关键词: 修理尺寸边界, 湿热环境, 振动特性, 合并修理, 分别修理, 复合材料

Abstract: In view of the multiple damages in a small range of composite structures, how to determine the reasonable repair size boundary under the hygrothermal environment has an important engineering application value for the design of the repair scheme of the super manual and the formulation of the composite repair standard for civil aircraft. Through ABAQUS software simulation and experimental verification, the influence of the repair size boundary on the vibration characteristics of carbon fiber/epoxy plywood with double-hole damage under the hygrothermal effect is investigated. Based on the first-order shear deformation theory (FSDT) and Hamilton’s principle, the intrinsic equations and the free vibration control equations of the laminate under moist heat effect were derived. A double-sided merged/separate step-repair plywood model was established by using ABAQUS software, and the vibration characteristics of double-sided gouge-repair plywood with different damage hole spacing and intact boards were analysed under different temperatures, humidities and hygrothermal coupling effects. The results show that the intrinsic frequency of the combined repair decreases with the increase of hole spacing, the intrinsic frequency of the separate repair increases with the increase of hole spacing, and this trend does not change with the change of temperature and humidity. When the damage hole distance is less than 20 mm, i.e., when the damage hole distance is less than 5 times the damage hole diameters, the combined repair is more effective; when the damage hole distance is 20 mm and 22 mm, the combined repair or separate repair has little effect on the recovery effect of the performance of the plywood; when the damage hole distance is greater than 22 mm, i.e., when the damage hole distance is greater than 5.5 times the damage hole diameters, the separate repair is more effective, and this kind of repair boundary can be well resisted by the temperature and humidity. Repair boundary can well resist the influence of temperature and humidity.

Key words: repair of dimensional boundaries, hygrothermal environments, vibration characteristic, combined repairs, separate repairs, composites