Development of in-plane thermal diffusivity evaluation method in laser spot periodic heating method

Nagata, Sho*; Nishi, Tsuyoshi*; Ota, Hiromichi*; Igarashi, Takahiro  ; Miyake, Shugo*

A spot periodic heating method is a highly accurate, non-contact method for evaluation of anisotropy and relative thermophysical property distribution. However, accurately evaluating thermal diffusivity is difficult due to the influence of temperature wave reflection from the whole surface of the sample. In a previous paper, we proposed a method to derive thermal diffusivity using a parameter table based on heat transfer equations using the concept of optimum distance between of heating-point and measurement point considering the finite sample size, sensitivity distribution of infrared ray detector, intensity distribution of heating laser and sample thickness. In these results, the obtained thermal diffusivity of pure copper was in good agreement with some literature values. However, in the measurement of pure copper with different thicknesses, the temperature response was different from that obtained by the analytical solution. The effect of reflection of temperature waves is significant and needs to be verified by numerical analysis using the finite element method.