On calculation of DGS diagrams for a normal transducer with a rectangular piezoelectric plate and reflectors in the form of circular flat-bottom holes

Additional results in numerical calculations of DGS diagrams for a transducer with a rectangular piezoelectric plate and a reflector in the form of a circular flat-bottom hole obtained using the formula for an acoustic path, which was obtained earlier, are presented.     

On calculation of the DGS diagrams of an angle transducer

The acoustic path of an angle transducer is calculated in the Kirchhoff approximation for a reflector of the flat-bottom-hole type. The formula obtained can be used for constructing DGS diagrams. In the limiting case of the far-field zone, an asymptotic formula is obtained for the acoustic path confirming the validity of using analogous relationships, which were heuristically obtained earlier. Numerical calculations of the DGS diagram of an angle transducer are performed, the results of which are compared to those obtained via the recalculation of the diagram for a normal transducer.     

Calculation of DGS diagrams for elliptic flat-bottom holes

The DGS diagrams for a normal transducer and a model of a reflector—an elliptic flat-bottom hole—have been calculated via numerical calculation of the integral representation of the normalized amplitude of a detected signal. The boundary of the reflecting surface is specified by the angular-coordinate-dependent distance from the center to the current point on the contour. Examples of calculations are presented. An effect of the shape of the hole on the change in the DGS curves, which is especially pronounced in the near-field zone, has been established.     

On calculation of DGS diagrams of normal transducers for spherical and cylindrical reflectors

Formulas for the acoustic path were obtained and DGS diagrams were calculated in a general case and in a scalar approximation for a hollow spherical reflector positioned axially symmetrically relative to a normal transducer. The convergence of DGS diagrams to the asymptotic value determined by the formula for the far-field zone, the difference between them obtained using the reflection coefficients with exact and approximate accounting of the boundary conditions at the reflector, and the effect of a pulsed transmission-reception mode were studied. The DGS diagrams for a hollow circular cylindrical reflector (side drilled hole) were calculated using I.N. Ermolov’s method.     

An electromagnetic model of a piezoelectric transducer

A one-dimensional electromechanical model of a piezoelectric transducer, which reproduces excitation of ultrasonic pulses in a product, reception of echo signals, and calculation of waves in all its elements (damper, protector, piezoelectric element, contact-liquid layer, etc.), is considered. The results of calculations of electric and wave processes in a normal ultrasonic transducer, when it operates jointly with a generator of probing pulses, are presented. Good agreement between the calculation and experimental results is demonstrated.     

基于压电陶瓷的新型换能器的研究

Cymbal换能器是一种新型压电复合换能器,能输出较大的位移和驱动力。应用软件分别分析和实验验证了Cymbal换能器的形状参数h对频响和结构特性的影响,同时比较了Cymbal和其它两种结构的换能器在位移方面的差异。     

Development of a broadband low-frequency mosaic ultrasonic piezoelectric transducer with a limited aperture

Broadband low-frequency mosaic ultrasonic piezoelectric transducers with apertures comparable with acoustic wavelengths, which are designed as sets of acoustically coupled piezoelectric elements of different heights, are considered. Examples of small-aperture broadband mosaic transducers and their production technology are presented.     

An efficient approach to approximation and practical application of DGS diagrams

A nonstandard experimental and mathematical approach to the development of analytical and numerical multidimensional approximations for DGS diagrams is proposed. This method features sufficiently high accuracy, versatility, and reliability for different types of piezoelectric probes (PPs) and test objects (TOs). The efficiency of the approach is demonstrated by a test example and is also checked in its implementation in software for the UD4-S device based on standard specimens simulating flaws. Issues related to the solution of the direct and inverse problems of ultrasonic nondestructive testing are discussed.Translated from Defektoskopiya, Vol. 40, No. 10, 2004, pp. 49–61.Original Russian Text Copyright © 2004 by Sviridov, Gaburov, Veremeenko, Pokladov.     

Free vibration analysis of a thin rectangular plate with multiple circular and rectangular cut-outs

The present work is to investigate the variation in the natural frequency of a rectangular plate with the change in position of cut outs of different sizes along its diagonal and major axis line by considering different aspect ratios of plates. In this regard the free vibration analysis of an isotropic rectangular plate of various aspect ratios with different sizes of multiple circular and rectangular cut-outs is carried out by using an Independent coordinate coupling method (ICCM) under simply supported boundary condition. The ICCM utilizes independent coordinates separately for plate domain and hole domain, in which the reduced mass and stiffness matrices can be derived, by matching the deflection conditions for each hole imposed on the expressions. The resulting equation is useful for the calculation of the Eigen values. The position, size, and number of cutouts have been varied in all the possible ways to investigate their effects on the natural frequency of the rectangular plate.     

Induction ultrasonic piezoelectric transducers: Theoretical analysis of the operation of a piezoelectric transducer

The main expressions for the coefficients of electroacoustic transformation and the electric and acoustic impedances of a new type of ultrasonic transducers—induction piezoelectric transducers—have been obtained as functions of their geometric and electromagnetic parameters.     

