Diagnostic and monitoring of the state of load currying structures on the basis of quantum approach to the measurement and analysis of acoustic emission signals

Section – aerospace transport systems design, operation.

Banov M.D, Shanyavsky A.A., Mikolaychuk Y.A., Pogorodny P.G.

The method of acoustic emission (AE) belongs to non-destructive testing (NDT) methods. Universality of AE method is the registration and monitoring of dangerous destruction processes without the removal of controlled objects from operation. Being a passive NDT method, in which defect itself informs about its presence and having the property of integrality, the AE method monitors the whole volume of the object by the single sensor. The sensor attached to any of accessible surface of the monitored products or the sensor is connected via the acoustic pipe. This is especially important when controlling the hard-to reach and inaccessible places of the facility, such as, for example, load currying spars of aircraft wings under the fillet and the load currying structures under the wing covering.

The currently used AE systems can be conditionally broken down into three categories. The first category systems register only the speed and the total number of AEs. Systems of the following category – determine the relative arrival time of the signals in real time. The third category allows immediately determine the location of AE source. The general principle of all existing systems is obtaining data about the AE signal either at regular intervals ∆t=const, or through equal intervals of cycling loading ∆n=const. In this case one to ten AE parameters are analyzed, such as the sum of pulses, intensity, energy, etc., which requires bulky multichanel AE systems.

According to the quantum principle proposed by the authors, the act of elementary measurement of AE signals is to determine the time interval i=tx-ti, for which «the quantum» (portion) of the analog signal =const accumulates. It is only necessary to isolate AE signals with a given reliability, to regulate the magnitude of this «quantum» for each control object, achieved by means of experimental analysis in accordance with a pre-selected form on nondestructive loading of the controlled article.

Preliminary evaluation of the proposed approach realizes the possibilities that are inaccessible for existing AE measurement systems, namely: adaptive sampling and adaptive spectrum limitation, which significantly reduces the amount of information being registered and processed (up to two orders of magnitude); eliminates the dynamic, static and methodological measurement errors and the error caused by the transformation of the spectrum during sampling; allows significantly increase the threshold of sensitivity, the dynamic range of equipment, and ultimately, the accuracy of the measurements; requires a small energy supply (a fraction of a watt); the price of the elemental base of the quantum device is used is much lower than that of existing devices measuring AE on multi-bit ADC-s; significantly reduces the difficulties of subsequent signal analysis. Moreover, the adding of an electronic switcher in the measuring system, which interrogates a specified number of installed sensors, implements the possibility of switching to a single channel data collection system, which will eliminate unknown errors of each channel, thus increases the reliability of the results.