[PDF] Mechanics Of Bi Material Beams And Its Application To Mixed Mode Fracture Of Wood Frp Bonded Interfaces eBook

Author : Cole S. Hamey
Publisher :
Page : 110 pages
File Size : 11,83 MB
Release : 2007
Category : Civil engineering
ISBN :

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In this study, mechanics models for bi-layer beams suitable for bi-material interface characterization are introduced, and their application to mixed mode fracture of wood-FRP bonded interface is studied. First, an engineering approach for evaluating the mixed-mode (Mode-I/II) fracture toughness of wood/FRP composite bonded interfaces is presented. Two four-point bending specimens, i.e., four-point asymmetric end-notched flexure (4-AENF) and fourpoint asymmetric mixed-mode bending (4-AMMB), are proposed for the study of the mixed-mode fracture. With proper design, the rate of compliance change with respect to crack length can be determined to be independent of the crack length for the specimens. The proposed specimens can be used to determine the mixed-mode fracture toughness without the need of measuring the crack propagation length. Mode decompositions are evaluated for each specimen, and with previously determined Mode-I and Mode-II data, a number of failure criteria and failure envelopes are determined for the wood-FRP interface. Second, an intuitive mechanics-based approach is presented to analyze layered beams using the split beam model, from which the layered beam is modeled as individual subbeams and the stress acting throughout each sub-beam is used to determine the forces acting on the sub-beams. The split beam model is adapted to evaluate the compliance and ERR of three common groups of fracture specimens and loading conditions: Mode-I dominant (ADCB and DCB), Mode-II dominant (AENF and ENF), and Mixed-Mode (ASLB and SLB). It is demonstrated that the split beam model generates solutions consistent with those of existing specimens found in literature. Also, derived specimens are provided to allow for different ways of viewing the specimen configurations and possible ways of applying loads to achieve certain conditions. The compliance and ERR of two derived specimens are presented. The ERR for these two specimens is shown to be the same as the existing solutions, thus validating the accuracy of the approach. The simplified bi-layer models and related application to fracture of bi-material interface introduced in this study improve the data reduction techniques in fracture characterization and facilitate analysis and design of bi-material fracture specimens.

Author : P.J.M. Monteiro
Publisher : Elsevier
Page : 313 pages
File Size : 46,5 MB
Release : 2001-08-29
Category : Technology & Engineering
ISBN : 0080535593

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"Long Term Durability of Structural Materials" features proceedings of the workshop held at Berkeley, CA in October, 2000. It brought together engineers and scientists, who have received grants from the initiative NSF 98-42, to share their results on the study of long-term durability of materials and structures. The major objective was to develop new methods for accelerated short-term laboratory or in-situ tests which allow accurate, reliable, predictions of the long-term performance of materials, machines and structures. To achieve this goal it was important to understand the fundamental nature of the deterioration and damage processes in materials and to develop innovative ways to model the behavior of these processes as they affect the life and long-term performance of components, machines and structures. The researchers discussed their approach to include size effects in scaling up from laboratory specimens to actual structures. Accelerated testing and durability modeling techniques developed were validated by comparing their results with performance under actual operating conditions. The main mechanism of the deterioration discussed included environmental effects and/or exposure to loads, speeds and other operating conditions that are not fully anticipated in the original design. A broad range of deterioration damage, such as fatigue, overload, ultraviolet damage, corrosion, and wear was presented. A broad range of materials of interest was also discussed, including the full spectrum of construction materials, metals, ceramics, polymers, composites, and coatings. Emphasis was placed on scale-dependence and history of fabrication on resulting mechanical behavior of materials.

Author : Magd Abdel Wahab
Publisher : DEStech Publications, Inc
Page : 328 pages
File Size : 48,41 MB
Release : 2015-10-05
Category : Technology & Engineering
ISBN : 1605950939

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Adhesive technologies for bonding composites to multiple materialsInformation on adhesive formulation, selection, joint configuration Presented in this volume is a detailed scientific analysis of strategies for adhering composite materials to plastics, concrete, metals, and wood, as well as to other composites, using a variety of adhesives. The theory and analysis of composite bonding with adhesives are explained, along with information on adhesive formulation and selection, material preparation, joint geometry and joint design. Attention is given to how different types of adhered composite joints are empirically tested, e.g., for strength and under stress, and how models of joints with adhesives are developed. The book includes an intensive discussion of the uses of adhesives for composite repair. Part two focuses on applications of adhesive composite bonding in aircraft, automobiles, buildings, ships, railroads and dental restoration.

