Estudo dos efeitos da microestrutura do material e da frequência do sinal ultrassônico na análise de flutuações

Abstract

It is usual the application of ultrasonic non-destructive evaluation to detect discontinuities in different materials applied in industry Furthermore information about the microstructure of the inspected material can be obtained by signal processing of time series produced during the inspection Simulation of ultrasonic testing can be an important tool to help the understanding and predicting the interaction of mechanical wave in materials First of all computational materials modeling to reproduce the characteristics of specimens through which the wave propagates is necessary Five different one-dimensional materials composed of domains (grains) with different average size and same density were designed in this work Simulations of ultrasonic wave propagation in the modeled materials were performed at four different wave frequencies Concomitantly ultrasonic signals were acquired from five steel samples containing different average grain sizes using probes with central frequency of 225 5 10 and 20 MHz Detrended fluctuation analysis DFA and rescaled range analysis R/S two techniques for analyzing fluctuations in time series were used to process the signals in order to filter out spurious information and evaluate the influence of selected variables (grain size and frequency of the signal) on the ultrasonic signals obtained Finally simulated and experimental data and compared in order to evaluate the simulation performance