چكيده به لاتين
The aim of this study is to present a developed damage-entropy model for analyzing the fatigue behavior of steel cord-rubber composite (SCRC) material. SCRC materials are composed of rubber and steel cords that are used in various industrial structures. The off-axis SCRC lay-ups exhibit a nonlinear stress-starin behaviour similar to the rubber matrix. Hence, the Newton-Raphson method is employed to capture the nonlinear stress-strain behavior of SCRC material. The main advantage of the damage-entropy model is that it accounts for the viscoelastic property and temperature increase during the fatigue life process, which are crucial for analysis of SCRC structures. In this thesis, in order to characterize the longitudinal, transverse, and in-plane shear behavior of SCRC, static and fatigue experimental tests on [0]2, [90]4, and [±45]s are conducted. The damage evolution parameters in the longitudinal, transverse and in-plane shear directions are determined by the continuum damage mechanics (CDM) based on experimental tests, to estimate the damage energy during the fatigue life cycle. Moreover, the dynamic mechanical thermal analysis (DMTA) is used to characterize the dynamic damping behavior of SCRC structure to estimate the energy dissipation due to viscoelastic behavior. Furthermore, the heat transfer to the environment through conduction, convection, and radiation processes during fatigue loading are estimated. The failure criterion in the damage-entropy model is based on the fracture fatigue entropy (FFE) value. The experimental results of [±60]s and [45]4 lay-ups are utilized to validate the damage-entropy model that is developed for SCRC structures. Finally, the experimental and modeling results of hysteresis energy, temperature change and fatigue life for various SCRC lay-ups are compared. The comparison between the simulated results and experiments indicates, the model can simulate successfully.
