The Mechanical Properties of WoodBy Samuel J. RecordUnlike some other reproductions of classic texts (1) We have not used OCR(Optical Character Recognition), as this leads to bad quality books with introduced typos. (2) In books where there are images such as portraits, maps, sketches etc We have endeavoured to keep the quality of these images, so they represent accurately the original artefact. Although occasionally there may be certain imperfections with these old texts, we feel they deserve to be made available for future generations to enjoy.
Wood-based materials are CO2-neutral, renewable, and considered to be environmentally friendly. The huge variety of wood species and wood-based composites allows a wide scope of creative and esthetic alternatives to materials with higher environmental impacts during production, use and disposal. Quality of wood is influenced by the genetic and environmental factors. One of the emerging uses of wood are building and construction applications. Modern building and construction practices would not be possible without use of wood or wood-based composites. The use of composites enables using wood of lower quality for the production of materials with engineered properties for specific target applications. Even more, the utilization of such reinforcing particles as carbon nanotubes and nanocellulose enables development of a new generation of composites with even better properties. The positive aspect of decomposability of waste wood can turn into the opposite when wood or wood-based materials are exposed to weathering, moisture oscillations, different discolorations, and degrading organisms. Protective measures are therefore unavoidable for many outdoor applications. Resistance of wood against different aging factors is always a combined effect of toxic or inhibiting ingredients on the one hand, and of structural, anatomical, or chemical ways of excluding moisture on the other.
Most industrial and natural materials exhibit a macroscopic behaviour which results from the existence of microscale inhomogeneities. The influence of such inhomogeneities is commonly modelled using probabilistic methods. Most of the approaches to the evaluation of the safety of structures according to probabilistic criteria are somewhat scattered, however, and it is time to present such material in a coherent and up-to-date form. Probabilities and Materials undertakes this task, and also defines the great tasks that must be tackled in coming years. For engineers and researchers dealing with materials, geotechnics, solid mechanics, soil mechanics, statistics and stochastic processes. The expository nature of the book means that no prior knowledge of statistics or probability is required of the reader. The book can thus serve as an excellent introduction to the nature of applied statistics and stochastic modelling.
This book provides basic information on the design of structures with tropical woods. It is intended primarily for teaching university- and college-level courses in structural design. It is also suitable as a reference material for practitioners. Although parts of the background material relate specifically to West and East Africa, the design principles apply to the whole of tropical Africa, Latin America and South Asia. The book is laced with ample illustrations including photographs of real life wood structures and structural elements across Africa that make for interesting reading. It has numerous manual and Excel spread sheet worked examples and review questions that can properly guide a first-time designer of wooden structural elements. A number of design problems are also solved using the FORTRAN programming language. Topics covered in the thirteen chapters of the book include a brief introduction to the book, the anatomy and physical properties of tropical woods; a bri ef review of the mechanical properties of wood, timber seasoning and preservation, uses of wood and wood products in construction; basic theory of structures, and structural load computations; design of wooden beams, solid and built-up wooden columns, wood connections and wooden trusses; as well as a brief introduction to the design of wooden bridges.
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.
