On the Anisotropy of Lotus-Type Porous Copper

This paper addresses the thermal and mechanical properties of lotus-type porous copper. Due to their cellular metal characteristics in combination with strong anisotropy, lotus-type materials exhibit unique properties. As an example, directional thermal conduction enables the controlled transport of thermal energy in the pore direction without the need of strong thermal insulation. In this paper, thermal and mechanical finite element analyses are performed. The effective thermal conductivity, Young's modulus, and the 0.2%-offset yield strength are determined. Special consideration is given to the anisotropy of the material. In order to guarantee accurate discretization of the complex material geometry, calculation models are directly based on computed microtomography data. Elastic properties are compared to experimental data and good agreement is found. For the characterization of the thermal anisotropy, a second numerical approach, called the Lattice Monte Carlo method, is used along with thermal finite element analysis. In addition to the numerical methods, the analytical Maxwell, Dulynev, and Bruggeman models are applied. Good agreement for the application of two-dimensional versions of Dulynev's and Bruggeman models is observed whereas the Maxwell model significantly overestimates the material properties.