The three-dimensional stress distributions on the planes which do not intersect the glass fibers are analysed in the fiber-reinforced cylinders made by unidirectional filament-winding. Taking into account the three kinds of fracture mechanisms, the fracture strengths of cylinders under axial tension, axial compression and torsion are predicted and are compared with exper mental results on glass-epoxy composites, showing a good agreement between them.
A series of epoxy resin of varied YOUNG's modulus is developed for photoelastic use. Using two types of photoelastic materials as fiber- and matrixmaterials, stress analyses of fiber and matrix are carried out in the same time. Interesting facts in the stress distributions of fiber and matrix are found, for the cases of (1) tension in a direction perpendicular to fiber axis, and of (2) tension of unidirectionally-and two-directionally reinforced Plates.
Two experimental investigations of end-closed filament-wound vessels are described in this paper. The first is on how tom ake filament-wound vessels that bear more than 80kg/mmmm2 maximum hoop stress at burst pressure. The second is to establish the relation between the cyclic internal pressure and the fatigue life of the vessels that hold 80kg/mmmm2 hoop stress. From the tests, the results were as follows. 1) End-closed filament-wound vessels that had 80kg/mmmm2 maximum hoop stress were made. 2) The relation between the cyclic internal pressure P and the fatigue life Nf was expressed as PNfα=C where the values of the constants α and C were given as α=0.034 and C=178.
The strength defects in the filament-wound materials are essentially inevitable, and simultaneously unfavorable in view-point of structural design. However, the detection of such strength defects, say, the inside delamination, flaws, air bubbles and other foreign inclusions, is still quite difficult in spite of associated non-destructive inspection activities. In the present short report, the possible approach to the detection of strength defects in the filament-wound materials is made through the ultrasonic technique by employing the concept of artificial defect, resulting in the close agreement between the strength degradation and the ultrasonic output.
Two types of tensile testers for mono-filament fiber were tested. One is a modified balance type, the other is a strain gauge type. Tensile strength of E-glass mono-filament was measured with these two type testers, and from the variance of the data the strain-gauge type is more accurate than the balance type. The standard deviation obtained by the straingauge type tester is assumed to be the deviation of tensile strength of the mono-filament. Conventional alkali glass rods were drawn at high temperature to make mono-filament, and tested by this tensile tester. RAE carbon fiber mono-filament was measured by this tensile tester, and Young's modulus for carbon fiber mono-filament and also E-glass mono-filament were measured. X-ray diffraction study for lattice structure of carbon fiber and glass filament was carried out, and mechanical properties according to structure were discussed.
Ablative behavior of cloths of impregnated carbon, silica and ceramic with phenolic resin, was investigated experimentally by oxygen-acetylene torch testings and aluminized solid propellant motor firing. The heat transfer coefficient on specimens under torch testings and motor firing test was 0.05 to 0.2 and 0.5 to 1.6kcal/mm2sec°C, respectively. From the data obtained by torch testing and sub-scale solid motor firing test, a combination of carbon GF-20/phenolic 5900 was chosen as the throat material of the 6-in solid motor. The ablative characteristic of the composite material was obtained successfully by firing. Of interest was the fact there was no variation in the throat diameter ofter firing. It was shown that the calculated temperature history agreed well with experiment, and that, due to ablation, the equivalent heat transfer rate decreased to 4 % of heat transfer rate without ablation.