NEW ASME VIII div2 2007 changes - Part 5 Design by Analysis
NEW ASME VIII div2 2007 changes - Part 5 Design by Analysis
(OP)
See 5.3.2 in the new code.
for "Protection Against Local Failure":
"The sum of the local primary membrane plus bending principal stresses" are compared to 4*S.
Whenever working with membrane stresses and ANSYS, I have used PLSECT to get the membrane stresses ACROSS A SECTION. Has anyone determined how to get the "membrane plus bending PRINCIPAL stresses" at every point in an FEA model (using ANSYS) so that the sum of these principals at the worst node can be compared to 4*S?
I look forward to discussions about this new Part 5.
for "Protection Against Local Failure":
"The sum of the local primary membrane plus bending principal stresses" are compared to 4*S.
Whenever working with membrane stresses and ANSYS, I have used PLSECT to get the membrane stresses ACROSS A SECTION. Has anyone determined how to get the "membrane plus bending PRINCIPAL stresses" at every point in an FEA model (using ANSYS) so that the sum of these principals at the worst node can be compared to 4*S?
I look forward to discussions about this new Part 5.





RE: NEW ASME VIII div2 2007 changes - Part 5 Design by Analysis
So a thing that's unclear to me is whether the new code refers to primary only, or to primary plus secondary stresses.
That said, a membrane plus bending stress is only defined via linearization (see FAQ794-982: How to calculate the membrane and bending stresses in a section), so, if I'm not badly mistaken here, the maximum of the algebraic sum of the principals may only be at one of the two faces of a section, just like for stress intensities.
Hence the calculation is done with exactly the same methods.
Note also that I never found a situation where that rule was controlling: could be only where a state of very high compression is present, e.g. in a vessel wall highly pressurized from both sides.
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