Hello everyone,
We are currently working with Shell Seam Weld Fatigue Analysis in nCode DesignLife and would appreciate some clarification and best‑practice guidance from the community and Altair experts—particularly regarding material mapping and the thickness reference value.
Context
- We are following different available guidelines, including the Volvo Method.
- The material currently applied is Seam‑Steel.
- From the DesignLife help documentation, we refer to the following statement:
“Although the tensile strength of structural steels may vary widely, when welded their fatigue performance becomes very similar, and for this reason generic SN curves may reasonably be used for design evaluation purposes.”
This implies that the generic SN curve approach is appropriate, but we are facing uncertainty when setting the reference thickness for thickness correction. Our structure has thick shells of about 20/30mm and it looks like the correction is too excessive.
Thickness Reference Value – Open Questions
We see differing recommendations depending on the guideline or tool:
- IIW suggests a reference thickness of 25 mm
- BS standards indicate a value closer to 16 mm
- In other Altair products (e.g. OptiStruct), seemingly using the same algorithm, a reference value of 1 appears to be internally converted to 25mm, assuming the original value was defined in inches, Hyperlife has 1mm as default
Because of this, we are unsure:
What is the recommended reference thickness when using the Seam‑Steel material in nCode DesignLife?
Any clarification, recommended approach, or references to documentation/examples would be very helpful—not only for us, but likely for others facing similar questions.
Thank you in advance for your support and insights.
Best regards,
Marco
