[PDF] A Fundamental Study Of The Fracture And Fatigue Characteristics Of Single Wood Pulp Fibres eBook

Author : Wadwood Y. Hamad
Publisher :
Page : 492 pages
File Size : 36,31 MB
Release : 1994
Category :
ISBN :

GET BOOK

"The engendered conclusions may be summed up as follows. From a litany of tenuously-oriented microcracks, dominant macrocracks propagate along the axis of the fibre which may sharply deflect in the presence of natural bias (e.g. pits in the fibre wall). The material property degradation characteristics further include: volumetric expansion due to internal fibrillation in the cell wall, extensive external fibrillation, gradual delamination of the layers and partial peeling-off of the cell wall material. Cumulative damage due to cyclic shear is shown to be the most significant, further supported by the high structural collapsibility of the fibre wall layers. The mechanisms of fracture are either due to the development of transverse cracks at regions of high stress concentration (such as bordered pits), or owing to the gradual slippage of the fibre wall layers." --

Author : Wadood Y. (Wadood Yasser) Hamad
Publisher : National Library of Canada = Bibliothèque nationale du Canada
Page : 492 pages
File Size : 16,27 MB
Release : 1994
Category :
ISBN : 9780315946293

GET BOOK

"The engendered conclusions may be summed up as follows. From a litany of tenuously-oriented microcracks, dominant macrocracks propagate along the axis of the fibre which may sharply deflect in the presence of natural bias (e.g. pits in the fibre wall). The material property degradation characteristics further include: volumetric expansion due to internal fibrillation in the cell wall, extensive external fibrillation, gradual delamination of the layers and partial peeling-off of the cell wall material. Cumulative damage due to cyclic shear is shown to be the most significant, further supported by the high structural collapsibility of the fibre wall layers. The mechanisms of fracture are either due to the development of transverse cracks at regions of high stress concentration (such as bordered pits), or owing to the gradual slippage of the fibre wall layers." --

Author : Ian Smith
Publisher : John Wiley & Sons
Page : 248 pages
File Size : 36,4 MB
Release : 2003-06-02
Category : Technology & Engineering
ISBN : 9780471487081

GET BOOK

Damage in wood is principally the result of fatigue. Fatigue is the process of progressive localised irreversible change in a material, and may culminate in cracks or complete fracture if conditions that initiated or propagated the process persist. Comprehensive understanding of fatigue and fracture in engineered wood components must be founded on a proper understanding of the damage processes. Although wood is the world's most widely used structural material, whether measured by volume consumed or value of finished construction, its behaviour is not well understood even by people who have spent their careers studying it. * What is known about failure processes comes almost entirely from empirical evidence collected for engineering purposes. * Hypotheses about behaviour of wood are based on macroscopic observation of specimens during and following tests. * With only limited resources and the need to obtain practical results quickly, the timber engineering research community has steered away from the scientific approach. * Forestry practices are changing and are known to influence characteristics of wood cells therefore there is a need to periodically reassess the mechanical properties of visually graded lumber the blackbox approach. Fatigue and Fracture of Wood examines the above issues from a scientific point of view by drawing on the authors' own research as well as previously published material. Unlike the empirical research, the book begins by examining growth of wood. It briefly examines its structure in relation to how trees grow, before assessing the fatigue and fracture of wood and discussing the scientific methods of modelling fatigue. * Covers from macro to micro behaviour of wood * Presents direct evidence of how wood fractures using Scanning Electron Microscopy * The first book to present a physically correct model for fracture in wood * Provides experimental proof of so-called memory in wood (i.e. dependence of fatigue behaviour on the loading sequence) * Givse practical illustrations of how theories and models can be applied in practice An essential resource for wood scientists/engineers, timber-engineering practitioners, and graduate students studying wood and solid mechanics.

Author : Wadood Y. Hamad
Publisher : Springer Science & Business Media
Page : 257 pages
File Size : 14,88 MB
Release : 2013-11-27
Category : Technology & Engineering
ISBN : 1461508258

GET BOOK

The objectives of this book are twofold: 1. To provide a thorough examination of the materials science of cellulosic fibers with emphasis on the characterization of structure-property relations, and 2. To advance knowledge of how to best analyze cellulosic fibrous networks and composites, and, ultimately, engineer "novel" cellulose-based systems of superior performance and functionality. The design of new materials through the study of living systems, or bio-imitation, is burgeoning to become an established field, generally referred to as biomimetics. The latter, as with materials science, in general, prominently features multi-disciplinarity where new developments in mathematics, physics, chemistry and engineering continue to inspire novel areas of research and development. The book is structured in five chapters which provide a sequential treatment of the running theme: deformation mechanics and the physical, morphological and mechanical characterization of native cellulose fibers networks and composites. The heart of the book is Chapter 3, Damage Accumulation in Fibers, which treats the experimental methodology for fatigue testing of single fibers and the engendered results. In-depth examinations of the morphology, structure and chemical composition of native cellulose fibers, and the mechanics of deformation in these natural composite fibers are proffered in Chapters 1 and 2, respectively. The fourth chapter, Fractal Simulation of Crack Propagation, presents a fractal-based approach to modeling damage accumulation in materials. Fractals lend themselves well to modeling such randomly-oriented phenomena as crack propagation and fracture. The last chapter, Fibrous Structures: Networks and Composites, comprises analytical approaches for handling networks and composites.

Author : Richard A. Horn
Publisher :
Page : 462 pages
File Size : 29,66 MB
Release : 1974
Category : Fibers
ISBN :

GET BOOK

To achieve full utilization of each harvested tree, interest centers on use of all of the tree components. The objective of the study is to determine the influence of the morphological characteristics of pulp fiber from 12 western U.S. softwood species, representative of a wide range of fiber. The effect of the morphology of the wood pulp fiber as distinguished from that of the wood fiber is emphasized because differences in performance of fiber-based products are traced to the pulp fiber. Interrelationships of fiber morphology and pulp sheet properties are discussed. The results indicate that it is not possible to fully characterize the performance of a pulp by a single morphological characteristic and that the morphological characteristics significantly influence strength properties of sheets.

Author : Terrance E. Conners
Publisher : CRC Press
Page : 357 pages
File Size : 17,73 MB
Release : 2020-04-15
Category : Science
ISBN : 1000693473

GET BOOK

First published in 1995, Surface Analysis of Paper examines surface analysis techniques from a paper industry perspective and places heavy emphasis on applications. Modern techniques, including ion mass spectrometry, infrared spectroscopy, and optical profilometry are reviewed in a straightforward manner. This new book provides details on widely used methods and instruments, and discusses how they can be used to attain, for example, contour maps of the microscopic constituents on paper surfaces and accurate analyses of the physical properties of paper. Organized into three sections, Surface Analysis of Paper provides thorough coverage of the physical characteristics of paper, and a clear picture of new and emerging analytical methods. Carefully chosen background material on fundamental concepts is included wherever such material assists in understanding the uses of analysis methods. Each chapter contains: An introduction A description of the technique A discussion of the type of information that can be obtained with the particular technique Practical examples to demonstrate the advantages of the technique