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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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in materials with small annual sales volume, so even licensing the new material to one
of these companies may not be commercially feasible .
This foregoing discussion highlights a commonly encountered inconsistency between
technical innovation and commercial progress. Until a production-scale source exists,
pricing of new materials is at best highly uncertain and potentially unstable over time.
This is in part due to the uncertainty surrounding demand and the associated volume of
material that will be required. Taken together, these factors act as a clear deterrent to
the adoption of new materials of literally all classes (polymers, metals, and ceramics).
For heavily loaded structures or structures that will experience temperatures higher
than about 200 °Celsius, Ti alloys are the preferred material class. Ti alloys are about
half as dense as steel or Ni-base alloys and possess a density-corrected strength and
stiffness competitive with that of other metallic materials. Numerous grades of Ti alloys
are in use today, and a strong domestic industrial base of suppliers exists for nearly all
these grades . Ti alloys for structural applications can be divided into three groups based
on their metallurgy: near a alloys, a+p alloys, and metastable p alloys (commonly called
p alloys for short) . Both the aircraft and propulsion original equipment manufacturers
and several private engineering firms have extensive design experience with Ti alloys.
Although most of this experience is with Ti-6Al-4V (Ti-6-4 ), other alloys also are widely
used, particularly in jet engines and liquid-fueled rocket engines. The alloy most likely
to be used in a launch vehicle, Ti-6-4, has been available and in use for more than 40
years but is still highly competitive with newer grades in large part because of its
versatility. Potential applications of other alloys that have particularly attractive
characteristics, such as a higher temperature capability, are discussed in the Reusable
Reentry Vehicle and Propulsion Systems sections of this document.
The most commonly used structural grade of Ti alloy today, Ti-6-4, can be readily
fusion welded, formed both by forging and as a sheet product, and conventionally
machined, although each of these operations requires special precautions. In addition,
the feasibility of friction stir weld ing has been demonstrated. Ti-6-4 also can be
superplastically formed and diffusion bonded, enabling synthesis of innovatively shaped
components. For launch vehicles, the most likely application for Ti alloys is in the
structure that carries the reactions from the propulsion system to the vehicle itself.
These applications typically involve heavy sections to accommodate the large loads,
and the main property requirements are high strength, fatigue resistance, and fracture
toughness. Ti alloys have been used in both military and commercial aircralt. Heavily
loaded components in service today include the wing box of the B-1B bomber (Ti-6-4),
the landing gear beam in the B-747 (Ti-6-4), and the landing gear truck beam in the B-
777 (higher strength Ti-10V-2Fe-3AI [Ti-10-2-3]). The choice of Ti-10-2-3 for the
landing gear truck beam reflects the time-based maturation of the newer p-Ti alloys,
such as Ti-10-2-3. These alloys have the advantage of being "deep hardenable"
compared with Ti-6-4, they can develop full strength in thicker sections during heat
treatment . For example, that the B-777's truck beam is up to 6 inches th ick in some
locations factored significantly in the choice of Ti-10-2-3. Because Ti alloys are about
half as dense as steel, they are very competitive on a density-corrected basis. However,
mass is not the only driver for some applications; the volume of a component also must
be compatible with the space available for it. This factor also is a consideration in the
choice ofTi -1 0-2-3 for the B-777 truck beam. And it also applies to an application such
as land ing gear, because it is retracted into the fuselage for aerodynamic reasons.
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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.