Matrix and Interface Stresses in a Discontinuous Fiber Composite Model

The method of finite element analysis is applied to an axially symmetrical model of a single filament glass-resin composite under tension. Fiber end geometries are varied by considering ellipsoids of revolution with one axis length equal to the fiber diameter while the second varies from one-tenth to ten times the fiber diameter. Tapered tips with these same axis ratios are considered also. The results show that the best ellipsoidal end shape for minimizing matrix shear stress concentration is one having the longitudinal axis equal to twice the fiber diameter. The shear stress concentration for this geometry, however, is still greater than that of the slowly tapered end, which causes the lowest stress concentration. General stress patterns in the matrix as found by the finite element method are compared to previous analytical and experimental predictions.