Analysis Of The Model And Mechanical Property Of Three-dimensional Four-directional Braided Composites

The traditional laminate composite not only has the weakness of the lower strength between layers, easy damaged after impacted, the much more reduced strength in mechanism joint with abrupt geometry shape, but also has the defaults that includes delamination, fibre-matrix shearing, matrix crack and lower life. Because of the whole braid of the multi-orientations, braided composite materials over come the defects of the traditional laminate composite and reinforce the equality of intensity in every orientation, and it is a new advanced material for the time being. Braided composite materials with distributed piezoelectric systems are widely applied in many industries, such as aerospace industry etc.Building up rational 3-D braided composite materials has important effect to the finite element calculation result of the mechanics function. Considering the four directions 3-D braided composite materials and basing on the observation and research, body structural model of "lemniscate" type is brought, whose new cross section is ellipse. This body structural model reflects the interweavement of the fiber correctly, which accords with the structure of four directions three-dimensional compound material more. Owing to the element model, the geometrical relationship between the parameter and the structural model parameter is inferred and the volume of the fiber is calculated. Adopting the finite element method software to carry out mechanics analysis on that model, the equivalent relevance elasticity function parameters is got and the result indicated that finite element method calculates 3-D weaving the equivalent compound material elasticity function and the experiment result and theory forecast value fit fairly well, which verifies the validity of the model thereby. Besides, owing to the new element body, four direction three-dimensional strain field distributions of braid compound material is ascertained, which verifies fiber strengthening mechanism and establishes a basis for the calculation of intensity in the further.