Residual stresses are “locked-in” within a material, and exist without any external loads.
Such stresses are developed during most common manufacturing processes, for example
welding, cold working and grinding. These “hidden” stresses can be quite large, and can
have profound effects on engineering properties, notably fatigue life and dimensional
stability. To obtain reliable and accurate residual stress measurements for uniform and
non-uniform stress states, a novel and practical method using crossing-slitting and ESPI
is presented here. Cross-slitting releases all three in-plane stress components and leaves
nearby deformation areas intact. The ESPI (Electronic Speckle Pattern Interferometry)
technique gives an attractive tool for practical use, because measurements provide a large
quantity of useful data, require little initial setup and can be completed rapidly and at low
per-measurement cost. A new ESPI setup consisting of shutter and double-mirror device
is designed to achieve dual-axis measurements to balance the measurement sensitivities
of all in-plane stress components. To evaluate data quality, a pixel quality control and
correction procedure is also applied. This helps to locate bad data pixels and provides
opportunities to correct them. The measurement results show that this procedure plays an
important role for the success of residual stress evaluation. Based on the observed
displacement data and finite element calculated calibration data, an inverse computation
method is developed to recover the residual stresses in a material for both uniform and
non-uniform cases. By combining cross-slitting and ESPI, more reliable results for the
three in-plane residual stress components can be obtained.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU./5028 |
| Date | 11 1900 |
| Creators | An, Yuntao |
| Publisher | University of British Columbia |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | 1921448 bytes, application/pdf |
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