Research On Brochure Cultural Relics Detection Technology Based On Coupling Ultrasound

As a kind of writing material,paper has been favored by scholars and writers since ancient times.In ancient times,the widely circulated pen,ink,paper and inkstone,the "paper" mentioned in the Four Treasures of the Study,was rice paper,and it is also the main component of the existing paper cultural relics.The characteristics of non-corrosion and non-discoloration have enabled a series of classical works to be circulated.However,due to the passage of time and changes in the external environment,paper cultural relics have many diseases.Coarsening is one of the most common problems.If not detected and repaired,it will lead to irreversible consequences such as damage and chalking;It is a key indicator of the quality of paper cultural relics,so the detection of its two characteristics is very important.At present,optical inspection and ink drop methods are the general methods to detect the coarseness and wetness of rice paper,respectively.However,optical inspection is easy to cause secondary damage to rice paper and accelerates aging.The drop ink method is greatly affected by human subjective factors and has low detection accuracy.In view of the above problems,this paper uses non-contact,non-polluting Air-coupled ultrasonic detection technology to detect paper cultural relics,and builds a Lab VIEW-based Air-coupled ultrasonic paper detection C-scan system,which realizes Z-shaped high-speed scanning,detection area delineation,Defect location and other functions can accurately and quickly present the scanning results.In order to reduce the influence of electromagnetic noise and the clutter signal in the one-dimensional signal,and improve the signal-to-noise ratio and detection accuracy,EMC filter and arithmetic average filtering method are used to effectively filter out the high-order harmonics in the output current of the driver,which is used for waveform judgment and detection.Imaging processing laid the foundation.According to the different characteristics of different paper fiber content,this paper selects several different thicknesses of rice paper and newsprint for experiments.Experiments show that when a 400 k Hz probe and a scanning speed of 200mm/s are used,the C-scan results can characterize the roughness of rice paper and newsprint with different thicknesses,which is in line with the detection results of GB/T22881-2008 on the roughness of paper.The C-scan images were quantitatively analyzed by means of color histogram and circularity,and the ink wetness of rice paper was characterized in the form of a histogram,which was in line with the test results of GB/T18739-2008 for ink wetness.The above results show that this paper provides some theoretical and practical references for the nondestructive testing of paper cultural relics' coarsening degree and ink wettability.