Abstract: When designing repair plans for composite honeycomb panel structures, the influence of hygrothermal effects on their vibration characteristics is generally not considered. Reasonable repair parameter design can effectively restore the natural frequency of the repaired honeycomb panel. Through finite element simulation and modal testing, the variation law of the natural frequency of carbon fiber epoxy resin/aramid paper honeycomb board repaired by single-sided patching with different repair parameters under the influence of damp heat was comprehensively analyzed. A finite element model of single-sided patch repair of honeycomb panels was established using segmented shear deformation theory and combined with wet heat equivalent theory, and the influence of repair parameters on the natural frequency of repaired honeycomb panels under different wet heat conditions was analyzed. The results indicate that when the number of patch layers is the same as the number of patch layers on the panel to be repaired, the natural frequency of the repaired panel is less affected by hygrothermal conditions, while the effect is greater when there are too few or too many patch layers. When the overlap length of the patch is 0.5~1 times the damage diameter, the natural frequency of the repair board is less affected by hygrothermal, and when the overlap length further increases, it is more significantly affected by hygrothermal. The reduction of natural frequency of repaired honeycomb panels is more significant in wet environments than in thermal environments, and the combined effect of hygrothermal has a greater impact on the natural frequency of composite honeycomb repair panels than single moisture and heat effects.

Key words: hygrothermal environments, patch repairing, repair parameter, natural frequency, composite honeycomb panels