Materials Needs and R&D Strategy for Future Military Aerospace Propulsion Systems (2011) / Chapter Skim
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3 Materials Development Assessment
3 Materials Development Assessment
Pages 68-117
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From page 68... ...
engine manufacturers' competitiveness in the global market.1 The first six sections of this chapter provide assessments of the following: Section 3.1, the materials development process used for structural materials research and development (R&D) ; Section 3.2, the organizations in the Air Force Research Laboratory (AFRL)
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From page 69... ...
The elements above 6.3 are the Air Force's Acquisition Program, managed by the system program offices. Within the S&T program, basic research (6.1)
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From page 70... ...
For noncritical components, materials that have already transitioned into a system and are subsequently modified typically require much less time for reinser tion than for the original development effort. In general, the 6.1 step is eliminated for reinsertion.
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From page 71... ...
The directorate explores new materials, processes, and manufactur ing technologies for use in aerospace applications, including aircraft, spacecraft, missiles, rockets, and ground-based systems, along with their structural, electronic, and optical components. Areas of expertise in this directorate include thermal protection materials, metallic and nonmetallic structural materials, nondestruc tive inspection, materials used in aerospace propulsion systems, electromagnetic and electronic materials, and laser-hardened materials.
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From page 72... ...
The AFRL consists of 10 technical directorates, including the AFOSR: • AFOSR, located in Arlington, Virginia; • Air Vehicles Directorate, at Wright-Patterson AFB, Ohio; • Directed Energy Directorate, at Kirtland AFB, New Mexico; • Human Effectiveness Directorate, at Wright-Patterson AFB, Ohio; • Information Directorate, at the Rome Research Site, New York; • Materials and Manufacturing Directorate, at Wright-Patterson AFB, Ohio, and Tyndall AFB, Florida; • Munitions Directorate, at Eglin AFB, Florida; • Propulsion and Power Directorate, at Wright-Patterson AFB, Ohio, and Edwards AFB, California; • Sensors Directorate, at Wright-Patterson AFB, Ohio; and • Space Vehicles Directorate, at Kirtland AFB, New Mexico; 2 See http://www.wpafb.af.mil/afrl/rz/. Accessed September 11, 2009.
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From page 73... ...
5 The committee recognizes that the Materials and Manufacturing Directorate's approach to FLTCs is evolving and dynamic at this time and that some changes in the approach are forthcoming. 6 Information received during presentations to the committee at Wright-Patterson AFB, Ohio, May 27, 2009.
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From page 74... ...
Materials, especially high-temperature materials, are important in a number of the FLTCs, and the Materials and Manufacturing Directorate is involved with nearly all of the FLTCs to some degree. The Materials and Manufac turing Directorate has management responsibility for the sustainment FLTC.
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From page 75... ...
The current AFOSR basic research program is divided into three director ates. Research on aerospace propulsion materials is funded primarily through the Aerospace, Chemical, and Materials Science Directorate under 12 topical areas.8 The area most relevant to propulsion systems is topical area (7)
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From page 76... ...
The directorate's areas of ex pertise include thermal protection materials, metallic and nonmetallic structural materials, nondestructive inspection, materials for aerospace propulsion systems, electromagnetic and electronic materials, and laser-hardened materials. Figure 3.2 presents the directorate's organizational chart.
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With a host of modern material analysis laboratories, the directorate performs research on thermal protection materials, metallic and nonmetallic structural materials, nondestructive inspection, materials used in aerospace propulsion systems, electromagnetic and electronic materials, and laser hardened materials. It also provides real-time operating problem solutions and failure analysis, along with support to Air Force weapons system acquisition offices and maintenance depots, including work on advanced manufacturing technology programs and affordability initiatives.
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From page 78... ...
