Pulsed flying spot with the logarithmic parabolas method for the estimation of in-plane thermal diffusivity fields on heterogeneous and anisotropic materials

Abstract

A novel thermal non-destructive technique based on a Pulsed Flying Spot is presented here by considering in-plane logarithmic processing of the relaxing temperature field around the heat source spot. Recent progress made in optical control, lasers, and infrared cameras permits the acquisition of 2D temperature fields and localized thermal excitation on a small area instead of the entire recorded image. This study focuses on a new method based on spatial logarithm analysis of a temperature field to analyse and measure different parameters, such as the in-plane thermal diffusivity and localization of the spot. In this paper, this method is presented and the first results of heterogeneous anisotropic materials are depicted. The in-plane thermal diffusivity is estimated with an error lower than 4%, and the initial location of the heating spot is determined.

Heat Capacity and Anisotropic Thermal Conductivity in Cr2AlC Single Crystals at High Temperature

“…Using the measured density ρ = 5210 kg/m 3 and the temperature-dependent heat capacity C p (T ) [see In addition, the in-plane thermal diffusivity at RT is measured using the PFS with the logarithmic parabolas method. 36 A value of a = 11.4 mm 2 /s is measured, leading to a κ = 40.8 Wm −1 K −1 at RT. This PFS measurement is useful to validate the MPTR values.…”

Determination of thermal conductivity of inhomogeneous orthotropic materials from temperature measurements

“…where, for simplicity, we write T and Y instead of T (x i , y j , t; k 11 , k 22 ) and Y i,j (t), respectively, in the corresponding terms attached to the double sum. Alternatively, if one uses an infrared camera [11], the temperature reading (pixels) Y i,j (t) could be considered as the average temperature of the sample over a small square corresponding to the projection of the pixel. In that case, the Dirac delta functions could be replaced by rectangular window functions.…”

“…In this paper, we consider a two-dimensional coefficient identification problem to estimate the thermal conductivity of inhomogeneous orthotropic materials from internal temperature measurements. A quite different approach based on infrared thermography and pixels correlations has recently been proposed in [11].…”

Comparative study of Line Scan and Flying Line Active IR Thermography operated with a 6-axis robot

“…Twenty years ago, Krapez et al [1] proposed the "flying spot technique" based on a constant displacement of the laser spot to detect cracks in steel. Later, the Pulsed Flying Spot (P.F.S) [2] was developed to obtain in-plane thermal diffusivity fields on heterogeneous and anisotropic materials. Though the laser spot is a very interesting approach due to its known analytical solution, it has a lower scanning rate than the line scan method.…”