ANALYSIS OF MECHANICAL FATIGUE PHENOMENA IN WOOL AND WOOL BLEND SUITING FABRICS

Fatigue phenomena in fabrics can be quantified by increases in mechanical hysteresis properties. Increase in the mechanical hysteresis properties of fabrics with wear are considered with respect to the structural modification of fiber assemblies, the increase in interfiber friction, and the changes in the mechanical properties and crimp of fibers. The crimp of both yarns and fibers decreased due to considerable extension of the fabrics during wear; the yarns became flattened, thus increasing the lateral pressure and contact region at yarn crossover points in the fabrics. The shear torque parameter C1, which represents the effect of interfiber friction, increased with wear. Increased interyarn and interfiber friction is considered to govern the increase in the hysteresis properties of fabrics with wear. The yield stress and strain of fibers for tensile and torsional properties decreased with wear. The removal of fiber scales and the ragged fiber surfaces after wear were observed using scanning electron microscopy. Mechanical degradation and decreased crimp of kid mohair and polyester fibers with wear were greater than those of coopworth fibers.