Damage and stress analysis on pipework using thermoelastic stress analysis

In this thesis, a technique that uses the non-adiabatic thermoelastic response from a standard Thermoelastic Stress Analysis (TSA) system to evaluate the severity of damage is proposed. The theoretical basis of the new approach is described. A procedure for finite element simulation of TSA incorporating non-adiabatic behaviour is also developed to be used as a basis to understand the behaviour of the non-adiabatic response around the sub-surface damage. Both TSA and FEA are used to examined severity of the sub-surface flaws in details. It is found that a unique relation between the phase response from TSA and a dimensionless parameter (the ratio between the thermal diffusion length and the ligament length) can be used to identify the level of the contribution that made to the surface material which can then be related to the damage severity in terms of sub-surface stress. In this investigation, attention has been paid to the analysis of damage on the inner surface of a cylindrical section which can not be observed from the outside surface. This means that the approach can be used to determine the damage severity of the internal damage of the pipework or pressure vessel components. As composite materials have been widely used in Marine applications re­cently, Glass Reinforced Plastic (GRP) pipe is employed in pipe network and tubular structure. However; information about strength behaviour and stress analysis in this pipe component is very rare particularly on tee-intersection where the most complex stress occurs. A preliminary study of stress analysis of GRP and steel pipe structure is included in this thesis to demonstrate that TSA technique can also be used on large cylindrical structure component in both composite and metallic pipework structure.