Weld fatigue life prediction?

Richard Smith

Within my assemblies i need to conduct fatigue life evaluations on both base material and weld lines within HyperLife.

My fatigue environment is random vibration in nature therefore I understand I must utilize an FRF model with PSD input approach.

I note that because of this i can't use the Volvo method (as a PSD input is not an option) so i must use the Weld Certification tool approach (which I understand is an entirely different approach but this is generally preferred for my applications due to its simplicity).

I note that within the Weld Certification tool the only option to evaluate welds within a random vibration environment is to invoke IEC61373 Specification which enables the "Input PSD with FRF" option within the Load Map dialogue.

Without reading this entire specification standard I was wondering how IEC61373 is implemented? Is this specification equally valid for Steel welded structures and Aluminium? Noting that the other option of Eurocode 3 (for Steel) is available (but not for random vibration) but Eurocode 9 (Aluminium) is not available as a spec option?

In other words, can i evaluate both steel and aluminium welded structures within HyperLife under random vibrations conditions using the Weld Certification tool and using only the IEC61373 specification?

Thanks for any assistance.

 

Omar_NDIAYE

Hello Richard,

Yes, the IEC61373 regulation under HyperLife Weld Certification could be used for a Random Vibration fatigue.

This implementation is based on the Steinberg's 3 bands method which is shown in our documentation: https://help.altair.com/hwdesktop/hlwc/topics/fatigue/welds_iec_r.htm.

The SN curve to be provided in IEC method is not stick to any specical specification. You can define SN curves according to Eurocode 3 or another guideline and use it with IEC method.

That being said, if you want to use Volvo approach with PSD loading, this is supported with OptiStruct as you can see in the table available here https://help.altair.com/hwsolvers/os/topics/solvers/os/analysis_fatigue_c.htm.

I hope this helps.

Beest regards,

Omar.