Terahertz non-destructive testing technique based on the thickness of the adhesive layer of aerospace ceramic glued structural parts estimation method

Precision ceramic bonded structural parts have an irreplaceable position in the aerospace business and are widely used in various industries due to their various advantages, but at the same time, the uneven thickness of the adhesive layer will affect the quality of ceramic adhesive structural par. In this paper, terahertz time-domain spectroscopy is used for nondestructive detection of the adhesive layer inside the sample, and the thickness information is reconstructed from the experimental data using an autoregressive spectral extrapolation method based on improved covariance, and the difference in the time of flight of the echoes on the upper and lower surfaces of the adhesive layer is used to find the thickness of the adhesive layer. This paper analyzes the thickness of the adhesive layer of 0.5mm and 1mm respectively, and finally gets the error rate of 7.2% and 6.3%. This error rate is basically in line with the quality of the product and provides reliable technical support for the aerospace business.