Finite element simulation and modeling of 2-D arrays for 3-D ultrasonic imaging

McKeighen, R.E.

doi:10.1109/58.949749

Cited by 14 publications

(8 citation statements)

References 7 publications

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“…Time-domain schemes have been used to predict the performance of ultrasound transducers in terms of impedances and efficiencies. The effect of matching layers, backing layers, bonding layer and electrodes on the operation of the transducer can be addressed using this technique (Zhou et al, 2006;McKeighen, 2001). However, a large number of elements and simulation time are usually required for high frequency simulations.…”

Section: Introductionmentioning

confidence: 99%

“…Mention is made here of Saravanos and Heyliger (1995), Saravanos et al (1997), Ramirez et al (2006), and references therein. FEM has also been used to model ultrasound transducers (Lerch, 1990;Hossack and Hayward, 1991;McKeighen, 2001;Zhou et al, 2006). Time-domain schemes have been used to predict the performance of ultrasound transducers in terms of impedances and efficiencies.…”

Section: Introductionmentioning

confidence: 99%

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Dispersion of elastic guided waves in piezoelectric infinite plates with inversion layers

Cortés

Datta

Mukdadi

2008

International Journal of Solids and Structures

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a b s t r a c tIn this work, we study the dispersion of elastic waves in piezoelectric infinite plates with ferroelectric inversion layers. The motivation is to analyze the effect of ferroelectric inversion layers on wave dispersion and resonant behavior under impulsive line loads. A semianalytical finite-element (SAFE) method has been adopted to analyze the problem. Two model problems are considered for analysis. In one, the plate is composed of a layer of 36°rotated y-cut LiNbO 3 with a ferroelectric inversion layer. In the other, material is PZT-4 with a ferroelectric inversion layer. Comparison with experimental results, reported in the literature for isotropic materials, shows a very good agreement with theoretical predictions obtained using SAFE method. Furthermore, comparison of the resonance frequencies of the S 1 modes, calculated using KLM approximation (f 0 = C d /2h) and SAFE method, are illustrated for each problem. The frequency spectra of the surface displacements show that resonant peaks occur at frequencies where the group velocity vanishes and the phase velocity remains finite, i.e., a minimum in the dispersion curve below the cut-off frequency. The effect of the ratio of the thicknesses of the inversion layer (IL) and the plate on the frequencies and strength of the resonant peaks is examined. It is observed that for PZT-4 with 50% IL to plate thickness ratio the frequency for the second resonant peak is about twice that for the first one. Results are presented showing the dependence of resonant frequencies on the material properties and anisotropy. Materials selection for single-element harmonic ultrasound transducers is a very important factor for optimum design of transducers with multiple thickness-mode resonant frequencies. The theoretical analysis presented in this study should provide a means for optimum ultrasound transducer design for harmonic imaging in medical applications.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dispersion of elastic guided waves in piezoelectric infinite plates with inversion layers

Cortés

Datta

Mukdadi

2008

International Journal of Solids and Structures

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“…Time-domain schemes have been used to predict the performance of plates and ultrasound transducers (Zhou et al, 2006;McKeighen, 2001;Mills and Smith, 2002;Hossack and Hayward, 1991;Lerch, 1990). The effect of matching layers, backing layers, bonding layer and electrodes on the operation of the transducer can be addressed using this technique (Zhou et al, 2006;McKeighen, 2001). However, a large number of elements and simulation time are usually required.…”

Section: Finite Element Modelingmentioning

confidence: 99%

Elastic guided wave dispersion in layered piezoelectric plates: Application to ultrasound transducers and acoustic sensors

