PART III TIMBER TESTING

Working plan
Forms of material tested
Size of test specimens
Moisture determination
Machine for static tests
Speed of testing machine
Bending large beams
Bending small beams
Endwise compression
Compression across the grain
Shear along the grain
Impact test
Hardness test:  Abrasion and indentation
Cleavage test
Tension test parallel to the grain
Tension test at right angles to the grain
Torsion test
Special tests
Spike pulling test
Packing boxes
Vehicle and implement woods
Cross-arms
Other tests

APPENDIX

Sample working plan of United States Forest
Service
Strength values for structural timbers

Bibliography

Part I:  Some general works on mechanics, materials of
construction, and testing of materials
Part II:  Publications and articles on the mechanical
properties of wood, and timber testing
Part III:  Publications of the United States Government on
the mechanical properties of wood, and timber
testing

ILLUSTRATIONS

Frontispiece Photomicrograph of a small block of western
hemlock
1.  Stress-strain diagrams of two longleaf pine beams
2.  Compression across the grain
3.  Side view of failures in compression across the
grain
4.  End view of failures in compression across the
grain
5.  Testing a buggy-spoke in endwise compression
6.  Unequal distribution of stress in a long column due
to lateral bending
7.  Endwise compression of a short column
8.  Failures of a short column of green spruce
9.  Failures of short columns of dry chestnut
10.  Example of shear along the grain
11.  Failures of test specimens in shear along the
grain
12.  Horizontal shear in a beam
13.  Oblique shear in a short column
14.  Failure of a short column by oblique shear
15.  Diagram of a simple beam
16.  Three common forms of beams—­(1) simple,
(2) cantilever, (3) continuous
17.  Characteristic failures of simple beams
18.  Failure of a large beam by horizontal shear
19.  Torsion of a shaft
20.  Effect of torsion on different grades of hickory
21.  Cleavage of highly elastic wood
22.  Cross-sections of white ash, red gum, and eastern
hemlock
23.  Cross-section of longleaf pine
24.  Relation of the moisture content to the various
strength values of spruce
25.  Cross-section of the wood of western larch showing
fissures in the thick-walled cells of the late
wood
26.  Progress of drying throughout the length of a
chestnut beam
27.  Excessive season checking
28.  Control of season checking by the use of S-irons
29.  Static bending test on a large