Liquid ingress recognition in honeycomb structure by pulsed thermography

¹ School of Material Science and Engineering, Beihang University, 37 Xueyuan Road, Beijing 100191, P.R. China
² Institute of Physics and Electronic Engineering, Chongqing Normal University, 12 Tianchen Road, Chongqing 400047, P.R. China
³ Department of Physics, Capital Normal University, 105 Xisanhuan North Road, Beijing 100048, P.R. China

^a e-mail: zzh406@hotmail.com

Received: 9 December 2012
Revised: 14 February 2013
Accepted: 20 February 2013
Published online: 30 April 2013

Abstract

Pulsed thermography has been proven to be a fast and effective method to detect fluid ingress in aircraft honeycomb structure; however, water and hydraulic oil may have similar appearance in the thermal image sequence. It is meaningful to identify what kind of liquid ingress it is for aircraft maintenance. In this study, honeycomb specimens with glass fiber and aluminum skin are injected different kinds of liquids: water and oil. Pulsed thermography is adopted; a recognition method is proposed to first get the reference curve by linear fitting the beginning of the logarithmic curve, and then an algorithm based on the thermal contrast between liquid and reference is used to recognize what kind of fluid it is by calculating their thermal properties. It is verified with the results of theory and the finite element simulation.