Due to its advantages of low cost, portability and easy field operation, no radiation, and fast detection speed, the acoustic-based non-destructive testing method has been widely applied in the area of wood materials. In this paper, we present first the basic principles of common acoustic-based nondestructive testing methods, including the impact stress wave method, the ultrasonic method, the resonance method, the acoustic emission, the acousto-ultrasonics, and the tomography technology, and analyze and compare their characteristics. Then, we review the applications of these methods in the wood industry, such as the evaluation of physical and mechanical properties of wood and the detection of wood internal defects, and the studies of improving the detection accuracy, and analyze the difficulties in the acoustic-based wood non-destructive testing. Finally, we discuss the development trend of the wood non-destructive testing equipment in terms of signal source, signal transmission mechanism, signal analysis and processing, portability and real-time performance, and point out that the emergence of new theories and technologies will greatly promote the development of non-destructive detection for wood.

nondestructive testing  /  wood  /  acoustic method  /  ultrasound  /  stress wave  /  acoustic emission  /  acousto-ultrasonics