The monitoring of acoustic emission (AE) has allowed tracing of the damage in wooden cultural objects exposed to variations in ambient relative humidity (RH). A year-long on-site AE monitoring of the Song Dynasty shipwreck confirmed the usefulness of the technique in tracing climate-induced damage in wood. New coupling material is tested to make it conform to the conservation rules which is non-corrosive to monitoring objects and a reversible operation. As sensitive parameter of wood damage caused by variations RH, the accumulated ringing counting tends to increase with the increase of daily fluctuation of RH (DFRH). In addition, the damage of wooden cultural objects during shrinkage is stronger than that during swelling. The relationship between the probability of AE activity and the daily DFRH is established and it is determined that the daily variation of RH for long-term protection of the Song Dynasty shipwreck should be controlled within 4%, and an early warning will be given if it exceeds 10%.

In order to monitor the crack growth of the wood material better and reduce failure risks, this paper studied the attenuation characteristics of acoustic emission signals in wood through pencil lead breaking (PLB) tests, in the aim of estimating the true amplitude value of the acoustic emission source signal. The tensile test of the double cantilever beam (DCB) specimens was used to simulate the crack tip growth within wood material, monitoring acoustic activity and location of crack tips within wood material using acoustic emission technology and digital image correlation (DIC). Results showed that the attenuation degree of acoustic emission signals increased exponentially as the propagation distance increased, and the relationship between relative amplitude attenuation rate and the propagation distance of the acoustic emission signal was established by the regression method, which provides the input parameters for the establishment of the crack instability prediction model in the next step. Based on a thermodynamic approach, a theoretical model for predicting crack instability was established, and the model was verified by DCB tests. The model uses acoustic emission parameters as the basis for judging whether the crack is instable. It provides theoretical support for the application of acoustic emission technology in wood health monitoring.