Assessment of Lateral Thermal Diffusion of Impulse Thermography Method in Measuring Size of Non-Planar Defects

Abstract

Internal defects are normally developed in concrete bridge structural components during long-term operations under heavy loads of the vehicles. Conventional methods for the structural health monitoring, such as visual inspection, chain dragging, and hammer sounding, provide only surface cracks and partial subsurface defects, hence, it might be less accurate to predict the subsurface delamination. Infrared thermography has proven to be an effective way to detect delamination. However, sizing of the delamination is a difficult task, especially for special shapes. This study aims to investigate the effect of lateral thermal diffusion on predicting delamination size by using Finite Volume Method (FVM), then points out the drawbacks of Full Width at Half Maximum (FWHM) method in measuring non-planar subsurface delaminations. In addition, results of the numerical method and the experimental study of impulse thermography (IT) are compared. It indicates that FVM is a reliable tool for modelling infrared thermography (IRT) technique.