Non-steady effective thermal properties of semi-infinite unidirectional fiber-reinforced composites using thermal wave method

Photothermal techniques and effective medium method combining with image method are applied to investigate the non-steady effective thermal properties of semi-infinite unidirectional fiber-reinforced composites, and the effect of the semi-infinite surface on the non-steady effective thermal properties is considered. The dispersion relation for the effective wave number in the semi-infinite random composites is derived. The image method is used to satisfy the adiabatic boundary condition at the semi-infinite surface. The numerical solutions of the non-steady effective thermal properties are obtained by using an iterative scheme. Analyses show that the variation of the non-steady effective thermal properties near the semi-infinite surface is significantly different from those of the infinite composite structure. The effects of the circular frequency of thermal waves, the volume fraction of fibers, and the properties contrast ratio on the maximum non-steady effective properties near the surface are examined. Comparison with the steady case is also given.