Investigation of the mechanical behaviors of polymer materials due to damage accumulation

In recent years, the applications of polymeric materials in engineering structures have increased considerably. For this reason, the number of studies to understand the inelastic deformation mechanism of polymeric materials has increased considerably. In the light of the observed properties of polymeric materials, the models to be revealed; Nonlinear high velocity and temperature dependence, nonlinear discharge behavior, flow under hydrostatic loading, cyclic softening and recovery at zero stress level should be considered. Polypropylene (PP) has been used as a carrier element in many fields for the last half century. The main factors in the selection of this material are its viscoelastic properties, low cost and very good design criteria. Although PP is used in applications with its many positive features, the failure of equipment before the expected life time as a result of plastic deformation, fatigue and damage creates limitations in terms of applications. In this thesis, it is aimed to carry out experimental and theoretical researches on the mechanical behavior of other polymeric materials, especially PP. In accordance with this purpose, some tests were carried out under uniaxial monotonic loading conditions in the first stage. These experiments aiming to reveal short-term elastic and inelastic deformation behaviors; It includes convolutional relaxation tests to determine strain velocity sensitivity in loading-unloading, cyclic loading, relaxation, and loading history dependence. In this study, the application of standard static and dynamic property tests, which should be provided before a passenger tire is put into mass production, has been applied. For this purpose, a tire with a certain size was selected and general durability, bead durability, carcass durability, bead drop, rolling resistance, plunger and ECE R30 Approval (High Speed) tests were applied to this tire. The main purpose of the study is to understand the deformation behavior of solid polymeric materials, especially PP, and to produce results suitable for modeling these deformation behaviors.