The honeycomb sandwich structure is a structural part made of two or more layers of skin and honeycomb glued together by gluing technology. The main materials of the skin are carbon fiber, glass fiber reinforced plastic, aluminum alloy, etc. The honeycomb mainly includes NOMEX paper honeycomb, aluminum honeycomb, etc., which are used in structural parts. Considering the requirements of strength and electrical properties,carbon fiber skin and NOMEX honeycomb sandwich structure are generally used.
The forming of honeycomb structural parts generally consists of several steps, such as forming the inner and outer skins, bonding the inner skin and the honeycomb, and bonding the outer skin and the honeycomb. The forming methods include autoclave forming method, vacuum oven forming method and press forming method. These forming methods are briefly described below.
1.Autoclave forming method
The autoclave forming method uses the negative pressure of the vacuum and the positive pressure outside the vacuum bag, which is generally used for the forming of the skin and the bonding of the skin and the honeycomb. The advantage is that the craftsmanship is good. By adjusting the pressure, the forming quality of the skin and the bonding quality of the structural parts can be improved. It is suitable for the forming of structural parts with complex profiles and high mechanical performance requirements, especially for the skin forming and honeycomb bonding of thick-skin honeycomb structural parts. The disadvantage is that the cost is high.
2. Vacuum oven molding method
The vacuum oven forming method is to use the negative pressure of vacuum to heat and heat up the skin and honeycomb bonding in the oven. The advantages are low cost, suitable for the forming of thin skins and the bonding of thin skins and honeycombs, and are often used for the forming and bonding of complex parts with thin skins. The disadvantage is that it is not suitable for the forming of thick skins and the bonding of thick skins and honeycombs.
3. Press molding method
The press forming method uses the positive pressure of the press and heating to form the skin and honeycomb bonding. The advantages are low cost and simple process operation, and it is generally used for the skin of simple profile and the gluing of skin and honeycomb. The disadvantage is that it is not suitable for skin forming and honeycomb bonding of complex profiles.
There is no certain standard for the forming method of honeycomb structural parts. It mainly considers the complexity of structural parts, technical requirements and cost factors. Several methods can also be used alternately.
The excellent electrical and mechanical properties of honeycomb structural parts will surely make it more and more widely used in aviation structural parts. At the same time, with the development of aviation aircraft, higher requirements will be put forward for the constituent materials of honeycomb structural parts. At this stage, research on materials with higher electrical and mechanical properties and simple and practical molding methods to reduce the price of honeycomb structural parts has become an urgent problem to be solved.
