Structural Panel Fabrication
And other special machining techniques
Any reference to patents on this page can be viewed in full at the
Unitied States Patent Office,
but you will probably need their tiff viewer.
Or go to Google Patents
Sandwich Structured Composite Conventional
sandwich or structural panel construction:
-
The wekipedia
definition gives a very good description of the typical honeycomb
panel
construction. This is a very dependable lightweight solution that has
been used for many years. For more demanding applications where large
internal pockets are required consider some variation of the GridLock,
IsoGrid or cellular metal truss core designs.
-
Specifications
- MIL-STD-1530................................ Aircraft
Structural Intregrity Program (ASIP)
-
MIL-A-83444 .................................. Airplane Damage Tolerance Requirements SUPERSEDED by
MIL-A-87221
-
Publications
-
Vendor Data
- Hexcel
Composites............................ Honeycomb
Attributes and Properties.
- New Focus........................................ Offers honeycomb solutions for laser research, microscope workstations and optics platforms.
-
Cellular metal truss core .................... CMI's solution to replace a honeycomb core.
GridLock
- The patented BF Goodrich GRID-LOCKŪ
joints (US Patent no. 5,273,806),
developed by Goodrich's
Aerostructure
- Division, allow for easy assembly by incorporating machined
grooves into skin build ups, essentially eliminating the need for
alignment tools. Here is an image
of a panel used on the F15, which is a link from the Goodrich image library.
- Defect
Identification: A
dissertation
submitted for partial fulfillment of the requirements for the degree of
Doctor of Philosopy, Mechanical Engineering.
-
Other Vendors
- Elbit
Systems.................................... Composite and
Metal Processing Technologies.
-
US Patents
-
5273806............................................
Structural Element with Interlocking Ribbing.
IsoGrid
- Wikipedia
definition: This is
conventionally a machining operation, however; new techniques are being
investigated.
- Water Jet machining to specified
depths:
This article, although old,
indicates that water jetting is a viable machining alternative for
isogrids.
It is projected that a 48-inch-diameter skirt 12 inches high could be
milled with an isogrid pattern in 6.3 hours. Milled isogrid patterns
can be controlled to 0.001 inch, and thin walls of less than 0.025 inch
are achievable. See the Water Jet section.
-
Specifications
- AIAA
2008-2274...........................................Postbuckling of Composite Panels with Isogrid
Stiffeners
- NASA-CR-124075.......................................IsoGrid
Design Handbook
-
Companies using IsoGrid
- General Dynamics.......................................This article
states that it is King of Lightweight Design.
- PS Associates....................................IsoGrid-SST,
Pictures of
IsoGrid Structures.
-
US Patents
-
6007894...........................................
Quasi-Isotropic Composite Isogrid structure.
-
6286289...........................................
Multiple Face Sheet Isogrid Structures.
-
6054352...........................................
Composite Isogrid structures for Parabolic surfaces.
Water Jet Cutting
-
The wekipedia
definition gives a little more insight into this attractive
machining alternative for large panel fabrication.
-
Specifications
- AWS Welding Handbook.................
Ninth Edition, Volume 3 Welding Processes, Part 2, mentions water jet cutting at the end.
-
Publications
-
Vendors
- Ormond, LLC.................................
They have machined a .75 thick aerospace part with .012 internal walls. Check out their brochure.
-
Waterjets.org ................................. The most complete water jet resource on the web.
-
Omax worldwide ............................
Some machines
will take work pieces up to 6'8" x 13'4" (2 m x 4 m).