Automatic stress measurement by integrating photoelasticity and spectrometry

Abstract

By integrating the white light photoelasticity (WLP) and spectrometry, a novel stress measurement method called transmissivity extremities theory of photoelasticity (TEToP) has been recently developed. The key of TEToP is to establish the systematic three-dimensional relationship of transmissivity with stress and wavelength (3DRoTwSW) and further derive the stress quantifying formula (SQF). Based on the high resolution and sensitivity of the spectrometer and the high measurement accuracy of the WLP, in contrast to the traditional photoelasticity, TEToP can measure the low level stress even in low birefringence materials. However, until now, TEToP has not been used in higher level stress measurement. The primary purpose of this paper is to extend the application of TEToP to higher level stress measurement. By analyzing the 3DRoTwSW, the correlation between different transmissivity extremities linear equations (TELEs) can be proved definitely and the feasibility of the development of TEToP on automatic stress measurement can be further confirmed. Furthermore, the measurement results of the specimens with different thicknesses were investigated. By exploring the connection between the parameters in TEToP and thicknesses of specimens, the SQFs of different thicknesses can be further derived. In this paper, both glass and PSM-1 were used to verify the generality of TEToP.