Transient bending of a piezoelectric circular plate

Thin, piezoelectric circular plates are frequently used as active components in transducer and smart materials applications. This paper reports on the exact, explicit solution for the transient motion of a piezoelectric circular plate, built-in or simply supported on the edge and electrically grounded over the entire surface. Expressed by elementary Bessel functions and obtained via exact inverse Laplace transforms, the solution enables the efficient calculation of accurate system parameters.     

悬臂梁式压电换能器能量获取特性研究

研究了悬臂梁式金属-陶瓷压电复合换能器的工作机理,运用有限元理论,借助ANSYS软件建立了压电换能器的有限元分析模型,通过模态分析得到了其固有频率;并且在模型表面施加动载荷,通过瞬态分析,获得了一般环境周期载荷频率和固有频率载荷下换能器的电压输出情况,为今后研究此类换能器的环境吸能特性和可能的应用场合提供了理论依据.     

Basic regularities of the behavior of DGS diagrams in the near-field and transition zones of a transceiver

Studies are considered in which calculations of DGS diagrams of an ultrasonic transceiver are proposed. It is shown that the assumptions adopted in these calculations may lead to an unpredictably large error in the near-field and transition zones of the transceiver. New parameters that characterize the behavior of DGS diagrams in the near-field and transition zones (r < 4r _b) are proposed. The dependences of these parameters on the size of a flat-bottom reflector and on the distance between it and the transceiver’s piezoelectric plate are constructed.     

PVDF压电传感器信号调理电路的设计

设计PVDF压电传感器信号调理电路,详细介绍前置放大、工频陷波和低通滤波电路的设计原理.利用数字示波器对PVDF压电传感器信号调理电路进行测定.试验结果表明设计的信号调理电路工作稳定可靠、重复性好、噪声小,抗干扰能力强,工频及工频倍频陷波效果明显,信号处理实时、准确,PVDF压电传感器能够用于工业现场信号检测.     

四立柱压电换能器装配机研制

针对传统压电换能器装配方法中存在的压电换能器电声转换效率低、易发热、陶瓷片易破碎、压电换能器易松开、压电换能器和超声波发生器难以匹配等问题,为实现压电换能器的自动装配,提高装配精度,对压电换能器装配方式进行了研究。通过采用有限元的方法,设计了一种四立柱压电换能器的装配机。论述了该装配机的基本组成部分,并对机械结构进行了力学分析,介绍了电机的控制方法和控制系统的流程。利用该装配机进行了装配,并对新装配压电换能器进行了每天测量。研究结果表明,使用压电换能器的装配机装配效率得到了极大的提升,压电换能器的质量、稳定性和可靠性得到了提高。新装配的压电换能器在装配完后性能仍有一定的提升,在7天之后趋于稳定。     

Operation of a piezoelectric transducer in a voltage generator and current generator circuits

Methods for obtaining all transfer functions of a piezoelectric transducer with allowance for its electrical load were considered. In the emission mode, equivalent voltage and current generators were introduced. In the reception mode, Tevenen’s and Norton’s theorems for equivalent voltage and current generators were used. A comparison of the main formulas obtained with the previously found solutions has shown that the constructed derivation schemes are true. These formulas can be applied to transducers with an arbitrary number of active and passive layers. Recommendations for using the results of this work were presented. These results can be useful in developing both transducers and flaw detectors.     

Influence of the size of a normal probe’s piezoelectric plate on the amplitude of a detected echo signal

A computer model for operation of ΠPиз-д11 Π111-2.5-K12-002, Π111-2.5-K20-002) normal probes combined with a Yд2-12 flaw detector was used to consider the effect of the size (radius) of a piezoelectric plate on the amplitude of a detected echo signal. It is shown that the amplitude variation is mainly related to the acoustic part of the electroacoustic channel (a function of signal damping during wave propagation to and from a flaw).     

压电换能器装配液压扭矩扳手设计

针对压电换能器传统装配中存在的扭矩不稳定和大批量装配时不能保证统一性与准确性的问题,分析了液压扭矩扳手结构特点及其关键设计,提出了压电换能器装配液压扭矩扳手的具体方案。研究结果表明,该方案实现了大批量压电换能器装配扭矩恒定的要求,也为大批量恒扭矩装配压电换能器奠定了基础。     

Design of a piezoelectric transducer cylindrical phase modulator for simulating acoustic emission signals

To conveniently carry out the pipeline leak experiment in a laboratory, leak acoustic signals are simulated by using the converse piezoelectric effect of a piezoelectric transducer (PZT) cylindrical phase modulator. On the basis of the piezoelectric equations and electromechanical equivalence principle, the transfer function of a PZT cylindrical phase modulator is delivered. A PZT cylindrical phase modulator is designed, and the numerical simulation is conducted. Results prove that the PZT cylindrical phase modulator can effectively simulate leak acoustic emission signals when the frequency is lower than 25 KHz. __________ Translated from Journal of Beijing University of Technology, 2006, 32(8): 683–687 [译自: 北京工业大学学报]