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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

Micromechanics Based Design/Analysis Codes for Advanced Composites

Advanced high temperature Ceramic Matrix Composites (CMC) hold an enormous potential for use in aero and space related applications specifically for propulsion system components. Consequently, this has led to a multitude of research activities pertaining to fabrication, testing and modeling of these materials. The efforts directed at the development of ceramic matrix composites have focused primarily on improving the properties of the constituents as individual phases. It has, however, become increasingly clear that for CMC to be successfully employed in high temperature applications, research and development efforts should also focus on optimizing the synergistic performance of the constituent phases within the as-produced microstructure of the complex shaped CMC part. Despite their attractive features, the introduction of these materials in a wide spectrum of applications has been excruciatingly slow. The reasons are the high costs associated with the manufacturing and a complete experimental testing and characterization of these materials. Often designers/analysts do not have a consistent set of necessary properties and design allowables to be able to confidently design and analyze structural components made from these composites. Furthermore, the anisotropy of these materials accentuates the burden both on the test engineers and the designers by requiring a vastly increased amount of data/characterization compared to conventional materials.

Mital, Subodh K.↗
NASA NTRS1985

Mechanical Fasteners for Advanced Composite Materials

Advanced composite materials, which are increasingly being used to build aircraft, have different properties than the metals they replace. Fasteners intended for composite-material joints must be designed and selected to allow for these differences. For example, blind fasteners (one-sided access) used to assemble composite-to-composite joints have been redesigned to expand to larger diameters to resist pull-through and cocking failures. The fastener designs needed for composite materials are reviewed. Topics discussed are: galvanic corrosion, pull-through resistance, fastener rotation, installation damage, fastener galling and conductivity. A blind fastener recently developed by SPS Technologies is described to show how these requirements are incorporated.

Landt, R. C.↗
NASA NTRS1991

Experiment M0003-10: Advanced composites

The Advanced composites Sub-experiment includes numerous metal matrix composites, primarily graphite fiber reinforced aluminum and magnesium, and several classes of graphite fiber reinforced organic matrix (epoxy, polysulfone, polyimide) composites with and/or without thermal control or protective coatings. The experiment included over 500 flight samples, mounted on the leading and trailing edges of LDEF, and a full complement of the laboratory control samples. Preliminary results are presented reviewing changes in the visual appearance of the samples, atomic oxygen erosion of the organic matrix composites, contamination effects, and the effects of micrometeorite impacts and thermal fatigue on the metal matrix composites.

Steckel, Gary L.↗
NASA NTRS1992

Probabilistic design of advanced composite structure

Advanced composite technology offers potentials for sizable improvements in many areas: weight savings, maintainability, durability, and reliability. However, there are a number of inhibitors to these improvements. One of the biggest inhibitors is the imposition of traditional metallic approaches to design of composite structure. This is especially detrimental in composites because new materials technology demands new design approaches. Of particular importance are the decisions made regarding structural criteria. Significant changes cannot be implemented without careful consideration and exploration. This new approach is to implement changes on a controlled, verifiable basis. Probabilistic design is the methodology and the process to accomplish this. Its foundation is to base design criteria and objectives on reliability targets instead of arbitrary factors carried over from metallic structural history. The background is discussed of probabilistic design and the results are presented of a side-by-side comparison to generic aircraft structure designed the 'old' way and the 'new'. Activities are also defined that need to be undertaken to evolve available approaches to probabilistic design followed by summary and recommendations.

Gray, P. M.↗
NASA NTRS2017

Verification and Validation Process for Progressive Damage and Failure Analysis Methods in the NASA Advanced Composites Consortium

The Advanced Composites Consortium is a US Government/Industry partnership supporting technologies to enable timeline and cost reduction in the development of certified composite aerospace structures. A key component of the consortium's approach is the development and validation of improved progressive damage and failure analysis methods for composite structures. These methods will enable increased use of simulations in design trade studies and detailed design development, and thereby enable more targeted physical test programs to validate designs. To accomplish this goal with confidence, a rigorous verification and validation process was developed. The process was used to evaluate analysis methods and associated implementation requirements to ensure calculation accuracy and to gage predictability for composite failure modes of interest. This paper introduces the verification and validation process developed by the consortium during the Phase I effort of the Advanced Composites Project. Specific structural failure modes of interest are first identified, and a subset of standard composite test articles are proposed to interrogate a progressive damage analysis method's ability to predict each failure mode of interest. Test articles are designed to capture the underlying composite material constitutive response as well as the interaction of failure modes representing typical failure patterns observed in aerospace structures.

