Accumulated Fatigue Damage based on measured wave data

[wojcz]

Hi all,

I am working on a project regarding re-certification of a drilling riser. I need to estimate accumulated damage based on measured wave data. I am not sure how to approach it because, for example I have a measurments for particular riser configuration for, let say 5 days, in 12 hour intervals. For some instances there are no available data. So for example:

1. Hs1, Tp1, 12 hour
2. Hs2, Tp2, 12 Hour
3. N/A
4. Hs3, Tp3, 12 hour
5. N/A
6. Hs1, Tp1, 12 hour
.
.
.

How can I calculate damage accumulated during these 5 days of operation? Should I construct a wave scatter diagram (not sure how to obtain probablities of occurance based on such data), then estimate damage per year and use it to estimate 5 days accumulated damage?

If I have data for each 12 hour interval I think i could estimate damage per year for each Hs, Tp configuration and then for 12 hour duration and sum it all. But how to cope with "blank" period of N/A? I will be grateful for any advice in this topic.

 

[PersonalProfile]

I propose those in the know would be able to provide more qualified guidance, however this may be of interest:

https://journals.tdl.org/icce/index.php/icce/article/viewFile/3179/2843

Regards,
Lyle

 

[PersonalProfile]

I omitted to mention it earlier, though the following reference also provides some guidance regarding analyzing data.

http://www.booktopia.com.au/fatigue-of-structures-and-materials-jaap-schijve/prod9781402068072.html

Regards,
Lyle

 

[wojcz]

Hi, thank you for your response. I will take a look on the reference you have mentioned.