ACCELERATED METHOD OF PREDICTING CYCLIC DURABILITY OF POLYMER COMPOSITE MATERIALS

Statement of the problem. A widespread use of polymer composite materials is currently constrained by the complexity of predicting the deformability and strength characteristics under cyclic loading, as well as due to insufficient knowledge of the behavior of polymer composites under such kinds of loading. There is rather limited theoretical and experimental data on the stress-strain state of polymer composites with prolonged loading. These led to the need for a careful consideration of these issues. Results. The limits of endurance of polymer composites were experimentally determined using the accelerated method based on the study of the internal friction coefficient. It was found that the long-term effect of cyclic loading leads to a change in the structure of polymer composites due to local self-heating in the tops of growing submicrocracks. This causes a change of flexible and resistant properties of the composite material, which causes a fatigue energy to manifest itself. Conclusions. The proposed method enables the evaluation of the endurance limit of the composite in any database testing and whereby a cycle life of the composite polymer material. The proposed method can be used to characterize the stress-strain state of composite materials under cyclic loading types based on different polymeric binders.