The historic model described in Figure 3.1 continues to frame the current approach for Air Force propulsion materials development.9 Several organizational and programmatic changes over the past few years have changed the materials development environment, resulting in changes in this decade compared with the previous several decades. These changes include a significant reduction in applied research in other agencies working on propulsion materials technology, and a contract focus for the materials work on the Integrated High Performance Turbine Engine Technology (IHPTET)
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These reductions have a dual effect on the production of materials advances: they lead to fewer and less diversified ideas and approaches being pursued and to a loss of the competitive atmosphere among contractors. Compounding this effect is the reduced investment in new materials through Materials and Manufacturing Direc torate research found in these demonstrators.15 Other issues that were raised during the committee's visit to Wright-Patterson AFB on May 27, 2009, included a reduced emphasis on traditional propulsion materials technology at the level of the Director, Defense Research and Engineer ing (DDR&E)
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The teams also include members from the AFRL planning group who are responsible for structuring the planning and budgeting document for the entire AFRL. The directors of the Materials and Manufacturing and the Propulsion and Power Directorates had recently organized a Propulsion Materials Workshop that resulted in signs of improved communications and coordination between the two directorates.
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From page 81... ...
In addition, the further analysis should consider the internal investment in materials research through the AFRL and potential interactions with efforts funded by other agencies such as the ONR and NASA. Complementing the AFOSR materials science activities and coordinated with these activities is the work at the Office of Naval Research.
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From page 82... ...
33) , under the Code 332 High Temperature Materials Program, has continuous thrusts to develop higher temperature materials to meet future naval challenges and capability requirements for future aircraft and shipboard gas turbine engines, hypersonic vehicles, and criti cal missile components.19 Reliable high-temperature materials are also needed to improve engine efficiency and decrease maintenance costs.
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Heat transport, atomic transport, high-temperature corrosion and oxidation, deformation, frac ture, and fatigue are among the complex phenomena involved in the performance of high-temperature materials in the extreme environment of turbine engines and rocket propulsion systems. Current state-of-the-art incumbent materials, their processing and manufacturing technologies, and the engineering know-how sur rounding these materials were not developed for their own sake, but rather to meet the needs created by advancing propulsion systems; they are the result of decades of materials research and practical engineering experience.
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From page 84... ...
In cluded in these developments are contributions to the advancement of superalloy turbine disk materials, thermal barrier coatings, single-crystal blade alloys, gamma TiAl, and ceramic-matrix composites for combustion liners, discussed in Chapter 2. The close linkage of military applied materials development and demonstrator programs dates back to the Advanced Turbine Engine Gas Generator programs of the 1970s.
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From page 85... ...
Advanced materials demonstrations based on work from previous programs include advanced nickel disk alloys, the application of material-behavior-and-life-prediction methods, and ceramic and ceramic-matrix composite materials. The two demonstration compo nents of VAATE are the Advanced Versatile Engine Technology (ADVENT)
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From page 86... ...
It is a mechanism for cooperation and potential collaboration, not a "program" in the sense of a single funded entity. The AFRL Materials and Manufacturing Directorate and the ONR have par ticipated in the VAATE Program since its inception, and both organizations have funded materials development efforts at the engine manufacturers that advance the state of the art of turbine engine materials.
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From page 87... ...
Wider access to materials property data for advanced materials would provide property bench marks for materials developers, enable researchers to develop and validate property models, and eliminate the cost of redundant testing. A widely accessible database of 23 Art Temmesfeld, Air Force Research Laboratory, "Air Force Manufacturing Technology Program, Propulsion Manufacturing Readiness Assessment and the Advanced Manufacturing Propulsion Ini tiative," presentation to the committee, Washington, D.C., March 23, 2009.
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From page 88... ...
This latter organization is chartered by the DOD to serve as a repository for materials and manufacturing reports as well as to analyze and disseminate technical information for advanced materials.25 Despite these resources, however, the materials commu nity does not have access to the most important and recent industrial materials property data for advanced propulsion materials.
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From page 89... ...
There appears to be an appropriate level of controlled cooperative programs26 among engine manufacturers, materials and component suppliers, and external materials scientists that could reduce the cost and time to develop material property data for advanced materials. 3.4 MATERIALS CONTRIBUTION TO CURRENT AND EMERGING PROPULSION SYSTEMS 3.4.1 Turbine Engines For more than 50 years, materials have been the major enabler for the evo lution of aircraft turbine engines.
