<title>Three-dimensional dynamic thermal imaging of structural flaws by dual-band infrared computed tomography</title>

Abstract

Thisis a preprint of a paper intended forpublicationin a joumalorproceedings.Since changes may be made before publication, this preprintis made available with the understanding thatit will nut be cited or reproducedwithout the permission of the author. DISCLAIMER This document was prepared a.s an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accu racy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, ._ does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. o Three-dimensional dynamic thermal imaging of structural flaws by dual-band infrared computed tomography

Dual-band infrared (DBIR) imaging inspections of Boeing 737 and KC-135 aircraft panels

“…• geothermal aquifers under 6 to 60 meters of dry soil 1,2 • cemetery walls, trenches and a building foundation under 80 cm of asphalt and debris 3 • buried mines, rocks and objects under 1 to 20 em of disturbed sand, soil, or sod 3-8 • sea ice thicknesses varying from 5 to 50 cm. 9,10 This paper discusses the analysis of DBIR images to identify hidden defects within flash-heated test specimens and aircraft structures.We are developing a wide-area, non-contact, non-destructive inspection (NDI) tool to depict hidden defects within: w • adhesively-bonded aluminum lap joints with disbond (no-adhesive) sites replicating the skin of a Boeing 737 aircraft 9,11,12 • an aged Boeing 737 aircraft (see AppendixA, Figs. A-1 and A-2) at Sandia National Laboratories in Albuquerque, NM ,t…”

Advanced Signal Processing for Thermal Flaw Detection

“…Alternative analytical based methods for detecting flaws have investigated different surface heating protocols to optimize the flaw excitation 15,16 , use of dual infrared bands to minimize the influence surface artifacts 17 , analytical metrics related to bulk thermal properties (e.g., thermal diffusivity 18,19 and thermal inertia 20 ), characteristics of the temporal contrast curve 21 , and tomographic analysis methods [22][23][24][25] . Each of these research efforts has improved flaw detection reliability for some inspection applications by enhancing the flaw visibility, reducing noise, or providing a quantitative basis for evaluating the results.…”

Numerical simulation of thermal signatures of buried mines over a diurnal cycle

“…Pregowski and Swiderski 9 present a qualitative discussion of the effects of soil cover and water content. Another work, obliquely related to the effort proposed here, is that of Del Grande et al, 10 who discuss the use of computed tomography and a Þnite difference thermal analysis code (TOPAZ3D) for imaging structural ßaws in materials. Discussions of the physics of non-thermal hyperspectral sensors are rare.…”