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Title: Advances in the deep-hole drilling technique for residual stress measurement
Author: Kingston, Edward James.
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2004
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Most engineering components contain defects (e. g. cavities and cracks) which are usually generated during the manufacture process. During the service life of the component it is possible that the defects could grow leading to ultimate failure of the component. For safety critical engineering components, such as those used in nuclear power plant systems, rail track systems and aerospace systems, ultimate failure is not permitted. To eliminate failure, the structural integrity of the component is assessed using knowledge of both the applied and residual stress distributions present. The applied stress distributions are calculated, whereas the residual stress distributions are measured using methods like the deep-hole drilling technique. The deep-hole drilling residual stress measurement technique was investigated to increase its accuracy and reliability in measuring the residual stress distributions present within components. It is a semi-invasive technique that involves drilling a small hole through the component and then the accurate diameter measurement thereof. A cylinder of material containing the hole is then extracted from the component causing the hole to deform due to the relaxation of the residual stresses present. The hole diameter is then re-measured and the change is used to determine the pre-existent residual stress distribution. The applicability of the technique was extended through modifications made to the machining processes, to include both thicker and thinner components. The accuracy of the measurements recorded and analysis thereof were improved. A portable machine was made to carry out "on-site" deep-hole drilling residual stress measurements on large components. Calibration experiments were carried out on components containing various known stress distributions to test the accuracy and modifications of the technique, and its applicability to different materials. Finally, an extensive set of residual stress measurements were undertaken on different components varying in geometry and material composition to test the accuracy and reliability of the technique in comparison with alternative measurement methods.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available