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high strength-to-weight ratios. In addition, they provide styling freedom to reduce aerodynamic drag forces and part consolidation advantages for vehicle system design. Consequently, they may play an increasing role in the reduction of fuel consumption in the next generation of automobiles.

Traditionally, prevention of mechanical failure has been a key automotive design goal. This is necessitated because our products are often subjected to abuse for lack of required periodic inspections and maintenance. Failures lead to product liability claims, high warranty repair costs, and dissatisfied customers. Failure prevention is difficult because of the wide variety of operating conditions and environments our product experiences, and because the product must be produced by a mass production technology at a cost our customers can afford. Considering the fact that there are over 15,000 parts in an average automobile, our components must be designed for very high reliability. Because of the nature of advanced composite materials, particularly their anisotropy and their multiple failure modes, the design and analysis procedures currently employed to minimize failure on metal structures are not adequate for composite structures. In anticipation of the need to address the automotive design possibilities of composite materials, a study has been conducted to determine what modifications are needed in the existing finite element structural analysis procedures. It has been found that a composite material analysis program, SQ5, now widely used in the aerospace industry, offers potential for automotive structural analysis.

SQ5 is based on classical laminate plate theory and can be used in two modes. The first is an input pre-processor to compute equivalent orthotropic properties from a laminate description. The second is an output post-processor to predict first ply failure and safety margins from laminate strength data. The program has been modified to employ the interactive Tsai-Wu tensor polynomial lamina strength failure criterion. Limited comparisons have been performed with theoretical solutions, based on classical laminate plate theory, and with test data for static and dynamic response of composite panels. Predicted failure loads have also been compared with measurements.

Fiberglass reinforced plastics use in transportation vehicles, R. D. Pistole, SP563, p. 134 (Oct. 1979).

Key words: fiberglass composites; fiberglass reinforced plastics.

The use of Fiberglass Reinforced Plastics (F.R.P.) in ground vehicles has steadily increased in recent years.

In 1975 one of F.R.P.'s largest penetrations into exterior passenger car panels was grille opening panels or front headers. This use was cost effective due to the consolidation of many metal parts by one F.R.P. molded panels.

Today, with the need for lighter weight automobiles to improve fuel economy, F.R.P. is again the answer with its additional advantages.

One piece truck hoods are becoming more popular as they too turn to fiberglass composites. Many new truck designs utilizing F.R.P. are appearing on our highways.

The manufacturing of F.R.P. car and truck components will be discussed in this presentation.

Designing automotive components with continuous fiber composites, H. T. Kulkarni and P. Beardmore, SP563, pp. 135-151 (Oct. 1979).

Key words: automotive component design; continuous fiber composite materials; fabrication; finite element stress analysis; front end; graphite; part integration; wheel.

The primary characteristics of continuous graphite fiber reinforced plastics as structural materials are high specific strength and modulus and exceptional fatigue strength. All these properties are a function of fiber orientation in the individual layers and the lay up sequence. The advantages of continuous fiber reinforced composites relative to the conventional chopped fiber systems currently utilized in automobiles lies in the ability to apply these composites in major load/stiffness critical components. The application of a composite materials design methodology to prototype automotive components is described. Examples of different types of components are given, specifically wheel and body structures. Both the design and the fabrication of these structures in composite materials are described and any specific problems are outlined.

Fabrication of large composite spars and blades, O. Weingart, SP563, pp. 155-172 (Oct. 1979).

Key words: composite materials; filament winding; large composite structures; rotor blades; wind turbine.

A national wind energy program has been established to develop the technology necessary to enable wind energy systems to be cost-competitive with conventional power generation systems and capable of rapid commercial expansion for producing significant quantities of electrical power. Wind Turbine Generators being developed under this program will require rotor diameters of up to 300 ft.

Because of the considerable extension in the technology required to design and construct blades of this size, it was highly desirable to establish an early technology base. To that end, the Department of Energy, through NASA-Lewis Research Center has awarded several contracts for the design, fabrication and test of large low-cost wind turbine blades built of composite materials.

