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Nagata, Sho*; Miyake, Shugo*; Igarashi, Takahiro; Ota, Hiromichi*; Nishi, Tsuyoshi*
Jikken Rikigaku, 22(2), p.105 - 111, 2022/06
Thermal easy axis and thermal diffusivity of uniaxial carbon fiber-reinforced plastic sheets were determined by a offset periodic laser heating method, and investigated relationship between the thermal easy axis and fiber orientation with different thickness of CFRP sheet specimen, experimentally. It was clarified that the orientation of the thermal easy axis spreads in the in-plane direction with the sheet thickness deceases. Then, thermal diffusivity of CFRP specimens in the out-of-plane and in-plane direction were measured by two method: a variable-frequency method and a variable-displacement method, respectively. In the results of the out-of-plane directions, thermal diffusivity almost consistent with the carbon fiber direction were obtained. In contrast, the in-plane directions of those were exhibited unexpected value. Moreover, thermal diffusivity determination by offset periodic heating method was carried out. Finally, it is found that the thermal diffusivity considering the thermal easy axis with fiber angle was different characteristics from the in-plane direction measurement.
Nagata, Sho*; Nishi, Tsuyoshi*; Ota, Hiromichi*; Igarashi, Takahiro; Miyake, Shugo*
Proceedings of 34th International Microprocesses and Nanotechnology Conference (MNC 2021) (CD-ROM), 2 Pages, 2021/10
Due to the increasing heat generation density of electronic devices, unidirectional Carbon-fiber-reinforced Plastic (CFRP) has gained interest as a heat-dissipating material owing to its high thermal conductivity, high anisotropy, and high strength. If CFRPs can be used to conduct heat in the desired direction of dissipation, more efficient thermal designs are possible. To control heat propagation, it is necessary to understand the heat propagation behavior within CFRPs at each fiber angle by determining the direction of heat propagation, referred to as thermal orientation. We previously demonstrated an approach for determining the thermal orientation of CFRPs using a periodic heating method, wherein the heat propagation in CFRPs was classified into two directions: the direction of the carbon fiber direction and the direction of the fiber-matrix interface. It has been suggested that the fiber-matrix interface has a significant effect on the heat propagation of CFRPs, which increases with the increase in CFRP thickness. However, the effect of CFRP thickness on thermal orientation is yet unknown. In the current study, we investigated the effect of the fiber-matrix interface on thermal orientation using the periodic heating method for CFRPs with varying thicknesses.
Nagata, Sho*; Nishi, Tsuyoshi*; Ota, Hiromichi*; Igarashi, Takahiro; Miyake, Shugo*
no journal, ,
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.