Hii everyone,
I tried calculating PSD moments my own for damage calculation and want to compare the hyperlife tool results.
I exported PSD stress vs Freq plot for an element. I used statistics in hypergraph it gave the area under curve as 5201.201 which is essentially M0.
using the rectangualr integration formula given by altair,
I calculated n as 0, the value i got is 4812.972.
then I got the value as 5201.201 exact as using trapezoidal integration,
Please clarify me, I'm using steinberg three damage model,
The thing is when i calculate moments using rectangular integration the number of cycles for 1sigma is 31.76 and RMS stress is sqrt(4812.972) is 69.376 MPa.
by using trapezoidal integration the number of cycles for 1sigma is 31.91 and RMS stress is sqrt(5201.201) is 72.11 MPa.
I tried PSDM, the Nzcross is 46.53176 so no.of cycles is 31.78 and RMS stress is 72.11 MPa
The report given by hyperlife tool is 31.6743 cycles for RMS stress 72.365 MPa.
Please clarify me, if i use rectangular integration in altair help the RMS stress wont match, but the trapezoidal integration isn't given in altair.