This paper describes SCI's fabrication of a 20,000 lb. one piece, composite spar for a 150 ft. long developmental blade. Also discussed are a recent SCI design study of a composite blade for the 300 ft. diameter Mod-2 Wind Turbine, and a new SCI contract from DOE/NASA for design and possible fabrication of low cost composite blades for the 125 ft. diameter Mod-OA Wind Turbine.

The effect of fiber orientation on the design parameters of reinforced and filled thermoplastic compounds, P. J. Cloud and R. T. Alvord, SP563, p. 173 (Oct. 1979).

Key words: fiber reinforced; thermoplastics.

To determine the limiting design stress and modulus value which can be substituted into Hookeian stress-strain equations to enable the engineer to safely design with discontinuous fiber reinforced injection moldable thermoplastics.

Quality assurance of manufactured components, R. D. Margolis, SP563, p. 174 (Oct. 1979).

Key words: adhesive bond integrity; control testing; sonic testing device.

This paper describes progress to date on a joint effort of Rockwell Plastics and Ford Motor Company to apply nondestructive testing techniques in the quality control testing of adhesive bonded plastic truck hood assemblies. The program involves selection of a suitable sonic testing device to measure adhesive bond integrity along with laboratory trials to establish procedures and measure the instrument's flaw detection capabilities. In addition, several plant trials are underway to test the instrument's viability in an industrial environment and provide a data base for establishing quality control specifications.

Degradation data of Kevlar pressure vessels, W. D. Humphrey, SP563, pp. 177-197 (Oct. 1979).

Key words: degradation; epoxy resins; Kevlar 49; moisture; one-tenth scale motor case; S-glass; temperature effects; water boil.

Recent hydroburst tests of Kevlar/epoxy composite pressure vessels showed losses in strength when subjected to extended periods of high temperature and high humidity. These pressure vessels had served to monitor the aging characteristics of Rocket Motor Cases during Engineering Development tests. Since Kevlar was a relatively new material replacing fiberglass in this application, it was considered important that these results be verified in a controlled experiment utilizing accelerated aging methods.

To measure these effects, two series of tenth-scale models of Rocket Motor Cases were fabricated, which included two different resin systems and two very different design concepts. The accelerated degradation of Kevlar composites from high temperature and humidity was evaluated by means of water boil tests for periods of up to ten days.

Hydroburst tests of these aged vessels showed Kevlar to have much less degradation than fiberglass. Actual values were determined to be dependent on the resin system used and also dependent upon the dryness of the composite at the time of test. Wet composites acted as if a plasticizer was added to the resin system and in the configuration tested actually regains virgin strength.

Design assurance of a leak failure mode for composite overwrapped metal tankage, W. W. Schmidt, SP563, pp. 198-207 (Oct. 1979).

Key words: composite materials; critical flaw size; cyclic fatigue life; filament wound tankage; leakage failure mode; linear elastic fracture mechanics; metal liner.

Assuring a leakage failure mode requires that the outer composite shell be designed such that its minimum cyclic fatigue life is approximately an order of magnitude greater than that of the metal liner. This requires making an accurate fatigue life prediction for both the composite shell and metal liner. It is further possible to determine the critical flaw size for unstable crack growth within the metal liner by application of fracture mechanics principles. A semiempirical formula has been developed for this purpose since the stresses induced in the metal liner upon initial pressurization exceed the yield strength of the liner material in all cases, which violates a basic assumption of linear elastic fracture mechanics. It is often found that the critical flaw depth is greater than the thickness dimension of the metal liner. In these instances, leakage will occur prior to unstable crack growth. For designs in which unstable crack growth can occur, a dynamic analysis has been developed. This analysis provides a means of assessing the magnitude of shock induced stresses in the composite shell due to the sudden loss of the liner's load carrying capability. Details of these design procedures are provided.

Composite materials in recreational equipment, D. Ratchford, SP563, p. 208 (Oct. 1979).

Key words: composites; durability; flexural characteristics; recreational equipment; strength-to-weight ratio.