The book is a fundamental reference source on reaction wood for wood scientists and technologists, plant biologists, silviculturists, forest ecologists, and anyone involved in the growing of trees and the processing of wood. It brings together our current understanding of all aspects of reaction wood, and is the first book to discuss both compression wood and tension wood. Trees produce reaction wood to maintain the vertical orientation of their stems and the optimum angle of each branch. They achieve this by laying down fibre cell walls in which differences in physical and chemical structure from those of normal fibres are expressed as differential stresses across the stem or branch. This process, while of obvious value for the survival of the tree, causes serious problems for the utilisation of timber. Timber derived from trees containing significant amounts of reaction wood is subject to dimensional instability on drying, causing twisting, bending and splitting. It is also difficult to work as timber, and for the pulp and paper industry the cost of removing the increased amount of lignin in compression wood is substantial. This has both practical and economic consequences for industry. Understanding the factors controlling reaction wood formation and its effect on wood structure is therefore fundamental to our understanding of the adaptation of trees to their environment and to the sustainable use of wood. The topics covered include: -Morphology, anatomy and ultrastructure of reaction wood -Cell-wall polymers in reaction wood and their biosynthesis -Changes in tree proteomes during reaction wood formation -The biomechanical action and biological functions of reaction wood - Physical and mechanical properties of reaction wood from the scale of cell walls to planks -The detection and characterisation of compression wood -Effects of reaction wood on the performance of wood and wood-based products - Commercial implications of reaction wood and the influence of forest management on its formation
At present, the use of polymer composites filled with wood (WPC) is becoming increasingly popular. In particular, flooring of terraced premises, siding, decorative fences, fence systems, steps, universal profiles, among others are made from WPC. In 1977, the first enterprise for the production of WPC appeared in Sweden. The first experience was not very successful – the demand turned out to be low, and the wear of technological equipment was very high. Therefore, developments in this field were resumed only in the 1990s and continue to this day. This book describes the basic physical and mechanical properties of modern WPC, such as tensile and compression strength, and hardness. Also, the influence of climatic factors on the performance properties of products from WPC is described, while the thermal and rheological properties of WPC materials are considered, which directly affect the consumer characteristics of the products. The book contains theoretical developments related to the prediction of the mechanical and thermal properties of polymers and composites. The Van der Waals volume and the energy of the intermolecular interaction are estimated. This book will be of interest to representatives of the WPC market, designers, and architects, as well as technology engineers, students and post-graduate students of higher educational institutions in the fields of chemistry and physics of composite polymer materials.
To obtain the best attainable end-use stability of a wooden product it is essential to have information on the movement and shrinkage that may be expected. In this context, it is essential when drying timber to choose an accurate drying schedule in relation to the shrinkage figures and the risk of deformation. Generally, many timber properties are closely related to the density and the nominal specific gravity. With the given detailed information (per wood species), the water content (amount of evaporation and energy in timber drying) or the void volume (in case of impregnation, in order to estimate the maximum uptake of a liquid) in the wood can be calculated. The physical properties of 145 commercial timbers have been determined in the past decades. They comprise the shrinkage and swelling values, equilibrium moisture content, hysteresis, density and nominal specific gravity, including the variation coefficients of these values. The shrinkage, swelling and hysteresis are presented in graphic form; the other information in tabular form. Additional information about some other properties of physical nature has been added, e.g. gluelam products and rattan.
The degradable nature of high-performance, wood-based materials is an attractive advantage when considering environmental factors such as sustainability, recycling, and energy/resource conservation. The Handbook of Wood Chemistry and Wood Composites provides an excellent guide to the latest concepts and technologies in wood chemistry and bio-based composites. The book analyzes the chemical composition and physical properties of wood cellulose and its response to natural processes of degradation. It describes safe and effective chemical modifications to strengthen wood against biological, chemical, and mechanical degradation without using toxic, leachable, or corrosive chemicals. Expert researchers provide insightful analyses of the types of chemical modifications applied to polymer cell walls in wood, emphasizing the mechanisms of reaction involved and resulting changes in performance properties. These include modifications that increase water repellency, fire retardancy, and resistance to ultraviolet light, heat, moisture, mold, and other biological organisms. The text also explores modifications that increase mechanical strength, such as lumen fill, monomer polymer penetration, and plasticization. The Handbook of Wood Chemistry and Wood Composites concludes with the latest applications, such as adhesives, geotextiles, and sorbents, and future trends in the use of wood-based composites in terms of sustainable agriculture, biodegradability and recycling, and economics. Incorporating over 30 years of teaching experience, the esteemed editor of this handbook is well-attuned to educational demands as well as industry standards and research trends.
