Sponsored by: Jt. SMD-MSD Composite Materials Committee
Program Organizer: P.K. Liaw, Materials Science and Engineering Department, The University of Tennessee, Knoxville, TN, 37996-2200; R. Pitchumani, Mechanical Engineering Department, University of Connecticut, Storrs, CT 06269-3139; S.G. Fishman, Office of Naval Research, 800 N. Quincy Street, Arlington, VA 22217
Monday, AM Room: Marquis 1&2
February 5, 1996 Location: Anaheim Marriott Hotel
Session Chairperson: R. Pitchumani, Mechanical Engineering Department, University of Connecticut, Storrs, CT 06269-3139; P.K. Liaw, Materials Science and Engineering, The University of Tennessee, Knoxville, TN, 37996-2200
8:30 am
PROPERTY-MICROSTRUCTURE-PROCESS RELATIONSHIPS OF TEXTILE STRUCTURAL COMPOSITES: Tsu-Wei Chou, Jerzy L. Nowinski, Professor of Mechanical Engineering and Materials Science, Center for Composite Materials and Department of Mechanical Engineering, University of Delaware, Newark, DE 19716
The term "Textile structural composites" is used to identify a class of advanced composites utilizing fiber performs produced by textile forming techniques for structural and functional applications. The recent interest in textile structural composites stems from the need for improvements in intra-and inter-laminar strength and damage tolerance. Textile composites offer the potential of providing adequate structural integrity as well as shapeability for near-net-shape manufacturing. This presentation will review recent advances in the processing/fabrication, microstructural design/analysis and performance characterization of textile composites. The relationship among processing, microstructure and property is demonstrated by (a) a multi-step braiding process for fabricating three-dimenstional preforms with controlled microstructure, (b) thermal and electrical property modeling and analysis of two-dimensional woven fabric composites, and (c) non-linear behavior and damage evolution in two- and three- dimensional brittle matrix composites. Textile composites based upon polymer and ceramic matrix materials with fiber preforms produced by weaving, braiding and knitting will be examined.
9:00 am
INVESTIGATIONS ON EDDY CURRENT EVALUATION OF METAL MATRIX COMPOSITES: Ranga Pitchumani, Mechanical Engineering Department University of Connecticut, Storrs, CT 06269-3139; Peter K. Liaw, Materials Science and Engineering Department, University of Tennessee, Knoxville, TN 37996-2200
Particulate-reinforced metal matrix composites are being considered as strong candidates for use in many engineering applications. Widespread deployment of these materials, however, requires reliable material qualification techniques. Nondestructive evaluation using ultrasonics or eddy currents provides a viable means of characterizing the composites and their properties. In this regard, considerable theoretical and experimental investigations have been carried out by the authors in recent years on the application of eddy current technqiues to evaluate metal matrix composites. Studies include development of predictive models for the anisotropic composite condustivities, for binary and multiphase composites; development of a technique for nondestructive inspection of product quality in terms of the constituent phase concentrations; and eddy current measurements on a wide array of Al/SiCp composites extrusions. A summary of the research accomplishments will be presented and discussed.
9:30 am
THERMAL AND ELECTRICAL CONDUCTIVITY OF COMPOSITES, CALCULATED USING SIMPLE UNIT CELL MODELS: K.S. Ravichandran, Department of Metallurgical Engineering 412 WBB, The University of Utah, Salt Lake City, UT 84112
Prediction of thermophysical properties including thermal and electrical conductivity of composites is of interest in the contexts of their use in high temperature structural, electrical and electronic applications. In the present research, simple microstructure-based unit cell models will be used to predict the thermal and electrical conductivities of composites having discrete second phases in continuous matrix materials. This method is based on the divisions of the unit cell into parallel and series configurations of two phases. Comparisons of predicted trends with experimental data on metal-metal, metal-ceramic and ceramic-ceramic composites will be made. The experimental thermal conductivity data of epoxy-graphite, ZrO2-Ni, ZrO2-Mo as well as electrical conductivity data of several eutectic alloys including Bi-Bi2Pb, Pb-Mg2Pb and pseudoalloys such as Cu-Pb, Cu-Fe will be used for comparison. The accuracy of the present method will also be evaluated in the light of other methods.
10:00 am
MODULI OF CONTINUOUS FIBER REINFORCED CERAMIC COMPOSITES: P.K. Liaw, N. Miriyala, Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996-2200; N. Yu, Department of Mechanical and Aerospace Enginering and Engineering Science, The University of Tennessee, Knoxville, TN 37996-2030; X. Mao, Department of Mechanical Engineering, University of Calgary, Calgary, ABT2NIN4, Canada; D.K. Hsu, Center for NDE, Iowa State University, Ames, IA 50011
The moduli of woven Nicalon fiber fabric reinforced Al2O3 matrix composites have been investigated. Both through-thickness and in-plane (fiber fabric plane) moduli were measured using ultrasonic techniques. The through-thickness moduli were found to be much less than the in-plane moduli. Increased porosity significantly decreased both in-plane and through-thickness moduli. An analytical model using a homogenization method was formulated to predict the effect of porosity on the moduli of woven fabric composites. Moreover, numerical modeling work was formulated to predict the influence of porosity on the moduli. The predicted results using both analytical and numerical techniques were found to be in good agreement with the experimental data. The present work is supported by the Oak Ridge National Laboratory, the Department of Energy under contract Nos. Martin Marietta 11X-SN191V and SL261V.
10:30 am
MODELING OF YOUNG'S MODULUS OF COMPOSITES REINFORCED WITH 3-D ORIENTED SHORT FIBERS: Y.T. Zhu, W.R. Blumenthal, M.G. Stout, T.C. Lowe, Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545
Young's modulus is one of the most important design parameters in applications of composite materials. This paper develops a theory for calculating the Young's modulus of composites reinforced with three-dimensionally (3-D) oriented short fibers. Assuming a composite strain in the loading direction, the fiber stress and its ineffective length with different orientations are first calculated as a function of [[epsilon]]. The total load carried by a composite sample is calculated by integrating the load contributions from these short fibers and the matrix. The composite stress and Young's modulus are subsequently derived. Comparisons with other models show the advantages of our new approach.
11:00 am
YOUNG'S MODULUS MEASUREMENT OF InSnOx FILM USING DYNAMIC AND STATIC METHODS: Youngman Kim, R & D Center, Korea Gas Corp. Ansan, Korea; Min-Tae Kim, KIA Motors, Seoul, Korea
ITO(InSnOx) thin film was produced on plate glass substrates by reactive
sputtering under various conditions for automobile applications. Young's
modulus of the ITO films was measured using the sonic resonance method and
strain gages. For the dynamic Young's modulus measurement (sonic resonance
method) a simple beam vibration theory was used to obtain film modulus with the
knowledge of the substrate modulus values. For the static method (strain gage
method) strain gages were attached to the specimen surfaces, parallel to the
beam axis. The specimens were then bent in a four-point bend fixture with a
dead load. The elastic moduli were determined from the strains recorded. The
perfect bonding, linear elasticity and no stress relaxation were assumed
throughout this study.
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