The general requirements of materials for recreational equipment are discussed, these being high strength-toweight ratio, fatigue resistance, the ability to store and release energy, durability, aesthetic acceptability, and manufacturing capability.

It is developed, by engineering analysis, that composites of glass fibers, graphite fibers, or their combination, bonded into a resinous matrix of thermo-setting polyester or epoxy are uniquely suited to these purposes. These composites have extremely high strength-to-weight ratio, excellent durability and excellent fatigue characteristics, all unaltered through wide environmental extremes. Additional advantages are that the flexural characteristics of the material can be designed, through stress-directed fibers, to suit the purpose; and that glass fibers are nonyielding, i.e., yield and ultimate strength are the same, meaning that lower safety factors can be used. Such composites are ideally suited for handling, for the storage and release of energy and for the durability required of rough treatment.

An important and large scale application is limbs for bows used in archery. Design parameters would be light weight, high strength, fatigue resistance and quick energy release.

The limbs may be solid FRP composites, or FRP composites in the form of "backing" which is laminated to wood cores. In either case the limb is formed to a taper in order to minimize weight and to reduce inertia and present a low profile to wind resistance upon release. Load requirements are almost purely flexural, therefore fiber orientation is 100% parallel to the longitudinal axis of the limb. Glass or graphite fiber content is usually in the order of 70%. The limb has a flexural strength of approximately 150,000 psi, and a flexural modulus of 5.5 × 10 psi. High heat-distortion resins are used so that the bow can be stored in automobile trunks where temperatures can go above 150 °F. An aesthetically attractive, abrasive-resistant finish is usually applied to the limb.

Additional applications in archery are bows molded entirely in one piece, and arrow shafts.

Holographic nondestructive evaluation of spherical kevlar/epoxy pressure vessels, D. M. Boyd and B. W. Maxfield, SP563, pp. 211-212 (Oct. 1979).

Key words: composites; holography; interferometers; matrix crazing; nondestructive testing; pressure vessels.

Three spherical kevlar/epoxy pressure vessels were evaluated using holographic interferometry. The holographic interferograms provide information on the failure modes, displacement profile, and possible fiber damage. The holograms show a symmetric anisotropic displacement pattern even though the vessels failed due to a leak in the aluminum mandrels. The presence of a biconvex fringe pattern found during the testing of vessel three is believed to indicate matrix crazing. This information would be useful for burst-type failure analysis. Holographic interferometry has been shown to supply information on the characteristics of kevlar/epoxy pressure vessels under stress.

The Air Force “Manufacturing Cost/Design Guide (MC/DG)", B. R. Noton and D. L. Shunk, SP563, pp. 226227 (Oct. 1979).

Key words: airframe structure; cost-trade comparisons; manufacturing technologies; structural performance/cost trade-offs.

The purpose of the MC/DG is to enable designers at all levels to conduct, firstly, urgently needed, quick, simple, cost-trade comparisons of manufacturing processes, and, secondly, structural performance/cost trade-offs on both components and subassemblies. The MC/DG will consist of two volumes—“Airframe Structure” and “Manufacturing Technologies." The MC/DG is being developed for the Air Force by a team consisting of Battelle's Columbus Labora

tories (BCL) and the following aerospace companies: General Dynamics Corporation, Fort Worth Division; Grumman Aerospace Corporation; Lockheed-California Company; Northrop Corporation, Aircraft Group; Rockwell International Corporation, Los Angeles Division.

Tensile strength and failure modes of boron-epoxy composite with a notch, C. E. S. Ueng, SP563, pp. 228-238 (Oct. 1979).

Key words: boron-epoxy; edge cracks; failure modes; finite element method; tensile strength.

The purpose of this paper is to study the tensile strength and failure modes of boron-epoxy composites with an edged notch. Through the use of finite element crack program, both heterogeneity and orthotropy of material properties are brought into consideration in this paper. For comparison purposes, tension tests of actual composite samples with notches are also performed. Notch insensitivity and the failure modes are discussed. The fracture toughness of the test material is also determined. The results obtained here are important for further understanding of the failure of unidirectional boron-epoxy advanced composites.

