Monitoring residual stress in machinery using holographic techniques

摘要

We report the development of a nondestructive portable holographic technique for the detection of residual stress in materials. The technique we have used to achieve in-situ quantitative measurements is based on real-time holography. While the real-time holography concept has been demonstrated by other researchers, our approach is novel and results in a portable instrument which can carry out in-situ measurements. In all previous techniques for the measurement of internal stress the application of real-time holography had to be carried out on a large vibration isolation table and the results were only qualitative in nature. In the approach we will discuss we have used a technique which forces the reference and object wave and the recording material to move together when vibrators are present. In our experiment we have measured the internal stress in an aluminum structure using our holographic technique and find good agreement between our measurement, a measurement taken using a strain gauge, and computer simulations. The experiment was performed without vibration isolation using a HeNe laser, thermo-plastic holographic camera, and a small hole drilled in the aluminum structure. The two new features of our result are that the technique is portable and can be used in real situations and the technique provides quantitative, as opposed to qualitative, measurements of residual stress. As a results, the instrument can be used to monitor the development of residual stress in machinery.