Inverse heat transfer approach for IR image reconstruction: Application to thermal non-destructive evaluation

Abstract An inverse heat transfer method is developed to characterize subsurface defects in ceramic materials through the reconstruction of the IR image obtained by numerical simulation. This study focuses on the application of the Conjugate Gradient Method (CGM) of minimization for the determination of the thermal conductivity and the depths of defects present in ceramic materials. To this aim, an inspection method which consists of imposing a transient regime process in the sample test is proposed, starting from an elevated and uniform temperature and applying a cooling process over the time. Surface thermal images are collected during the cooling process using an infrared camera. A mathematical model based on the transient behavior of the ceramic sample during the inspection is proposed to study the different heat transfer mechanisms and detectability levels of the simulated defects. The numerical solution of the model was developed using the Finite Volume Method (FVM), in which the approximated equations are obtained by performing energy balances for each elementary volumes. Experimental and simulated temperature decay curves of defective areas are used to determine the properties of the above-mentioned defects.

[1]  Cheng-Hung Huang,et al.  A two-dimensional inverse problem in imaging the thermal conductivity of a non-homogeneous medium , 2000 .

[2]  S. Churchill,et al.  Correlating equations for laminar and turbulent free convection from a vertical plate , 1975 .

[3]  Chin‐Hsiang Cheng,et al.  Non-destructive inverse method for determination of irregular internal temperature distribution in PEMFCs , 2005 .

[4]  M. N. Özişik,et al.  Inverse Heat Transfer: Fundamentals and Applications , 2000 .

[5]  Cheng-Hung Huang,et al.  An inverse problem in simultaneously measuring temperature-dependent thermal conductivity and heat capacity , 1995 .

[6]  M. Hanke.  Conjugate gradient type methods for ill-posed problems , 1995 .

[7]  Xavier Maldague,et al.  Theory and Practice of Infrared Technology for Nondestructive Testing , 2001 .

[8]  I. Cañas Guerrero,et al.  Thermal–physical aspects of materials used for the construction of rural buildings in Soria (Spain) , 2005 .

[9]  Chin-Hsiang Cheng, Chun-Yin Wu.  AN APPROACH COMBINING BODY-FITTED GRID GENERATION AND CONJUGATE GRADIENT METHODS FOR SHAPE DESIGN IN HEAT CONDUCTION PROBLEMS , 2000 .

[10]  E. Barreira,et al.  Evaluation of building materials using infrared thermography , 2007 .

[11]  Fábio Santana Magnani,et al.  Infrared thermography applied to the quantitative determination of spatial and thermophysical parameters of hidden included objects , 2007 .

[12]  Yvon Jarny,et al.  An inverse analysis to estimate linearly temperature dependent thermal conductivity components and heat capacity of an orthotropic medium , 1995 .