Failure criteria for composites under complex loading, P. W. Mast, L. A. Beaubien, D. R. Mulville, S. A. Sutton, R. W. Thomas, J. Tirosh, and I. Wolock, SP563, p. 241 (Oct. 1979).

Key words: bonded joints; composites; failure criteria; inplane loads.

Studies are in progress to develop failure criteria for composites and bonded joints under a broad range of inplane loads. Criteria for predicting the conditions under which a defect will grow in composites structural components, in such applications as Naval high performance craft, will be demonstrated. Validity of a new technique for determining failure criteria for composites has been verified in laboratory tests.

Failure analysis of an idealized composite damage zone, C. T. Herakovich and D. A. O'Brien, SP563, pp. 242-254 (Oct. 1979).

Key words: compression; failure; finite elements; graphiteepoxy; interlaminar stresses; laminated composites; stress concentrations; tension; tensor polynomial.

First failure of finite width laminates with an idealized composite damage zone is analyzed through the use of a linear elastic finite element stress analysis and the tensor polynomial failure criterion. Crossply and angleply (±45], laminates are analyzed under tension and compression loading. It is shown that a boundary layer exists near the damage zone which is very similar to the boundary layer which has been shown previously to exist along free edges. Comparisons are made between predicted initial failure of damaged and undamaged laminates. Transverse tension is the dominate mode of failure for tensile loading, but compressive loading leads to a variety of failure modes depending upon the laminate configuration.

Interlaminar failure in epoxy based composite laminates, A. S. Wang, F. W. Crossman, and G. E. Law, Jr., SP563, pp. 255-264 (Oct. 1979).

Key words: delamination mechanisms; energy release rate; finite element method; free-edge stresses; graphite epoxy composites; interlaminar cracks; stability of cracks; virtual crack closure.

One of the common failure modes in fibrous composite laminates involves interlaminar cracks which cause delamination. Several questions arise in the course of a delamination analysis. Notably these include (a) how is a delamination initiated? (b) under what condition will a delamination grow? and (c) what determines the stability of a delamination growth? Owing to the unusual complexity of composite laminate systems, there appears no simple way to answer these questions satisfactorily.

In this paper, a method is developed based on the energy principle of the classical linear fracture mechanics, in order to describe the various aspects of the delamination mechanisms. Specifically, free-edge induced delamination failure in some epoxy based composite laminates are investigated employing this method. And, the results obtained are compared with experiments. It will be shown that the energy method predicts well free-edge delamination in laminates under uniaxial tension, including the initiation, the growth and the growth stability of the delamination.

Current developments in advanced composites for naval ship application, J. J. Kelly and H. H. Vanderveldt, SP563, pp. 267-275 (Oct. 1979).

Key words: composites; hydrofoils; maintenance requirements; naval ship application.

The reasons for and the limitations on the use of composites for ship applications are described. The current exploratory development program in advanced composites for Navy ship applications emphasizes high performance craft such as hydrofoils. The future program will complete these efforts and stress broader applications for composites. Development of fire resistant composites, survivable structural concepts and materials which reduce maintenance requirements will be emphasized.

Environmental effects on fiber reinforced organic matrix composites, M. Silvergleit, A. B. Macander, F. A. Brauer, and H. P. Edelstein, SP563, pp. 276-285 (Oct. 1979).

Key words: advanced composites; cavitation erosion; extended immersion; flammability; glass reinforced plastics; graphite epoxy; impact; marine environment.

A review is presented on the effects of the marine environment on fiber reinforced organic matrix composites. In addition to the effects of extended immersion in seawater on composite properties, the limiting utility of composites due to cavitation erosion, flammability and smoke spread evolution and damage due to impact are discussed. In general, high quality, low void content glass reinforced plastics (GRP) and graphite epoxy composites retain over 90% of their initial strength after three years immersion in seawater. Organic matrix composites, which are subjected to high speed fluid flow are degraded by erosion due to the collapse of the cavitation cloud, however, erosion resistance can be improved by using elastomeric or thin metallic overlays. With the exception of polyimides, organic matrix composites have poor resistance to flammability and emit large quantities of dense smoke. Impact resistance of composites is a function of fiber/resin properties and composite orientation. Incorporation of high toughness flexible matrices and/or high strength, low modulus fibers will increase composite impact resistance.

