Download or read book Isothermal Aging Effects on Pmr 15 Resin written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-10-22 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Specimens of PMR-15 polyimide neat resin were aged in air at temperatures of 288, 316, and 343 C. Weight losses and dimensional changes were monitored during the course of the exposure time. Physical changes were also observed by optical and electron microscopy. It was found that polyimide polymer degradation occurred within a thin surface layer that developed and grew during thermal aging. The cores of the polymer specimens were protected from oxidative degradation, and they were relatively unchanged by the thermal treatment. Surface cracking was observed at 343 C and was probably due to an interaction between voids and stresses that developed in the surface layer. Bowles, Kenneth J. and Jayne, Douglas and Leonhardt, Todd A. Glenn Research Center RTOP 510-01-50...

Download or read book Isothermal Aging Effects on PMR 15 Resin written by and published by . This book was released on 1992 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Thermo oxidative Stability of Graphite PMR 15 Composites written by Madhu S. Madhukar and published by . This book was released on 1994 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physical and Chemical Aging Effects in PMR 15 Neat Resin written by JE. Kamvouris and published by . This book was released on 1997 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this study was to determine whether a shifting approach can be used to account for both chemical and physical effects during long-term aging of high temperature polyimide thermoset polymers, such as the commercial material PMR-15. Stress relaxation curves measured after aging at 316°C for times up to 800 h could be shifted to form a master curve. The horizontal shift factors were found to increase with increasing aging time, consistent with a reduction in molecular mobility that occurs as a result of either physical aging or increased cross-linking. There was a correlation between the vertical shift factors and cure related chemical changes that cause Tg to increase and mass to decrease. Aging effects were partially reversed by heating the aged specimen above its glass transition temperature, indicating that a large portion of the aging is physical in nature. Specimens aged in nitrogen had a larger reversible component than specimens aged in air.

Download or read book Ageing of Composites written by Rod Martin and published by Elsevier. This book was released on 2008-08-29 with total page 543 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ageing of composites is a highly topical subject given the increasing use of composites in structural applications in many industries. Ageing of composites addresses many of the uncertainties about the long-term performance of composites and how they age under conditions encountered in service.The first part of the book reviews processes and modelling of composite ageing including physical and chemical ageing of polymeric composites, ageing of glass-ceramic matrix composites, chemical ageing mechanisms, stress corrosion cracking, thermo-oxidative ageing, spectroscopy of ageing composites, modelling physical and accelerated ageing and ageing of silicon carbide composites. Part two examines ageing of composites in transport applications including aircraft, vehicles and ships. Part three reviews ageing of composites in non-transport applications such as implants in medical devices, oil and gas refining, construction, chemical processing and underwater applications.With its distinguished editor and international team of contributors, Ageing of composites is a valuable reference guide for composite manufacturers and developers. It also serves as a source of information for material scientists, designers and engineers in industries that use composites, including transport, chemical processing and medical engineering. - Addresses many of the uncertainties about the long-term performance of composites and how they age under conditions encountered in service - Reviews processes and modelling of composite ageing including chemical ageing mechanisms and stress corrosion cracking - Discusses ageing of composites in both transport and non-transport applications ranging from aircraft to implants in medical devices

Download or read book Thermal Stability Relationships Between PMR 15 Resin and Its Composites written by and published by . This book was released on 1993 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Stress and Damage in Polymer Matrix Composite Materials Due to Material Degradation at High Temperatures written by Hugh L. McManus and published by . This book was released on 1996 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multiscale Modeling and Simulation of Composite Materials and Structures written by Young Kwon and published by Springer Science & Business Media. This book was released on 2007-12-04 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the state-of-the-art in multiscale modeling and simulation techniques for composite materials and structures. It focuses on the structural and functional properties of engineering composites and the sustainable high performance of components and structures. The multiscale techniques can be also applied to nanocomposites which are important application areas in nanotechnology. There are few books available on this topic.

Download or read book Time Dependent and Nonlinear Effects in Polymers and Composites written by Richard Allan Schapery and published by ASTM International. This book was released on 2000 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: Annotation Improved reliability in commercial and military applications requires improved understanding of and predictive models for the time- dependent and nonlinear mechanical behavior of polymeric composites. The May 1998 American Society for Testing and Materials symposium sought to fuse the efforts in this direction of specialists in polymers and composites; these 18 papers are therefore grouped under the subheadings of polymers and composites. Primary polymer topics are chemical and physical aging, nonlinear viscoelasticity, and viscoplasticity. Composites' issues include: the effect of physical aging on time-dependent behavior, multiaxial nonlinear effects, compressive behavior, nonlinear viscoelasticity and viscoplasticity, failure mechanisms, hygrothermal effects, durability, and accelerated strength testing. Schapery is affiliated with the U. of Texas at Austin, and Sun is at Purdue U. Annotation copyrighted by Book News, Inc., Portland, OR.

