Hardware-software complex of nondestructive testing of aircraft parts
MESC Air Force “Air Force Academy named after professor N.E. Zhukovskii and Yu.A. Gagarin”, 54a, Starykh bol'shevikov, Voronezh, 394064, Russia
In order to increase the efficiency of the optical methods of the nondestructive testing of assembly units, equipment and component parts of the aerial vehicle of the Russian aircraft, the complex of statistical and natural tests on use of a method of speckle-structures of optical radiation and correlation analysis of images, for diagnostics of a status of surface and subsurface structure of aviation details was carried out.
During numerical and experimental studies it is established that the value of an interval of correlation of the registered speckle-pictures directly depends on the dimension of defect of the probed sample, the bigger the dimension of defect, then the smaller the interval of correlation of a speckle-picture. The limits of applicability of algorithms of correlation analysis of digital speckle-pictures for determination of parameters of roughness of the controlled objects are also defined, it is established that in case of registration of a speckle-picture by scheme using radiation transmitting through optical system (through sample material) the range of the dimension of roughness for which a method of correlation processing is applicable is about 4 times bigger than in case of reflection of wave front from a surface with the subsequent registration of a picture at once on a screen matrix. It is established that it is effectively to use the correlation analysis for determination of high-rise parameters of a controlled surface at the maximum height of roughness of hmax ≤ 8λ− for reflection and hmax ≤ 32λ − for a radiation transmission through a sample.
During an experimental study on application of the method of speckle-structures of optical radiation for an estimation of the internal structures of composite materials it was established that with the increase of the dimension of internal defect the value of the radius of correlation of the speckle-picture increases, and the width of the energy spectrum decreases witch is explained by a smaller transmission of laser radiation through the material in the area with a bigger diameter of the internal defect. In case of control of the optically nontransparent surfaces the inverse relation is observed, so the bigger the high-rise parameter of roughness or width and depth of the defect, the smaller the value of the radius of correlation of the registered speckle-picture. It is established that the most sensitive parameter of the registered speckle-pictures in using correlation analysis is the value of the radius of correlation of a speckle-picture.
Consideration of the features of realization of the method speckle-structure optical radiation in laboratory conditions and also the existing optoelectronics element base in use allowed to develop the model of the test mobile speckle-laser defectoscope. The software module which would allow to automate the process of defectoscopic control with the use of a method of speckle-structures of optical radiation is developed for the correlation processing of speckle-pictures with the use of the Qt tools, QWT libraries and the compiler GNU C ++. This software module carries out the following tasks:
— capture of a speckle-picture from a mobile defectoscope;
— definition of the speckle-picture parameter (radius of correlation and width of the energy spectrum);
— displaying information on the defect-free or malfunctioning of the controlled unit to the operator.
Thus, the hardware-software complex of non-destructive control allowing executing operations of defectoscopic control of aviation details and manufacturing conditions is developed.
The results of the work can be used for justification of tactical technical requirements on creation of devices of non-destructive control, which principles of operation are based on use of the method of speckle-structures of optical radiation.
Keywords:nondestructive testing, roughness, speckles, correlation
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