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Composite technology for marine application, W. P. Couch, SP563, pp. 286-298 (Oct. 1979).

Key words: advanced composites; advanced ships; elastic properties; fatigue tests; nondestructive tests; structural analysis; ultimate strength.

Under the sponsorship of the Naval Sea Systems Command (NAVSEA 035), the David W. Taylor Naval Ship Research and Development Center (DTNSRDC) has been conducting a program to assess the current technology status of advanced composites, and to determine the feasibility of application to marine structures. The approach being utilized to achieve this objective involves a coordinated structures/materials community effort seeking input from private industry and other government agencies. As a result of feasibility studies performed by the McDonnell Douglas Astronautics Company and the Grumman Aerospace Corporation and a review of high payoff areas for structural application of advanced composites by the Naval Ship Composites Community, the hydro-foil strut/foil system was selected as the primary structural element to evaluate the use of advanced composites for advanced naval ship structures. Two subcomponents were selected for this evaluation; a foil test component (tapered box beam), and a hydrofoil control flap. Concurrently, analytical methods incorporating composite mechanics developed by the aerospace composites program are reviewed, modified and utilized when applicable to determine the structural behavior for marine, load-carrying components. In addition, preliminary design studies are conducted on other naval ship structures to determine the feasibility of composite construction. The following text describes the current effort under investigation related to the four program subtasks: box beam validation, foil flap validation, analytical methods and design application studies.

SP565. A history of walkway slip-resistance research at the National Bureau of Standards, S. C. Adler and B. C. Pierman, Nat. Bur. Stand. (U.S.), Spec. Publ. 565, 36 pages (Dec. 1979) SN003-003-02142-3.

Key words: friction; measurement; reference standards; safety research; walkway slip-resistance.

This report summarizes NBS research in the area of walkway and shoe slip-resistance measurement since 1924 and outlines current activities that will provide a technical basis for slip-resistance measurement. The work of Sigler, Hunter, Boone and Brungraber represents the historic perspective. Current activities in data base development and identification of standard reference surfaces contribute to a rational basis for quantitative slip-resistance criteria for building codes and standards. Proposed future research thrusts include personal factors such as human biokinetic and perceptual variables, as well as environmental factors such as lighting in the built environment. This research will contribute to the development of new intervention strategies to reduce deaths and injuries due to slips and falls.

5.7. APPLIED MATHEMATICS SERIES

Mathematical tables, manuals, and studies of special interest to physicists, engineers, chemists, biologists, mathematicians, computer programmers, and others engaged in scientific and technical work.

No publications issued in this series during this period.

5.8. NATIONAL STANDARD REFERENCE DATA SERIES

Provides quantitative data on the physical and chemical properties of materials, compiled from the world's literature and critically evaluated. Developed under a worldwide program coordinated by NBS. Program under the authority of National Standard Data Act (Public Law 90-396).

NSRDS-NBS3, Section 8. Selected tables of atomic spectra. A: Atomic energy levels-Second edition. B: Multiplet tables. O vi, O VII, O VIII, C. E. Moore, Nat. Stand. Ref. Data Ser., Nat. Bur. Stand. (U.S.), 3, Sec. 8, 31 pages (Jan. 1979) SN003-003-01964-0.

Key words: atomic energy levels, O vi-O vi; atomic spectra, O VI-O VIII; multiplet tables, O VI-O VIII; oxygen, spectra, O VI-O VIII; spectra, O VI-O VIII; wavelengths, O vi-O

VIII.

The present publication is the eighth Section of a series being prepared in response to the need for a current revision of two sets of the author's tables containing data on atomic spectra as derived from analyses of optical spectra. As in the previous Sections, Part A contains the atomic energy levels and Part B the multiplet tables. Section 8 includes these data for O vi, O VII, and O VIII, thereby completing the spectra of oxygen. The form of presentation is described in detail in the text to Section 1.

