Parameter fitting for a non-linear viscoelastic material model

Textile materials have such mechanical properties that are difficult to explain. These properties depend on many complex physical parameters of the material and the environment influences them. In this paper a method for fitting mechanical parameters for a uni-axial non-linear mathematical model is introduced. The mathematical model is developed on the basis of the Kelvin-Voigt rheological model. The non-linear parameters are calculated through solving a system of non-linear algebraic equations with the data obtained from tension experiments. These experiments were done with different strain rates. The mathematical procedure is based on the least square solution for systems of inconsistent non-linear algebraic equations. The results of the introduced approach are the stiffness and damping parameters for the Kelvin-Voigt mathematical model. The mathematical model accuracy is proved with the comparison of the real thread respond and the mathematical model respond.