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The Engineering Foundation Conference on Processing and Design Issues in High Temperature Materials was held in Davos, Switzerland, 19-24, 1996. Approximately fifty participants represented academic institutions, industrial research laboratories and government organizations. The goal of the conference was to exchange areas of common concern among developers and users of high temperature materials of differing types, including superalloys, ceramics, intermetallics and composites. Levels of design ranging from atomic theory to processing techniques were covered in nine oral technical sessions and a poster session. The keynote lecture, entitled "Implementation Challenges for High Temperature Composites" was followed by 26 invited and 15 contributed papers, of which four were poster presentations. The participants were noteworthy for the wide range of their technical specialties. It was evident that many participants were exposed to relatively unfamiliar materials and topics as a result of efforts by the organizing committee to have an extremely diverse group of conferees. Since superalloys dominate current high temperature applications in the 800-1100 C range, it was considered to be important to discuss alloy design principles, microstructures and mechanical properties of potentially competitive materials such as ceramics and intermetallics, as well as their composites. Environmental effects on mechanical properties were highlighted; it was shown, for example, that water vapor can be detrimental to both intermetallics at low temperatures and ceramics at high temperatures. Oxidation of high temperature materials was another environmental issue of great importance that was discussed in several papers.

The Engineering Foundation Conference on Processing and Design Issues in High Temperature Materials was held in Davos, Switzerland, 19-24, 1996. Approximately fifty participants represented academic institutions, industrial research laboratories and government organizations. The goal of the conference was to exchange areas of common concern among developers and users of high temperature materials of differing types, including superalloys, ceramics, intermetallics and composites. Levels of design ranging from atomic theory to processing techniques were covered in nine oral technical sessions and a poster session. The keynote lecture, entitled "Implementation Challenges for High Temperature Composites" was followed by 26 invited and 15 contributed papers, of which four were poster presentations. The participants were noteworthy for the wide range of their technical specialties. It was evident that many participants were exposed to relatively unfamiliar materials and topics as a result of efforts by the organizing committee to have an extremely diverse group of conferees. Since superalloys dominate current high temperature applications in the 800-1100 C range, it was considered to be important to discuss alloy design principles, microstructures and mechanical properties of potentially competitive materials such as ceramics and intermetallics, as well as their composites. Environmental effects on mechanical properties were highlighted; it was shown, for example, that water vapor can be detrimental to both intermetallics at low temperatures and ceramics at high temperatures. Oxidation of high temperature materials was another environmental issue of great importance that was discussed in several papers.

The Engineering Foundation Conference on Processing and Design Issues in High Temperature Materials was held in Davos, Switzerland, 19-24, 1996. Approximately fifty participants represented academic institutions, industrial research laboratories and government organizations. The goal of the conference was to exchange areas of common concern among developers and users of high temperature materials of differing types, including superalloys, ceramics, intermetallics and composites. Levels of design ranging from atomic theory to processing techniques were covered in nine oral technical sessions and a poster session. The keynote lecture, entitled "Implementation Challenges for High Temperature Composites" was followed by 26 invited and 15 contributed papers, of which four were poster presentations. The participants were noteworthy for the wide range of their technical specialties. It was evident that many participants were exposed to relatively unfamiliar materials and topics as a result of efforts by the organizing committee to have an extremely diverse group of conferees. Since superalloys dominate current high temperature applications in the 800-1100 C range, it was considered to be important to discuss alloy design principles, microstructures and mechanical properties of potentially competitive materials such as ceramics and intermetallics, as well as their composites. Environmental effects on mechanical properties were highlighted; it was shown, for example, that water vapor can be detrimental to both intermetallics at low temperatures and ceramics at high temperatures. Oxidation of high temperature materials was another environmental issue of great importance that was discussed in several papers.

