Isogrid
 | This article includes a list of general references, but it lacks sufficient corresponding inline citations. (December 2010) |
An isogrid is a plate (or face sheet) with triangular integral stiffening ribs (often called stringers). The stiffeners of an isogrid are generally machined from a single sheet of material with a milling machine, though below 0.040 in. (1.0 millimeter) thickness chemical milling processes must be used.[1] The triangular pattern is very efficient because triangular trusses are very efficient structures. The term isogrid is used because the structure acts like an isotropic material, with equal properties measured in any direction, and grid, referring to the sheet and stiffeners structure.
Metal isogrids (often aluminum), are constructed by milling material from one face of a sheet. Composite isogrids are rib-skin[clarification needed] configurations formed by various manual or automated processes, and can give extremely high strength-weight ratios.[2] Traditionally, the equilateral triangle pattern was used because it was amenable to simplified analysis.[3] Since the equilateral triangle pattern has isotropic strength characteristics (no preferntial direction), it was named isogrid. The traditional equilateral pattern can be abandoned in favor of stiffener patterns optimized to specified loading situations; these structures are referred to as composite grid structures or advanced grid stiffened (AGS) structures.[citation needed]
Isogrid panels form self-stiffened structures where low weight, stiffness, strength and damage tolerance are important, such as in aircraft or space vehicles. Aerospace isogrid structures include payload shrouds, and boosters which must support the full weight of upper stages and payloads under high G loads.
Some spacecraft and launch vehicles which use isogrid structures include:
- Delta families [3][5]
- Atlas V rocket [citation needed]
- Skylab spacestation Orbital Workshop module [3]
- CST-100 crew capsule [citation needed]
- Dragon crew capsule [citation needed]
- MPCV formerly Orion crew capsule [citation needed]
The Space Shuttle lightweight and superlightweight external tanks use an integrally machined stringer system which is not a true isogrid, though it is somewhat similar. Since the structure is arranged at right angles it is considered an "orthogrid" rather than an isogrid with triangular stiffeners of an isogrid.[citation needed]
Isogrids are beginning to be used in consumer products where extremely light weight, strength, and stiffness are important, like tennis rackets.[citation needed]
References
- ^ Slysh, Paul. "The Isogrid". Retrieved May 27, 2011.
- ^ Wegner, Peter M.; Higgins, John E.; VanWest, Barry P. (2002). "Application of Advanced Grid-Stiffened Structures Technology to the Minotaur Payload Fairing". 43rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference. Denver, CO.
{{cite conference}}: Unknown parameter|booktitle=ignored (|book-title=suggested) (help) - ^ a b c Meyer, R. R; Harwood, O. P. (Oct 1, 1973) [1973], Isogrid design handbook, Marshall Space Flight Center, 19730000395, archived from the original (PDF) on Sep 30, 2010
{{citation}}: Text "0%26N%3D4294753258" ignored (help)CS1 maint: date and year (link) - ^ US patent 4012549, Paul Slysh, "High strength composite structure", published Oct 10, 1974, issued Mar 15, 1977
- ^ Knighton, D. J., D.J. (Sep 1, 1972) [1972], Delta launch vehicle isogrid structure NASTRAN analysis, Goddard Space Flight Center, 19720025227, archived from the original on Jun 11, 2007
{{citation}}: Text "1&N%3D4294759313" ignored (help)CS1 maint: date and year (link)