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Develop ments in advanced materials have been the major contributor to the unparalleled growth in the thrust-to-weight ratio in gas turbine engines. For example, the sub stitution of Ti- and Ni-based superalloys for steel was a major evolutionary step.
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Figure 3-4 pressures can increase to 40 to 50 atm in the HPT. The materials and their associ R01976 Propulsion in the engine to provide ated processes will accordingly change with their location bitmapped the necessary thermal stability.
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Wrought nickel alloys replaced steel alloys, allowing higher temperature and improved performance. Going to a casting process provided a temperature increase of about 100°C due to the ability to incorporate cooling channels as well as higher creep resistance due to larger grain size.
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Summary and Future Directions for Turbine Engines The near-term future no doubt promises fewer transition opportunities than were available in the past for the development of new materials or for the improve
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to accelerate to the speed at which scramjets can operate efficiently, which is above about Mach 5. As discussed in the Section 3.4.1, turbine engines have a series of complex, rotating parts such as those used to compress the air used for combustion.
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2004. "High Speed Propulsion: Performance Advantage of Advanced Materials," Journal of Materials Science 39(19)
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and managed by the Propulsion and Power Directorate of the AFRL.36 In flight tests scheduled for the spring of 2010, the vehicle was to be accelerated from Mach 4.5 to Mach 6 by a hydrocarbon-fueled scramjet. Three additional tests were then scheduled at 4- to 6-week intervals following the initial test.
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Figure 3-8 R01976 Propulsion 3.4.3 Rocket Propulsion bitmapped As with turbine engines and scramjets, rocket engine performance is driven by the materials used in the construction of the engine. Also as with turbines, designs that use cooling mechanisms are critical to engine performance.
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From page 98... ...
Composite systems such as glass and carbon fibers have been used as candidate systems to reduce weight and increase performance. Solid Rocket Motor Nozzle Materials The materials used to manufacture SRM nozzles generally fall into the follow ing groups: structural materials; housing and nonstructural materials, such as adhesives; sealants and greases; thermal insulating materials; and ablative mate rials.
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From page 99... ...
Both the combustion inlet temperature and the combustion exit temperature directly affect the thermal effi ciency of a gas turbine engine. The efficiency of the combustion process is nearly 100 percent in modern gas turbine engines in that the available heat release of the fuel is fully achieved.
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Further, as in the case of the gas turbine engines, even fewer transition opportunities are likely owing to the military sector's lack of new rocket and launch systems.
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From page 101... ...
version of the aircraft. These positions brought Rolls technologies to the program, with examples being superplastically formed diffusion-bonded hollow fan blades and linear friction welding of rotating components and thrust vectoring component technologies used directly in the lift fan and nozzle systems on the JSF STOVL version of the aircraft and incorporated into the joint-venture-proposed alternate engine.
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From page 102... ...
• United Kingdom • China • Japan • Russia • Ukraine European Union EuMaT is the organization within the European Union that facilitates advanced research in the development and application of advanced engineering materials and related manufacturing processes.39 EuMaT works closely with the European Materials Forum and the European Materials Research Society. EuMaT provides a technology platform to bring together government, industry, and academia to establish R&D priorities and to oversee the dispersal of funds within the European Union Research Framework Program.
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systems: metals-plastic, ceramic-metals, compounds, and others; • Materials with functionally gradient composition or structure; • Thin or thick films and coatings: magnetic films, thermal barrier coatings, corrosion protection, and others; • High-temperature materials: heat-sink materials, creep-resistant materials (structural materials for long-term application including lightweight aspects and oxidation resistance) ; in particular, metals, composites, and coating systems; • High-strength and corrosion-resistant materials (ultra-steels, materials for bridges, marine environment, pressure equipment, and so on)
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Funding within European Framework No. 7 is estimated to exceed 4 billion euros for advanced materials development.
