Numerical simulation of the dynamic thermostructural response of a composite rocket nozzle throat

The finite element method, in the form of the commercial finite element code ADINA, is used to investigate the dynamic thermostructural response of a composite rocket nozzle throat. ADINA’s thermoelastic analysis capability is validated by the comparison of its solution for the thermoelastic response of a thick, homogeneous, cylindrically orthotropic tube heated internally, to an analytical one. The spatially reinforced Carbon–Carbon nozzle throat examined here forms part of a low-erosion solid rocket motor nozzle model that is subjected to structural and thermal loading, with the effects of material ablation being neglected. An initial transient quasi-static thermostructural analysis is performed to determine the validity of the nozzle design, following which, an uncoupled dynamic thermostructural analysis of the nozzle’s throat and entrance section for the initial transient phase of the nozzle’s operation, is carried out. The results of this analysis are then compared to those of the equivalent transient quasi-static analysis to assess the degree of variance in either solution. It is found that the dynamic response oscillates about the quasi-static response in all cases, and that, in general, the variance in stress magnitudes between the two solution techniques is significant.