Measurement of the three-dimensional distribution of uniaxial stress by terahertz time domain spectroscopy.

This paper presents a method to measure the three-dimensional distribution of uniaxial stress based on Terahertz Time Domain Spectroscopy (THz-TDS). The measurement principle was first established, which combines the computed tomography (CT) method and the photo-elastic effects. A classic filtered back-projection algorithm is adopted to calculate the three-dimensional stress fields from THz-TDS scanning images. Then, in verification experiment, the uniaxial stress distribution in the compressed cylinder and the stretched screw is obtained based on the measurement principle. Finally, the reliability of the proposed method has been verified by comparing the experiment results with the finite element simulation. A reasonable agreement is obtained.