Author: K. G. Kibler Publisher: ISBN: Category : Languages : en Pages : 152
Book Description
Experimental and analytical investigations have been conducted to determine the individual and combined effects of temperature and absorbed moisture on the time-dependent mechanical response of unidirectional and cross- plied graphite-epoxy composite. Tensile creep response was measured at room temperature and four elevated temperatures (up to the glass transition region of the materials) for dry specimens and for specimens moisture-saturated at 75% and 95% relative humidity. Results were obtained for two material systems: Narmco T300-5208 and Hercules AS/3502. The stress levels used were demonstrated to be within the range of linear viscoelastic response. Superposition techniques were used to determine compliance master curves from the results for individual temperature and moisture condition, and quasi-elastic conversion was employed to extract relaxation modules behavior. Expansional strains due to temperature and moisture were measured. From measured principal properties, laminate response was predicted using time-stepped elastic analyses for the environments considered. Analytical procedures for transient and nonuniform temperature and moisture conditions were formulated. An analytical method for minimizing residual stresses during cure was developed, and sample results for the present materials are presented. Observations and recommended resulting from these investigations are included in this final report.
Author: P.K. Mallick Publisher: CRC Press ISBN: 9780824793043 Category : Technology & Engineering Languages : en Pages : 1270
Book Description
Offers information on the fundamental principles, processes, methods and procedures related to fibre-reinforced composites. The book presents a comparative view, and provides design properties of polymeric, metal, ceramic and cement matrix composites. It also gives current test methods, joining techniques and design methodologies.
Author: Christopher C. Pauly Publisher: ISBN: Category : Nature Languages : en Pages : 64
Book Description
The increasing acceptance and incorporation of fiber-reinforced polymer matrix composites (PMCs) as engineering construction materials have led many to look to the infrastructure as an application for these versatile materials. One such system is pultruded graphite fiber-reinforced epoxy (graphite/epoxy). Some PMC systems degrade when subjected to environmental conditions (e.g., moisture, stress, UV light, electrochemical polarization). These variables are typically studied either singularly or in series, but in real applications (e.g., aerospace, marine, infrastructure), these materials are subjected to many of these conditions simultaneously. To simulate field conditions, this study investigated the combined effects of an aqueous environment, electrochemical polarization, and applied bending stress on the durability of a pultruded graphite/epoxy composite. The findings indicate that graphite/epoxy composites cannot be assumed to be insensitive to degradation by environmental variables. Further, electrochemical polarization, as might occur with contact with a metal such as a fastener, can accelerate degradation. This damage requires the presence of moisture. Chloride and sulfate concentrations in rain are sufficient to establish an electrolyte within creviced regions, but deicing salts would overtake these as a contributor to conductivity. Further findings may be summarized as follows: 1.) Application of polarization in an aerated 0.6M NaCl environment led to breakdown of the fiber/matrix interface. The high pH environment created during the oxygen reduction reaction was necessary but not sufficient to create this breakdown, as the unpolarized specimen exposed to a pH 13 environment did not degrade. Cathodic polarization as would occur by coupling to steel or aluminum is required. 2.)Application of cathodic polarization did not significantly alter strength. Average measurements of shear strength, however, did decrease with the application of cathodic polarization for 70 and 90 days.
Author: Y. Jack Weitsman Publisher: Springer Science & Business Media ISBN: 1461410592 Category : Technology & Engineering Languages : en Pages : 189
Book Description
Fluid Effects in Polymers and Polymeric Composites, written by the late Dr. Y. Jack Weitsman, addresses the wide range of parameters that affect the interaction of fluids with polymers and polymeric composites. The book aims at broadening the scope of available data, mostly limited up to this time to weight-gain recordings of fluid ingress into polymers and composites, to the practical circumstances of fluctuating exposure. Various forms of experimental data are given, in conjunction with theoretical models derived from basic scientific principles, and correlated with severity of exposure conditions and interpreted by means of rationally based theoretical models. The practical implications of the effects of fluids are discussed. The issue of fluid effects on polymers and polymeric composites is of concern to engineers and scientists active in aerospace and naval structures, as an increasing portion of these structures are made of polymeric composites and employ polymeric adhesives as a joining device. While the book is intended for this audience, it will also interest researchers and graduate students interested in the mechanics and materials aspects of this matter.
Author: K. G. Kibler
Author: Sang Chel Kim
Author: Yew Thye Yeow
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Author: Konstantinos Peimandis
Author: P.K. Mallick
Author: L. W. Rehfield
Author: Christopher C. Pauly
Author: Y. Jack Weitsman