Properties & Structure of Wood Flashcards Preview

Technology 3 - Building Science and Structures > Properties & Structure of Wood > Flashcards

Flashcards in Properties & Structure of Wood Deck (40):
1

What are the characteristic properties of timber

- Low density and relatively high tensile strength

- Subject to dimensional changes due to variation in moisture content.

- Combustibility

- Anistropy due to fibrous nature of wood. material has different properties in different directions.

- Mechanical properties are fixed by the growth cycle.

2

What the three main functions of tree trunks

- Support the crown

- conduct mineral solutions from the roots to crown

- transport food from the crown and store it.

3

What is the outer region of a tree trunk called

Sapwood

4

Sapwood is the...

Outer region of a tree trunk

5

conduction of fluids and food storage are restricted to the...

Sapwood, outer region.

6

The inner region of a tree trunk is called...

Heartwood

7

Heartwood is...

The inner region of a tree trunk

8

What are observed in trunk cross-sections...

Growth rings

9

How to growth rings become annual

If trees are in temperature regions resulting from distinct seasons.

10

Growth rings occur because...

Different growth rates in different parts of the growing season.

11

What are the two different types of wood associated to different seasonal growth rates...

- Early Wood, softer coarser and more porous.

- Late Wood

12

What are the two classifications of commercial timber...

- Softwood

- Hardwood

13

Softwood and Hardwood are classified by...

Structural differences and not the mechanical properties

14

What type of tree are softwoods derived from...

Coniferous

15

Coniferous trees produce...

Softwood

16

What is the characteristic of coniferous trees...

needle shaped leaves (gymnosperms)

17

What type of tree are hardwoods derived from...

Broad leaved trees

18

Broad leaved trees produce...

Hardwoods

19

Trees which shed their leaves annually are called

Angiosperms

20

What are the four main types of cells in timber

(P) - Parenchyma
(T) - Tracheids
(F) - Fibres
(V) - Vessels

21

What is the function of Tracheids

they conduct fluids and contribute to mechanical support.

Needle shaped cells 2-5mm long which occur parallel to the stem axis.

22

they conduct fluids and contribute to mechanical support.

Needle shaped cells 2-5mm long which occur parallel to the stem axis.

Are the characteristics of...

Tracheids

23

What is the function of Parenchyma

They store food. occur n the rays and are block like cells

24

They store food. occur n the rays and are block like cells. Is the characteristic of...

Parenchyma

25

What is the function of fibres...

Support. long thin cells.

26

What cell type is responsible for support

Fibres

27

What is the function of Vessels...

Conduction. they are short relatively wide cells placed on top of each other.

28

What cell types to softwoods consist of...

Parenchyma
Tracheids

29

Parenchyma & Tracheids are consistent with...

Softwoods

30

Hardwoods have all four cell types because...

they are broad leaved tress which have to support a greater mass due to foliage.

31

What are the three sides of a wedge shapes piece of timber sample

Transverse - Top section

Radial - Side section going into centre

Tangential - Front facing side.

32

Vessels formed early on in growing season are wider and thinner, and the decease in size throughout the growth ring is slow. These species of tress are known as...

Diffuse-Porous hardwoods (beech, sycamore)

33

Diffuse-Porous hardwoods (beech, sycamore) are formed due to...

Vessels formed early on in growing season are wider and thinner, and the decease in size throughout the growth ring is slow

34

The abrupt transition from large vessels of the early wood to the small vessels of the late wood create...

Ring-porous hardwoods (oak, ash, elm)

35

Ring-porous hardwoods (oak, ash, elm) are formed due to...

The abrupt transition from large vessels of the early wood to the small vessels of the late wood

36

The structure of the cell wall consists of what components

Fibre & Matrix

37

What is the constituent of the fibre

Cellulose

38

Cellulose is a constituent of..

The Fibre.

39

What are the constituents of the Matrix

Lignin & Hemicelluloses

40

Lignin & Hemicelluloses are the constituents of...

The Matrix.