Results demonstrated that spiral grain
substantially reduced the strength of utility pole wood.
Examination of the photo of the tusk taken at the time of capture shows that a concentric spiral grain
at that position of the tusk was about 15 cm long (~ length of the steel portion of the transmitter) for a 180[degrees] rotation.
Two of the trees have straight trunks, but the other has a somewhat spiral growth form that is associated with a spiral grain
in the wood.
During the final period of drying, several visual characteristics of the poles were measured and recorded, including spiral grain
, ovality, taper, rate of growth, sweep, fissures, and knots.
The presence of spiral grain
combined with the hardness of the wood requires extra attention when machining.
For instance, consideration is now being given to such log properties as stiffness, strength, density, spiral grain
, extractives content, and consumption of energy for processing (Andrews 2002, So et al.
53 (a) MAD = maximum angular deviation (sum of maximum left and right spiral grain
deviations); BD = basic density (calculated from ovendry weight and green volume).
To assess the geospatial and within-tree variation in wood density and spiral grain
in Douglas-fir stems, over 400 wood disks were collected from 17 sites in the Cascade and Coastal Ranges of Oregon.
1995); 2) spiral grain
angle--the higher the spiral grain
angle, the larger the twist (Balodis 1972, Mishiro and Booker 1988, Johansson et al.
It is known that spiraled wood decreases the strength and stiffness of wood when the grain is not followed, therefore, the top Master grade of tonewood must have almost no spiral grain
Twist is caused by spiral grain
in combination with anisotropic shrinkage and is most pronounced in small dimension lumber sawn near the pith for fast-grown Norway spruce and Sitka spruce according to Danborg (1994).
It is speculated that since spiral grain
is a leading cause of twist in lumber, trees with high sweep may have a lesser amount of spiral grain