1970 Volume 19 Issue 206 Pages 968-973
The fracture strength of filament-wound composite structure can be determined by relating the fundamental strength of the unidirectional reinforcement materials to the three-dimensional stress components on a plane which contains fibers. The object of the present paper is to report the experiments intended to find the values of the fundamental strength of the unidirectional filament-wound materials which correspond to the three kinds of fracture mechanisms, glass-epoxy filament-wound composites have been used for specimens. There has yet been no established method for the experiments. Our experiments have therefore been carried out to find the fundamental strength against the tensile strength in line with the fibers, that against the tensile strength at right angle to the fibers and that against the shearing strength at the fiber-matrix interface. In the experiments concerning the shearing strength, special attention has been paid to examining the effects that the angle of the shearing to the fibers and the normal stress will have on the shearing strength. These are important factors for determining the exact fracture strength according to the three-dimensional stress analysis.
The fundamental strength of the unidirectional composite materials will also give clue to determining analytically the fracture strength of the helically wound cylindrical tubes under axial tension, under internal pressure, and under torsion, showing good agreement with the experimental values of on the glass-epoxy specimens. The detailed description regarding these fracture strengths will be reported in the forthcoming papers.