Download or read book Response of Composite Plates to Quasi Static Impact Events written by RB. Bucinell and published by . This book was released on 1991 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: A two degree of freedom, spring-mass model is used to investigate the response of filament-wound composite plates subjected to transverse impacts. From this model, it is concluded that it is the ratio of impactor to target frequencies that determines whether the structural response to impact is quasi-static or dynamic in nature. In addition to the model development, a test matrix is designed to isolate the effects of impactor mass, velocity, and energy on quasi-static impact response and damage formation. These data compared well with the model predictions.

Download or read book On the Use of Quasi static Testing to Assess Impact Damage Resistance of Composite Shell Structures written by Brian Lee Wardle and published by . This book was released on 1997 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: The response of various composite structures to transverse loading was studied through impact and quasi-static testing. The AS4/3501-6 graphite/epoxy composite structures considered have a [±45n/0n]s layup configuration and include convex and concave shell sections, plates, and full cylinders. The impact tests fall within the so-called large-mass, low-velocity regime where previous findings for composite plates indicate that quasi-static tests accurately represent the impact response, i.e., impact and quasi-static tests can be considered equivalent. This equivalence includes damage if the same peak force is reached in both the impact and quasi-static tests. The present work extends the impact and quasi-static equivalence from composite plates to various composite (shell) structures, even when the shell response exhibits an instability. Over nearly the entire range of impact events and shell structures tested, impact and quasi-static response (including damage extent and distribution) is found to be equivalent. A small number of the most flexible (large span, thin) specimens displayed a large-amplitude oscillatory impact loading response which was not observed for the quasi-static tests. These few specimens indicate a regime which may limit the general equivalence of impact and quasi-static testing demonstrated herein. The general equivalence of impact and quasi-static response demonstrated herein for a wide range of composite structures, especially in regard to damage resistance, has important implications for testing and design of damage tolerant aerospace components. Furthermore, the findings suggest that quasi-static experimentation can often be used to simulate the impact response (including damage) of composite shell structures.

Download or read book On the Use of Quasi static Testing to Assess Impact Damage Resistance of Composite Shell Structure written by Brian Lee Wardle and published by . This book was released on 1997 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: The response of various composite structures to transverse loading was studied through impact and quasi-static testing. The AS4/3501-6 graphite/epoxy composite structures considered have a [±45n/0n]s layup configuration and include convex and concave shell sections, plates, and full cylinders. The impact tests fall within the so-called large-mass, low-velocity regime where previous findings for composite plates indicate that quasi-static tests accurately represent the impact response, i.e., impact and quasi-static tests can be considered equivalent. This equivalence includes damage if the same peak force is reached in both the impact and quasi-static tests. The present work extends the impact and quasi-static equivalence from composite plates to various composite (shell) structures, even when the shell response exhibits an instability. Over nearly the entire range of impact events and shell structures tested, impact and quasi-static response (including damage extent and distribution) is found to be equivalent. A small number of the most flexible (large span, thin) specimens displayed a large-amplitude oscillatory impact loading response which was not observed for the quasi-static tests. These few specimens indicate a regime which may limit the general equivalence of impact and quasi-static testing demonstrated herein. The general equivalence of impact and quasi-static response demonstrated herein for a wide range of composite structures, especially in regard to damage resistance, has important implications for testing and design of damage tolerant aerospace components. Furthermore, the findings suggest that quasi-static experimentation can often be used to simulate the impact response (including damage) of composite shell structures.

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:

Download or read book Composite Materials written by Abdul-Hamid Zureick and published by ASTM International. This book was released on 2002 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: From a March 2001 symposium in Phoenix, Arizona, 17 papers consider such topics as tabbed versus untabbed fiber-reinforced composite compression, qualification using a nested experimental design, determining and characterizing imperfections in composite pressure vessels, philosophies for assessing t

