Numerical Simulation of the Fracture Resistance of a Flame Deflector Under Impact and High Temperature by Using the Extended Finite-element Method

During the launch of rockets at sea, the flame deflector of the launch platform is subject to transient impact loads and high temperatures, which can result in the fracturing of the flame deflector, thereby endangering the platform and launch safety. In this study, dynamic crack propagation in a flame deflector under the aforementioned conditions was numerically investigated using the extended finite-element method (XFEM). The bulk of the flame deflector was modeled using shell elements, the local area in which the crack evolves was modeled using solid elements, and discontinuities were modeled using enrichment functions in the XFEM. The degrees of freedom of the bulk region and local crack propagation area were coupled using the multipoint constraint method. Three hot spots were identified in the XFEM simulation of a scenario without any initial crack. Initial cracks were set perpendicular to the direction of the principal tensile strain. The maximum principal stress criterion was used to predict crack evolution. The crack evolution results obtained through XFEM reveal that the region 1 on the upper surface is the weakest part of a flame deflector (in terms of fracture resistance). The use of reinforcing ribs in the most vulnerable areas of a flame deflector is proposed for effectively enhancing its crack resistance.