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hiranwale_bharat

Fatigue Load case i/p

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Hello everyone,

 

For defining load in fatigue can I give displacement as in input in the static load case which is defined. I need to give certain amount of displacement for 1 lac cycles which is sinusoidal in nature.

 

Also,how can I give this 1 lac cycles as input? Do I have to manually do it in the .csv file and import it or can I define one sine wave have some kind of repeat command which will repeat the pattern of sine wave for rest of 99999 cycles? (like what is the tab "repeat" is in fatigue manager?)

 

Regards,

Bharat

 

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Hi Bharat,

 

I dont think it is possible to have displacement based fatigue as the life prediction methods are stress based.

 

Do you see NC in MATFAT card?

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Bharat,

 

Yes, but comment 2 says " Repeat number (N#) has no effect on the results of a Factor of Safety (FOS) analysis"

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@Prakash Pagadala

I did not get this point: 

Yes, but comment 2 says " Repeat number (N#) has no effect on the results of a Factor of Safety (FOS) analysis"

If you are not interested in results you can go ahead for only life prediction.

 

I did fatigue analysis on a component by both methods:

1. By increasing the number of cycles in .csv file

2. By changing N# (number of repeats in FATSEQ)

 

Results by both the methods are same i.e. Life and damage o/p is same.

Optistruct fatigue does not give any other o/p except these two stated above. How do we calculate FOS analysis?

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@bhumkaromkar

 

Have you included torision fatigue limit, hydrostatic stress  sensitivity value which are required for FOS in MATFAT?

 

Also, include the Dang Van criteria under FATPARAM. You need to add this manually in text editor.

fos2.PNG

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