Interlaminar fracture surfaces resin

The ILSS of a u.d. composite may be calculated by two extreme approaches. The most optimistic estimate for ILSS is obtained by neglecting stress concentrations. Consider a triangular array of fibres that is subject to a longitudinal shear stress equal to the interlaminar shear strength in a horizontal plane. On the assumption that at fracture the horizontal resin bridges between the fibres bear the matrix yield stress X and that an effective fraction a of the fibre surface bears the interface strength x, it can be derived that ... 

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