Wanthal, Steven↗
NASA NTRS1974

Analysis and design of advanced composite bounded joints

Advances in the analysis of adhesive-bonded joints are presented with particular emphasis on advanced composite structures. The joints analyzed are of double-lap, single-lap, scarf, stepped-lap and tapered-lap configurations. Tensile, compressive, and in-plane shear loads are covered. In addition to the usual geometric variables, the theory accounts for the strength increases attributable to adhesive plasticity (in terms of the elastic-plastic adhesive model) and the joint strength reductions imposed by imbalances between the adherends. The solutions are largely closed-form analytical results, employing iterative solutions on a digital computer for the more complicated joint configurations. In assessing the joint efficiency, three potential failure modes are considered. These are adherend failure outside the joint, adhesive failure in shear, and adherend interlaminar tension failure (or adhesive failure in peel). Each mode is governed by a distinct mathematical analysis and each prevails throughout different ranges of geometric sizes and proportions.

Hart-Smith, L. J.↗
NASA NTRS1989

The Advanced Composition Explorer

The Advanced Composition Explorer (ACE) was recently selected as one of two new Explorer-class missions to be developed for launch during the mid-1990's. ACE will observe particles of solar, interplanetary, interstellar, and galactic origins, spanning the energy range from that of the solar wind (approx. 1 keV/nucleon) to galactic cosmic ray energies (several hundred MeV/nucleon). Definitive studies will be made of the abundance of nearly all isotopes from H to Zn (1 less than or = Z less than or = 30), with exploratory isotope studies extending to Zr (Z = 40). To accomplish this, the ACE payload includes six high-resolution spectrometers, each designed to provide the optimum charge, mass, or charge-state resolution in its particular energy range, and each having a geometry factor optimized for the expected flux levels, so as to provide a collecting power a factor of 10 to 1000 times greater than previous or planned experiments. The payload also includes several instruments of standard design that will monitor solar wind and magnetic field conditions and energetic H, He, and electron fluxes. The scientific objectives, instrumentation, spacecraft, and mission approach that were defined for ACE during the Phase-A study period are summarized.

Stone, E. C.↗
NASA NTRS1992

M0003-10: LDEF advanced composites experiment

The Advanced Composites Experiment includes nearly 500 samples of metal matrix, organic matrix, and glass matrix composites that were flown on the leading and trailing edges of the Long Duration Exposure Facility (LDEF). The experiment is a cooperative effort with participation by several aerospace companies. This paper is a review of the preliminary observations and test results. Estimated recession rates from atomic oxygen exposure for organic matrix composites are reported. Preliminary scanning electron microscopy observations for organic and metal matrix composites and microstructural analyses for metal matrix composites are presented.

Steckel, Gary L.↗
NASA NTRS1990

The Advanced Composition Explorer

The Advanced Composition Explorer (ACE) was recently selected as one of two new Explorer-class missions to be developed for launch during the mid-1990s. ACE will observe particles of solar, interplanetary, interstellar, and Galactic origins, spanning the energy range from that of the solar wind to Galactic cosmic ray energies. Definitive studies will be made of the abundance of nearly all isotopes from H to Zn, with exploratory isotope studies extending to Zr. The scientific objectives, instrumentation, spacecraft, and mission approach that were defined for ACE during the Phase-A study period are summarized.

Stone, E. C.↗
NASA NTRS1996

Integrated Airframe Technology: The Future of Advanced Composites

The challenge for advanced composites in integrated airframe technology is that: airframes must provide ever increasing performance at an affordable cost; reduce costs as compared to current airframe technology; and integration of design and manufacturing. The trend in technology is that a gap exists between the potential of advanced composites and our ability to effectively utilize them (cost/weight).

Taggart, David F.↗
NASA NTRS1991

High resolution computed tomography of advanced composite and ceramic materials

Advanced composite and ceramic materials are being developed for use in many new defense and commercial applications. In order to achieve the desired mechanical properties of these materials, the structural elements must be carefully analyzed and engineered. A study was conducted to evaluate the use of high resolution computed tomography (CT) as a macrostructural analysis tool for advanced composite and ceramic materials. Several samples were scanned using a laboratory high resolution CT scanner. Samples were also destructively analyzed at the locations of the scans and the nondestructive and destructive results were compared. The study provides useful information outlining the strengths and limitations of this technique and the prospects for further research in this area.

