I'd suggest doing a harmonic analysis and determining design changes to minimize the peak response rather than doing a time history analysis to try and simulate the entire event. If you reduce the peak dynamic response, you'll reduce the peak dynamic stresses, thereby increasing your fatigue life.
what dynamic? nonlinear dynamic or linear dynamic modal time history?
what are you thinking the fatigue analysis is going to do for you that you're not going to see in the dynamic analysis?
what do you think causes the damage and failure? let's make sure the study you choose is the right one.
the errors are probalby both related to the length of time you're trying to analyze for.
Running a modal time history. I couldn't import results from nonlinear dynamic into the fatigue study.
The fatigue anaylsis was recommended by a colleague, as we didn't feel like the dynamic analysis would accurately model the full half hour long dwell.
The damage is caused by the excitation of the Mr/10 rev harmonic on the part. The part is essentially two cocentric cylinders with some circular cuts and slots cut into the cylinders to increase the frangibility of the part. The cracks propogate radially from the ends of these slots.
I figure the 97200 seconds used to try to represent the half hour are why this is failing (it takes well over 12 hours to run the study to failure).
Thanks for any tips you can offer.
One solution may be to take the high points of stress which you see from the harmonic test and then create hand calculations for the fatigue.
All the best,
Nick LuysterOnline SolidWorks Simulation Training
The only reason to do a time domain over a frequency domain is if the transient solution matters. I can't imagine your system not reaching steady-state conditions within 30 minutes (although you know it better than I do), so a frequency domain analysis should be sufficient.
Run a harmonic analysis and look at the peak stresses, then use the appropriate S-N curve to determine the allowable number of cycles. Within a 30 minutes test at 54 Hz there will be (roughly) your 97,200 cycles.
The fatigue anaylsis was recommended by a colleague, as we didn't feel like the dynamic analysis would accurately model the full half hour long dwell. > unless you're doing an analysis with nonlinear von mises material in a dynamic analysis, you're not going to see any damage
even with your export to a fatigue, this is just comparing the max stress at a certain location to the SN curve so it may not meet your needs either. like shaun said, run a harmonic and compare with SN curve manually.