Friday, May 1, 2009
HEXAFLEX HONEYCOMB COMPARISON
1. SURFACE BONDING AREA
In this 3D view of Hexaflex, one can very quickly grasp the fact, purely by observation, that the hexagons have a much larger surface area available for bonding to the face sheets in comparison to the surface area of the edges available in conventional honeycomb. The blue color denotes bonding area.
Hexaflex core design has two different surface architectures. the side which is shown above, which we think of as the outside surface, and the other, inside surface, below, which as you can see, has only half as much bonding area as the outside, but none-the-less, still has a large bonding area in comparison to conventional honeycomb.
2. FAST VENTING CORE
Each cell in a honeycomb sandwich is an airtight vessel. When heated, the air in each expands, increasing the pressure. If the pressure gets too high, the film adhesive bond may fail, initiating a delamination.
Hexaflex overcomes any possibility of this occurring because it is an open fast-venting core design that prevents any pressure differentials from building up within its geometry.
Some adhesives give off gases or solvent vapors during cure, which can interact with resin systems in some non-metallic cores, or with the node adhesive in some metallic honeycombs. The entire bonding process must be checked to ensure that no reduction in mechanical bonding properties has occurred.
One could quickly purge the assembled Hexaflex sandwich panel with gases or liquids by virtue of the ventways that inherently run through the core design. (see red arrows)
These ventways could also be utilized for service runs for electrical pneumatic or hydraulic lines.
Compression and shear forces can be tailored to suit the application by placing foam metal hexagonal cross-sectioned inserts into the blind hexagonal cells on the one face of the core material.
Hexaflex conforms naturally to compound curvature with its cells normal to the face surface, without the need for curving, rolling or heat forming operations. It does not suffer from cell wall damage, columnar failure, node separation or distortion of the hexagonal cells when subjected to compound curvature.
Honeycomb cores are heavier due to the fact that they consist of multiple ribbons of core material glued together (see red lines below) requiring one of the six cell walls of every cell in a regular honeycomb core to be double thickness.
Hexaflex core has no glue, is a single thickness throughout and is formed from a single sheet. In the event of excessive forces the core will demonstrate superior structural integrity.
6. EDGE JOINING AND STACKING
Hexaflex core material can be edge-lapped upon itself allowing hexaflex panels to be joined together with superior seam strength. Hexaflex core material can be stacked upon itself to allow efficient storage.
Nested partially deployed configuration