Fluctuation analysis

Information about the microstructure of the inspected material can be obtained from the processing of the time series produced during the inspection. Ultrasonic testing simulation is an important tool for understanding and predicting the interaction of mechanical waves with the medium. However it is necessary to model the medium that reproduces the characteristics of a sample the object of study through which the wave propagates. Five one-dimensional media composed of domains with different average sizes and the same average density were defined in this work. Simulations of ultrasonic wave propagation in the modeled media were performed for four different wave frequencies. At the same time ultrasonic signals were captured on five steel samples containing different average grain sizes. All the signals obtained were subjected to DFA and R/S analysis two techniques for analyzing fluctuations in time series with a view to filtering spurious information and evaluating the influence of the selected variables on the ultrasonic signals obtained. Finally a comparison is made between the simulated and experimental data and an evaluation of the quality of the simulation.