Mechanical properties of quasi-isotropic glass-cloth laminated composites under uni-axial tension and uni-axial bending loadings were discussed experimentally and theoretically. The results obtained are summarized as follows.
(1) In regard to the elastic properties, the results calculated by the lamination theory agreed well with the experimental results.
(2) The degree of anisotoropy of flexural modulus decreased with decreasing the thickness of homologous lamina and the laminated plate became approximately isotropic. “Homologous lamina”means the lamina group which has the same orientation angle of fiber.
(3) It is clear that both the tensile and flexural strength are anisotropic and their anisotropy can be relaxed by dividing each homologous lamina into many thin laminate and laying-up them alternately.
(4) A way of theoretical prediction of anisotropic strength was proposed based on the fracture mechanism. In regard to the tensile strength, the estimated values agreed well with the experimental results. As to the flexural strength, however, the estimation did not agree well with the experimental ones except the plate composed of four layers.