Download or read book Introduction to the Dimensional Stability of Composite Materials written by Ernest G. Wolff and published by DEStech Publications, Inc. This book was released on 2004 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a comprehensive introduction to the quantitative analysis of dimensional instability in composite materials. It will aid in predicting deformations in a wide range of composite materials products and parts, under mechanical, thermophysical, and environmental stresses over time.

Download or read book Nontraditional Methods of Sensing Stress Strain and Damage in Materials and Structures written by David A. Stubbs and published by ASTM International. This book was released on 1997 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: These facsimiles of 16 contributions from the symposium held in May 1996 in Orlando provide information on the behavior of materials and structures. The authors describe novel ways to measure point to point deformation (or strain, when normalized), procedures for measuring crack length and the stres

Download or read book Long Term Isothermal Aging Effects on Carbon Fabric Reinforced PMR 15 Composites Compression Strength written by Kenneth J. Bowles and published by . This book was released on 1996 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study was conducted to determine the effects of long-term isothermal thermo-oxidative aging on the compressive properties of T-650-35 fabric reinforced PMR-15 composites. The temperatures that were studied were 204, 260, 288, 316, and 343 C. Specimens of different geometries were evaluated. Cut edge-to-surface ratios of 0.03 to 0.89 were fabricated and aged. Aging times extended to a period in excess of 15,000 hours for the lower temperature runs. The unaged and aged specimens were tested in compression in accordance with ASTM D-695. Both thin and thick (plasma) specimens were tested. Three specimens were tested at each time/temperature/geometry condition. The failure modes appeared to be initiated by fiber kinking with longitudinal, interlaminar splitting. In general, it appears that the thermo-oxidative degradation of the compression strength of the composite material may occur by both thermal (time-dependent) and oxidative (weight-loss) mechanisms. Both mechanisms appear to be specimen-thickness dependent.

Download or read book Thermal Stability Relationships Between Pmr 15 Resin and Its Composites written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-20 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study was conducted to investigate the relationship between the thermo-oxidative stability of PMR-15 matrix resin and the stability of graphite-fiber-reinforced composites that contain this resin as the matrix material. Three areas were investigated. The first was the effect of fiber/matrix interfacial bond strength on the isothermal aging weight loss of composites. By using type-A graphite fibers produced by Hercules, it was possible to study composites reinforced with fibers that were processed to receive different surface treatments. One of the fibers was untreated, a second fiber was treated by oxidation to enhance fiber/matrix bonding, and the third type of fiber was coated with an epoxy sizing. These treatments produced three significantly different interfacial bond strengths. The epoxy sizing on the third fiber was quickly oxidized from the bare fiber surfaces at 288, 316, and 343 C. The weight loss due to the removal of the sizing was constant at 1.5 percent. This initial weight loss was not observed in thermo-oxidative stability studies of composites. The PMR-15 matrix satisfactorily protected the reinforcemnt at all three temperatures. Bowles, Kenneth J. and Jayne, Douglas and Leonhardt, Todd A. and Bors, Dennis Glenn Research Center RTOP 510-01-50...

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 804 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Download or read book Time Dependent Constitutive Behavior and Fracture Failure Processes Volume 3 written by Tom Proulx and published by Springer Science & Business Media. This book was released on 2011-05-10 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: This the third volume of six from the Annual Conference of the Society for Experimental Mechanics, 2010, brings together 56 chapters on Time-Dependent Constitutive Fracture and Failure. It presents early findings from experimental and computational investigations on Time Dependent Materials including contributions on Thermal and Mechanical Characterization, Coupled Experimental and Computational Analysis of Fracture Path Selection, Procedures for Mixed Mode Fracture Testing of Bonded Beams, and Experimental Study of Voids in High Strength Aluminum Alloys.

Download or read book Mechanical Properties of Degraded PMR 15 Resin written by Luis Christophe Tsuji and published by . This book was released on 1998 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermo-oxidative aging produces a non-uniform degradation state in PMR-15 resin. A surface layer, usually attributed to oxidative degradation, forms. This surface layer has different properties from the inner material. A set of material tests was designed to separate the properties of the oxidized surface layer from the properties of interior material. Test specimens were aged at 316°C in either air or nitrogen, for durations of up to 800 hours. The thickness of the oxidized surface layer in air aged specimens, and the shrinkage and coefficient of thermal expansion (CTE) of nitrogen aged specimens were measured directly. The nitrogen-aged specimens were assumed to have the same properties as the interior material in the air-aged specimens. Four-point-bend tests were performed to determine modulus of both the oxidized surface layer and the interior material. Bimaterial strip specimens consisting of oxidized surface material and unoxidized interior material were constructed and used to determine surface layer shrinkage and CTE. Results confirm that the surface layer and core materials have substantially different properties.

Download or read book Composite Structures written by Peter Grant and published by ASTM International. This book was released on 2000 with total page 557 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of the May 1999 symposium from which these 29 papers were drawn was to bring together practitioners and theoreticians in the composite structural mechanics field to better understand the needs and limitations each group works with. Papers are organized under seven general headings: str