PASS/NOZZLE-FEM 3.5. Program Manual

5.8. Design by Analysis

The section introduces assessment of specified codes that are implemented by PASS/NOZZLE-FEM. These are based on the elastic stress analysis.

Note, the use of elastic stress analysis combined with stress classification procedures to demonstrate structural integrity for heavy-wall (R/t ≤ 4) pressure-containing components, especially around structural discontinuities, may produce non-conservative results and is not recommended. The reason for the non-conservatism is that the nonlinear stress distributions associated with heavy wall sections are not accurately represented by the implicit linear stress distribution utilized in the stress categorization and classification procedure. The misrepresentation of the stress distribution is enhanced if yielding occurs. For example, in cases where calculated peak stresses are above yield over a through thickness dimension which is more than five percent of the wall thickness, linear elastic analysis may give a nonconservative result.