Nondestructive testing of rubber materials based on the reflective terahertz time-domain spectroscopy

With the wide use of rubber as high performance sealing material in aerospace field, an effective nondestructive testing method is urgently needed to detect the product quality and thickness distribution of rubber materials. In this paper, the sample made by rubber material and metal plate bonding was detected by the reflective THz time-domain spectroscopy system. In order to avoid the problem of missed detection due to the pulse width of time domain signal itself, the time domain signal of the system was processed by deconvolution technique, which has effectively reduced the pulse width and improved the resolution of the system. The abnormal area was found by analyzing the test result. Combined with the manufacturing process of the sample, these abnormal area were judged to delamination defects. Through the processing of the flight time information of the timedomain waveform of each point in the test data, the two-dimensional thickness distribution of the rubber part of the sample was plotted under the precondition that the refractive index is known, which realize visualization of thickness distribution information. The study indicate that reflective THz time-domain spectroscopy technology can effectively detect delamination defect and thickness distribution of rubber material.