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Evaluation of stresses in carbon fiber composites for aerospace applications employing LCR waves and ultrasonic arrays

Abstract

Aircraft components must be monitored continuously to allow the safe operation of the aircrafts. The inspection of mechanical stress state is of paramount importance to ensure such safety. Nondestructive techniques for evaluating stresses are the most suitable for components that cannot be replaced or removed from the operating site. Among the non-destructive techniques, those which are based on the acoustoelasticity stand out for their simplicity and low cost. The acoustoelastic theory relates the variation of the elastic wave speed with the change of the stress in the material. For measuring from the surface, the most sensitive technique is based on Longitudinal Critically refracted waves (LCR). However, not only the stress influences the wave velocity, but also the uniformity of materials inspected, and other factors, such as temperature. Non uniformity is a problem particularly important for the inspection of structural composites, because such variation can lead to changes in the wave speed. The objective of this research project is to evaluate the variation of propagation speed of LCR waves in carbon/epoxy composites, aiming to correlate its variation to the applied stress. The evaluation of non-uniformity shall be performed using ultrasonic arrays and the TFM technique (Total Focusing Method). As a result of this project, it is expected to develop a nondestructive method for stress measurements that provide safer, more reliable, and economically viable inspections. As additional results it is expected to submit papers to scientific journals and conferences in the area, the graduation of students, and the generation of patents on innovative aspects of the technique developed. (AU)

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Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
GONCALVES, V. V.; DOS SANTOS JUNIOR, A. A. Effect of Non-uniformity on Time-of-Flight Measurement of Critically Refracted Longitudinal Waves for Stress Evaluations of Carbon Composite Materials. EXPERIMENTAL TECHNIQUES, v. 46, n. 1, p. 1-15, FEB 2022. Web of Science Citations: 0.
PEREIRA JR, PAULO; DOS SANTOS JR, AUTELIANO ANTUNES. INFLUENCE OF THE TEMPERATURE ON ULTRASONIC IMAGES GENERATED BY ARRAYS IN ASTM A36 STEEL. TRANSACTIONS OF THE CANADIAN SOCIETY FOR MECHANICAL ENGINEERING, v. 41, n. 5, p. 872-883, DEC 2017. Web of Science Citations: 0.
PEREIRA, P.; BUENOS, A. A.; SANTOS, A. A. On the Evaluation of the Effect of Microstructure on the SNR of Ultrasonic Images and on the Velocity of L-cr Waves. JOURNAL OF TESTING AND EVALUATION, v. 45, n. 4, p. 1401-1409, JUL 2017. Web of Science Citations: 0.

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