STRENGTH, TOUGHNESS, FAILURE AND FRACTURE MORPHOLOGY There are two fundamentally different approaches to the concept of strength and failure. The first is the classical strength of materials approach, attempting to understand strength and failure of timber in terms of the strength and arrangement of the molecules, the fibrils, and the cells by thinking in terms […]
FACTORS AFFECTING DURABILITY OF TIMBER Photochemical Degradation On exposure to sunlight the coloration of the heartwood of most timbers – e.g. mahogany, afrormosia and oak – will lighten, though a few timbers will actually darken, e.g. Rhodesian teak. Indoors the action of sunlight will be slow and the process will take several years, but outdoors
Performance of Timber in Fire The performance of materials in fire is an aspect of durability that has always attracted much attention, not so much from the research scientist, but rather from the material user who has to conform with the legislation on safety and who is influenced by the weight of public opinion on
MECHANICAL PROCESSING OF TIMBER Solid Timber Sawing and planing: The basic requirement of these processes is quite simply to produce as efficiently as possible timber of the required dimensions having a quality of surface commensurate with the intended use. Such a requirement depends not only on the basic properties of the timber, but also on
CHEMICAL PROCESSING OF TIMBER Treatability The ease with which a timber can be impregnated with liquids, especially wood preservatives, is generally referred to as its treatability. Treatability is related directly to the permeability of timber. The permeability is a function not only of moisture content and temperature, but also of grain direction, sapwood/heartwood, earlywood/latewood and
MOLECULAR STRUCTURE AND ULTRASTRUCTURE Chemical constituents Chemical analysis reveals the existence of four constituents and provides data on their relative proportions. This information may be summarised as in Table 1 proportions are for timber in general and slight variations in these can occur between timber of different species, or in different parts of a single
Manufacturing of Glass MANUFACTURING OF FLAT GLASS Flat glass manufacturing is a key industrial process and has been subject to continuous development to achieve lower cost and higher quality since its transition from the craft of mouth-blown glass. Float glass is the dominant process for flat glass, while rolled plate remains in use for patterned
Appearance of Timber in Relation to Structure Most of you will agree that many timbers are aesthetically pleasing and the various and continuing attempts to simulate the appearance of timber in the surface of synthetic materials bear testament to the very attractive appearance of many timbers. Although a very large proportion of the timber consumed
PHYSICAL PROPERTIES OF GLASS Density, Thermal Expansion Coefficient, Thermal Conductivity, Emissivity and Selectivity of Coated Glasses The physical properties of float glass produced in Europe do not vary significantly between manufacturers and can be taken as standard values according to BS EN 572-2. Float glass produced in other parts of the world may vary in
Mass Volume Relationship of Timber Density The density of a piece of timber is a function not only of the amount of wood substance present, but also of the presence of both extractives and moisture. In a few timbers extractives are completely absent, while in many they are present, but only in small amounts and usually