Filament wound (FW) structures present a geometric characteristic in their helical layers: the winding pattern. The pattern, however, is usually disregarded in conventional experimental or numerical approaches even though it can affect the behavior of FW structures, and most studies that account for the pattern are only theoretical. This study aims at deepening the understanding of pattern effects via a comprehensive experimental campaign focusing on composites cylinders under radial compression. Ten winding patterns were considered, from 1 to 10 units along the circumferential direction. Strength, stiffness, absorbed energy and failure mechanisms were evaluated. The results show that the pattern may have a strong influence on both maximum bearing load and absorbed energy, whereas stiffness is less affected.
A special feature of the Filament Winding (FW) process is known as pattern: diamond-shaped mosaic that results from the sequence of movements of the mandrel and tow delivery eye. One of the main factors to generate different patterns is the return path of the tow and, for a non-geodesic trajectory, the path depends on the friction between tow and mandrel. Aiming at a practical description of the FW process, a novel geometric approach on pattern construction is presented. Pattern generation, skip configurations and definitions of geodesic and non-geodesic trajectories in regular winding and return regions are described based on developed surfaces, residue classes and modular arithmetic. The influence of mandrel's length, mandrel's rotation angle and variation of the winding angle in the return region are presented, for they are important parameters of the process. Examples of winding angle, mandrel rotation and non-geodesic path in cylindrical and non-cylindrical surfaces of revolution are shown and discussed.
This work focuses on the viscoelastic response of carbon/epoxy filament-wound composite rings under radial compressive loading in harsh environments. The composites are exposed to three hygro-thermo-mechanical conditions: (i) pure mechanical loading, (ii) mechanical loading in a wet environment and (iii) mechanical loading under hygrothermal conditioning at 40 ∘C. Dedicated equipment was built to carry out the creep experiments. Quasi-static mechanical tests are performed before and after creep tests to evaluate the residual properties of the rings. The samples are tested in (i) radial compression, (ii) axial compression, and (iii) hoop tensile strength. Different laminates wound at off-axis orientations are manufactured via filament winding and analyzed. Key results show that creep displacement is affected by both hygrothermal and mechanical conditionings, especially at a higher temperature. Moreover, residual properties are quantified showing that creep generates permanent damage in the cylinders.
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