Compaction behaviour of weft-knitted rib fabrics from glass yarn

Single- and multi-layer compressibility behaviors of weft-knitted glass yarn fabrics with 1x1, 2x2, English and fisherman rib architectures were analyzed in this study. Compaction and relaxation curves were modeled with the power-law (P=aV(f)(n) where P, and V-f are pressure and fiber volume fraction, respectively). The analysis of "a" constant (i.e. pressure to achieve fiber volume fraction of one) revealed that: 1) repetitive relaxation and reloading to maximum compaction stiffened the fabric stack and improved the fiber content 2) 1x1 rib architecture required the highest compaction to achieve fiber volume fraction of one due to its loose and porous structure 3) adjacent fabric layers nested in each other in multi-layer fabrics. The analysis of "n" exponent (stiffening index) indicated that: 1) initial compaction stiffened the fabric stack 2) while the slack English rib architecture exhibited the lowest index, the tight fisherman rib exhibited the highest index 3) number of layer did not alter the index. Absorbed strain energy analysis indicated that 1x1 and 2x2 ribs relaxed better than the other architectures. The side-by-side and alternating placement of face and back plain loop bars in these architectures eased the sliding of the bars over each other that increased the energy absorption. The number of fabric layer increased the relaxation at statistically insignificant level.