Measurement of structural stresses using hole drilling

• Main Author: Harrington, Joshua S.
• Language: English
• Published: University of British Columbia 2015
• Online Access: http://hdl.handle.net/2429/55049

From a measurement standpoint structural stresses can be divided into two broad categories: stresses that can be measured straightforwardly by adjusting loads, e.g., live loads on a bridge, and those that are much more difficult, e.g., gravitational loads and loads due to static indeterminacy. This research focuses on the development of a method that combines the hole-drilling technique, a method used to measure residual stresses, and digital image correlation (DIC), an optical method for determining displacements, to measure these difficult-to-measure structural stresses. The hole-drilling technique works by relating local displacements caused by the removal of a small amount of stressed material to the material stresses. Adapting the hole-drilling technique to measure structural stresses requires scaling the hole size and modifying the calculation approach to measure deeper into a material. DIC is a robust means to measure full-field displacements and unlike other methods used to measure hole-drilling displacements, can easily be scaled to different hole sizes and corrected for measurement artifacts. There are three primary areas of investigation: the modification of the calculation method to account for the finite thickness of structural members, understanding the capabilities and limitations of DIC for measuring hole-drilling displacements, and evaluating the effects hole cutting has on the measurement. Experimental measurements are made to validate the measurement method as well as apply it to the real world problem of measuring thermally induced stresses in railroad tracks. === Applied Science, Faculty of === Mechanical Engineering, Department of === Graduate