Abstract
Plain knitted fabric made of cotton, commonly used in the clothing industry, has undergone severe cyclical loading, generated by dynamic fatigue tester, simulating the constraints applied to the structure during its use. An energy model, developed from the viscoelastic parameters of Burger's model, is used to study the knitted relaxation after fatigue test. The rheological parameters of the Burger's model are calculated by fitting the experimental curves of the deformation during relaxation of tested knit, using the Microcal Origin 6 software and the equation of Burger's recovery. As shown in this paper, cyclic loadings present a significant effect on viscoelastic parameters, which manifests as the decrease of the elastic deformation (23.96%) and the increase of the viscoelastic and plastic deformation (83.76% and 148.49%, respectively) when the number of fatigue cycles increases from 6000 to 36,000 cycles. We also noticed that the cyclic deformation of the knitted fabric decreases the energy dissipation rate (86.44%). Indeed, the decrease of energy dissipation rate indicates that the velocity of the recovery during relaxation decreases due to increasing of the friction interfilamentous. The friction opposes to the recovery of the structure until a blocked state. This state corresponds to the permanent deformation. The energy model allows us to give an idea of the ability of the knitted fabric to recover its initial dimensions.