One of the many challenges in the behaviour of structures is to understand if the presence of residual stress plays an important role in contributing to failure of a structure operating at high temperature. Structural integrity assessments of components operating at high temperature require an accurate prediction of the creep crack initiation. In general, assessments are based on experiments carried out using standard laboratory scale creep test specimens tested under either displacement or load controlled conditions. In practice, structures are subjected to combinations of residual and applied stresses which in turn lead to mixed boundary conditions. Conventional laboratory creep tests do not represent these circumstances. This dissertation considers the effects of elastic follow-up , long-range residual stress and applied load on creep crack initiation of Type 316H stainless steel. Novel test rigs are designed for the purpose of investigating. The concept of rig is based on a three bar structure with an initial misfit introduced into the central bar to represent a long range residual stress and could be characterised easily without using time consuming residual stress measurement techniques. Initial results demonstrated that the magnitude and the interaction of the residual stress with the applied loading is a function of the initial misfit displacements and the relative stiffness of the components of the system. Additionally, the subsequent behaviour of the system, with and without the application of additional loading, is governed by (a) the degree to which the misfit is accommodated by plastic and creep strain and (b) the elastic follow-up provided by the system.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:649366 |
| Date | January 2014 |
| Creators | Shirahatti, Anilkumar |
| Publisher | University of Bristol |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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