Study On Geometric Molding Simulation & Algorithm Of 3D Braided Composites

Along with Three-Dimensional Braided Composites are widely used in many aspects in today's economy, studies on its compositional structure, producing techniques, and quantitative analysis have been a newly arisen topic. The paper relies on computers' powerful digital and graphical processing ability, creates the algebraic as well as geometrical models, and thus gives some contributions in mechanical analysis and design of the Three-Dimensional braided composites.This magisterial thesis commences from the braiding technique of Three- Dimensional Braided Composites, introducing in detail currently extensively applied of four-step and two-step braiding techniques. According to the movement traces of yarn carriers on the braiding machine bed, a perform was divided into three regions, i.e. interior, surface and comer, and distinct control volumes were defined for each region. Analyzing the control volume of each region, the yarn architecture of perform was described and three kinds of local unit cell were identified. Then the relations between the braiding parameters of the perform were derived. Based on the analysis of the perform, two local unit cells for the 3–D braided composite material were obtained and the relations between the braiding parameters were modified, Provided theories foundation for the design and analysis of algorithms.According to three dimension braided composites for braided technology–four -step and technology-two-step procedure and with reference to theories of braided fabric geometry and force models, a geometric model is built. In this model, the cross-section of thread is described as an ellipse and thread path as a cubic B-spline. By using the four-step method in 3D braiding technique as an example, the paper proposes the ideas of algorithms for simulating geometrical model of braiding composites, and provides the fixed grid method to simulate them step by step. More specifically, the paper firstly designs the algorithms for quadrate four-step braiding method. Then, analyzing the relationship between quadrate four-step braiding method and circular four-step braiding method. By spreading the cross section, the paper approximates the circular cross section to quadrate one so that relates these two different methods and then, fulfills the both algorithm design based on quadrate four-step braiding method. At last, some detailed explanations of realizing these two algorithms in code are given.At last, by using AutoCAD VBA as second developing platform, the paper simulates the braiding process with VBA, and thus realizes the pre-modeling's entity model.