scholarly journals A New Computerized Boundary Element Model for Three-Temperature Nonlinear Generalized Thermoelastic Stresses in Anisotropic Circular Cylindrical Plate Structures

2020 ◽  
Author(s):  
Mohamed Abdelsabour Fahmy
Keyword(s):  
Boundary Element ◽  
Element Model ◽  
Plate Structures ◽  
Thermoelastic Stresses ◽  
Generalized Thermoelastic

A Boundary Element Model of Perturbed Magnetic Flux Density Component in Eddy Current NDT of Flaws

2021 ◽  
Author(s):  
Prashanth Baskaran ◽  
Dario Pasadas ◽  
Helena Ramos ◽  
Artur Ribeiro
Keyword(s):  
Magnetic Flux ◽  
Boundary Element ◽  
Flux Density ◽  
Eddy Current ◽  
Element Model ◽  
Magnetic Flux Density

scholarly journals Investigation of Low-Sidelobe Beampattern Controlling Methods for Acoustic Transmitting Array of Underwater Vehicles

2017 ◽  
Vol 24 (s2) ◽  
pp. 103-110
Author(s):  
Zhengyao He ◽  
Qiang Shi ◽  
Shaoxuan Wu
Keyword(s):  
Boundary Element ◽  
Element Model ◽  
Optimization Method ◽  
Underwater Vehicles ◽  
Unmanned Vehicles ◽  
Driving Voltage ◽  
Sound Waves ◽  
Low Sidelobe ◽  
Acoustic Transducer ◽  
Weighting Vector

Abstract In underwater unmanned vehicles, complex acoustic transducer arrays are always used to transmitting sound waves to detect and position underwater targets. Two methods of obtaining low-sidelobe transmitting beampatterns for acoustic transmitting arrays of underwater vehicles are investigated. The first method is the boundary element model optimization method which used the boundary element theory together with the optimization method to calculate the driving voltage weighting vector of the array. The second method is the measured receiving array manifold vector optimization method which used the measured receiving array manifold vectors and optimization method to calculate the weighting vector. Both methods can take into account the baffle effect and mutual interactions among elements of complex acoustic arrays. Computer simulation together with experiments are carried out for typical complex arrays. The results agree well and show that the two methods are both able to obtain a lower sidelobe transmitting beampattern than the conventional beamforming method, and the source level for each transmitting beam is maximized in constraint of the maximum driving voltage of array elements being constant. The effect of the second method performs even better than that of the first method, which is more suitable for practical application. The methods are very useful for the improvement of detecting and positioning capability of underwater unmanned vehicles.

Numerical Prediction of Noise Radiated From a Panel Subjected to Boundary Layer Excitation

1999 ◽  
Author(s):  
Michael Allen ◽  
Nickolas Vlahopoulos
Keyword(s):  
Boundary Layer ◽  
Finite Element ◽  
Boundary Element ◽  
Transfer Functions ◽  
Element Model ◽  
Acoustic Response ◽  
Spectral Densities ◽  
Wind Noise ◽  
Element Analysis ◽  
Power Spectral

Abstract In this paper an algorithm is developed for combining finite element analysis and boundary element techniques in order to compute the noise radiated from a panel subjected to boundary layer excitation. The excitation is presented in terms of the auto and cross power spectral densities of the fluctuating wall pressure. The structural finite element model for the panel is divided into a number of sub-panels. A uniform fluctuating pressure is applied as excitation on each sub-panel separately. The corresponding vibration is computed, and is utilized as excitation for an acoustic boundary element analysis. The acoustic response is computed at any data recovery point of interest. The relationships between the acoustic response and the pressure excitation applied at each particular sub-panel constitute a set of transfer functions. They are combined with the spectral densities of the excitation for computing the noise generated from the vibration of the panel subjected to the boundary layer excitation. The development presented in this paper has the potential of computing wind noise in automotive applications, or boundary layer noise in aircraft applications.

A Finite Element Model for Viscoelastic Foundations Supporting Plate Structures

1987 ◽  
pp. 225-235
Author(s):  
Joseph J. Rencis ◽  
Kwo-Yih Jong ◽  
Sunil Saigal
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Plate Structures ◽  
Supporting Plate

Shape Optimisation of Multi-Chamber Acoustical Plenums Using BEM, Neural Networks, and GA Method

2016 ◽  
Vol 41 (1) ◽  
pp. 43-53 ◽  
Author(s):  
Ying-Chun Chang ◽  
Ho-Chih Cheng ◽  
Min-Chie Chiu ◽  
Yuan-Hung Chien
Keyword(s):  
Noise Reduction ◽  
Boundary Element ◽  
Transmission Loss ◽  
Real Data ◽  
Element Model ◽  
Shape Optimisation ◽  
Design Data ◽  
Input Design ◽  
Speed Up ◽  
Fixed Space

Abstract Research on plenums partitioned with multiple baffles in the industrial field has been exhaustive. Most researchers have explored noise reduction effects based on the transfer matrix method and the boundary element method. However, maximum noise reduction of a plenum within a constrained space, which frequently occurs in engineering problems, has been neglected. Therefore, the optimum design of multi-chamber plenums becomes essential. In this paper, two kinds of multi-chamber plenums (Case I: a two-chamber plenum that is partitioned with a centre-opening baffle; Case II: a three-chamber plenum that is partitioned with two centre-opening baffles) within a fixed space are assessed. In order to speed up the assessment of optimal plenums hybridized with multiple partitioned baffles, a simplified objective function (OBJ) is established by linking the boundary element model (BEM, developed using SYSNOISE) with a polynomial neural network fit with a series of real data – input design data (baffle dimensions) and output data approximated by BEM data in advance. To assess optimal plenums, a genetic algorithm (GA) is applied. The results reveal that the maximum value of the transmission loss (TL) can be improved at the desired frequencies. Consequently, the algorithm proposed in this study can provide an efficient way to develop optimal multi-chamber plenums for industry.

Vibration of Plate Structures Solved by DQEM Using EDQ

2003 ◽  
Author(s):  
Chang-New Chen
Keyword(s):  
Numerical Algorithms ◽  
Element Model ◽  
Equation System ◽  
Solution Procedure ◽  
Analysis Model ◽  
Engineering Structures ◽  
Discrete Eigenvalue ◽  
Plate Structures ◽  
Wide Range ◽  
Structural Boundary

The vibration of plate structures is solved by DQEM using EDQ. In the DQEM discretization, EDQ is used to define the discrete element model. Discrete eigenvalue equations defined at interior discrete points in all elements, transition conditions defined on the inter-element boundary of two adjacent elements and boundary conditions at the structural boundary form the overall discrete eigenvalue equation system. Numerical results obtained by the developed numerical algorithms are presented. They demonstrate the developed numerical solution procedure. This vibration analysis model can be used to solve wide range of offshore engineering structures.

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