The Woodruff School

SUMMARY

Corrosion often occurs in the inner aluminum lining of the HB-53 helicopter external fuel tank, resulting in fuel leaks. This project centers s on developing an in-situ ultrasonic inspection technique to detect corroded areas inside the fuel tank. Due to the complexity of the composite structure of the tank, the ultrasonic inspection is carried out from inside the tank using a monostatic backscattering technique. The backscattered field contains information related to the isonified surface properties (surface roughness scales). Numerical predictions are implemented with a simplified model of backscattered intensity (Ogilvy, 1991) based on the Helmholtz-Kirchhoff integral. Experimental results are obtained on artificially corroded plates, and on the actual fuel tank of the HB-53 helicopter. Signal processing techniques (cross-correlation and inverse technique) are used to detect corroded surfaces with data obtained with a focused 10 MHz pulsed transducer.

SUBJECT:	M.S. Thesis Presentation

BY:	Ghislain Retaureau

TIME:	Monday, May 15, 2006, 2:00 p.m.

PLACE:	MRDC Building, 4211

TITLE:	Corrosion Detection by Backscattering Ultrasonics

COMMITTEE:	Dr. Yves H. Berthelot, Chair (ME) Dr. Peter H. Rogers (ME) Dr. Jennifer E. Michaels (ECE)

SUMMARY Corrosion often occurs in the inner aluminum lining of the HB-53 helicopter external fuel tank, resulting in fuel leaks. This project centers s on developing an in-situ ultrasonic inspection technique to detect corroded areas inside the fuel tank. Due to the complexity of the composite structure of the tank, the ultrasonic inspection is carried out from inside the tank using a monostatic backscattering technique. The backscattered field contains information related to the isonified surface properties (surface roughness scales). Numerical predictions are implemented with a simplified model of backscattered intensity (Ogilvy, 1991) based on the Helmholtz-Kirchhoff integral. Experimental results are obtained on artificially corroded plates, and on the actual fuel tank of the HB-53 helicopter. Signal processing techniques (cross-correlation and inverse technique) are used to detect corroded surfaces with data obtained with a focused 10 MHz pulsed transducer.