Influence of filament winding parameters on composite vessel quality and strength

An experimental design investigation of manufacturing and design variables that affect composite vessel quality, strength, and stiffness was conducted. Eight 20-in. cylinders (with one additional cylinder as a replicate) were manufactured and tested for hoop strength, hoop stiffness, fiber and void volume fraction distribution through thickness, residual stress, and interlaminar shear strength. Material and processing variables were divided into five categories: (a) resin, (b) fiber, (c) fabrication process, (d) design, and (e) equipment. Five variables were selected (from a list of 12) for study using a 1/4 fractional factorial design of experiment setup. The five variables were: (a) winding tension, (b) stacking sequence, (c) winding-tension gradient, (d) winding time, and (e) cut-versus-uncut helicals. Statistical analysis of the data shows that the composite vessel strength was affected by the manufacturing and design variables. In general, it was found that composite strength was significantly affected by the laminate stacking sequence, winding tension, winding-tension gradient, winding time, and the interaction between winding-tension gradient and winding time. The mechanism that increased composite strength was related to the strong correlation between fiber volume in the composite and vessel strength. Cylinders with high fiber volume in the hoop layers tended to deliver high fiber strength. (C) 1997 Elsevier Science Limited.