Download or read book Impact and Quasi static Response of Cylindrical Composite Shells written by Brian Lee Wardle and published by . This book was released on 1995 with total page 1162 pages. Available in PDF, EPUB and Kindle. Book excerpt: Work was conducted to explore and begin to understand the impact response of composite shells over a range of impact events considered in the large-mass, low-velocity regime. Both impact and quasi-static experiments were conducted on various structural configurations including convex shells, concave shells, plates, and cylinders with boundary conditions of pinned/no in-plane sliding on the axial edges and free on the circumferential edges. Specimens with a planar aspect ratio of 1 were constructed in [±45n/On]s (n = 1, 2, 3) layups from Hercules AS4/3501-6 graphite epoxy prepreg. Basic structural parameters (radius, span, and thickness) were varied via scaling to determine the effects of these parameters and ratios of these parameters on the response. Damage states were characterized visually and with the dye-penetrant x-ray photography method and compared by defining damage metrics such as the average damage extent and damage extent ratio. An instability phenomenon was noted in the response of many convex shells which has a strong influence on the response. The Hertzian type contact relation does not capture the local response of indented shells and initial stiffness does not characterize the overall shell response. Relative contributions of membrane stiffness and bending stiffness are noted to be key in the overall convex shell response. Boundary conditions were also noted to have a strong influence on the response. Quasi-static and impact response are found to be nearly identical in all respects, including compelling evidence from the damage state comparisons. Two noted differences are that backface spalling was observed for a small number of specimens in impact tests only and that some showed a low frequency, high amplitude response in impact tests which was not observed in quasi-static tests. All structural parameters were shown to affect the response, including the shell height, although thickness was of particular importance. Nondimensional ratios were not found that capture the behavior of convex shells over the entire range of data but the data indicates regimes where different ratios are important, especially the height-to-thickness ratio. Peak force is found to be an excellent damage resistance metric. Impact energy consumption of convex shells through structural deformation, resulting in lower peak forces, is observed to give convex shells improved damage resistance over plate specimens. However, at the barely visible impact damage (BVID) level, convex shells that do not undergo an instability can incur more nonvisible damage than plates at a given force. This damage behavior, which includes different damage distributions, is attributed to differences caused by compressive versus tensile membrane stresses. The general response and resulting local stress and damage state, with relative contributions from both membrane and bending effects, needs to be determined through careful analysis to better determine the important parameters in the response. The damage distribution through the thickness needs to be characterized through experimentation, and then related to the stress state through analysis.

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.

Download or read book Composite Materials written by Roderick H. Martin and published by ASTM International. This book was released on 1986 with total page 517 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterizations of Some Composite Materials written by Hosam El-Din M. Saleh and published by BoD – Books on Demand. This book was released on 2019-01-16 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: Composite materials are materials made from two or more constituents with significantly different physical or chemical properties; when combined, a new material with characteristics different from the individual components is produced, while the individual components remain separate and distinct within the finished structure. The new composite material often displays many beneficial characteristics; in many cases, composites are stronger, of lower density, or less costly in comparison to established materials. Based on the classification of composites, we are already familiar with the fact that there exists a myriad of different types of these materials. It is a common saying that different types of composites differ in their performance. Yet, composites also have some characteristics in common. The proper material choice for an envisaged application is of outstanding importance and key in the development of a new product. Selecting the most suitable material determines the performance and characterization of the final product whether it will meet the designated function and performance requirements. The present book "Characterizations of some composite materials" contains eight selected chapters, starting with a general introductory chapter on composite materials, and covers different aspects in characterizing some composite materials. In this context, the present book is considered an appropriate way to communicate the advances in characterization of some composite materials to the scientific community. Chemists, scientists, and researchers from related areas, and undergraduates involved in materials issues and interested in approaches to improve the quality of life, as well as people from industry could find this book to be an inspiring and effective guide.

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1982 with total page 916 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Lightweight Ballistic Composites written by Ashok Bhatnagar and published by Woodhead Publishing. This book was released on 2006-06-30 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ballistic composites need to be lightweight and durable as well as exhibiting high impact resistance and damage tolerance. This important book reviews these requirements, how the materials used for ballistic composites meet them and their range of applications.After an introductory chapter, Lightweight ballistic composites is split into two main sections. The first part of the book explores material requirements and testing. There are chapters on bullets and bullet fragments, material responses to ballistic impact, standards and specifications, modelling and test methods. Part Two reviews the range of materials used, production methods and applications. Topics discussed include high-performance ballistic fibres and ceramics, non-woven ballistic and prepreg composites, and their uses in body armour, vehicle and aircraft protection.This major book is the first of its kind to give a comprehensive review of the current use of lightweight ballistic composites in both military and law-enforcement applications. It is an invaluable reference for all those involved in personnel and vehicle protection in defence and police forces around the world. - Reviews the current use of lightweight ballistic composites in both military and law-enforcement application - An authoritative overview of the range of materials used, production methods and applications - Explores material requirements and testing

Download or read book A Comparison of Quasi Static Indentation to Low Velocity Impact written by Alan T. Nettles and published by . This book was released on 2000 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: A static test method for modeling low-velocity foreign object impact events to composites would prove to be very beneficial to researchers since much more data can be obtained from a static test than from an impact test. In order to examine if this is feasible, a series of static indentation and low-velocity impact tests were carried out and compared. Square specimens of many sizes and thicknesses were utilized to cover the array of types of low-velocity impact events. Laminates with a [pi]/4 stacking sequence were employed since this is by far the most common type of engineering laminate. Three distinct flexural rigidities under two different boundary conditions were tested in order to obtain damage ranging from that due to large deflection to contact stresses and levels in-between to examine if the static indentation-impact comparisons are valid under the spectrum of damage modes that can be experienced. Comparisons between static indentation and low-velocity impact tests were based on the maximum applied transverse load. The dependent parameters examined included dent depth, back surface crack length, delamination area, and to a limited extent, load deflection behavior. Results showed that no distinct differences could be seen between the static indentation tests and the low-velocity impact tests, indicating that static indentation can be used to represent a low-velocity impact event.

