Author: John Jerome Davis
Publisher:
ISBN:
Category : Fibrous composites
Languages : en
Pages : 244

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Book Description

Author: PJ. Joyce
Publisher:
ISBN:
Category : Composite materials
Languages : en
Pages : 21

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Book Description
The effect of fiber waviness, which develops during the processing and manufacture of fiber-reinforced composite structures, on compressive failure was investigated. Analytical and experimental evidence has shown that out-of-plane waviness (also referred to as layer or ply waviness) is a major contributing factor in compressive strength reduction; however, there is a paucity of data concerning the effects of in-plane waviness or wrinkling on the compressive response of composites. In this paper, we present data from a series of compression tests examining the effects of varying levels of in-plane fiber waviness. These tests used a novel combined shear/end loading compression test fixture (WTF combined loading compression test fixture) in order to ameliorate problems typically associated with pure end-loading (brooming and end-damage) and pure shear loading (tab debonding and high stress concentrations due to discontinuity stresses). The fixture performed adequately when testing wavy specimens, but we experienced repeated tab failures in the non-wavy specimens. The compression test results exhibit a distinct linear trend of decreasing compressive strength with increasing waviness severity as represented by the maximum off-axis angle of the wavy fibers. Optical microscopy revealed that kink bands, leading to catastrophic failure, initiate at the most severe fiber misorientation sites in the wavy regions.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 32

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Book Description
This article presents a model for the uni-axial compressive response of uni-directionally reinforced fibrous composite. The model accounts for the non-linear shear response and the failure strain of the matrix, incorporating both aspects into a non-linear field equation which governs the load-deflection process. In addition, the model considers the effects of two kinds of geometric imperfections, namely, initial fiber waviness and random fiber spacing. It is shown that under uni-axial compression random fiber spacing may instigate the formation of severe transverse loadings on the fibers, which suggest the existence of a transitional mechanism from micro-buckling to micro-kinking. Computational results are presented which illuminate the effects of several material and geometric factors on the compressive strength of composites.

Author: Emile Greenhalgh
Publisher: Elsevier
ISBN: 1845696816
Category : Technology & Engineering
Languages : en
Pages : 608

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Book Description
The growing use of polymer composites is leading to increasing demand for fractographic expertise. Fractography is the study of fracture surface morphologies and it gives an insight into damage and failure mechanisms, underpinning the development of physically-based failure criteria. In composites research it provides a crucial link between predictive models and experimental observations. Finally, it is vital for post-mortem analysis of failed or crashed polymer composite components, the findings of which can be used to optimise future designs.Failure analysis and fractography of polymer composites covers the following topics: methodology and tools for failure analysis; fibre-dominated failures; delamination-dominated failures; fatigue failures; the influence of fibre architecture on failure; types of defect and damage; case studies of failures due to overload and design deficiencies; case studies of failures due to material and manufacturing defects; and case studies of failures due to in-service factors.With its distinguished author, Failure analysis and fractography of polymer composites is a standard reference text for researchers working on damage and failure mechanisms in composites, engineers characterising manufacturing and in-service defects in composite structures, and investigators undertaking post-mortem failure analysis of components. The book is aimed at both academic and industrial users, specifically final year and postgraduate engineering and materials students researching composites and industry designers and engineers in aerospace, civil, marine, power and transport applications. Examines the study of fracture surface morphologies in uderstanding composite structural behaviour Discusses composites research and post-modern analysis of failed or crashed polymer composite components Provides an overview of damage mechanisms, types of defect and failure criteria

Author: Scott E. Groves
Publisher: ASTM International
ISBN: 0803114990
Category : Composite materials
Languages : en
Pages : 372

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Book Description

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 28

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Book Description
This article presents a model for the uni-axial compressive response of uni-directionally reinforced fibrous composite. The model incorporates the non-linear shear response and the failure strain of the matrix, accounting for both aspects within a non-linear field equation which governs the load- deflection process. In addition, the model considers the effects of two kinds of geometric imperfections, namely, initial fiber waviness and random fiber spacing. It is shown that under uni-axial compression random fiber spacing may instigate the formation of severe transverse loadings on the fibers which suggest the existence of a transitional mechanism from micro-buckling to micro- kinking. Computational results are presented which illuminate the effects of several material and geometric factors on the compressive strength of composites.

