APPROXIMATE SOLUTION OF STRESS FIELD IN UNIDIRECTIONAL COMPOSITES UNDER TENSILE AND THERMAL LOADING.

An approximate solution of the stress field in unidirectional composites was obtained for tensile and thermal loading conditions based on the Airy stress function. The hexagonal packing of unidirectional fibers was assumed as an ideal arrangement. This solution is applicable to the transverse-isotropic fiber/isotropic matrix composite system. Explicit solutions for the local stress and average strain of composite were presented together with the instruction for the numerical process. The average strain became equal to the thermal expansion coefficient of composites when no tensile load was applied. The present results were compared with the previous exact solutions obtained for glass/polymer composites and were found to be satisfactorily accurate. Finally, the stress along the fiber-matrix interface and the average axial stress in both matrix and fiber were presented as a function of fiber volume fraction for glass/epoxy and carbon/epoxy composites.