Development of an optical sensor for non-destructive inspection of aeronautics and space structures

• Grant number: 16/12182-4
• Support Opportunities: Scholarships in Brazil - Master
• Start date: October 01, 2016
• End date: December 31, 2018
• Field of knowledge: Engineering - Aerospace Engineering
• Principal Investigator: João Marcos Salvi Sakamoto
• Grantee: Victória Spinardi Cabral Paiva
• Host Institution: Instituto de Estudos Avançados (IEAv). Departamento de Ciência e Tecnologia Aeroespacial (DCTA). Ministério da Defesa (Brasil). São José dos Campos , SP, Brazil
• Associated scholarship(s): 17/06935-2 - Short-term research project in Kumamoto University as part of the master's degree research project "Development of an optical sensor for non-destructive inspection of aeronautics and space structures"., BE.EP.MS

Abstract

The laser welding process has been used in the aviation sector, allowing weight reduction by dismissing the use of rivets, but keeping a high resistance. Weight reduction means fuel economy or availability for carrying more payload. Thus, a non-destructive inspection becomes necessary to ensure that each welded structure presents structural safety. The idea in this work is to detect and pick up information from the acoustic waves generated by the laser welding process itself. These waves, modulated by the welding process can reveal the quality of the weld and point out flaws or defects. Therefore, the main objective of this work is the research and development of an optical sensor able to detect sound or ultrasonic waves in order to be part of a non-destructive inspection system. To accomplish that, it is proposed the development of an optical microphone, known as optical wave microphone, aiming application on non-destructive inspection on laser welding of aircraft or space structures.The optical wave microphone working principle is based on the interaction between sound and light, refractive index variation, diffraction, and interference between the diffracted and the non-diffracted beams. The light diffracted by the sound waves keeps propagating together with the non-diffracted part of the laser beam. Therefore, there will be a region where the two beams will interfere (the photodetector is placed in this region) in a way to directly recover the sound signal from the optical signal. This type of microphone presents the advantage of dismissing a diaphragm, i.e., it is able to detect sound or ultrasound waves directly from its optical beam. Therefore, the optical wave microphone presents potential for an inspection technique that is non-contact, non-destructive, and without disturbing the sound field. Moreover, this sensor provides signals directly in time domain and is simple and low cost. (AU)

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)

MITSUGI, FUMIAKI; KIKUCHI, RYO; HONDA, SHO; PAIVA, VICTORIA; SAKAMOTO, JOAO; NAKAMIYA, TOSHIYUKI; SONODA, YOSHITO. Quantification of Two-Dimensional Acoustic Field Generated by a Surface Barrier Discharge With Fiber-Type Optical Wave Microphone Computer Tomography. IEEE TRANSACTIONS ON PLASMA SCIENCE, v. 49, n. 11, p. 3589-3596, NOV 2021. (17/06935-2, 16/12182-4)