Strength Analysis And Research On Dynamic Fracture Of Linear Explosive Separation Device

Linear explosive separation device, whose reliability has a great influence on the result of launch mission or the precision of orbit and impact point, is the key component of missile / rocket for stage separation, fairing separation and payload separation. According to the requirement of engineering, the linear explosive separation device must follow the rule of ‘connecting strongly and separating quickly'. That is to say, it must be guaranteed that the structure keep safe before separation and the fracture take place as soon as the separation signal is generated. Therefore, both the strength problem and the dynamic fracture problem should be taken into consideration during the process of structure design. In this thesis, some related researches about the two problems are involved. The main contents are summarized as follows:1. The structural integrity analysis method based on inertia relief and equivalent crack technology is proposed.The strength analysis for linear explosive separation device is conducted with traditional method and inertia relief technology respectively, the result of which indicates that the free flying state of linear explosive separation device can be modeled much more accurately with the application of inertia relief technology. O n the basis of the work above, the structural integrity analysis of linear explosive separation device under extreme working conditions is completed with inertia relief technology after treating the top relief as a crack.2. The dynamic enriched finite element method is established and re-development work is conducted.By enriching the asymptotic displacement field around the 2-D crack tip into that of the regular quad element, the enriched finite element which is effective for planar dynamic fracture problem is eatablished. Furthermore, the redevelopment of the new element based on MSC.Marc is conducted and its effectiveness is verified with some examples. The related verification result shows that the dynamic enriched finite element method is not only able to deal with the dynamic fracture problem quite well, but also prominently efficient in numerical calculation.3. The crack initiation analysis for linear explosive separation device is finished based on the dynamic enriched finite element method.The dynainc crack initiation analysis for linear explosive separation device is conducted with the redevelopment program of dynamic enriched finite element, through which the dynamic stress intensity factor and the crack initiation time is obtained. In addition, the influence of the material parameters, structure parameters and the explosive pressure on crack initiation property is studied, and the critical parameters are determined according to the analysis results.The research method proposed and the analysis result acquired in the work above have significant engineering application value for the structural design and property optimiazation of linear explosive separation device. O n the other hand, the research on dynamic enriched finite element method promotes the development of the numerical method for dynamic fracture problem to some extent, of which the academic meaning is significant.