Defektoskopiâ

In air-coupled ultrasonic non-destructive testing of a number of products (biological objects, products made of chemically active or explosive materials), the amplitude of the electrical signal applied to the transmitting piezoelectric transducer is limited and in some cases cannot exceed the value of the order of U ~ 10—15 V. In this case, the sensitivity of testing is significantly reduced and therefore all possible ways to increase it should be used. First of all, piezoelectric transducers with the highest possible electroacoustic conversion coefficient should be used. In addition, it is necessary to select such an air gap length d_a between the transmitting transducer and the test object, that ensures the maximum amplitude of the ultrasonic emission signal “at the input” of the product. And since the maximum amplitude of the ultrasonic signal emitted by the transducer is located in the near field of the transducer, it is necessary to select the value d_a corresponding to the length of the near field of the transmitting transducer in the air, provided that in this case there will be no re-reflections of the emission signals in the air gap. This in turn requires the use of short (broadband) ultrasonic signals and, consequently, the use of ultrasonic broadband piezoelectric transducers.

The article shows that the parameters of the matching layers of the air-coupled ultrasonic piezoelectric transducer affect both the bandwidth of the transducer and the spatial characteristics of the transducer, including the position of the acoustic field maximum. It is shown that it is possible to determine the maximum of the ultrasonic broadband signal in the air in order to determine the optimal length of the air gap, at which the ultrasonic signal with maximum amplitude is emitted into the product, by analyzing the correlation distribution of the field of an air-coupled broadband transducer.

The results of the experiments are presented, confirming the necessity of providing the optimal length of the air gap between the air-coupled ultrasonic transmitting transducer and the test object to increase the sensitivity of through-transmission testing of simulators of products made of explosive materials

The article presents the results of acoustic emission testing of an aircraft wing box made of composite material ACM 102 130 C UD. The load was changed in steps with a step of 10 % of its maximum value. Before loading, the control zones consisting of four piezoelectric transducers of acoustic emission were calibrated. In order to reduce the influence of anisotropy and design features of the wing box on the errors in defect location, a new technique consisting of analytical and tabular methods was developed. In the analytical method, the coordinates of defects were calculated using three sensors of the piezoantenna, and the location error included random and systematic components. Inaccurate determination of the difference in the times of signal arrival at the sensors of the piezoantenna was the main source of the random component of the error. The complexity of the design influenced the appearance of the systematic error. At the same time, the features of the test object hampered the rectilinear propagation of the sound wave. When using the tabular method, the caisson structure was divided into a number of zones and the matrix of correspondence between the difference in signal arrival times and the coordinates of the selected cells was calculated. It was shown that the number of signals localized using the tabular method was bigger than that using the analytical method. Practical application of the developed location method showed that the average value of the reduced error decreased two fold when calculating the X coordinate and six fold when calculating the Y coordinate. This made it possible to reduce the location errors associated with the location of the calibration points on the structure. If the signal location error exceeded the permissible value determined by the cell size, they were excluded from further consideration as not localized

During the picking, storage, and transportation processes, collisions between fruits can cause mechanical damage and reduce the overall quality of the fruit. In order to ensure the quality of fruits, it is necessary to carry out non-destructive testing on fruits. This paper investigates a method for non-destructive evaluation (NDE) of early mechanical damage in apples using pulsed infrared thermography (PIRT). By applying thermal excitation to the apples and using an infrared camera to capture temperature differential data, various data processing techniques, including Fast Fourier Transform (FFT), Principal Component Analysis (PCA), and morphological algorithms, were employed to process and analyze the acquired images. The experimental results show that the morphological algorithm performs better than other algorithms in defect edge detection, enabling clear identification of defect features and reducing noise interference. We provide an efficient and accurate NDE solution for mechanical damage in apples, which is significant for improving the quality of agricultural products and extending their shelf life

X-ray computed tomography (XCT) is one of the most informative methods of nondestructive testing of polymer composite materials (PCM) and products made of them. One of the important stages of XCT of PCM products is segmentation, the automation of which is of research interest. In the segmentation process it is important to identify isotexture zones containing local X-ray density variations. In this paper we investigated the possibilities of three-dimensional texture filtering (Gaussian filter, Gabor filters) in clustering of X-ray computed tomography data by simple linear iterative clustering (SLIC) algorithm and evaluated their efficiency in terms of parameters: the share of mismatches between the boundaries of clusters and the boundaries of segmented areas and sphericity of clusters, as well as the performance in terms of time to partition the dataset into the required number of clusters. The results of the study show that the application of three-dimensional texture filters improves the clustering accuracy and sphericity of isotexture clusters of PCM product XCT data without a significant increase in clustering time compared to the raw data. The maximum increase in clustering accuracy was observed when using a combination of Gaussian and Gabor filters, while clustering time increased

The influence of variation of annealing temperature on magnetic and magnetoacoustic properties of cold-deformed alloy 97 % Ni, 3 % Fe has been investigated. The study of the microstructure of the nickel—iron alloy showed the presence of rolling texture up to annealing temperatures of about 500 ºC. At further increase of annealing temperature of the investigated alloy as a result of recrystallization the texture disappears and anisotropy of its magnetic and magnetoacoustic parameters decreases significantly. The sensitivity of magnetic and magnetoacoustic parameters to the rolling-induced anisotropy of the nickel—iron alloy has been compared. It is shown that the differential magnetic permeability measured with the DIUS-1.21M hardware and software system is the most sensitive parameter to anisotropy