Book-bot.com - The Mechanical Properties of Wood - Including a Discussion of the Factors Affecting the Mechanical - Properties, and Methods of Timber Testing by Record, Samuel J.

The Mechanical Properties of Wood - Including a Discussion of the Factors Affecting the Mechanical - Properties, and Methods of Timber Testing by Samuel J. Record
page 22 of 237 (09%)

|--------------------------------------------------------------|
| TABLE II |
|--------------------------------------------------------------|
| RATIO OF STRENGTH OF WOOD IN TENSION AND IN COMPRESSION |
| (Bul. 10, U. S. Div. of Forestry, p. 44) |
|--------------------------------------------------------------|
| | Ratio: | A stick 1 square inch in |
| | | cross section. |
| | Tensile | |
| KIND OF WOOD | strength | Weight required to-- |
| | R = ----------- +----------------------------|
| | compressive | Pull apart | Crush endwise |
| | strength | | |
|---------------+-----------------+------------+---------------|
| Hickory | 3.7 | 32,000 | 8,500 |
| Elm | 3.8 | 29,000 | 7,500 |
| Larch | 2.3 | 19,400 | 8,600 |
| Longleaf Pine | 2.2 | 17,300 | 7,400 |
|--------------------------------------------------------------|
| NOTE.--Moisture condition not given. |
|--------------------------------------------------------------|

Failure of wood in tension parallel to the grain occurs
sometimes in flexure, especially with dry material. The tension
portion of the fracture is nearly the same as though the piece
were pulled in two lengthwise. The fibre walls are torn across
obliquely and usually in a spiral direction. There is
practically no pulling apart of the fibres, that is, no
separation of the fibres along their walls, regardless of their