|
|
||
|
|
|
|
From:
https://en.wikipedia.org/wiki/Isogrid
Text from the wikipedia site:
Isogrid is a type of partially hollowed-out structure formed usually from a single metal plate (or face sheet) with triangular integral stiffening ribs (often called stringers). It is extremely light and stiff. Compared to other materials it is expensive to manufacture, and so it is restricted to spaceflight applications and some particularly critical parts of more general aerospace use.
The triangular pattern is very efficient because it retains rigidity while saving material and therefore weight. 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.
A similar variant is the Orthogrid which uses rectangular rather than triangular openings. This is not isotropic (has different properties from different angles) but matches many use cases well and is easier to manufacture.
Traditionally, the equilateral triangle pattern was used because it was amenable to simplified analysis. Since the equilateral triangle pattern has isotropic strength characteristics (no preferential direction), it was named isogrid.
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. Their open configuration with a single, sealed sheet facing the outside makes them especially useful for propellant tanks for rockets, where sealing the propellant in but allowing it to drain in use or maintenance are necessary features.
Page 72 / 216