Design of Near-Zero Thermal Expansion Polymer Composites

The purpose of this paper is to develop a methodology for designing polymer composites with near-zero effective coefficients of thermal expansion (CTE). The peculiarity of the proposed methodology is that the required result can be obtained by using components having positive CTE. The implementation is carried out on the example of unidirectional reinforced fiberglass with a square fiber packing scheme. The homogenization technique involves modeling of free temperature deformation of the composite in the absence of macro-stresses. The micromechanical analysis within a representative cell is performed by the finite element method. The method involves iteratively altering boundary conditions to ascertain the effective elements of the thermal expansion tensor. At certain physical characteristics of fibers and matrix, relative radii of fibers were found at which thermal expansion in the plane perpendicular to the reinforcement is practically absent.