Pulsed Flying Spot Elliptic method for the estimation of the thermal diffusivity field of orthotropic materials

Abstract A novel contactless thermal technique based on the Grid Pulsed Flying Spot is presented here to estimate the in-plane fields of the thermal diffusivity in a homogeneous and orthotropic material oriented out of the main axes. The main novelty is to propose an analytical method based on the logarithmic decomposition of the pulsed spot temperature response to simultaneously analyse the location of the spot, the thermal diffusivity and the orientation angle of the orthotropic axes versus the Cartesian axis of the images. Several methods have been proposed to measure the in-plane thermal diffusivities along the main axes of orthotropic materials. To our knowledge, few methods exist that simultaneously estimate the thermal diffusivity tensor in the main axes of orthotropy and the orientation of these main axes. In this paper, we proposed a Logarithmic Ellipsometric Method based on the inverse processing method to estimate the thermal diffusivity from the recording of the transient thermal field at the front face. In this paper, the method is presented, and the first results on the homogeneous orthotropic materials are depicted. The in-plane thermal diffusivity is estimated with an error less than 6%, as is the angular orientation of the orthotropic axis compared to the image axis.