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AAWSAP DIRD, Materials for Advanced Aerospace Platforms, January 2010

U.S. Department of War · 2010-01-12 · 27 pages · text from the file's own layer

This Defense Intelligence Reference Document, DIA-08-0912-008, is dated 12 January 2010. It was prepared by the Defense Warning Office's Acquisition Support Division at the Defense Intelligence Agency as one of a series of FY 2009 technology reports under the Advanced Aerospace Weapon System Applications program. It reviews materials for launch vehicles, space vehicles and reusable rocket engines, including aluminum alloys, polymer and metal matrix composites, titanium and nickel alloys, and titanium aluminides. It concludes that newer materials and integrated design could improve on the space shuttle.

From the source: Release of 2026-09-18 Incident: 1/12/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys the structural materials needed for advanced aerospace platforms and argues that material choice cannot be separated from overall vehicle design, because launch vehicles, space vehicles, reusable systems, and propulsion hardware each face different temperature, durability, weight, and manufacturing constraints. The report reviews a range of candidate material classes, including advanced aluminum alloys; polymer-, aluminum-, and titanium-matrix composites; titanium alloys; nickel-base alloys; refractory metals; ceramic-matrix composites; carbon-carbon composites; and titanium aluminides. It emphasizes that balancing performance against practical limits such as fabrication methods, cost, inspection, contamination control, and service environment remains a major challenge. Its overall conclusion is that many promising materials exist, but their usefulness depends on application-specific tradeoffs and on closer integration of material selection with design and manufacturing, with some systems judged to be more valuable targets for development than others.

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material is not suitable for the reasons stated earlier. Clearly, the time required for
layup places practical limitations on component size.
• In automated tow placement, thin ribbons of a pre-preg are fed off a drum or rolled
into a computer numerically controlled machine that places them in the desired
position. In principle, this process trades recurring labor cost for up-front capital
investment (the tow placement machine) and programming time . If the anticipated
volume of identical parts is high enough to amortize the capital investment and,
particularly, the programming cost, this can be an attractive means of reducing
manufacturing costs. For axisymmetric shapes, such as cylinders, this essentially
becomes a winding process and is quite efficient. An example of a finished
composite fuselage barrel section for the Boeing 787 is shown in Figure 2. For more
irregular three -dimensional shapes, such as a spar or a strut, placing the tows
becomes much more difficult and presents a fundamental limitation. Consequently,
PMC structures with complex shapes are still for the most part made using the hand
layup process. A variant of automated t ow placement is compression, whereby a
preform, made by automated tow placement, is forced by a press into a preshaped
die. This process allows fabrication of more complex shapes, but the rigidity of the
fiber and the extreme anisotropy of the tows can lead to wrinkles, which are not
acceptable because of the reductions in properties these cause.
Figure 2. Specially Modified 747 Transporter Unloading a Boeing 787 Composite Fuselage Barrel
Section
• The third main composite fabrication method, resin transfer molding (RTM), begins
with a woven fiber mat or preform. The polymeric matrix is injected into this mat to
create a fully dense composite. The major benefit of RTM is that it permits use of a
three-dimensional weave that minimizes the risk of delamination between plies.
Note that, with the other two methods, the material is reinforced in only two
dimensions (the plane of the pre-preg or tows). RTM's limitations include the
viscosity of the resins used. If the resin is too viscous, injecting it will either distort
the fiber architecture of the woven preform or not fully penetrate the preform,
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Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 27 pages are in the text index: search them above, or from the library's search.