Calibration blocks for ultrasonic nondestructive testing

The main parameters of calibration blocks for ultrasonic testing that must be measured during metrological certification are considered: the geometric dimensions of reflectors, the velocity and attenuation of elastic waves, etc. A method for measuring the damping factor is proposed that simplifies the measurement procedure. A form of the certificate registered officially for calibration blocks that were subjected to metrological certification is presented.     

Modal analysis of the piezoelectric generation of ultrasonic guided waves for nondestructive testing of cylindrical structures

This paper presents a method based on a modal analysis, which allows efficient quantitative determination of such characteristics of the surface load of an ultrasonic probe as the mode-selection selectivity, the frequency characteristic, and the transient characteristic. The use of this method is illustrated by simulation of generation of axially symmetric and antisymmetric ultrasonic waves in pipes with a piezoelectric array transducer. The text was submitted by the authors in English.     

超声检测机械手控制系统的设计

为实现超声检测的自动化,研制了一种关节机械手控制系统.该机械手由传感检测系统、伺服系统、总线智能节点和PC机等组成,借助单片机、数字控制、现场总线、计算机、机器人等技术,利用CAN现场总线进行通讯,通过控制实现自动控制并实时获取坐标信息,有利于缺陷的定位分析,其结构简单,性能价格比高,可应用于其他场合,具有广泛的适应性.     

Sparsity enhancement for blind deconvolution of ultrasonic signals in nondestructive testing application

The received signal in ultrasonic pulse-echo inspection can be modeled as a convolution between an impulse response and the reflection sequence, which is the impulse characteristic of the inspected object. Deconvolution aims at approximately inverting this process to improve the time resolution so that the overlap between echoes from closely spaced reflectors becomes small. This paper presents a modified minimum entropy blind deconvolution algorithm for deconvolving ultrasonic signals. Enhancement of the resolution is achieved by using the presented method. In addition, the presented approach will, in many cases, lead to a faster computation. A nonlinear function is the key point to the efficiency of the modified blind deconvolution algorithm, which is used to increase the sparsity of the iteration output and to decrease the influence of the added noise by replacing each iteration output by output of the nonlinear function. Simulations showed the efficiency of the modification as compared with minimum entropy deconvolution when deconvolving synthetic ultrasonic signals. Experimental results using real ultrasonic data evaluated further that the exact solution consistently yields good performance. The thickness of a thin steel sample can be calculated by the modified blind deconvolution filter with a reasonable accuracy.     

Adaptive motion control of sensors of flexible manufacturing systems for nondestructive testing

A method for adaptive motion control of elements of flexible manufacturing systems for nondestructive testing is proposed. Their control principle is based on correction of motion parameters in accordance with current testing results. A modified evaluating-function method is used to interpolate the motion paths.     

Geoelectric nondestructive testing of hydraulic structures via differential induction facilities

The problem of differential induction profiling above an anomalous object is solved. It is shown that differential profiling enables monitoring of how the boundaries of the zones where water drains through the body of a dam change with time.     

Comparison of systems for ultrasonic nondestructive testing using antenna arrays or phased antenna arrays

This paper considers the features of forming the images of reflectors using phased antenna array technology and the images obtained by the C-SAFT method by echo signals measured in by double-scanning mode. It is shown that in some cases the images obtained by the phased antenna array technology are less informative, while the images obtained by the C-SAFT method have a higher frontal resolution over the entire area of image restoration; the partial images restored at different positions of the antenna array can be coherently combined to obtain a high and homogeneous resolution throughout the entire volume of thickwalled articles and increasing the signal/noise ratio. For the sake of brevity, the registration of echo signals in the double-scanning mode and restoration of the images of reflectors by the C-SAFT method will be called digital focusing by an antenna array (DFA). The ability to restore the partial images of reflectors by once measured echo signals according to many acoustic schemes with their consequent combination into one high-quality image should provide reliable automation of the process of recognition and dimensioning of scatterers. Another advantage of the images obtained by the C-SAFT method with three-dimensional focusing is the possibility of restoring images in the same coordinate system when using antenna arrays on prisms of different configurations. This facilitates the joint analysis of the images. Speeds of forming the images by the technology of phased-antenna arrays and the images obtained by the C-SAFT method are comparable. If the testing technique is based on the use of nonlinear effects, then in this case PA flaw detectors have a distinct advantage over DFA flaw detectors. However, within the framework of linear acoustics, PA flaw detectors have no fundamental advantages over DFA flaw detectors. It is fairer to say that PA flaw detectors have drawbacks. This article shows images that illustrate the features of the images that were obtained by PA and DFA flaw detectors.     

