The Numerical Simulation On Mechanics Properties Test Of Three-Dimensional Textile Composites

The structure of 3-dimensional textile composites is so complex that its mechanical properties have not been investigated clearly and there are many problems in the test of its mechanics properties. In this paper, analyses the influence factors in the test of mechanical properties of the 3-dimensional textile composites, using the numerical simulation method analyzes the influence of the mechanical capability for the 3-dimensional braided composites caused by the size effects, machining-induced, and the truncation and integrality of fiber in the specimens.As the 3-dimensional 4-step braided composites, by the method of improving on the 3-cells model and stiffness averaging method, it analyses the influence of the 3-dimensional braided composites effective modulus that caused by the different width and thickness. As the carbon/ epoxy composites for the example, when fiber volume content and braid angle is fixedness, the influence of the 3-dimensional braided composites effective modulus that caused by thickness is more than by width, when width larger certain value and thickness larger certain value the modulus that composite is steady.According to the 3D orthogonal composites structural character, it sets up three different structural model, adopted finite element method analyzed influence of machining-induced that towards the 3D orthogonal composites. we recognized that structure asymmetry by machining-induced, making the specimen bend and stress concentration on few reinforce fiber, caused premature failure.According 4D slanting textile composites'structural character, it sets up two model, it analyzes influence of mechanics properties that caused by the integrated fiber and interceptive fiber. We recognized that in the machining process of the specimen, slanting reinforce fiber will be cut off , then the structured integrity of the specimen will be destroyed, making structure incompact, caused composite that bear the weight of fiber turn to matrix and stress concentration on truncation part, making composite strength reduced.