Development of residual stress evaluation method for polymer products using THz polarization measurement

This paper proposes to utilize THz polarization measurement to nondestructively measure internal residual stress in polymer products. To verify the validity of the proposed method, a THz polarization measurement system was developed using a difference frequency light source, wire grid polarizers, and FMB diodes. Experimental analyses confirmed that THz polarization had a correlation with polymer orientations and the applied force by measuring these relationships with the developed system. The relationship between THz polarization factor and residual stress was finally investigated, which confirmed that our developed measurement system can achieve nondestructive and quantitative evaluation of the internal residual stress in polymer.