A Simulation Study of the Beam Steering Characteristics for Linear Phased Arrays (original) (raw)
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Numerical Modelling of Ultrasonic Phased Array Transducers and Their Application
2006
The ultrasonic nondestructive testing using a conventional inspection method with a single transducer consumes large inspection time and requires a lot of man power for controlling. Phased array techniques are famous for their inspection at shorter inspection time, electronic control, their real-time applicability and sensitivity to axial and lateral resolution. These ultrasonic phased array transducers are modelled using the numerical tool called elastodynamic finite integration technique (EFIT). A 64 element phased array transducer with different operating frequencies is modelled to perform ultrasonic inspection of a steel slab immersed in water. An ultrasonic pressure wave is injected into the water with a steering angle of 18° and by mode-conversion transmits a shear wave into the steel slab with approximately 42°. A steel slab with internal notches with different depths has been simulated. A-scans are recorded for each particular element of the phased array transducer which for...
Acoustic Field of Phased-Array Ultrasound Transducer with the Focus/Foci Shifting
Journal of Medical and Biological Engineering, 2019
Background High-intensity focused ultrasound (HIFU) is becoming popular in the treatment of solid tumors because of its non-invasiveness with few complications. The acoustic field is of importance in evaluating the safe focus shifting distance and determining the treatment plan. Methods The propagation of finite-amplitude acoustic wave from a 331-element HIFU phased-array with focus steering along and transverse to the transducer axis and 4-foci shifting on the focal plane was simulated using the angular spectrum approach (ASA) with a marching second-order operator-splitting scheme. In addition, the acoustic field produced by a truncated asymmetric transesophageal HIFU annular array was also simulated, and the effects of driving frequency and the number of concentric rings were investigated. Results Because of the nonlinear effects, the peak negative pressure is lower than that of peak positive pressure at the main lobe but has a larger beam size. However, the peak positive and negative pressures at the grating lobe are quite similar. The effects of the focus shifting distances on the main and grating lobe (both acoustic pressure and − 6 dB beam size) were evaluated. With the focus shifting axially away from the transducer surface, the main lobe has decreased acoustic pressure by ~ 1.9 fold and increased beam size by ~ 4.5 fold while the grating lobe has the increased acoustic pressure by ~ 1.8 fold. The focus shifting laterally leads to the reduced pressure at the main lobe by ~ 1.4 fold but the slight decrease at the grating lobe by ~ 1.1 fold. In comparison, the shifting of multi-foci has similar influences on the main lobe but increases the pressure at the grating lobe. Driving frequency of annular array is found to have greater influences on the peak pressure and beam size. Conclusion Our algorithm can simulate the acoustic field of phased-array in arbitrary shape and optimize the transducer design, and the focus shifting distance and strategy should be selected appropriately for the safe HIFU exposure.
Modeling of phased array transducers
The Journal of the Acoustical Society of America, 2005
Phased array transducers are multi-element transducers, where different elements are activated with different time delays. The advantage of these transducers is that no mechanical movement of the transducer is needed to scan an object. Focusing and beam steering is obtained simply by adjusting the time delay. In this paper the DPSM ͑distributed point source method͒ is used to model the ultrasonic field generated by a phased array transducer and to study the interaction effect when two phased array transducers are placed in a homogeneous fluid. Earlier investigations modeled the acoustic field for conventional transducers where all transducer points are excited simultaneously. In this research, combining the concepts of delayed firing and the DPSM, the phased array transducers are modeled semi-analytically. In addition to the single transducer modeling the ultrasonic fields from two phased array transducers placed face to face in a fluid medium is also modeled to study the interaction effect. The importance of considering the interaction effect in multiple transducer modeling is discussed, pointing out that neighboring transducers not only act as ultrasonic wave generators but also as scatterers.
Experimental study of phased array beam steering characteristics
Journal of nondestructive …, 1999
The influence of several geometric parameters of linear phased arrays was studied. A systematic approach using an automated testing assembly was used to assess the steering performance of the array in a solid medium. In addition to calibrating the transducer with respect to its steering accuracy, this arrangement provided a detailed study of the effects of steering angle, number of elements, inter-element spacing and array aperture on the beam directivity. The experimental results show good agreement quantitatively with the predicted steering characteristics.
Simulation of 2-D Linear Array Transducers and Beam Profile Used in Echolocation
2010
The reason for using sonar for mobile robot navigation comes from the ultrasonic sensing capabilities of bats which use echolocation to determine their prey position. During the project "Adaptive bio-mimetic sonar heads for autonomous vehicles" we intend to employ a new material to build up broadband ultrasonic transducers featuring good adaptation to air. In this specific case it is important to achieve accurate information about the magnitude and position of the peak pressure and intensity produced by the probe. The purpose of the simulation is to analyze the emitted beam pattern from 2Darray transducers in terms of the spatial impulse response that characterizes the three-dimensional extent of the ultrasonic field. Simulation results are provided for two different linear array element numbers to evaluate the effects on the beam profile.
Finite Element Modeling of Phased Array Ultrasound Transducer for Pipeline Inpsection
Phased array ultrasonic transducers (PAUT) are widely used in medical and non-destructive testing applications because of the increased productivity that can be derived from them. They consist of an array of single element piezo crystals that can either be used independently or all at once. In reality a number of operational features such as beam steering and focusing are much easier to achieve electronically. A mathematical model of a phased array allows for understanding and visualizing the response of phased array wave propagation. A simplified finite element model of a PAUT system is developed using ABAQUS ® package leveraging its coupled acoustic-structural solver to study the bean directivity of phased array transducer. The model is a two-layer model consisting of a fluid-structure interface. Ultrasonic beam steering is achieved through accurate time delayed excitation of transducer nodes. The model was particularly used for understanding the strength of the main lobe, grating...
Wave Motion, 2017
Beam characteristics of a linear phased array transducer are critical to its engineering applications as well as to its design. This paper proposes a method for the theoretical calculation of ultrasound field radiated by a linear phased array coupled to an elastic solid by a longitudinal wave couplant. In this case, the ultrasound field can be determined by superposition of the exact and analytical solutions of transient elastic waves induced by a number of discrete line sources normally acting on an elastic half-space. Based on the theoretical calculation, this work investigated the influences of several important parameters in a linear array transducer, such as wave length, array size, ratio of element width to inter-element spacing, to the ultrasound field characteristics. Interesting phenomena and useful results are obtained, which provide fast and accurate guidance for linear phased array transducer design. It also satisfies diverse and specific demands for actual engineering testing using arrayed transducers.