ИСТИНА

The bridged crack model is used for the efficiency evaluation of self-healing cracked polymer materials for stents application. In the frames of the bridged crack approach is assumed: there are artificial bonds between crack surfaces (the interface layer); any zone of these bonds is considered as a crack process zone (bridged zone) with distributed nonlinear spring-like ligaments between the crack surfaces. The bonds properties variation define the stress state at the crack process zone and, hence, the fracture toughness of the material. In a general case, the size of process zone of the crack is comparable to the whole crack size. The main task of the modeling consists of the computational analysis of the bridging stresses distribution and in the computing of the stress intensity factors which are the main characteristics of healing and self-healing efficiency. The mathematical background of the stresses problem solution is based on the singular integral-differential equations and the boundary element methods. The thermo-fluctuation kinetic model is used to evaluate the time of the crack bridged zone regeneration and formation. The healing time and efficiency are dependent on the chemical reaction rate of the healing agent, the crack size and the external loads. The non-local fracture criterion is used to evaluate the fracture toughness and the critical external loading in the frames of the bridged crack model. The model can be used for the evaluation of composite materials healing and durability. The measure of the self-healing efficiency is the level of the stress intensity factor at the crack tips.