Results of the analysis of acoustic-emission signals generated due to ultrasonic waves propagating in a polymer composite material and registered with piezoelectric and fiber-optic sensors are presented. The fiber-optic sensors were arranged into an adaptive interferometer based on using a dynamic hologram formed in a photorefractive crystal. Reducing the setpoint fading has made it possible to improve the noise immunity and sensitivity of the measurement system when using an adaptive interferometer on a photorefractive crystal. Optical fibers in the interferometer’s measurement system served as sensors of ultrasonic waves and were built into a polymer composite material when the sample was manufactured. The sample was a rectangular plate made of a multilayer fiberglass material. It has been discovered that the sensitivity of the adaptive interferometer makes it possible to detect acoustic- emission signals generated by a Hsu–Nielsen source. When determining the speed of sound in the polymer composite material, peculiarities of registering a group wave by fiber-optic sensors have been established that are due to the anisotropy of the medium the wave propagates in and the distributed character of sensor placement in the studied composite material. The wavelet transform has been used to separate the informative component of the wanted signal.

This work is devoted to the investigation of the characteristics of acoustic emission waves to establish their relations with the parameters of the fracture of the structure of the material. The paper presents the results of the analysis of acoustic emission signals recorded during the propagation of ultrasonic waves in metal sheet materials using piezoelectric sensors. The specimen was a rectangular aluminum plate. The piezoelectric sensor recorded acoustic emission signals generated by the Hsu-Nielsen source. The piezoelectric sensor is located in the center of the aluminum plate. Then sources are generated with different hardness to model various kinds of cracks at each specific location. To determine the informative component of a useful acoustic emission signal, the Morlet wavelet transformation was used. When excited by a fracture pencils of different hardness, the magnitude of the wavelet differ in the energy and intensity of the spectrogram.

This paper presents the results of the study of strength and fracture processes of FRP samples, obtained by vacuum and vacuum-autoclave molding methods. The experimental studies consisted of a three-point bending test with step loading, accompanied by an acoustic emission method. Based on the acoustic emission data recorded using the acoustic-emission software and hardware complex during the experiments, a method for estimating the accumulated damage using various techniques for analyzing acoustic emission parameters was tested. The results of methods for analyzing the power-law coefficient of accumulation of total AE, b-value and density distribution of amplitudes and median frequencies are considered. An estimate of the power-law coefficient of accumulation of the total AE made it possible to determine the bearing capacity of PCM samples. Using the techniques for analyzing the amplitude distribution of the AE signals and the distribution density of the amplitudes and median frequencies of the AE signals, destructive processes in the volume of samples were described and the stages of their damaging were revealed.

The paper presents the results of the study of the stage of accumulation of damage and fatigue rupture of titanium alloys (using the method of acoustic emission). The main object of research was the development of a method for designing a generalized fatigue diagram characterizing the stage of fatigue damage accumulation. The studies aimed at experimental verification of the hypothesis of the stage of damage accumulation, which can be established only by the registered parameters of acoustic emission with separate analysis by types of acoustic emission sources. In contrast to the method of research, which is carried out fractographic analysis, the use of acoustic emission method can significantly reduce the amount of testing. The types of acoustic emission sources on the distribution plane of two-parameter “AE signal energy E_AE vs. frequency parameter K_f” are considered. Fatigue stages in the tests of trial alloys were determined by the activity of the AE signals emitted by different types of AE sources (dislocation, micro - and macro-cracks). A generalized diagram of fatigue developed according to the specified stages. The developed method significantly reduces the volume of fatigue tests and fractographic studies.

A soft and hardware complex designed for recording and processing acoustic emission (AE) signals in real time is described. The hardware part of the complex includes a computer with PCI connectors,...