The sandwich material for composite sandwich structure is mainly: hard foam, PMI foam, honeycombs and light wood three categories. The hard foam mainly has polyvinyl chloride, polyurethane, polyetherimide, and acrylonitrile - polymethylene, polymethylacrylamide, foamed polyester, and the like. Honeycomb sandwich materials include glass cloth honeycombs, Nomex honeycombs, cotton honeycombs, aluminum honeycombs.
The intensity of the honeycomb interlayer structure is high, but the honeycomb is a hole structure, which is small with the bonding area of the upper and lower panels, and the bonding effect is generally no foam. Light wood clamping material is a natural product, and the market is commonplace. It mainly produces plantations from South America. Due to the climate, light wood is very fast, so it is much smaller than ordinary wood, and its fiber is It has good strength and toughness, especially suitable for composite sandwich structures.
The application field of the sandwich material is broad, involving energy, aerospace, ship, transportation, construction and other fields. The sandwich material is one of the key materials of the wind power blade, in order to increase the structural stiffness, prevent local instability, improve the anti-load capacity of the entire blade, the front edge of the blade, the trailing edge, and the shear rib, generally use the sandwich structure .
The sandwich material for wind power blades mainly has PMI foam, Balsa light wood and PET foam. A typical design is that a high-strength Balsa light wood with a density of 150 kg / m3, which is used to withstand a portion where the load is large close to the leaf root, and the cross-linking PVC foam (density is 60 kg / m3) for carrying Smaller near the tip of the tip, from the direction of the leaf root to the tip, the thickness of the sandwich material gradually decreases, and the blade manufacturer uses only Balsa light wood or foam.