This thesis describes the software design and implementation of a microprocessor-based, random load drive and data acquisition system on a Material Testing System (MTS) machine. A microprocessor, combination analog input/output module, magnetic cassette tape recorder, and strain gage network form a strain data acquisition system for recording sequential strain peaks and throughs on specimens subjected to flight load histories. The data will be used to estimate the fraction of the fatigue life expended in a test specimen. A high speed digital computer is linked by telephone line to a microcomputer development system to create the randomization of fatigue loads specified in Mil Spec 8866 Spectrum A for use by the MTS machine. (Author)

This thesis describes the software design and implementation of a microprocessor-based, random load drive and data acquisition system on a Material Testing System (MTS) machine. A microprocessor, combination analog input/output module, magnetic cassette tape recorder, and strain gage network form a strain data acquisition system for recording sequential strain peaks and throughs on specimens subjected to flight load histories. The data will be used to estimate the fraction of the fatigue life expended in a test specimen. A high speed digital computer is linked by telephone line to a microcomputer development system to create the randomization of fatigue loads specified in Mil Spec 8866 Spectrum A for use by the MTS machine. (Author)

No Abstract Available

This project consists of a collaborative synthetic, processing, physical characterization, and theoretical program aimed at the rational design, construction, evaluation, and fundamental understanding of new types of maximum- performance molecule/polymer-based materials exhibiting high second-order (X(2)) optical nonlinearities. Areas of emphasis include poled chromophore- functionalized glassy polymers, poled chromophore-embedded crosslinkable matrices, chromophoric self-assembled superlattices, the theoretical design and analysis of novel chromophores and chromophore environments, theoretical studies of poling dynamics, studies of optical damage phenomena, and fabrication of new types of NLO waveguides. Each research component of this highly interactive effort builds upon work already in progress as well as upon strong on-going collaborations in laser optics and quantum theory. Nonlinear optical material, Polymer, Chromophore, Crosslinking, Self-assembly, Second harmonic generation.

Computational modeling and simulations involving STEM (science, technology, engineering and mathematics) disciplines are highly interdisciplinary growing out of complex, challenging, multi-domain, multi-component and data intensive application needs of several disciplines and the need for high end computing hardware and software, algorithms and information driven technologies. The research efforts in this project focused on the synergistic coupling of: Computational material science and mechanics of hybrid and light weight polymeric composite structures. Computational multi-scale deformation behavior in metallic material systems. Computational enabling technologies of multi-scale flow simulation investigations with Lattice-Boltzmann equations and finite volume methods; physics based composite process flow. modeling in GPU systems; and probabilistic methods to understand uncertainties in deterministic composite processing flow models.

The goal of this research has been to find dispersants for ceramic processing applications. The polyelectrolytes currently in use in the industry are synthesized from toxic precursors which present health hazards to workers. We have investigated polyelectrolytes produced from natural sources such as bacteria and kelp, as well as some polymers which have been produced synthetically. The polyelectrolytes which we have investigated include polysaccharides (alginate and dextran) and polypeptides (polyglutamic acid and polyaspartic acid). Some have been obtained from cultures of bacteria grown in our laboratories, others have been obtained from chemical supply houses. In addition, we have investigated the feasibility of using an in situ process by which we incubate the polymer-producing bacteria in the presence of ceramic powders. In this system, polymer adsorbs to the powder in a high affinity state, allowing subsequent washing to remove the bacterial cells, while retaining the adsorbed polymer. jg

The goal of this research has been to find dispersants for ceramic processing applications. The polyelectrolytes currently in use in the industry are synthesized from toxic precursors which present health hazards to workers. We have investigated polyelectrolytes produced from natural sources such as bacteria and kelp, as well as some polymers which have been produced synthetically. The polyelectrolytes which we have investigated include polysaccharides (alginate and dextran) and polypeptides (polyglutamic acid and polyaspartic acid). Some have been obtained from cultures of bacteria grown in our laboratories, others have been obtained from chemical supply houses. In addition, we have investigated the feasibility of using an in situ process by which we incubate the polymer-producing bacteria in the presence of ceramic powders. In this system, polymer adsorbs to the powder in a high affinity state, allowing subsequent washing to remove the bacterial cells, while retaining the adsorbed polymer. jg

