Vol 53, No 5 (2017)

Results of applying the electromagnetic-acoustic multiple-shadow method to testing small-diameter cylindrical objects with Rayleigh waves are presented. The possibility for using the spectral and probabilistic-statistical approaches to processing detected signals is demonstrated. The capabilities of the method are evaluated when revealing surface flaws of different types, orientations, and dimensions in various objects.

Results of applying the electromagnetic-acoustic multiple-shadow method to testing smalldiameter cylindrical objects with Rayleigh waves are presented. The possibility for using the spectral and probabilistic-statistical approaches to processing detected signals is demonstrated. The capabilities of the method are evaluated when revealing surface flaws of different types, orientations, and dimensions in various objects.

The questions of modeling the process of failure under plastic restructuring of a material, the transformation of the strength state of the material of plastically deformed blanks into the state of the article material, the acoustic-emission assessment of the faultiness of the end item, and the liability of the flaws in a blank to development under rolling are considered.

Problems related to testing the integrity of conducting coatings in aircraft fuel tanks are considered. Different types of flaws are analyzed, and the main problems encountered when detecting these flaws are revealed. The design of a capacitive device that improves the accuracy of the known technical solutions for testing the integrity of conducting coatings is presented. Theoretical foundations are considered for developing a mathematical model for shaping data signals in the testing procedure based on calculating the irrotational part of electric field inside the capacitive-gauge structure.

A back-projection tomographic reconstruction algorithm using a fan-shaped beam is considered. The freeware that implements the method of back projections is mainly applicable only in the case of parallel radiation. Distinctions in how this approach is applied when using parallel and fan-shaped beams are described in part that is related to the geometry of an experiment. The implementation of the algorithm with allowance for the peculiarities of reconstruction with a divergent beam is presented as a flow chart. The results provided in the paper demonstrate the working capacity of the algorithm.

A brief review of leak hunting methods is presented as well as some estimates of sensitivity thresholds and other properties for different methods. It is shown that gas-analysis methods are of particular interest due to their high sensitivity and universality. The main problematic properties of these methods such as, mainly, their bulkiness and instantaneous nature of testing are formulated. Taking the above into account, the use of solid-state sensors is justified in designing gas-analysis leak-hunting systems, including systems that operate alongside technological equipment and use fumes of working substances inside the equipment as tracer leak-hunting gases. A sensor operating on surface acoustic waves (SAW-sensor) is considered as one of the most promising sensors.