Ib Dt Pp Timber 4.3

IB Design Technology SLOct 26th, 2008 Student: Leslie ChanInstructor: Mr. Schwartz

Natural timber is a natural composite material comprising fibers in a lignin matrix. The tensile strength of timber is greater along the grain (fiber) than across the grain

Wood consist of many fibers bonded together with glue

When load is applied parallel to the axis of the fibers = very strong in tension and have good compressive strength

When the load is applied perpendicular to the axis of the fibers = crush under compression and are weak in tension

We have to consider the temperature and tropical climate of the location of where the tree matured because this can lead to different types of timber.

Any of various mostly needle-leaved or scale-leaved, chiefly evergreen, cone-bearing trees or shrubs such as pines (Dictionary.com)

When we referred to conifers, we are referring to softwood.

Only grow in temperate regions

The wood from these trees is generally softer. (Obviously)

Softwoods reproduce* by cones. Softwoods have needles. They do not lose their needles in the fall.

They are sometimes called evergreens because the needles are green year round.

Some examples includes: pine, cedar, and cypress.

Trees that drop its leave every year It produces hardwood Able to grow in both temperate and

tropical regions

The wood from these trees is generally harder.

Hardwoods reproduce* by flowers. Hardwoods have broad leaves. Many lose their leaves every autumn Some examples includes: maple and

oak.

Time to maturity… Ex. It takes a mahogany tree 100 years to completely mature

Soil erosion is when the soil is blown away by the wind or washed away by the rain. Ex. Nepal and the Dust Bowl during the 1930s

Greenhouse Effect – trees help remove greenhouse effect gases

Extinction of Species – we are destroying animals, insects, and plants’ life by chopping wood.

Plywood Pinewood