The goal of this research has been to find dispersants for ceramic processing applications. The polyelectrolytes currently in use in the industry are synthesized from toxic precursors which present health hazards to workers. We have investigated polyelectrolytes produced from natural sources such as bacteria and kelp, as well as some polymers which have been produced synthetically. The polyelectrolytes which we have investigated include polysaccharides (alginate and dextran) and polypeptides (polyglutamic acid and polyaspartic acid). Some have been obtained from cultures of bacteria grown in our laboratories, others have been obtained from chemical supply houses. In addition, we have investigated the feasibility of using an in situ process by which we incubate the polymer-producing bacteria in the presence of ceramic powders. In this system, polymer adsorbs to the powder in a high affinity state, allowing subsequent washing to remove the bacterial cells, while retaining the adsorbed polymer. jg

The goal of this research has been to find dispersants for ceramic processing applications. The polyelectrolytes currently in use in the industry are synthesized from toxic precursors which present health hazards to workers. We have investigated polyelectrolytes produced from natural sources such as bacteria and kelp, as well as some polymers which have been produced synthetically. The polyelectrolytes which we have investigated include polysaccharides (alginate and dextran) and polypeptides (polyglutamic acid and polyaspartic acid). Some have been obtained from cultures of bacteria grown in our laboratories, others have been obtained from chemical supply houses. In addition, we have investigated the feasibility of using an in situ process by which we incubate the polymer-producing bacteria in the presence of ceramic powders. In this system, polymer adsorbs to the powder in a high affinity state, allowing subsequent washing to remove the bacterial cells, while retaining the adsorbed polymer. jg

The goal of this research has been to find dispersants for ceramic processing applications. The polyelectrolytes currently in use in the industry are synthesized from toxic precursors which present health hazards to workers. We have investigated polyelectrolytes produced from natural sources such as bacteria and kelp, as well as some polymers which have been produced synthetically. The polyelectrolytes which we have investigated include polysaccharides (alginate and dextran) and polypeptides (polyglutamic acid and polyaspartic acid). Some have been obtained from cultures of bacteria grown in our laboratories, others have been obtained from chemical supply houses. In addition, we have investigated the feasibility of using an in situ process by which we incubate the polymer-producing bacteria in the presence of ceramic powders. In this system, polymer adsorbs to the powder in a high affinity state, allowing subsequent washing to remove the bacterial cells, while retaining the adsorbed polymer. jg

The goal of this research has been to find dispersants for ceramic processing applications. The polyelectrolytes currently in use in the industry are synthesized from toxic precursors which present health hazards to workers. We have investigated polyelectrolytes produced from natural sources such as bacteria and kelp, as well as some polymers which have been produced synthetically. The polyelectrolytes which we have investigated include polysaccharides (alginate and dextran) and polypeptides (polyglutamic acid and polyaspartic acid). Some have been obtained from cultures of bacteria grown in our laboratories, others have been obtained from chemical supply houses. In addition, we have investigated the feasibility of using an in situ process by which we incubate the polymer-producing bacteria in the presence of ceramic powders. In this system, polymer adsorbs to the powder in a high affinity state, allowing subsequent washing to remove the bacterial cells, while retaining the adsorbed polymer. jg

The goal of this research has been to find dispersants for ceramic processing applications. The polyelectrolytes currently in use in the industry are synthesized from toxic precursors which present health hazards to workers. We have investigated polyelectrolytes produced from natural sources such as bacteria and kelp, as well as some polymers which have been produced synthetically. The polyelectrolytes which we have investigated include polysaccharides (alginate and dextran) and polypeptides (polyglutamic acid and polyaspartic acid). Some have been obtained from cultures of bacteria grown in our laboratories, others have been obtained from chemical supply houses. In addition, we have investigated the feasibility of using an in Situ process by which we incubate the polymer-producing bacteria in the presence of ceramic powders. In this system, polymer adsorbs to the powder in a high affinity state, allowing subsequest washing to remove the bacterial cells, while retaining the adsorbed polymer.

The development of high temperature containerless processing equipment and the design and evaluation of associated systems required for microgravity materials processing and property measurements are discussed. Efforts were directed towards the following task areas: design and development of a High Temperature Acoustic Levitator (HAL) for containerless processing and property measurements at high temperatures; testing of the HAL module to establish this technology for use as a positioning device for microgravity uses; construction and evaluation of a brassboard hot wall Acoustic Levitation Furnace; construction and evaluation of a noncontact temperature measurement (NCTM) system based on AGEMA thermal imaging camera; construction of a prototype Division of Amplitude Polarimetric Pyrometer for NCTM of levitated specimens; evaluation of and recommendations for techniques to control contamination in containerless materials processing chambers; and evaluation of techniques for heating specimens to high temperatures for containerless materials experimentation.

