Overview of the use of ultrasonic technologies in research on wood properties

Two ultrasonic technologies, acoustic emission and acousto-ultrasonics, are reviewed in terms of characteristics and applications to wood and wood-based materials. The background is given on the two technologies, including the effect of wood on wave propagation and sensitivity to defects and other properties. The factors that affect wave injection and processing are reviewed for each technology. Four applications are given as examples: particleboard springback, creep/creep-rupture, adhesive curing, and deterioration detection. Recent developments in the technologies are discussed.