INFLUENCE OF LOCAL FIBER UNDULATIONS ON THE GLOBAL BUCKLING BEHAVIOR OF FILAMENT-WOUND CYLINDERS

The predicted compressive stiffness and buckling strength of filament- wound cylinders using classical lamination theory is significantly hig her than those observed experimentally. This discrepancy is partially influenced by the variation of mechanical properties in the region of fiber undulations. These regions are localized geometric defects intri nsic to the filament-winding, weaving, and braiding processes. In the present work, the average mechanical properties of the fiber undulatio n region are quantified using modified models of woven-fabric composit es to account for the 3-dimensional effects. The mechanical properties thus determined can be incorporated as local element properties into global finite-element models. Preliminary results from large-displacem ent analyses of filament-wound cylinders are relatively more accurate when fiber undulations are accounted for.