The Song Dynasty Shipwreck Monitoring and Analysis Using Acoustic Emission Technique

Abstract

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%.

Application of Nondestructive Testing Technologies in Preserving Historic Trees and Ancient Timber Structures in China

“…Based on the unique preservation status of Song dynasty ships in Quanzhou Bay, urgent research is required for the preservation of the materials and structure of ancient ships. Recently, the research team at the Beijing Forestry University conducted NDT research on this shipwreck and some progress has been obtained [53]. In this project, researchers adopted an NDT method of AE technology combined with digital image technology to build a monitoring system for the Song Dynasty Shipwreck.…”

Thermodynamic Approach for the Identification of Instability in the Wood Using Acoustic Emission Technology

“…It shows that the propagation distance has a great influence on the signal amplitude. This change trend is approximately in the form of an index, so the relationship between the propagation distance and the relative amplitude attenuation rate is obtained by fitting in this paper: SA j = 6.823 exp(−0.019x) − 7.142 (18) where x is the distance from the sensor to the sound source, and SA j is the relative amplitude attenuation rate from the sound source x. The red dot in the figure is the relative amplitude attenuation rate obtained through the experiments.…”

“…Using the regression equation and Formula (18), two undetermined coefficients can be obtained (q = 0.014; p = 4.044).…”

“…An exponential equation can be used to describe the relationship between the crack body𝐶 𝑖 and 𝐿 𝑖 (as shown in Figure 9). Using the regression equation and Formula (18), two undetermined coefficients can be obtained (q = 0.014; p = 4.044).…”

“…Jakiela et al [16] found that there was a correlation between the energy and the fluctuation of relative humidity (RH) when the wood samples were placed in an environment where the humidity was changed to observe the AE phenomenon [17]. Similarly, Zhao et al [18] used acoustic emissions for tracking the AE signals of the Song Dynasty shipwreck exposed to variations in relative humidity. The results showed that the accumulated ring counting was highly correlated with the daily fluctuation of RH, and according to the AE parameters, the optimal humidity suitable for the preservation of a shipwreck was determined.…”