Finite element modelling and testing of filament-wound orthotropic components
Existing software for CNC filament winding of fibre reinforced plastics has been linked to typical finite element codes by automating the generation of finite element models of filament wound components. The algorithms required for this process have been created and encoded as computer programs. The program FILFEM I generates models of components manufactured using the CADFIL I CAD/CAM system for the filament winding of axisymmetric components. The suite of programs named FILFEM II achieves the same objective for non-axisymmetric components manufactured using CADFIL II although its method of operation is quite different from that of FILFEM I. FILFEM I has been tested by automatically generating models of a pinched cylindrical filament-wound tube manufactured from glass-reinforced polyester resin. The results from these models generally compared well with results obtained from experiments and from an analytical solution extended by the author from work by Calladine. However, the validity of a comparison with experiment depends upon the accuracy of the material properties assumed in the analyses. The material property values required for the analyses were investigated experimentally. Tests based upon pinched rings and a modified split-disc method are described together with more conventional tests of material properties. A method is presented for the determination of unidirectional material properties from the experimentally-measured properties of laminates. Difficulties in obtaining consistent results were attributed to problems with the quality of the specimens, inadequacies in the orthotropic model of material behaviour, and to material damage occurring during the experiments. In order to provide a test component for FILFEM II, a number of filament wound elbows were manufactured although some problems with winding quality remain. The fibre paths files used in manufacturing the elbows were used to test the operation of FILFEM II and further work including experimental verification is proposed.