P J Bendeich

The Role of Plasticity Theory on the Predicted Residual Stress Field of Weld Structures

Constitutive plasticity theory is commonly applied to the numerical analysis of welds in one of three ways: using an isotropic hardening model, a kinematic hardening model, or a mixed isotropic-kinematic hardening model. The choice of model is not entirely dependent on its numerical accuracy, however, as a lack of empirical data will often necessitate the use of a specific approach. The present paper seeks to identify the accuracy of each formalism through direct comparison of the predicted and actual post-weld residual stress field developed in a three-pass 316LN stainless steel slot weldment. From these comparisons, it is clear that while the isotropic hardening model tends to noticeably over-predict and the kinematic hardening model slightly under-predict the residual post-weld stress field, the results using a mixed hardening model are quantitatively accurate. Even though the kinematic hardening model generally provides more accurate results when compared to an isotropic hardening formalism, the latter might be a more appealing choice to engineers requiring a conservative design regarding weld residual stress.

Seismic analysis of the HIFAR nuclear reactor secondary coolant pipework and associated inlet and outlet headers

A seismic analysis was carried out to examine the integrity of the secondary coolant circuit within the reactor containment building for the HIFAR reactor located at Lucas Heights. Eigen evaluations of the structure for the first 40 modes were determined for a number of piping configurations. A response spectrum for a 0.2g earthquake was then used to excite the structure and the resulting stresses were examined for areas of potential failure.