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Book Relevance of Impacter Shape to Nonvisible Damage and Residual Tensile Strength of a Thick Graphite Epoxy Laminate

Download or read book Relevance of Impacter Shape to Nonvisible Damage and Residual Tensile Strength of a Thick Graphite Epoxy Laminate written by CC. Poe and published by . This book was released on 1991 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation was made to determine the relevance of impacter shape to nonvisible damage and tensile residual strength of graphite/epoxy cases for the solid rocket motors of the Space Shuttle. Impacters were dropped onto 30.5-cm (12-in.)-long rings (short cylinders) that were 76.2 cm (30 in.) in diameter and 36 mm (1.4 in.) thick. The kinetic energies ranged from 17.0 to 136 J (12.5 to 100 ft•lb). Some rings were filled with inert propellant and some were empty. A 5 kg (11 lb) impacter was used with a 12.7-mm (0.5-in.)-diameter hemisphere and a sharp corner attached. The rings were impacted numerous times around the circumference and cut into 51-mm (2-in.)-wide specimens. Because of a shortage of rings, impacts with a 6.3-mm (0.25-in.)-diameter bolt-like rod were simulated by quasi-statically pressing the rod against the face of individual specimens. All of the specimens were uniaxially loaded to failure in tension. Results from a previous impact study using a 25.4-mm (1.0-in.)-diameter hemisphere were also considered. For the range of impact energies investigated, the corner and rod always made visible damage on the surface, but the hemispheres did not. The damage on the surface consisted of a crater shaped like the indenter, and the damage below the surface consisted of broken fibers that appeared to result from shear failure of the matrix. The damage initiated when the contact pressure exceeded a critical level but did not become visible on the surface until an even higher pressure was exceeded. The contact pressures for the rod and corner exceeded the critical level to cause visible damage. The kinetic energy to initiate damage and to cause visible damage on the surface increased approximately with hemisphere diameter to the third power. For a given kinetic energy, the residual strengths did not vary significantly with indenter shape. However, the reduction in strength for nonvisible damage increased dramatically with increasing hemisphere diameter, 9 and 30% for the 12.7-mm (0.5-in.) and 25.4-mm (1.0-in.)-diameter hemispheres, respectively. Factors of safety for nonvisible damage increased with increasing kinetic energy. With the factor of safety for the filament-wound case (1.4), the maximum allowable kinetic energy was 123 J (91 ft •lb). The effects of hemisphere diameter on impact force, damage size, damage visibility, and residual tensile strength were predicted quite well assuming Hertzian contact and using maximum stress criteria and a surface crack analysis.

Book Composite Materials

Download or read book Composite Materials written by T. Kevin O'Brien and published by ASTM International. This book was released on 1991 with total page 831 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Scientific and Technical Aerospace Reports

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1990 with total page 976 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.

Book Dynamic Failure of Composite and Sandwich Structures

Download or read book Dynamic Failure of Composite and Sandwich Structures written by Serge Abrate and published by Springer Science & Business Media. This book was released on 2012-11-02 with total page 646 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a broad view of the current state of the art regarding the dynamic response of composite and sandwich structures subjected to impacts and explosions. Each chapter combines a thorough assessment of the literature with original contributions made by the authors. The first section deals with fluid-structure interactions in marine structures. The first chapter focuses on hull slamming and particularly cases in which the deformation of the structure affects the motion of the fluid during the water entry of flexible hulls. Chapter 2 presents an extensive series of tests underwater and in the air to determine the effects of explosions on composite and sandwich structures. Full-scale structures were subjected to significant explosive charges, and such results are extremely rare in the open literature. Chapter 3 describes a simple geometrical theory of diffraction for describing the interaction of an underwater blast wave with submerged structures. The second section addresses the problem of impact on laminated composite structures with chapters devoted to ballistic impacts on pre-stressed composite structures, tests developed to simulate dynamic failure in marine structures, damage mechanisms and energy absorption in low velocity impacts, perforation, the numerical simulation of intra and inter-ply damage during impact, and hail impact on laminated composites. Sandwich structures with laminated facings are considered in Section 3 with chapters dealing with the discrete modeling of honeycomb core during the indentation of sandwich structures, the behavior of fold core sandwich structures during impact, and impact on helicopter blades. The fourth section consists of two chapters presenting experimental results and numerical simulation of composite structures subjected to crash. This volume is intended for advanced undergraduate and graduate students, researchers, and engineers interested and involved in analysis and design of composite structures.

