	Applies To
	Product(s):	AutoPIPE
	Version(s):	2004, XM, V8i, CONNECT;
	Area:	Calculations
	Original Author:	Bentley Technical Support Group
	Date Logged & Current Version	Nov. 2015 10.00.00.10

Problem:

A Class 1 NB fatigue analysis. I've specified 4 temp cases, along with the number of cycles. Within the output report, it shows autopipe going thru the iterations, however, at the end, for the summary of usage factor, it only shows the usage of the highest alternating stress range, and not the remaining stress ranges. why?

Solutions:

The reason there are different numbers of lines and sometime no entries in the summary table is because the alternating stress value for the load pair becomes so small that it is beyond the end of the curve. The allowable cycles are >10^6 for Austenitic steel so getting very high. There were some recent extensions to the curves, increasing the number of cycles The development team will be meeting to discuss removing or reducing this limit value. It is a legacy limit and was likely introduced to reduce run time and output size with non significant entries when computing speeds were much slower.

If you would like to get more entries in your fatigue summary and want to take the analysis beyond the 10^6 limit of the default ADLPipe fatigue curves, then select one of the later curves that go up to 10^11. The default curves have hard stops at 10^6 (the limit of the curves pre 1983) and the alternating stress values less than 26200psi (Austenitic) and 12250psi (Carbon) are not considered.

Q. Class 1 NB fatigue analysis, results shows the usage of the highest alternating stress range, and

Problem:

Solutions:

See Also