Structural biological materials are all composites. The basic structural units include elastomers, strong polymers, and reinforcing minerals. These components are mixed in various proportions and with various architectures to produce a wide range of mechanical properties. Combinations of hardness with toughness and of softness with strength can give rise to mechanical responses which seem to be superior to the equivalent synthetic materials. The superior sophistication is easily seen by a comparison between micrographs of the complex morphology of bone or shell and of the equivalent ceramics or filled polymers. It is less easy to prove a superiority of properties since the component materials of bone, collagen, and hydroxyapatite cannot be regarded as high performance materials when compared to carbon fiber and polyimide. We therefore must make comparisons on a basis which allows for the different starting properties of the component materials. Assuming that we can convince ourselves of a performance improvement which arises from the material architecture we should consider how to develop synthetic materials with equivalent microstructures.

The work reported in this document is concerned with the efficient use of computers in materials research and in applications of the results of that research. Emphasis is on the development of computational methodologies which can facilitate the innovative design of materials and of materials processing, for high performance materials and for composite materials structures. Basic advances have been made in three areas of adaptive computing: in establishing the practice of functional-link neural-net computing for learning models of material behavior, in developing a parallel processing evolutionary search paradigm for optimization and in exploring various of establishing and using associative memories. This report also describes how these ovations in conceptual and theoretical matters can be used to effect in dealing with materials processing and design tasks. Applications include in-situ - real-time interpretation of ellipsometry data, optimal formulation of material composition, control of nonlinear dynamic systems, memory-based design and the implementation of visual displays for multi-dimensional data.

Our project on adaptive structural materials began with bone as a source of inspiration for adaptive materials systems. Examining the structure of natural bone leads to the five guiding principles for our research: (i) load bearing by hierarchically porous materials; (ii) adaptive, sensing load and supplying mass to reinforce at load-bearing sites through material deposition and dissolution; (iii) transport of materials using fluid flow through low density porous cy systems; (iv) energy to drive processes taken from storage sites, which are replenished by internal or external energy generation; (v) mechanisms, which are not fully understood for bone, but knowing the fundamental mechanisms allows these to be adjusted for application to synthetic systems. The problem as defined in the third year of the program was how to change soft materials into hard structures reversibly, in response to load or other environmental stresses. The approaches we used in the third year of the program include (i) reversible jamming, layering, welding and/or percolation; (ii) dissipative materials; and (iii) granular chemistry.

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This project consists of a collaborative synthetic, processing, physical characterization, and theoretical program aimed at the rational design, construction, evaluation, and fundamental understanding of new types of maximum- performance molecule/polymer-based materials exhibiting high second-order (CHI(2)) optical nonlinearities. Areas of emphasis include poled chromophore-functionalized glassy polymers, poled chromophore-embedded crosslinkable matrices, chromophoric self-assembled superlattices, the theoretical design and analysis of novel chromophores and chromophore environments, theoretical studies of poling dynamics, studies of optical damage phenomena, and fabrication of new types of NLO waveguides. Each research component of this highly interactive effort builds upon work already in progress as well as upon strong on-going collaborations in laser optics and quantum theory. Nonlinear optical material, Polymer, Chromophore, Cross-linking, Self-assembly, Second harmonic generation.

This project consists of a collaborative synthetic, processing, physical characterization, and theoretical program aimed at the rational design, construction, evaluation, and fundamental understanding of new types of maximum- performance molecule/polymer-based materials exhibiting high second-order (CHI(2)) optical nonlinearities. Areas of emphasis include poled chromophore-functionalized glassy polymers, poled chromophore-embedded crosslinkable matrices, chromophoric self-assembled superlattices, the theoretical design and analysis of novel chromophores and chromophore environments, theoretical studies of poling dynamics, studies of optical damage phenomena, and fabrication of new types of NLO waveguides. Each research component of this highly interactive effort builds upon work already in progress as well as upon strong on-going collaborations in laser optics and quantum theory. Nonlinear optical material, Polymer, Chromophore, Cross-linking, Self-assembly, Second harmonic generation.