Author: M. W. Hyer
Publisher: DEStech Publications, Inc
ISBN: 193207886X
Category : Technology & Engineering
Languages : en
Pages : 718

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Book Description
Updated and improved, Stress Analysis of Fiber-Reinforced Composite Materials, Hyer's work remains the definitive introduction to the use of mechanics to understand stresses in composites caused by deformations, loading, and temperature changes. In contrast to a materials science approach, Hyer emphasizes the micromechanics of stress and deformation for composite material analysis. The book provides invaluable analytic tools for students and engineers seeking to understand composite properties and failure limits. A key feature is a series of analytic problems continuing throughout the text, starting from relatively simple problems, which are built up step-by-step with accompanying calculations. The problem series uses the same material properties, so the impact of the elastic and thermal expansion properties for a single-layer of FR material on the stress, strains, elastic properties, thermal expansion and failure stress of cross-ply and angle-ply symmetric and unsymmetric laminates can be evaluated. The book shows how thermally induced stresses and strains due to curing, add to or subtract from those due to applied loads.Another important element, and one unique to this book, is an emphasis on the difference between specifying the applied loads, i.e., force and moment results, often the case in practice, versus specifying strains and curvatures and determining the subsequent stresses and force and moment results. This represents a fundamental distinction in solid mechanics.

Author: Valter Carvelli
Publisher: Elsevier
ISBN: 1782422935
Category : Technology & Engineering
Languages : en
Pages : 511

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Book Description
Fatigue of Textile Composites provides a current, state-of-art review on recent investigations on the fatigue behavior of composite materials, mainly those reinforced with textiles. As this particular group of composite materials is extremely important for a wide variety of industrial applications, including automotive, aeronautical, and marine, etc., mainly due to their peculiarities and advantages with respect to unidirectional laminated composites, the text presents comprehensive information on the huge variety of interlacement geometric architectures that are suitable for a broad range of different applications, their excellent drapability and versatility, which is highly important for complex double-curvature shape components and three-dimensional woven fabrics without plane reinforcement, and their main mechanical characteristics which are currently in high demand from industry. Presents the current state-of-the-art investigations on fatigue behavior of composite materials, mainly those reinforced with textiles Contains invaluable information pertaining to a wide variety of industries, including automotive, aeronautical, and marine, amongst others Provides comprehensive information on the huge variety of interlacement geometric architectures that are suitable for a broad range of different applications

Author: S. R. Reid
Publisher: Elsevier
ISBN: 1855738902
Category : Technology & Engineering
Languages : en
Pages : 318

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Book Description
This study covers impact response, damage tolerance and failure of fibre-reinforced composite materials and structures. Materials development, analysis and prediction of structural behaviour and cost-effective design all have a bearing on the impact response of composites and this book brings together for the first time the most comprehensive and up-to-date research work from leading international experts. State of the art analysis of impact response, damage tolerance and failure of FRC materials Distinguished contributors provide expert analysis of the most recent materials and structures Valuable tool for R&D engineers, materials scientists and designers

Author: Sai Bhargav Pottavathri
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 86

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Book Description
The purpose of this study was to investigate the strength and effectiveness of certain composite materials when induced by 'in-plane fiber tow waviness' in a composite ply. Fiber waviness is usually induced by infusion processes and inherent in fabric architectures. Composite structural details like ply drops and ply joints can cause serious fiber misalignment. These are usually dependent on parameters such as ply thickness, percentage of plies dropped, and location of ply drop, the gap between the plies, mold geometry and pressure, and pressure of the resin which slides the dry fibers during the resin transfer molding process. Fiber disorientation due to fiber tow waviness in „in-plane‟ direction has been the subject of recent studies on wind turbine blade materials and other aerospace laminates with reports of compression strengths and failure strains that are borderline, depending upon the reinforcement architecture, matrix resin and environment. Waviness is expected to reduce compressive strength due to two primary factors. The fibers may be oriented in such a way that the geometry that results because of the orientation may exacerbate the basic fiber, strand, or layer buckling mode of failure. The waviness could also shift the fiber orientation of the axis of the ply longitudinal direction which eventually results in matrix dominated failures for plies normally orientated in the primary load direction (00). The longitudinal tension and compression behavior of unidirectional carbon fiber composite laminates of different materials (different grades of carbon, glass and Kevlar with different resins) were investigated using finite element analysis tool ABAQUS. Both global and local stress & strain values generated by the finite element model were validated by the traditional mechanical methods using ply/local stiffness matrix and global/reduced stiffness matrix. A precise geometry of waviness on different materials was modeled with different wave severity factor and a parametric study was conducted. Three different defects were modeled where the angle of misalignment ranged from 5 to 15 degrees with a wavelength ranged from 1 inch to 1.5 inches and amplitude which ranged from 0.05 inches to 0.1 inches. This revealed the effect of 'in-plane fiber tow waviness' on the stress distribution and loss of strength in carbon-reinforced composite materials. The results clearly show that the effect of 'in-plane fiber tow waviness' leads to resin rich areas which causes high stress concentrations and decrease in the strength ratio, leading to delamination's.