final

Question 1

what are the important points concerning woods

Answer 1

1: economic/cost effective in most regions of the world
2 wood is a composite
3 natural material (many flaws/imperfections)
4 anisotropic (mechanical properties vary with respect to load orientation)

Question 2

what is the difference between wood and timber

Answer 2

wood(material) refers to small clear specimen free of any macroscopic defects
timber (structural) refers to sawn structural members and may contain a wide variety of macroscopic defects

Question 3

how strong is wood

Answer 3

very strong in tension, specific strength is very high but wood as a lot of variability

Question 4

how does growth ring vary in width

Answer 4

depends on species and site conditions. rings formed during short or dry seasons are thinner than those formed when growing conditions are more favourable
rings formed in shady conditions are usually thinner than those formed by the same species in sunny condition

Question 5

is it true that you can determine the age of a tree by counting the rings?

Answer 5

no, this method can lead to errors because abnormal environemental conditions can cause a tree to produce multiple growth increments or even prevent growth entirely for a peridod

Question 6

difference between softwood and hardwood

Answer 6

softwoods have needle like or scale like leaves and a relatively simple cell structure typically conifers (spruce, pine, cedar)
hardwood has broad leaves and a more complicated cell structure. typically deciduous (oak, maple. walnut..)

Question 7

what is the type of wood most commonly used in construction and why

Answer 7

softwood, even though its less dense, strong and decay resistant, softwood is more economic and usually is straigther than hardwood trees

Question 8

what is the wood microstructure

Answer 8

composed of hollow, elongated, spindle shaped cells that are arranged parallel to each other along the trunk of a tree.

Question 9

what properties are affected by the cell characteristic

Answer 9

strength and shrinkage as well as graùin pattern of the wood

Question 10

what type of material is wood

Answer 10

anisotropic material, mechanical properties vary on the direction of loading

Question 11

go see pp 13 slide 7 and 8

Answer 11

oui

Question 12

what does being a orthotropic material do to wood

Answer 12

it has unique and independant properties in 3 directions( longitudinal, radial and tangential)

Question 13

how are the different axes in wood defined

Answer 13

longitudinal is paralelle to the fiber (grain)
radial is normal to growth rings ( perpendicular to the grain in radial direction
tangential is perpendicular to the grain but tangent to the growth rings

Question 14

see pp 13 slide 9

Answer 14

oui

Question 15

what type of properties are affected by direction of loading on wood

Answer 15

all directions

Question 16

how are the mechanical properties along the longitudinal axis in wood defined

Answer 16

normally higher than radial and tangential

Question 17

what happens if wood is loaded in compression along the grain

Answer 17

most of cell walls are compressed axially thus failure involves localized buckling of cell wall. but if loaded across the grain the cell walls bend hollow wood cells simply collapse or flatten, compressive stength is therefore lower