Yancey, R. N.↗
NASA NTRS1978

Development of advanced composite structures

Composite structure programs: the L-1011 Advanced Composite Vertical Fin (ACVF), the L-1011 Advanced Composite Aileron, and a wing study program were reviewed. These programs were structured to provide the technology and confidence for the use of advanced composite materials for primary and secondary structures of future transport aircraft. The current status of the programs is discussed. The results of coupon tests for both material systems are presented as well as the ACVF environmental (moisture and temperature) requirements. The effect of moisture and temperature on the mechanical properties of advanced composite materials is shown. The requirements set forth in the FAA Certification Guidelines for Civil Composite Aircraft Structures are discussed as they relate to the ACVF.

Stauffer, W. A.↗
NASA NTRS2020

NASA Advanced Composites Project

The recently-completed NASA Advanced Composites Project (ACP) successfully developed several new technologies aimed at reducing the timeline to design and certify composite aircraft structures. Advancements in the areas of manufacturing simulation, nondestructive inspection and advanced structural design and analysis methodologies were completed in late 2019 under the Advanced Composites Consortium (ACC) public/private partnership as well as NRA-funded university contracts. In the area of Structures, the ACC made significant improvements in rapid design tools for preliminary sizing of structure, along with developing detailed static and fatigue strength prediction methods and methods for modeling high energy impact events in composite structures. These new methodologies and toolsets were validated against a range of representative test data using a comprehensive verification and validation approach which has been published and is now used extensively on other programs. Specific new tool improvements supported by ACC include NASA’s CompDam code and Floating Node Method code. CompDam is now available from NASA as open source code. The team alsoworked on improved impact modeling using LS-Dyna™ and improved delamination modeling using Abaqus™. Rapid design tool improvements are available through Hypersizer. The ACC team released well over 50 publications documenting these method improvements, and the ACP recently received the prestigious NASA Group Achievement Award for their work.Typical Hat Stiffened Panel Test Article Used for Method Validation

ACC↗
NASA NTRS1988

Advanced composite airframe program: Today's technology

The Advanced Composite Airframe Program (ACAP) was undertaken to demonstrate the advantages of the application of advanced composite materials and structural design concepts to the airframe structure on helicopters designed to stringent military requirements. The primary goals of the program were the reduction of airframe production costs and airframe weight by 17 and 22 percent respectively. The ACAP effort consisted of a preliminary design phase, detail design, and design support testing, full-scale fabrication, laboratory testing, and a ground/flight test demonstration. Since the completion of the flight test demonstration programs follow-on efforts were initiated to more fully evaluate a variety of military characteristics of the composite airframe structures developed under the original ACAP advanced development contracts. An overview of the ACAP program is provided and some of the design features, design support testing, manufacturing approaches, and the results of the flight test evaluation, as well as, an overview of Militarization Test and Evaluation efforts are described.

Good, Danny E.↗
NASA NTRS1974

Advanced composite structures

A monograph is presented which establishes structural design criteria and recommends practices to ensure the design of sound composite structures, including composite-reinforced metal structures. (It does not discuss design criteria for fiber-glass composites and such advanced composite materials as beryllium wire or sapphire whiskers in a matrix material.) Although the criteria were developed for aircraft applications, they are general enough to be applicable to space vehicles and missiles as well. The monograph covers four broad areas: (1) materials, (2) design, (3) fracture control, and (4) design verification. The materials portion deals with such subjects as material system design, material design levels, and material characterization. The design portion includes panel, shell, and joint design, applied loads, internal loads, design factors, reliability, and maintainability. Fracture control includes such items as stress concentrations, service-life philosophy, and the management plan for control of fracture-related aspects of structural design using composite materials. Design verification discusses ways to prove flightworthiness.

Source record↗
NASA NTRS1991

Advanced composite structural concepts and material technologies for primary aircraft structures

Structural weight savings using advanced composites have been demonstrated for many years. Most military aircraft today use these materials extensively and Europe has taken the lead in their use in commercial aircraft primary structures. A major inhibiter to the use of advanced composites in the United States is cost. Material costs are high and will remain high relative to aluminum. The key therefore lies in the significant reduction in fabrication and assembly costs. The largest cost in most structures today is assembly. As part of the NASA Advanced Composite Technology Program, Lockheed Aeronautical Systems Company has a contract to explore and develop advanced structural and manufacturing concepts using advanced composites for transport aircraft. Wing and fuselage concepts and related trade studies are discussed. These concepts are intended to lower cost and weight through the use of innovative material forms, processes, structural configurations and minimization of parts. The approach to the trade studies and the downselect to the primary wing and fuselage concepts is detailed. The expectations for the development of these concepts is reviewed.

Jackson, Anthony↗