Composite Materials

DURATION: THREE DAYS
COURSE NO.: 1030

Carbon fiber-reinforced polymers are now the baseline materials for most new spacecraft and launch vehicle structures. The continuing development of new reinforcements and resins is expanding the use of these materials to other applications, such as thermal management. At the same time, the three other classes of composites, carbon matrix, metal matrix and ceramic matrix are receiving increasing attention. This course provides an overview of these evolving and increasingly important materials. Well publicized catastrophic failures of major components in recent years emphasize a need for the kind of basic understanding that this course provides. Fiber-reinforced polymer matrix composites (PMCs), such as carbon (graphite)/epoxy, carbon/cyanate ester and carbon/siloxane, are now the materials of choice for spacecraft and launch vehicle structures and subsystems such as optical benches, instruments and antennas. Carbon matrix composites (CAMCs), especially carbon/carbon composites (CCCs), are baseline materials in high temperature applications such as re-entry vehicle nose tips, rocket motor nozzles and the Space Shuttle Orbiter leading edges. The Space Shuttle Orbiter and the Hubble Space Telescope have metal matrix composite (MMC) components. Use of composites is expanding to other space and launch vehicle subsystems, such as fuel tanks, mechanisms, thermal control, electronic packaging and propulsion. Application of composites in these subsystems is particularly valuable, because, in addition to providing performance improvements and direct component mass reduction, they have a ripple effect, resulting in additional system mass reductions. As satellite and launch vehicle production runs increase, use of low cost manufacturing methods is becoming important. The increasing use of composites in commercial applications is driving down their price, making them more competitive with conventional materials. For example, MMCs are now being used in production automobile applications, such as Honda engine blocks, Toyota pistons and electronic packaging. PMCs are widely used in commercial aircraft, sports equipment and industrial and medical equipment. Ceramic matrix composites (CMCs) are being applied in cutting tools and power generation and process industries equipment. The key driving force for the use of composites in structures is that they offer up to order-of-magnitude improvements in specific stiffness (stiffness-to-density) and specific strength (strength-to-density) ratios, combined with outstanding resistance to fatigue and creep. The near-zero thermal distortion achievable with composites has led to their widespread application in antennas, optical benches, instruments and other components for which dimensional stability is required. The extremely high thermal conductivity of some composites is resulting in their increasing use in thermal control components such as radiator panels. The high specific stiffness, low thermal distortion and isotropy of particle-reinforced MMCs make them attractive, along with PMCs, for mechanisms, such as gimbals and hinges. There is great potential for CMCs, MMCs, carbon matrix composites and selected PMCs in high temperature applications, such as propulsion systems. For example, CAMCs and carbon/polyimide PMCs have replaced high-temperature alloys in aircraft gas turbine engine parts. The continuing development of new materials and technology will greatly expand the payoffs for composites in the next generation of aerospace products. This course provides a comprehensive introduction to composites technology for spacecraft, launch vehicles and their subsystems, emphasizing basic principles that can prevent unnecessary failures. Participants are invited to bring issues for class discussion.

COURSE MATERIALS:
Include extensive notes and reference materials.

Spacecraft and launch vehicle engineers, scientists and managers involved in structures, mechanisms, propulsion, antennas, solar arrays, optical systems, thermal management and electronic packaging. The course is intended for those who have had little or no experience with composite and those with experience who wish to broaden their knowledge of materials of special interest to launch vehicles and spacecraft. Quality assurance and manufacturing engineers. Purchasing specialists. Material suppliers. Other professionals who need a knowledge of composites technology.

Properties of the four classes of composite materials: PMCs, MMCs, CMCs and CAMCs (which includes CCCs). Dimensionally stable composites. High temperature materials. Ultrahigh thermal conductivity composites. Properties of the many different types of carbon (graphite) fibers. Other key fibers. New resins for space applications. The importance of test methods. How to design composite components. Manufacturing methods, including low cost processes. Avoiding common pitfalls. Special considerations for the space environment. Microcracking. How to choose from the bewildering and rapidly expanding array of composite materials. Current and emerging applications in structures, mechanisms, optical benches instrument structures, solar arrays, antennas, booms and masts, propulsion systems, thermal control, electronic packaging and electronic enclosures.

1. Introduction.
   

   Overview. Brief history. Key classes of composite materials: PMCs, MMCs, CMCs, CAMCs and CCCs. Terminology. Importance of anisotropy.

2. Key Materials and Their Properties.
   

   Fibrous reinforcements: carbon (graphite) made from polyacrylonitrile (PAN), petroleum and coal tar pitch, aramid, E-glass, high strength glass, boron, silicon carbide, alumina and others. Particulate reinforcements. Key resin systems: epoxies, cyanate esters (polycyanurates), siloxanes, bismaleimides, polyimides and others. Test method considerations. Properties of key PMCs, MMCs, CMCs, CAMCs and CCCs: strength properties, elastic properties, thermal expansion, thermal conductivity, moisture expansion, and density. Property variability.

3. Special Considerations for Spacecraft and Launch Vehicle Applications.
   

   Microcracking, outgassing, EMI and ionizing radiation shielding, atomic oxygen degradation. Improving oxidation resistance of CCCs.

4. Manufacturing Methods and Nondestructive Evaluation.
   

   Key fabrication methods for PMCs, MMCs, CMCs, CAMCs and CCCs. Low cost processes. Overview of key NDE methods.

5. Design Methods.
   

   Special design considerations for composite materials: anisotropic strength and elastic properties, low transverse properties, stress concentrations, Microcracking. Laminated plate theory. Adhesive and mechanical joints. Avoiding common pitfalls.

6. Applications.
   

   Spacecraft structures, launch vehicle structures, optical benches, instrument structures, solar arrays, antennas, booms and masts, propulsion systems, thermal control, electronic packaging, mechanisms.