Experimental stress analysis is an important complement to the computational techniques used in the structures group. The results obtained can directly measure the deformation that a structure is undergoing. The experimental stress analysis lab uses a variety of techniques to directly measure stress and strain in structure under load. Current techniques used include: Strain Gauges and Extensometry, Automated Photoelasticity, Shadow Moiré, Fuji Pressure Sensitive Film, and others. Some of the newer techniques that are being investigated include: Digital Image Correlation (DIC) and Electronic Speckle Pattern Interferometry ESPI.
In this work, two experimental stress measurement techniques are used to measure stress concentration at a hole in a hollow shaft subjected to torsional and bending loading. The results are compared to a computational stress analysis results obtained by using finite element software. The two experimental techniques, namely, are rosette strain gage measurement technique and 3D electronic speckle pattern Interferometry technique (ESPI).
Stress concentration measurement at holes boundaries in different structures is not a new subject. There are a lot of work done in this area, so the purpose of this work is not to find the stress concentration at the hole boundaries in the shaft. The purpose is to compare the new ESPI technique measurement results to the traditional strain gage technique measurement results, and verify these results by looking at the finite element analysis results. In addition, this work will show the accuracy and the advantages of the ESPI technique and how powerful it is in comparison with the rosette strain gage technique.