Documents / Official release
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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not technology dependent but are cost intensive, no matter what technology is
employed to meet the requirements.
An additional characteristic of PMC structures-one related to the laminated
construction of components made by hand layup or automated tow placement
methods-is their susceptibility to formation of delaminations when impacted
perpendicular to the plane of the plies. This is due to the mismatch in bending stiffness
between adjacent plies that have different unidirectional fiber orientations. This
mismatch causes shear stresses to develop that can exceed the shear strength of the
interlaminate bonds, causing small, embedded cracks to form. Under subsequent
inplane compression loading, the laminates bow because of the Poisson stresses and
separate because of the lack of an interlaminar bond to hold them together. In
significant compression loads, the laminates buckle, and this leads to structural failure.
This phenomenon, called compression after impact, is an insidious failure mode because
the delaminations are not externally detectable unless ultrasonic inspection methods
are used. Sources of such an impact include dropped tools, foreign objects (for
example, meteorites), and, perhaps most commonly, hail storms. Ultrasonic inspection,
if required, is expensive and time consuming. The latter concern in turn affects vehicle
availability and turnaround time. PMC parts made using RTM typically have reinforcing
fibers in the through-thickness direction, so concerns about compression after impact
are minimal.
The maximum temperature at which PMCs can be used is limited by PMCs' susceptibility
to oxygen degradation of the polymeric matrix. The maximum-use temperature for
prolonged exposure is determined by the thermal oxidative stability (TOS) of a
particular resin. The TOS, like any chemical reaction, is determined by both time and
temperature . The glass transition temperature (T9 ) of the polymeric matrix also
imposes strength and dimensional stability limitations independent of the TOS limits.
This is particularly true for thermoplastics. However, the TOS limits usually impose
lower temperature limits than T9 if prolonged thermal exposure is contemplated. Three
distinct classes or groups of resins exist, each with a successively higher temperature
capability. These are conventional epoxies and most thermal plastics, bismaleimides
(BMis), and linear polyimides. The first class is limited by TOS to about 125° Celsius.
BMis can be used to about 175° Celsius. Linear polyimides, such as the in situ
polymerization of monomer reactants (PMR) group of thermosetting formulations, can
be used to about 300° Celsius. Many of the PMR resins contain the hazardous
compound methylenedianiline, which requires special care during use, including
protective clothing to limit personnel exposure (for example, during ply cutting and
hand layup). This requirement reduces productivity, adds cost, and creates a degree of
liability concern for the manufacturer of the PMC components. For RTM, the BMis and
PMR resins typically have higher viscosity and require commensurately higher injection
temperatures to reduce the viscosity to manageable levels for reasons discussed
earlier. New resins are constantly being developed, including some with attractive
properties. However, many of the sources of these resins are startup companies that
exist on R&D fund in g, often in the form of U.S. government SBIR (Small Business
Innovative Research) projects. Such companies are good at innovation but often have
limited experience transitioning new products from the laboratory to large -scale
production. Furthermore, in the current economic climate, access to sufficient capital to
set up production-scale capacity can be a form idable problem for a small company.
Larger companies (for example, BASF, DuPont, GE Plastics) typically are not interested
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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.