| Our country has raised the protection of cultural heritage to the level of national development strategy,among which the reliability of large-scale wooden cultural relics has attracted more and more attention from all over the world.At present,the research on engineering problems of large wooden cultural relics involves involve many disciplines such as mechanics,testing technology,materials science,architecture and so on.The department of cultural relics also put forward the demand for instruments,equipment,technology and achievements.Moreover,it is an effective means to carry out the long-term testing and evaluation of historical protection measures.On the basis of the research on the detection/monitoring of Song Dynasty shipwreck in Quanzhou Bay,this paper mainly studies and explores the reliability of Chinese fir board components,which are the main materials used for shipwreck,in the environment of temperature and humidity changes and sound environment and predicts the life of Chinese fir board components under the combined action of these two environmenta The purpose is to provide basic information for the development of scientific and effective testing instruments and monitoring systems.The main contents of this paper are as follows:Because it is difficult to obtain ancient ship wood samples,an effective artificial accelerated aging method is used to simulate the environmental conditions of Chinese fir board components subjected to environmental temperature and humidity for a long time.And the digital speckle correlation method is used to measure aged Chinese fir specimens.It is found that the failure mode of Chinese fir under long-term environmental temperature and humidity changes is radial cracking.And as the number of aging increases,the elastic modulus,Poisson’s ratio and compressive strength of wood are decreasing.The method is proved to be feasible by comparing with the results of previous studies.On the basis of considering the influence of environmental temperature and humidity on the humidity and horizontal grain stress of Chinese fir,the damage accumulation model of wood components is improved..The models for the relationship between the moisture transverse stress and the transverse tensile strength of Cunninghamia lanceolata varying with time was obtained by experiments.According to the improved model calculation,the annual damage of Chinese fir board components in the environment of temperature and humidity changes of Quanzhou Bay Shipwreck Museum of Song Dynasty is 1.25×10-3.Based on this study,it is determined that the appropriate environmental relative humidity of the hull is in the range of 68%-72%,and the damage per year of the board component is only3.3×10-4.The modal analysis of artificially accelerated aging Chinese fir board component is carried out by using finite element theory.The acoustic-vibration coupling calculation of Chinese fir board component is carried out by using boundary element theory.According to the theory of vibration fatigue,the damage amount of crack-free Chinese fir board component in one year under acoustic vibration environment is 3.19×10-4.The annual damage of cracked Chinese fir board members under acoustic vibration environment is 1.15×10-3.According to miner’s linear cumulative theory,the residual life of the fir-tree members under the combined action of environmental temperature and humidity and acoustic vibration is predicted.Finally,it was found that the environmental humidity was controlled within the range of 68%-72%,and the cracks of the fir-tree members were filled with the filling material,which greatly prolonged the life of the shipwreek of the Song Dynasty shipwreek in Quanzhou Bay. |
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