| The Song Dynasty Shipwreck in Quanzhou Bay is an earliest and biggest ancient shipwreck in China which was protected completely.The discovery has great academic value to do research on history of overseas traffic,shipbuilding,nautical and external relations.However,because of the display in open environment for many years,the hull of the shipwreck has many diseases,such as crack,rotten degradation,warping and discoloration.So how to keep The Song Dynasty Shipwreck in Quanzhou Bay stability for long time is a major problem which is needed to be solved urgently.According to this,the subject is trying to use testing technology,computer image processing technology and dynamics knowledge to develop a monitoring system.The system is used to monitor structural stability of The Song Dynasty Shipwreck in Quanzhou Bay.In order to develop the monitoring system,it is important to make clearly of the stability of The Song Dynasty Shipwreck in Quanzhou Bay timber(ancient timber)in different environment firstly.At first,the paper calculated fiber saturation point of ancient timber.And then it was focused on testing hygroexpansion in different timbers based on digital speckle method.The paper is to contrast the differences of physical property between modern timber and ancient timber,especially the ancient timber that soaked in seawater.So the paper chose modem timber and ancient wood as test material.Modern timber is divided into healthy timber,waterlogging timber and brinelogging timber.At last,the paper made a preliminary research on testing out-of plane displacement of timber based on digital speckle method.The results of the research show:(1)Fiber saturation point of ancient timber is 44%.It is bigger than modern timber.(2)During the process of hygroexpansion in timber,the relationship between moisture content of timber and humidity is a positive correlation.(3)The transformations of timbers are affected by many factors.They have obvious humidity effect,time effect,size effect and medium effect.(4)During the process of hygroexpansion in ancient timber,displacements in radial and tangential direction are quite different.Radial displacement is bigger than tangential displacement.(5)According to periodic change of humidity experiment,the best humidity to preservation ancient timber is 55%.(6)Digital speckle method can be used to test out-of-plane displacement correctly.According to the result of ANSYS,the error of tests is 1%.And with the increase of moisture content,the out-of-plane displacement will increase. |
