The Analysis Of Fracture Behaviour In Interface Structure Of Viscoelastic Material With Temperature Loads

The issue of cracks in the propellant structure has been the emphasis of the relevant research. Security issue caused by the existence of cracks is a hot spot in reliability analysis. However, the domestic research of cracks in interface has just started. This article contains a series of FEM calculation to cracks in the lining--propellant interface.Firstly, this article gives a simply introduction of basic viscoelastic theory and constitutive model of cohesive element, and demonstrates some literature and research progress about propellant and interface material. Secondly, in condition of a propellant system interface without any initial cracks, cohesive element is established to simulate interface debonding. Mechanical responding of the interface material and propellant is analyzed during a process of temperature decline in a constant velocity. The critical temperature difference is calculated when the interface material is damaged. Thirdly, based on the experiment aiming to measure the critical J-integral of the cracks in propellant, initial models with curves and rectangle experimental models based on J-integral experiment specimens were established.According to the load and the boundary constraints used in the experiment, J-integral of the2model groups is calculated. Critical J-integral of the initial models in different temperature is modified and a linear function is fitted referring to the result in the mentioned J-integral experiment. At last, a temperature decline and symmetry boundary constraints are given to the initial models, J-integral of models with different length of cracks is calculated. Referring to the linear function of critical J-integral, the length of cracks and the corresponding critical temperature of crack propagation can be obtained. According to the research mentioned, a linear function demonstrating the relation of the the length of cracks and the corresponding critical temperature of crack propagation will be calculated.The temperature load in models in this article is given in a hypothesis that70℃is the zero-stress temperature and the process of temperature decline is straight down from70℃.By calculating propellant system models with initial cracks and models without initial cracks,critical temperature about interface debonding and crack propagation is obtained. It is the purpose of this article. It is expected that this article can be a reference of interface security research and a guidance in practical engineering area.