Speaker
Description
Efficient bucking systems and careful timber handling are key factors in maximizing timber value. To evaluate the performance and long-term advancement of such systems, Skogforsk has conducted a series of large-scale wood value trials. The most recent study, conducted in 2025, compared seven leading harvester systems under operational conditions. Data were collected in a spruce-dominated final felling stand in central Sweden, which resulted in several complementary datasets used to study dimension measurement accuracy, bucking performance, positioning, timber handling, and system functionality according to StanForD 2010.
The present analysis examines how cutting dynamics influence the occurrence of bucking splits, which are caused by the gravitational forces acting on the freely hanging part of the log during the cut. Cutting time was determined from high-speed video recordings of cuts across a representative range of log diameters, and a comparison with cutting speed data from previous wood value trials will be presented. The video material was further used to describe the progression of the cut with regard to saw bar angle. Measurements of bucking splits were performed on the bucked logs from 210 stems. Discs were manually cut from the log ends and struck until breakage, allowing classification of the break as either natural or the result of a bucking split based on characteristic patterns.
A logistic regression model was developed to relate cutting dynamics to the likelihood of bucking splits. The model incorporates cutting time, saw bar angle, and log geometry to mechanistically capture the interplay between stress development and cut progression, which determines whether the cut is completed before split-inducing stress levels are reached. Preliminary analyses indicate that log geometry is the dominant factor explaining the occurrence of bucking splits, while aspects of the cutting process also show statistically significant effects.
| Keywords | harvesting; timber-value; harvester-head; structural-mechanics |
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