Download or read book Long Term Durability of Polymeric Matrix Composites written by Kishore V. Pochiraju and published by Springer Science & Business Media. This book was released on 2011-09-25 with total page 681 pages. Available in PDF, EPUB and Kindle. Book excerpt: Long-Term Durability of Polymeric Matrix Composites presents a comprehensive knowledge-set of matrix, fiber and interphase behavior under long-term aging conditions, theoretical modeling and experimental methods. This book covers long-term constituent behavior, predictive methodologies, experimental validation and design practice. Readers will also find a discussion of various applications, including aging air craft structures, aging civil infrastructure, in addition to engines and high temperature applications.

Download or read book Dynamic Response and Failure of Composite Materials and Structures written by Valentina Lopresto and published by Woodhead Publishing. This book was released on 2017-05-17 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamic Response and Failure of Composite Materials and Structures presents an overview of recent developments in a specialized area of research with original contributions from the authors who have been asked to outline needs for further investigations in their chosen topic area. The result is a presentation of the current state-of-the art in very specialized research areas that cannot be found elsewhere in the literature. For example, Massabò presents a newly developed theory for laminated composite plates that accounts for imperfect bonding between layers with new solutions for problems involving thermal effects. This theory is new and computationally-efficient, and the author describes how it fits in the broader context of composite plate theory. Abrate discusses the design of composite marine propellers and presents a detailed derivation of the equations of motion of a rotating blade, including centrifugal effects and the effects of pre-twisting and other geometric parameters. This book is a major reference resource for academic and industrial researchers and designers working in aerospace, automotives, and the marine engineering industry. - Presents recent developments in a research field that has experienced tremendous advances because of improved computational capabilities, new materials, and new testing facilities - Includes contributions from leading researchers from Europe and the USA who present the current state-of-the-art, including unique and original research - Provides extensive experimental results and numerical solutions - Appeals to a broad range of professional researchers working in aerospace, automotive, and marine engineering fields

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:

Download or read book Failure in Composites written by Anthony M. Waas and published by DEStech Publications, Inc. This book was released on 2013 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fourth volume of the ASC series on advanced composites contains critical information on static and dynamic composite failure and how it is predicted and modeled using novel computational methods and micromechanical analysis.

Download or read book The Impact Response of Carbon Epoxy Laminates Center Director s Discretionary Fund Project No 94 13 written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-11-23 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Low velocity dropweight impact tests were conducted on carbon/epoxy laminates under various boundary conditions. The composite plates were 8-ply (+45,0, -45,90)s laminates supported in a clamped-clamped/free-free configuration with varying amounts of in-plane load, N(sub x), applied. Specimens were impacted at energies of 3.4, 4.5, and 6 Joules (2.5, 3.3, and 4.4 ft-lb). The amount of damage induced into the specimen was evaluated using instrumented impact techniques, x-ray inspection, and cross-sectional photomicroscopy. Some static identation tests were performed to examine if the impact events utilized in this study were of a quasi-static nature and also to gain insight into the shape of the deflected surface at various impact load combinations. Load-displacement curves from these tests were compared to those of the impact tests, as was damage determined from x-ray inspection. The finite element technique was used to model the impact event and determine the stress field within the laminae. Results showed that for a given impact energy level, more damage was induced into the specimen as the external in-plane load, N(sub x), was increased. The majority of damage observed consisted of back face splitting of the matrix parallel to the fibers in that ply, associated with delaminations emanating from these splits. The analysis showed qualitatively the results of impact conditions on maximum load of impact, maximum transverse deflection, and first failure mode and location. Nettles, A. T. and Hodge, A. J. Marshall Space Flight Center EPOXY MATRIX COMPOSITES; LAMINATES; IMPACT TESTS; DYNAMIC TESTS; X RAY INSPECTION; STRESS DISTRIBUTION; PLATES (STRUCTURAL MEMBERS); LOADS (FORCES); FAILURE MODES; DISPLACEMENT; DEFLECTION; DAMAGE; BOUNDARY CONDITION