This thesis describes the software design and implementation of a microprocessor- based, random load drive and data acquisition system on a Material Testing System (MTS) machine. A microprocessor, combination analog input/output module, magnetic cassette tape recorder, and strain gage network form a strain data acquisition system for recording sequential strain peaks and troughs on specimens subjected to flight load histories. The data will be used to estimate the fraction of the fatigue life expended in a test specimen. A high speed digital computer is linked by telephone line to a microcomputer development system to create the randomization of fatigue loads specified in Mil Spec 8866 Spectrum A for use by the MTS machine.

This thesis describes the software design and implementation of a microprocessor- based, random load drive and data acquisition system on a Material Testing System (MTS) machine. A microprocessor, combination analog input/output module, magnetic cassette tape recorder, and strain gage network form a strain data acquisition system for recording sequential strain peaks and troughs on specimens subjected to flight load histories. The data will be used to estimate the fraction of the fatigue life expended in a test specimen. A high speed digital computer is linked by telephone line to a microcomputer development system to create the randomization of fatigue loads specified in Mil Spec 8866 Spectrum A for use by the MTS machine.

The goal of this research has been to find dispersants for ceramic processing applications. The polyelectrolytes currently in use in the industry are synthesized from toxic precursors which present health hazards to workers. We have investigated polyelectrolytes produced from natural sources such as bacteria and kelp, as well as some polymers which have been produced synthetically. The polyelectrolytes which we have investigated include polysaccharides (alginate and dextran) and polypeptides (polyglutamic acid and polyaspartic acid). Some have been obtained from cultures of bacteria grown in our laboratories, others have been obtained from chemical supply houses. In addition, we have investigated the feasibility of using an in situ process by which we incubate the polymer-producing bacteria in the presence of ceramic powders. In this system, polymer adsorbs to the powder in a high affinity state, allowing subsequest washing to remove the bacterial cells, while retaining the adsorbed polymer.

The goal of this research has been to find dispersants for ceramic processing applications. The polyelectrolytes currently in use in the industry are synthesized from toxic precursors which present health hazards to workers. We have investigated polyelectrolytes produced from natural sources such as bacteria and kelp, as well as some polymers which have been produced synthetically. The polyelectrolytes which we have investigated include polysaccharides (alginate and dextran) and polypeptides (polyglutamic acid and polyaspartic acid). Some have been obtained from cultures of bacteria grown in our laboratories, others have been obtained from chemical supply houses. In addition, we have investigated the feasibility of using an in situ process by which we incubate the polymer-producing bacteria in the presence of ceramic powders. In this system, polymer adsorbs to the powder in a high affinity state, allowing subsequest washing to remove the bacterial cells, while retaining the adsorbed polymer.

The relative values of thermal conductivity of solid and liquid HgCdTe are critically important in the design configuration of the furnaces used for Bridgman crystal growth. The thermal diffusivity of the material is closely linked to the conductivity by the defining relation D = k/rho c, where D is the diffusivity, K is the thermal conductivity, rho is the density, and c is the specific heat. The use of transient and periodic heating approaches to measure the diffusivity are explored. A system for securing and extracting heat from silica or glass tubes under high C vacuum conditions is described.

Biomimicking is now regarded as an area of research in which the analysis of natural materials will provide insights into the design of novel manmade materials, resulting in superior structures able to withstand the requirements placed upon advanced materials. It is well recognized that biological systems efficiently produce complex composites possessing unique properties with greater control than is possible with synthetic materials. Biological materials often have hierarchical structures with unprecedented properties at spatial levels on the molecular, micrometer, and macrometer seals. The dynamism of these systems allows the collection and transport of constituents; the nucleation, configuration, and growth of new structures by self-assembly; and the repair and replacement of old or damaged components. With this in mind, this workshop is intended to identify the most critical issues and to establish future directions for biomimicking in materials science and engineering. The goals of this workshop are to further educate the Air Force participants in the possibilities of biomimetric design and processing and to encourage the research participants to address the interfacing of these possibilities with aerospace needs. Natural materials cannot be used for many aerospace applications because of their chemical instability at the temperatures associated with their use.

