Research On Stiffness, Damage And Failure Prediction Method Of Filament Wound Composite

Filament wound composite was widely used in aeronautic and astronautic. It took place metal material in engine of many type rockets and missiles in order to reduce Weight and improve performance. The major advantage is of filament wound composite is high fiber volume fraction (about 80% ) can be obtained, the quality of production can be controlled easily, internal surface is smooth and high productivity. Therefore, it's important to research on stiffness, damage and failure of filament wound composite. The main research of this thesis work includes:(1) Building the micro stiffness predicting model. Base on representative volume(RVE) element and periodic arrangement of RVE, the stiffness of filament wound composite is treated as stiffness field. The function of this stiffness field is obtained by 2D fourier series, numerical integration and analytical method is applied in deduction of relation of stiffness function and stiffness matrix of fiber tow. Numerical example shows that the model build in the thesis can predict the stiffness and effect of micro structure on stiffness better.(2) Base on the stiffness predicting model build in the thesis and progressive damage method, structural analysis method of filament wound composite is developed. Firstly, the finite element analysis technology of filament wound composite base on micro stiffness model is established, then this technology is introduced in finite element analysis of geometric large deformation and elastic parameters, Hashin criterion is used for damage decision. Numerical example and test results shows that method established in this thesis can reflect the arrangement of strain in filament wound composite, for different program of winding tension and curing, the finite element result of strain agree with the test well, for different winding pattern, the axial failure strength and damage can be predicted well(3)Tests research on stress-strain, axial strength and effect of winding pattern, winding tension and curing program by axial tension test of filament wound composite pipe manufactured under different winding pattern, program of winding tension and curing. The effect of micro structure of filament wound composite on characteristic of stress-strain is investigated first time. The test result shows that strain of filament wound composite is not uniform distribution, strain in the area of fiber tow cross is larger than laminated area under same load, the program of winding tension and curing has definite effect on axial modulus and strength of filament wound composite pipe, the winding pattern has effect on axial strength.(4)Test research on micro structure of filament wound composite is carried out. Cutting the cylindrical specimen and taking macro photo of specimen and the micro photo of cross-section to research the arrangement of fiber and matrix, direction of fiber, thickness of layers, and geometry of fiber tow undulation and mathematical model of undulation. The result shows that in filament wound composite arrangement of fiber tow is close; there is no rich matrix region; fiber bow undulates in fiber tow cross region, the geometry of undulation is straight line and linear model can be used. The program of winding tension has definite effect on thickness layer and length of undulation region.