Energy transfer and modal coupling in coated composite spatial shells under thermal loading

To address the vibration prediction and suppression requirements of fiber-reinforced composite spatial shells with protective coating (PC-FRCSSs) in thermal environments, this study develops an integrated framework combining dynamic modelling, coating preparation, thermal protection testing, and experimental validation. A theoretical model of PC-FRCSSs assembled from cylindrical and toroidal substructures is established by introducing virtual springs, spatial corner coupling, temperature-dependent material properties, and a higher-order shear deformation displacement field. The modal strain energy ratios and a degeneracy-sensitive coupling index are further proposed to quantify energy transfer and modal coupling. Then, the convergence analysis, literature verification, and finite element comparisons demonstrate the accuracy of the proposed model for coated and uncoated spatial shells. The coating preparation process is presented, and the thermal protection performance of the protective coating is evaluated under continuous heating at 473.15 K. Experimental results show that the maximum frequency errors of the uncoated and coated specimens are 3.96 % and 4.03 %, respectively, and the response prediction error remains within 10.91 %. The displacement responses of the coated specimens decrease by 23.5 % and 29.3 % at 299.15 K and 373.15 K, respectively. Finally, parametric results further reveal the effects of laying angle, spatial corner, and thickness-radius ratio on mode degeneracy and high-response regions.