Effects of anisotropic voids on thermal properties of insulating media investigated using 3D printed samples

An insulating medium is a material designed for reducing heat conduction through entrained voids in the material. A specimen of insulating media contains numerous voids, the spatial distribution of which strongly affects the physical properties of the material, such as thermal conductivity and strength. The thermal performance of the material improves as the void ratio increases while the strength of the material decreases. Therefore, an appropriate method for examining the void distribution in the materials is necessary for better understanding of the material behavior. In this study, the effect of anisotropic voids on the material properties of insulating media is investigated. A 3D printer is utilized to generate a series of insulating media with different anisotropic voids. The void distributions of the specimens are characterized using probabilistic functions, and the thermal and mechanical properties of the specimens are also evaluated by means of real and numerical experiments. The results demonstrate an effect of anisotropic voids on the material properties that appropriately arranged anisotropic voids strongly affect the reduction of thermal conductivity for a specific direction, and that anisotropic voids can be utilized as a promising approach to develop high-performance insulating materials.