Inwestgaton Of The Effective Praided Composites With Random Distributed Flaws

The mechanical properties of the three-dimensional (3d) braided composites arebetter than that of the laminated composites, such as the shear resistance andanti-damage performance. The 3d braided composites are widely used in fields ofnational defense and social activities. A large number of researchers in many countriesdevoted their energies to those materials. And they achieved good results. In spite of thisthere are a lot of problems which need to be solved.In this paper the effective mechanical properties of a type of 3D braidedcomposites with random distributed flaws are studied. A representative element modelfor the 3D braided composites is built. The nonhomogeneous finite element method isadopted in this paper. When the volume fraction of the flaws is constant the moduli andthe Poisson ratios of the 3D braided composites with random distributed flaws areobtained. It is found that the flaws can weaken the mechanical property of the 3Dbraided composites. And the effects on different components of the mechanical propertyof 3D braided composites are different.The randomness of the components materials of the 3d braided composites and theflaws have been studied. The moduli and the passion ratios of the components materialswere obtained by the experiment. The random samples are got by the results and theeffective properties of the 3d braided composites were calculated of each randomsample. When the volume fraction of the flaws is constant the effects on the effectiveproperties of the material by the randomness of the flaws were studied.