Author : Liviu Librescu
Publisher : Springer Science & Business Media
Page : 627 pages
File Size : 38,7 MB
Release : 2006-01-15
Category : Technology & Engineering
ISBN : 1402042035

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Annotation This is the first monograph devoted to the foundation of the theory of composite anisotropic thin-walled beams and to its applications in various problems involving the aeronautical/aerospace, helicopter, naval and mechanical structures. Throughout the theoretical part, an effort was made to provide the treatment of the subject by using the equations of the 3-D elasticity theory. Non-classical effects such as transverse shear, warping constraint, anisotropy of constituent materials yielding the coupling of twist-bending (lateral), bending (transversal)-extension have been included and their implications have been thoroughly analyzed. Thermal effects have been included and in order to be able to circumvent their deleterious effects, functionally graded materials have been considered in their construction. Implications of the application of the tailoring technique and of the active feedback control on free vibration, dynamic response, instability and aeroelasticity of such structures have been amply investigated. Special care was exercised throughout this work to address and validate the adopted solution methodologies and the obtained results against those available in the literature and obtained via numerical or experimental means.

Author : Jang-Kyo Kim
Publisher : Elsevier
Page : 416 pages
File Size : 45,22 MB
Release : 1998-10-21
Category : Technology & Engineering
ISBN : 0080530974

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The study and application of composite materials are a truly interdisciplinary endeavour that has been enriched by contributions from chemistry, physics, materials science, mechanics and manufacturing engineering. The understanding of the interface (or interphase) in composites is the central point of this interdisciplinary effort. From the early development of composite materials of various nature, the optimization of the interface has been of major importance. While there are many reference books available on composite materials, few of them deal specifically with the science and mechanics of the interface of fiber reinforced composites. Further, many recent advances devoted solely to research in composite interfaces have been scattered in a variety of published literature and have yet to be assembled in a readily accessible form. To this end this book is an attempt to bring together recent developments in the field, both from the materials science and mechanics perspective, in a single convenient volume. The central theme of the book is tailoring the interface properties to optimise the mechanical peformance and structural integrity of composites with enhanced strength/stiffness and fracture toughness (or specific fracture resistance). It deals mainly with interfaces in advanced composites made from high performance fibers, such as glass, carbon, aramid, ultra high modulus polyethylene and some inorganic (e.g. B/W, A12O3, SiC) fibers, and matrix materials encompassing polymers, metals/alloys and ceramics. The book is intended to provide a comprehensive treatment of composite interfaces in such a way that it should be of interest to materials scientists, technologists and practising engineers, as well as graduate students and their supervisors in advanced composites. We hope that this book will also serve as a valuable source of reference to all those involved in the design and research of composite interfaces. The book contains eight chapters of discussions on microstructure-property relationships with underlying fundamental mechanics principles. In Chapter 1, an introduction is given to the nature and definition of interfaces in fiber reinforced composites. Chapter 2 is devoted to the mechanisms of adhesion which are specific to each fiber-matrix system, and the physio-chemical characterization of the interface with regard to the origin of adhesion. The experimental techniques that have been developed to assess the fiber-matrix interface bond quality on a microscopic scale are presented in Chapter 3, along with the techniques of measuring interlaminar/intralaminar strengths and fracture toughness using bulk composite laminates. The applicability and limitations associated with loading geometry and interpretation of test data are compared. Chapter 4 presents comprehensive theoretical analyses based on shear-lag models of the single fiber composite tests, with particular interest being placed on the interface debond process and the nature of the fiber-matrix interfacial bonding. Chapter 5 is devoted to reviewing current techniques of fiber surface treatments which have been devised to improve the bond strength and the fiber-matrix compatibility/stability during the manufacturing processes of composites. The micro-failure mechanisms and their associated theories of fracture toughness of composites are discussed in Chapter 6. The roles of the interface and its effects on the mechanical performance of fiber composites are addressed from several viewpoints. Recent research efforts to augment the transverse and interlaminar fracture toughness by means of controlled interfaces are presented in Chapters 7 and 8.

Author : Jia-Liang Le
Publisher : Oxford University Press
Page : 332 pages
File Size : 19,53 MB
Release : 2021-11-19
Category : Brittleness
ISBN : 0192846248

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Many modern engineering structures are composed of brittle heterogenous, or quasibrittle, materials. These include concrete, composites, tough ceramics, rocks, cold asphalt mixtures, and many brittle materials at the microscale. Understanding the failure behavior of these materials is of paramount importance for improving the resilience and sustainability of various engineering structures including civil infrastructure, aircraft, ships, military armors, and microelectronic devices. Designed for graduate and upper-level undergraduate university courses, this textbook provides a comprehensive treatment of quasibrittle fracture mechanics. It includes a concise but rigorous examination of linear elastic fracture mechanics, which is the foundation of all fracture mechanics. It also covers the fundamental concepts of nonlinear fracture mechanics, and introduces more advanced concepts such as triaxial stress state in the fracture process zone, nonlocal continuum models, and discrete computational models. Finally, the book features extensive discussion of the various practical applications of quasibrittle fracture mechanics across different structures and engineering disciplines, and throughout includes exercises and problems for students to test their understanding.