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For example, ceramics, ceramic compos ites, reinforced Ni-aluminides. Literature and patent searches indicate significant research activity in improved efficiency of turbojet/turbofan engines, ramjet and scramjets for hypersonic flight, and increased-performance liquid-fueled and solid rocket motors.
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. Domestic leaders within China include Sinoma Advanced Materials Co., Ltd., and Shenyang Starlight Advanced Ceramics Co., Ltd.
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Within the Russian Federation, NPO Energomash has a long history of suc cess in designing and manufacturing liquid-fuel rocket engines. These engines are used in other international launch vehicles such as the United Launch Alliance (U.S.)
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3.6.1 Review of Relevant Focused Long Term Challenges and Roadmaps In assessing propulsion material technology needs, the committee reviewed a wide range of Air Force requirements and planning and implementation activity. One of the difficulties in assessing the relative adequacy of the propulsion materials program(s)
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In addition, both legacy and pipeline systems must be sustained and retrofitted with improved capability and robustness. The degree of complexity of evolving requirements and technologies is fur ther reinforced when one reviews the Focused Long Term Challenges (FLTCs)
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addresses the more traditional Air Force role of responsive precision engagement with the require ment for global delivery of the full spectrum of nonkinetic and kinetic effects. 45 AFRL, Materials for Advanced Aerospace Propulsion and Power Systems , AFRL/RZ and AFRL/RX Workshop, AFRL-RZ-WP-TM-2008-2127, 2008.
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These products are identified as turbine engines, both liquid-fueled rocket engines and solid rocket motors, and scramjets. For each of these product areas, requirements have been identified for the focus of materials research and development.
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In the case of the liquid-fueled rocket engines, the materials programs recog nized a series of materials advances as noted above; however, the linkage to new systems' requirements47 was not as clear as that noted in the turbine engine work. One requirement noted in the liquid rocket engine review was that there be a con tinental United States (CONUS)
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The committee's assessment of this planning was based on the Air Force docu ment Materials for Advanced Aerospace Propulsion and Power Systems48 and was conducted as a review and evaluation of the USAF strategic plan for materials research and development to support future propulsion and power needs of the USAF. No other sources were consulted.
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The approach used in the workshops followed a well-developed roadmapping technique that provides a logical, well-defined, iterative process that guided the development of the strategic plan. The process is wholly contained within the Materials and Manufacturing Directorate and the Propulsion and Power Directorate of the AFRL and collaboration between the two directorates, but did not include the warfighter, representatives of system program offices, or the AFOSR.
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3.7 FINDINGS The Materials and Manufacturing Directorate and the Propulsion and Power Directorate of the Air Force Research Laboratory and the AFOSR have cooper ated in the past through the institutionalized 6.1, 6.2, and 6.3 funding categories and formal programs such as the IHPTET Program to provide USAF and the U.S. industry a global competitive advantage in propulsion technology and fielded sys tems; however, the current VAATE Program does not have the same level of indus trial competition and funded materials support as in the past, and indications are that future 6.3 demonstrator programs will see further reductions in these areas.
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Finding: The current planning process of the AFRL Materials and Manufacturing Directorate and Propulsion and Power Directorate is evolving to address the FLTC approach. The reduction in the number of technology demonstrators has significantly reduced the number of opportunities to demonstrate advanced materials and pro cesses prior to insertion in existing and emerging propulsion systems.
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From page 117... ...
The strategy should include the regular review and updating of the directorates' propulsion materials plan, with an emphasis on the consequences of unfunded items, the changing external environment, and maintaining a balance for the near-, mid-, and far-term activities in response to the Focused Long Term Challenges and funding commitment. Recommendation: The AFRL Materials and Manufacturing Directorate and Pro pulsion and Power Directorate should increase their communication and collabo ration with the AFOSR, system program offices, industry, and academia relative to propulsion materials needs, advances, technology readiness, and the potential systems payoffs of technology insertion.
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