Temperature and frequency dependent complexmoduli of polymer under kinematic harmonicloading

Modeling of the cyclic deformation of viscoelastic materials is one of the key aspectsof analysis of the behavior of structure. In the present research, the Goldberg constitutivemodel is used to predict the time dependent inelastic response of polymer materials. Theapproach that uses the complex-value amplitude relations is preferred rather than directnumerical integration of the complete set of constitutive equation for the material, in theother words, to simulate the response in terms of amplitudes, the relations between theamplitudes of main field variables are established with making use of complex moduliconcept. It is done by making use of equivalent linearization technique. It is shown thatthis technique leads to overestimation of stress amplitude. To avoid this, the modifiedequivalent linearization technique is applied. Characterization of the complex modulidependence on frequency and temperature as well as amplitude of strain intensity isperformed. Results demonstrate a weak dependence of loss moduli on the frequency ofthe loading within the wide interval of it, while variation of storage moduli withincreasing temperature is more pronounced.

Keywords:

harmonic loading , amplitude relations , inelastic deformation , complex moduli