|
The Mechanical properties and availability of wood have made it a
natural material for building structures,
furniture, tools, vehicles, and decorative objects. Worldwide
it is used more than metal or plastic.
Wood is a natural product and when used responsibly is a sustainable
resource which need not result in damage to the environment. Forests can
be protected by recycling and reusing the wood, using less wood and by
supporting sustainable forest management
All wood is composed of cellulose,lignin, hemicelluloses,
and minor amounts (5% to 10%) of extraneous materials
contained in a cellular structure.
Wood comprises about 50% of cellulose which responsible for most
of its mechanical properties.
Natural wood is generally composed of bundles of long fibres which are
effectively water carrying tubes. These fibres are laid in the direction of the
tree trunk or branch from which the wood is removed.
The strength of wood is highly dependent on the loading direction.
Wood is strongest in tension along the fibres and is weakest in the
radial and tangential direction.
To use wood to its best advantage and most effectively in engineering
applications, specific characteristics or physical properties
must be considered.
|