Interaction analysis of multiple coated fibers in cement composites by special n-sided interphase/fiber elements

This paper describes a new numerical approach for modeling the microscopic and macroscopic thermal behaviors of cement composites filled with multiple natural fibers coated with thin homogeneous interphase layers. The coated fibers are assumed to have regular or non-regular distributions in the cementitious matrix. In the present method, special n-sided interphase/fiber elements are developed with special two-phase fundamental solution kernels analytically satisfying the heat transfer equations in the fiber and interphase constituents and the continuum conditions between them to entirely discretize each coated fiber, in despite of the thickness of interphase layer. As a result, the number of nodes and computing costs can be significantly reduced. For such elements, all integrals involved are evaluated along the element boundary such that any polygonal elements with n sides can be constructed. Simultaneously, it's allowed for accurate calculation of the thermal fields anywhere within material phases including the matrix, fibers and interphases. Numerical experiments are conducted to study the interaction of multiple coated fibers and evaluate the effective thermal conductivities of the composites. Comparisons with numerical benchmark results from the conventional finite element method are made to demonstrate the property of the presented special n-sided interphase/fiber elements.