Wave Propagation and Broadband Dynamic Analysis of the Stitched Sandwich Structure

The stitched sandwich structure is a newly developed thermal protection structure for the reusable launch vehicle, which could suffer broadband dynamic loads under service. The efficient wave finite element method is developed to predict the wave propagation property and broadband dynamic response of the stitched sandwich structure. The contribution of various waves to the structural dynamic response in different frequency bands is firstly evaluated by analyzing the dispersion relation. The influences of structural design parameters on the dynamic broadband responses are further investigated. Simulation results indicate that the broadband structural dynamic response could be efficiently and accurately predicted by using the wave finite element method. The dynamic response of the investigated stitched sandwich structure is mainly determined by the propagation characteristics of six far-field propagating waves. The structural dynamic response in the medium and high frequency ranges could be significantly suppressed by introducing stitches into the sandwich structure. The investigated design parameters have a more significant influence on the structural mass than the structural stiffness. More intensive stitch density, larger stitch diameter, thicker upper skin, and thicker core layer could make the resonance peaks of structural displacement response shift towards lower frequency, which is more obviously in medium and high frequency.