Requirements for choosing the parameters of broadband transducers for testing objects with high damping of ultrasonic signals

The main concepts of the theory of optimal signal processing as applied to tasks of ultrasonic testing of articles with high integral damping of acoustic vibrations are considered. The conditions for ensuring the optimal transfer coefficient of the receiving section of an ultrasonic flaw detector’s electroacoustic channel are formulated. The requirements for the characteristics of broadband piezoelectric transducers aimed at the insurance of undistorted transmission of ultrasonic signals are formulated.     

Features of the development of geoinformation systems for the nondestructive testing of the states of critical objects

As shown by practice, it is necessary to develop geoinformation systems of the widest spectrum for the continuous monitoring (or control) of the states of technogenic objects, rock masses, and their elements. However, for a number of reasons, including socioeconomic factors, geoinformation systems have not been developed properly. The fact that geoinformatics itself is still in a formative stage is high among such reasons. Some data on geoinformation systems, along with the results obtained on a certain object with the use of tilt gauges, are represented.     

Increasing the reliability of the detection of flaws in complex structures by integrating the information of multiparametric nondestructive testing

The basic principles and methods for integrating information from multiparametric nondestructive testing for the purpose of detecting anomalies, flaws, and damage in different objects and structures are considered. Some experimental data and the results of the development of algorithms for the integration of nondestructive testing techniques that are aimed at solving formulated problems on the basis of telescoping-effect estimation methods and the construction of the multidimensional analogues of inverse probability methods are cited.     

Application of the double-scanning method in ultrasonic nondestructive testing of metals for reconstruction of model defect images

The results of application of the double-scanning method for obtaining images of model defects during ultrasonic flaw detection in metals are presented. It has been shown in model experiments that, during reconstruction of flaw images, the amplitudes of parasitic reflections formed by echo signals, which were transformed and repeatedly scattered by inhomogeneities, decrease considerably. These properties of the double-scanning method may be useful in the practice of ultrasonic inspection of heavily loaded objects, especially in the case of the pressing problem of classifying the detected flaws. To identify the type of defects and determine their number accurately, it is desirable to use images obtained in both the double-scanning and transceiver modes. The images obtained during operation of a transducer in these two modes are compared.     

The acoustic path in the method of multiple reflections during nondestructive testing of linearly extended objects

An approach is presented to the construction of the acoustic path for the waveguide method of testing using multiple reflections during nondestructive testing of linearly extended objects. The results of the studies on the method’s sensitivity, which depend on the test parameters, are given.     

The possibility of using the maximum-entropy method in ultrasonic nondestructive testing for increasing the resolution of echo signals

The problem of deconvoluting echo signals via regularization according to the maximum entropy method followed by the reconstruction of 2D images via the Fourier transformation synthetic aperture focusing technique (FT-SAFT) is considered. Numerical and experimental simulations have been performed. The possibility of improving the ray resolution of echo signals and reducing the speckle-noise level is demonstrated. The results obtained are compared to the results of constructing an AR model of the spectrum of echo signals.     

超声与涡流复合式无损检测的机理及应用

基于超声与涡流复合检测技术的国内外现状,总结国内外各阶段复合式无损检测技术的特点,归纳研究热点,展望复合式检测技术的发展趋势。     

大厚壁焊缝串列式超声波检测工艺研究

为了提高大厚壁焊缝中垂直于工件表面缺陷的检测率,对串列式超声波检测工艺进行一定的改进,并针对如何制作标定试块、选择检测参数、确定扫查区域等方面的问题进行浅要探讨;并在实际工件中进行验证,确保了检测结果的可靠性。     

Reference specimens of nonmetallic materials for penetrant nondestructive testing

A method for manufacturing reference specimens for penetrant nondestructive testing that are based on a nonmetallic material (epoxy glue) with metal foil flaws is considered.     

Estimated efficiency of slit collimation of a high-energy radiation source for radiometric testing of large objects

An approach to estimating the contribution of scattering to the integral flux of detected radiation is developed. The proposed method may be used for radiometric testing of large objects. A method for selecting parameters of slit collimators for sources of high-energy bremsstrahlung is proposed.     

An algorithm for disintegrating large and complex rapid prototyping objects in a CAD environment

A CAD application tool kit interfacing with a Unigraphics (UG) system was developed for disintegrating large and complex rapid prototyping objects into smaller and simpler components which can be fabricated by a rapid prototyping system. As the core of the tool kit, the algorithm of such disintegration is described in detail in this paper. The algorithm combines the flat planar parting method and feature-based volume decomposition. Due consideration is also given to the optimisation of the surface accuracy, the build time, and the strength and number of segments generated. Based on the algorithm and the CAD application tool kit, the disintegration of two RP objects was realised in a selective laser sintering system.