NSRDS-NBS61, Part II. Physical properties data compilations relevant to energy storage. II. Molten salts: Data on single and multi-component salt systems, G. J. Janz, C. B. Allen, N. P. Bansal, R. M. Murphy, and R. P. T. Tomkins, Nat. Stand. Ref. Data Ser., Nat. Bur. Stand. (U.S.), 61, Part II, 442 pages (Apr. 1979) SN003-003-02051-6.

Key words: corrosion; data compilation; electrochemical energy storage materials; molten salts; physical properties; safety and hazards; thermal energy storage materials; thermal properties; thermodynamic properties; transport properties.

The present work provides selected data with value judgements for a set of 49 salt systems of interest as candidate materials for thermal energy storage sub-systems and for electrochemical energy storage systems. The physical properties assessed are: melting points; phase diagrams; eutectic compositions; density; surface tension; viscosity; electrical conductivity; diffusion constants for ions; heat of fusion; heat capacity; volume change on fusion; vapor pressure; thermal conductivity (liquid and solid); and cryoscopic constant. The status of corrosion studies in the form of annotated bibliographic summaries, and salient observations on safety and hazards are also reported. A summarizing series of tables is provided as index to the data-gaps status for this set of candidate materials.

NSRDS-NBS61, Part III. Physical properties data compilations relevant to energy storage. III. Engineering properties of single and polycrystalline sodium beta and beta"-alumina, G. R Miller and D. G. Paquette, Nat. Bur. Stand. Ref. Data Ser, Nat. Bur. Stand. (U.S.), 61, Part III, 19 pages (June 1979) SN003-003-02079-6.

Key words: battery application; engineering properties data; evaluated data; polycrystalline; single crystal, sodium beta alumina; sodium beta double prime alumina.

A review of the properties of the two dimensional superionic conductors of the sodium beta alumina family is presented, with emphasis on the variability of properties with composition and processing. Processing methods, including methods of distributing additives, may strongly influence engineering properties of these substances through changes in microstructures. Described are common methods of measurement of properties with generally accepted ranges of property values. The need to compromise in the design of devices requiring several coincident optimal properties is, at this time, a necessary ingredient in the use of these materials as device components.

NSRDS-NBS64. Rate coefficients for ion-molecule reactions. Organic ions other than those containing only C and H, L. W. Sieck, Nat. Stand. Ref. Data Ser., Nat. Bur. Stand. (U.S.), 64, 27 pages (Feb. 1979) SN003-003-02027-3.

Key words: chemical kinetics; data evaluation; gas phase ion-molecule reactions; mass spectrometry; organic molecules; rate coefficients.

A compilation is presented of all experimentally determined bimolecular and termolecular rate coefficients for the reactions of organic ions (other than those containing only C and H) with neutral molecules in the vapor phase. The literature covered is from 1960 to the present, and both positive and negative ions are considered. Five hundred and seventy-seven separate reaction-partners are tabulated, and experimental conditions are specified wherever possible. Preferred values are suggested for a number of these processes.

NSRDS-NBS65. Rate constants for reactions of inorganic radicals in aqueous solution, A. B. Ross and P. Neta, Nat. Stand. Ref. Data. Ser., Nat. Bur. Stand. (U.S.), 65, 62 pages (June 1979) SN003-003-02072-9.

Key words: aqueous solution; carbonate radical; chemical kinetics; halogen radical anions; nitrate radical; oxyanion radicals; phosphate radical; photolysis; radiolysis; rates; selenium radicals; sulfate radical; thiocyanate radical anion.

Rate constants have been compiled for reactions of various transient inorganic radicals produced by radiolysis or photolysis in aqueous solution. Data are included for the carbonate radical, sulfate radical, phosphate radical, nitrate radical and other nitrogen-, sulfur- and selenium-containing radicals, and the halide and pseudohalide radicals Cl1⁄2 ̄, Br1⁄2 ̄, I1⁄2 ̄, and (SCN), ̄. The radicals react with other inorganic ions, as well as aliphatic, aromatic and heterocyclic compounds.

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