New directions for NDT in forestry

The need for improved timber quality assessment is important to the forestry industry. Scotland's harvestable softwood population will reach the peak of its 50 year plantation cycle in 2020. Current mechanical grading results in waste and the underlying theory behind typical timber condition assessment is limited. Such methods of quality control are only applicable after sawing, resulting in a high rejection rate for engineering use. Increasing the yield of higher-strength timber from this crop is vital to the sector's economic security. Emphasis falls on identifying high-strength timber before it reaches the sawmill and incurs the costs of felling, recovery, transportation and processing. This research summarises NDT methods and introduces the authors' work on the use of acoustic testing (based on time-of-flight, resonant frequencies, and damping ratios) to assess timber quality. Recommendations for future applications of NDT in forestry are made and include: density, taper, static moduli of elasticity and rupture, micro fibril angle, grain, and knot area and volume ratios. Ultimately, the research will develop new predictive algorithms accounting for these non-visible characteristics of standing trees, thus improving the accuracy of field-based measurements.