an overview of different adaptations.

Sign in / Sign up

Export Citation Format

Share Document