Correales¹,

Daniel²

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Elastic wave propagation in layered media has been of interest in many disciplines including non-destructive material characterization, acoustic sensors and medical ultrasound imaging. A great variety of devices are based on the propagation of electromechanical waves in piezoelectric plates. Despite the diversity of applications, the principles and characteristics of wave propagation are the same regardless the design or configuration of the device. The aim of this study is to develop numerical and analytical tools to model and design devices based on the wave propagation in piezoelectric layered media; particularly, ultrasound transducers for medical imaging and acoustic sensors for biological applications. Single-element ultrasound transducers can be modeled as infinite layered piezoelectric plates. A Semi-Analytical Finite Element (SAFE) method has been implemented and used to theoretically predict the resonant frequencies and the dispersion behavior of these plates. The analysis of piezoelectric layered plates showed that the resonant frequencies at the ZGV points of the Lamb wave modes are more significant than those at the cutoff frequencies. On the other hand, 1D array ultrasound transducers are modeled as periodic piezoelectric plates with finite cross-section using a modified SAFE method. Dispersion curves, group velocity spectra and mode shapes are obtained using this method. Geometric parameters of the piezoelectric element, such as, aspect ratio and subdicing width and depth of the piezoelectric element had an important effect on the dispersion behavior. In general, the lower aspect ratios, as well as lower subdicing depth, tend to increase the cutoff frequency and the resonance of all modes. An analytical model is presented to study the dynamic behavior of single-element ultrasound transducers and acoustic sensors. This model is based on leaky Rayleigh and Lamb wave analysis, which has been widely used for NDT applications. A procedure to calculate the resonance frequencies for ultrasound transducers based on the dispersion curves has been derived and experimentally validated. This analytical solution has also been used to calculate and optimize the sensitivity and coupling coefficient of Rayleigh and Lamb wave sensors. The procedures and results obtained in this study can be used to analyze and design devices based on the wave propagation on multilayered piezoelectric plates, i.e. ultrasound transducer and sensors. It is believed that an accurate characterization of the wave propagation and dynamic properties, as well as an optimized configuration of the device can substantially improve its performance. These developments can be applied on ultrasound biomicroscopy, medical imaging, NDT techniques, MEM devices and biosensors. iii To my wife Nohemy, my parents Martha and Baltazar and my sister Marcela Finally but not less important, I am grateful to my friends in Colombia and Morgantown for ameliorating the stress inherent to Ph.D. studies. v

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“…With demonstrated speed/size advantage factors of 100 over conventional implicit algorithms, broadband imaging transducer models became tractable on desktop computers. Recently, Mckeighen (2001) used FEM software based on the above algorithms to simulate 2-D arrays with acceptable accuracy and simulation speed. In this thesis, FEM analysis is used to study the characteristics of the array, and their effect on the radiation field.…”

Section: Ultrasonic Transducer Modelingmentioning

confidence: 99%

“…This code is based on the above finite element method algorithms, specialized in piezoelectric problems. In piezoelectric transducer simulations, it shows at least 10 times faster simulation speed than that of conventional implicit algorithms based FEM code (McKeighen, 2001).…”

Section: Finite Element Formulation For Transient Responsesmentioning

confidence: 99%

Design and optimization of ultrasonic array transducers for medical imaging applications

Wang¹

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Currently array transducers are being studied with narrowband theory, however, it raises problems when the theory is used in medical imaging applications where broadband signals are used. This thesis investigates the properties of ultrasonic array transducers based on broadband analysis, in particular their radiation fields. And furthermore, the methods to design and optimize broadband sparse arrays are developed for both 1D and 2D arrays, which can be used to satisfy different application requirements. The radiation fields from the broadband arrays as well as the narrowband arrays are first analyzed and compared starting from the same mathematical model. Despite the simplification of the model, broadband fields show much more complicated behaviours than the narrowband ones, due to the coupling of spatial dimension and temporal dimension in broadband fields. This means that narrowband theory is not adequate to be used in broadband analysis. The efficient algorithms to calculate the broadband radiation field are then developed. Although the rigorous model for broadband transducers is available, it is not suitable for array calculation because of its low efficiency. The developed algorithms dramatically reduce the complexity of calculation procedure while the accuracy is still comparable with the rigorous model. Finite element method is used as alternative methodology to study arrays performance. The interaction between transducer and loading material, and cross coupling effect can be fully considered. The results show that when the cross coupling level is low, the radiation field matches well with the results from previously developed model. However, under high cross coupling level, the side lobe level dramatically increases, while the main lobe ATTENTION: The Singapore Copyright Act applies to the use of this document. Nanyang Technological University Library iii Table of contents iv List of figures vi List of tables xii Nomenclatures xiii Chapter 1-v-5.4 Cross coupling in 1D array transducers 5.5 Simulation of array transducers radiation field 5.6 Conclusions Chapter 6 Sparse Array Transducers Design and Optimization 6.1 Introduction 6.2 Periodic and non-periodic sparse arrays 6.3 Introduction of Genetic Algorithms 6.4 GAs operators and parameters 6.5 Sparse array optimization 6.6 Conclusions Chapter 7 Experimental Validation 7.1 Synthetic method for array radiation field measurement 7.2 Experimental set up and procedure 7.3 Experimental results-1D arrays 7.4 Experimental results-2D arrays 7.5 Conclusions Chapter 8 Conclusions and Recommendations 8.1 Conclusions 8.

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Finite element simulation and modeling of 2-D arrays for 3-D ultrasonic imaging

Cited by 14 publications

References 7 publications

Dispersion of elastic guided waves in piezoelectric infinite plates with inversion layers

Dispersion of elastic guided waves in piezoelectric infinite plates with inversion layers

Elastic guided wave dispersion in layered piezoelectric plates: Application to ultrasound transducers and acoustic sensors

Design and optimization of ultrasonic array transducers for medical imaging applications

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