A multi-length scale computational methodology is developed to analyze processing/microstructure and microstructure/properties/performance relationship in advanced structural materials. Such methodology is based on combining scientific and engineering disciplines of fluid mechanics, heat transfer, chemical gas/surface thermodynamics and kinetics, atomistic modeling techniques, stochastic microstructure evolution simulation methods, nonlinear fracture and singular stress analysis, and micro-mechanics analytical and computational approaches. This methodology is then applied to advanced coating and functionally graded materials processed by the chemical vapor deposition (CVD) and the Laser Engineered Net Shaping (LENS(Trademark) processes. The methodology allows the establishment of direct links between process parameters (temperature, pressure, flow rates, laser rastering velocity, etc.), the resulting materials microstructure (grain size and distribution, morphological and crystallographic texture, etc.) and properties (strength, strain-to-fracture, etc.). in response to the computational challenges of multi-length scale modeling, parallel computing is utilized and a highly-efficient inter-processor communications method is developed which substantially reduces the simulation time.

A multi-length scale computational methodology is developed to analyze processing/microstructure and microstructure/properties/performance relationship in advanced structural materials. Such methodology is based on combining scientific and engineering disciplines of fluid mechanics, heat transfer, chemical gas/surface thermodynamics and kinetics, atomistic modeling techniques, stochastic microstructure evolution simulation methods, nonlinear fracture and singular stress analysis, and micro-mechanics analytical and computational approaches. This methodology is then applied to advanced coating and functionally graded materials processed by the chemical vapor deposition (CVD) and the Laser Engineered Net Shaping (LENS(Trademark) processes. The methodology allows the establishment of direct links between process parameters (temperature, pressure, flow rates, laser rastering velocity, etc.), the resulting materials microstructure (grain size and distribution, morphological and crystallographic texture, etc.) and properties (strength, strain-to-fracture, etc.). in response to the computational challenges of multi-length scale modeling, parallel computing is utilized and a highly-efficient inter-processor communications method is developed which substantially reduces the simulation time.

The development of high temperature containerless processing equipment and the design and evaluation of associated systems required for microgravity materials processing and property measurements are discussed. Efforts were directed towards the following task areas: design and development of a High Temperature Acoustic Levitator (HAL) for containerless processing and property measurements at high temperatures; testing of the HAL module to establish this technology for use as a positioning device for microgravity uses; construction and evaluation of a brassboard hot wall Acoustic Levitation Furnace; construction and evaluation of a noncontact temperature measurement (NCTM) system based on AGEMA thermal imaging camera; construction of a prototype Division of Amplitude Polarimetric Pyrometer for NCTM of levitated specimens; evaluation of and recommendations for techniques to control contamination in containerless materials processing chambers; and evaluation of techniques for heating specimens to high temperatures for containerless materials experimentation.

The development of high temperature containerless processing equipment and the design and evaluation of associated systems required for microgravity materials processing and property measurements are discussed. Efforts were directed towards the following task areas: design and development of a High Temperature Acoustic Levitator (HAL) for containerless processing and property measurements at high temperatures; testing of the HAL module to establish this technology for use as a positioning device for microgravity uses; construction and evaluation of a brassboard hot wall Acoustic Levitation Furnace; construction and evaluation of a noncontact temperature measurement (NCTM) system based on AGEMA thermal imaging camera; construction of a prototype Division of Amplitude Polarimetric Pyrometer for NCTM of levitated specimens; evaluation of and recommendations for techniques to control contamination in containerless materials processing chambers; and evaluation of techniques for heating specimens to high temperatures for containerless materials experimentation.

This report describes the organization, format and content of the NASA Johnson damage tolerant database which was created to store damage tolerant property data for non aerospace structural materials. The database is designed to store fracture toughness data (K(sub IC), K(sub c), J(sub IC) and CTOD(sub IC)), resistance curve data (K(sub R) VS. delta a (sub eff) and JR VS. delta a (sub eff)), as well as subcritical crack growth data (a vs. N and da/dN vs. delta K). The database contains complementary material property data for both stainless and alloy steels, as well as for aluminum, nickel, and titanium alloys which were not incorporated into the Damage Tolerant Design Handbook database.