Filament-wound Composite Elbow Cad / Cam System

Filament winding is a production technique for composite structures, in which impregnated fiber bundles are guided through a pay-out eye on a rotating mandrel. It follows from production procedure that it is relatively easy to wind axisymmetric parts, however, it is much harder to design an manufacture non-axisymmetric parts such as elbows and T-pieces. Advanced filament winding machines and CAD/CAM software for filament winding are required for the design and production of non-axisym metric parts. At present, there is no CAD/CAM software for non-axisymmetric filament winding in China.This paper researches into method to design fiber paths of non-axisymmetric filament winding, generalizes splines in traditional CAGD, successfully applies them to the fiber path design of winding elbows, presents mathematical principles and methods of winding elbows, and develops a CAD/CAM system for elbow fabrication. The main features of this system are:(1) design and calculate stable fiber paths fulfilling all technical requirements;(2) update of the geometry of the mandrel surface with the increase of the thickness; (3) the transfer of laminate data to FEA-program for detail stress analysis; (4) generation of the control data file for four axes winding and (5) the real time simulation of fiber paths and machine paths.Chapter 1 outlines filament winding and states background and important significance of developing CAD/CAM system for elbow fabrication.Chapter 2 gives mathematical model of filament winding on general surfaces, obtains the necessary and sufficient condition of stable filament winding and presents concept and design method of axisymmetric filament winding algebraic pattern.Chapter 3 introduces a new class of trajectories -surface splines, which have more freedom than geodesies and semi-geodesies commonly used in filament winding industry, gives the calculation formula of slippage resistance of surface splines. Furthermore, discusses surface splines on cylinders and cones and obtains conditions to make them stable. Stability of geodesies on torus and semi-geodesies on cylinders are discussed in chapter 4; The definition of algebraic pattern of filament winding elbows and pattern design method are given in chapter 5, and this method is able to design the fiber path with uniform coverage.Chapter 6 discusses post processing of fiber paths and collision control during winding, proposes mathematical principles and detail algorithm of generating machine paths. Finally, examples of elbow fabrication are shown in chapter 7 to prove the reliability of this system.