Том 52, № 10 (2016)
- Год: 2016
- Статей: 10
- URL: https://journals.rcsi.science/1061-8309/issue/view/11290
Acoustic Methods
Development of passive ultrasonic tomography techniques
Аннотация
Passive ultrasonic tomography is described. Results of developing, modeling, and testing some key techniques in passive ultrasonic tomography are provided. The techniques include an algorithm for determining arrival times of noisy acoustic signals with sloping leading edge; a method for determining the source coordinates and onset times of acoustic signals and estimating the accuracy of those; and regularizing procedures for tomographic reconstruction of nonuniform distributions of propagation speed of acoustic signals. The results of modeling the effect of measurement noises on the accuracy of source location and the mutual influence of the source location accuracy and the soughtfor nonuniform distribution of propagation speed of acoustic signals are described. Results of experimental testing of the developed techniques are also provided.
A facility for measuring the thickness of thin metal films
Аннотация
A facility is described for measuring the thickness of a thin metal film. A measurement method is proposed that is based on the dependence of the phase velocity of harmonic antisymmetric Lamb waves that propagate along the film on the film thickness. A continuous method for excitation of acoustic waves has been applied to velocity measurements. It makes it possible to eliminate the effect of dispersion of the Lamb-wave velocity on the measurement accuracy.
Optimization of the Cascade Feed Forward Back Propagation network for defect classification in ultrasonic images
Аннотация
Ultrasonic Time of Flight Diffraction (TOFD) is now a well established NDE technique finding wide applications in the industry for inspection during manufacture, pre-service and also inservice. While conventionally interpretations of UT images are done by the inspector, a need has always been felt for automated evaluation and interpretation especially when large inspection volumes are involved. Apart from enhancing the speed of inspection, automated evaluation and interpretation provides better reliability of inspection. A number of approaches based on signal analysis coupled with artificial neural networks (ANN) are being tried internationally and limited success has also been obtained. This paper focuses on the development of a semi automatic toolbox for reliable and fast flaw classification in TOFD images using ANN. TOFD images are first acquired and statistical parameters such as mean, standard deviation, energy, skewness and kurtosis are calculated for the region of interest in the images. The classification of the flawed region like Crack, Lack of Fusion, Lack of Penetration, Porosity and Slag Inclusion was materialized using different ANN approaches which made use of these statistical parameters as their input. The process of optimization of a network involves comparison of classification accuracy and the sensitivity of the selected networks. The Cascade Feed Forward Back Propagation (CFBP) network with log sigmoidal activation function proved to be the optimized network model for the data set considered in this study.
X-Ray Methods
Comparative analysis of techniques for revealing cracks in noisy X-ray tomography and introscopy images
Аннотация
A review is provided of techniques for digital processing of noisy X-ray computed tomography and introscopy data that are represented by halftone images. The most hazardous crack flaws placed against a background with a wide range of brightness have been studied. Difference median and slit filters are proposed for processing such images.
Reconstructing the melting channel shape in electron-beam welding from the parameters of penetrating X-ray radiation. Part I. Posing inverse geometrical problem
Аннотация
Direct and inverse problems of reconstructing the shape of melting channel from the parameters of secondary penetrating bremsstrahlung X-ray radiation are posed. The inverse problem is shown to be reducible to solving an integral convolution-type equation and, in general case, Hadamard well-posed in the entire range of electron-beam welding (EBW) modes. The shape of melting channel is reconstructed based on the known theorem on the Fourier image of convolution.
Magnetic Methods
Using magnetic testing to optimize the technology of manufacturing stain-proof austenitic steels
Аннотация
Some results are presented that are concerned with the use of magnetic methods and tools for nondestructive testing of articles made of OAO Izhstal’ austenitic chrome-nickel steels. It is shown that modern magnetic-testing techniques help significantly in optimizing the industrial process while improving the technical specs of the produce.
Thermal Methods
A LED-based thermal detector of hidden corrosion flaws
Аннотация
Results of using powerful LED matrices to inspect metal articles for hidden corrosion by active thermal-wave method are described. The effect of the color of paint-and-lacquer coating on the efficiency of heating with LED and halogen emitters is analyzed. The possibility of using powerful LED panels as thermal stimulation sources in portable flaw detectors is described.
Radiowave Methods
Determining the position of hydrate blocks in gas pipelines by a radiowave method
Аннотация
A radiowave method of detecting and positioning hydrate blocks in pipelines is considered. The method consists in probing a pipeline with a high-frequency nanosecond-duration radio pulse with subsequent measurement of its travel time to the hydrate block and back. Results of a natural experiment and flow charts of a device for determining the position of a hydrate block imitator (ice) in a stub pipe with a diameter of 273 mm. A Gunn diode is used as a generator of microwave pulses with a duration of 10 ns and a basic frequency of 10 GHz. The decay of microwave pulses in the pipe and the potential of the radiowave method are estimated.
General Problems of Nondestructive Testing
Applying nondestructive testing to quality control of additive manufactured parts
Аннотация
Possibilities, application domains, advantages, and limitations are considered for currently used physical methods of nondestructive testing of additive manufactured parts. The methods are classified according to the physical principle of operation.
Ultrasonic and eddy-current study of plastic deformation in austenitic-steel welds
Аннотация
The effect of plastic deformation of a 08Kh18N10T (analogue AISI321)-steel welded joint on electromagnetic and acoustic properties of the material has been studied by eddy-current and ultrasonic methods. It has been established that structural inhomogeneity in heat- affected zone leads to a nonuniform distribution of acoustic properties in the weld. The possibility for determining the plastic resource of material from ultrasonic data is demonstrated.