Book Applied Mechanics Reviews

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1994 with total page 1036 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book The Shock and Vibration Digest

Download or read book The Shock and Vibration Digest written by and published by . This book was released on 1991 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Composite Materials Fatigue and Fracture

Download or read book Composite Materials Fatigue and Fracture written by and published by . This book was released on 1989 with total page 850 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Summary of a Study to Determine Low Velocity Impact Damage and Residual Tension Strength for a Thick Graphite Epoxy Motor Case

Download or read book Summary of a Study to Determine Low Velocity Impact Damage and Residual Tension Strength for a Thick Graphite Epoxy Motor Case written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-10-11 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: Impacters of various shapes and masses were dropped from various heights onto 36 mm (1.4 in.) thick graphite/epoxy cylinders, which represented filament wound cases (FWC) for the booster motors of the Space Shuttle. Insert solid propellant was cast into some of the cylinders. The cylinders were impacted numerous times around the circumference and then cut into 51 mm (2.0 in.) wide tension specimens, each containing an impact site. Four indenters were used: a sharp corner, two hemispheres, and a bolt-like rod. The diameters of the hemispheres were 12.7 mm mm (0.5 in.) and 25.4 mm (1.0 in.), and the diameter of the rod was 6.3 mm (0.25 in.). Impacts with the rod were simulated by pressing the rod against the face of specimens. For the hemispheres, the damage initiated beneath the surface at a critical contact pressure and was not visible on the surface until an even larger pressure was exceeded. The damage consisted of matrix cracking and broken fiber. The rod an corner made visible surface damage in all tests. For the hemispheres, the tension strength was reduced considerably before the damage was visible on the surface, 30 percent for the 25.4 mm (1.0 in.) diameter hemisphere and 10 percent for the 12.7 mm (0.5 in.) diameter hemisphere. Analytical methods were used to predict the damage and residual tension strength. A factor of safety to account for nonvisible damage was determined. Poe, C. C., Jr. Langley Research Center RTOP 505-63-01-05

Book Polymer Matrix Composites

Download or read book Polymer Matrix Composites written by United States. Dept. of Defense and published by . This book was released on 1994 with total page 502 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Residual Tensile Strength of Graphite epoxy and Kevlar epoxy Laminates with Impact Damage

Download or read book Residual Tensile Strength of Graphite epoxy and Kevlar epoxy Laminates with Impact Damage written by Douglas Scott Cairns and published by . This book was released on 1988 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study was conducted to examine the damage tolerance of composite laminates with impact damage. A model is presented to predict the residual strength of such laminates. The in-plane strain distribution near the region of damage is determined using Lekhnitskii's solution for an anisotropic inclusion in an anisotropic medium with compromised constitutive properties of the impact region used for the properties of the inclusion. The residual strength is then predicted using an average criterion based on strain. Results from experiments of impacted specimens of [±45/0]s Kevlar/epoxy and [±45/0]2s graphite/epoxy show good correlation with the analytical predictions. The model is applied over a wide range of impactor conditions with equally good results. Although the damage was inflicted with different impactor masses, velocities, and laminate boundary conditions, the data indicates that the residual strength is only a function of the damage present and not the manner in which the damage is introduced. The use of the measured damage in conjunction with the predicted properties of the compromised region thus shows good promise to be applied over a wide range of structures in a practical fashion. An overall analytical philosophy to deal with the problem of impact in composite laminates is discussed.

Book Government Reports Announcements Index

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1990 with total page 990 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Residual Tensile Strength of Graphite Epoxy and Kevlar Epoxy Laminates with Impact Damage

Download or read book Residual Tensile Strength of Graphite Epoxy and Kevlar Epoxy Laminates with Impact Damage written by DS. Cairns and published by . This book was released on 1990 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study was conducted to examine the damage tolerance of composite laminates with impact damage. A model is presented to predict the residual strength of such laminates. The in-plane strain distribution near the region of damage is determined using Lekhnitskii's solution for an anisotropic inclusion in an anisotropic medium with compromised constitutive properties of the impact region used for the properties of the inclusion. The residual strength is then predicted using an average criterion based on strain. Results from experiments of impacted specimens of [±45/0]5 Kevlar/epoxy and [±45/0]25 graphite/epoxy show good correlation with the analytical predictions. The model is applied over a wide range of impactor conditions with equally good results. Although the damage was inflicted with different impactor masses, velocities, and laminate boundary conditions, the data indicates that the residual strength is only a function of the damage present and not the manner in which the damage is introduced. The use of the measured damage in conjunction with the predicted properties of the compromised region thus shows good promise for its application over a wide range of structures in a practical fashion. An overall analytical philosophy to deal with the problem of impact in composite laminates is discussed.

Book The Engineering Index Annual

Download or read book The Engineering Index Annual written by and published by . This book was released on 1992 with total page 2264 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since its creation in 1884, Engineering Index has covered virtually every major engineering innovation from around the world. It serves as the historical record of virtually every major engineering innovation of the 20th century. Recent content is a vital resource for current awareness, new production information, technological forecasting and competitive intelligence. The world?s most comprehensive interdisciplinary engineering database, Engineering Index contains over 10.7 million records. Each year, over 500,000 new abstracts are added from over 5,000 scholarly journals, trade magazines, and conference proceedings. Coverage spans over 175 engineering disciplines from over 80 countries. Updated weekly.