bending moment due to ship motion

[NAVMAR]

any one know how to calculate wave induced bending moment due to ship motion, i found that ship motion module in maxsurf package produce wave spectrum using linear strip theory, any one know how to get bending moment from that , and is there any programs to calculate it?

 

[TANSL]

I think, I can not say because I am speaking from memory, that Maxsurf is prepared to calculate the distribution curve of the bending moments along the length of the boat. But for this, Maxsurf and any other application, requires that you give the weight distribution. That can not be deducted by any software.
If Maxsurf gives the curve of thrust due to the wave, you can use it for superimposing the weight curve and calculate the bending moments at each point.
To calculate the variation of this curve "due to ship motion", if indeed this is what you want to calculate, you'll need a lot of help. It is best that you estimate the worst case, it will be with the crest of the wave in the middle of the boat or at the ends, and you figure that one condition.

 

[NAVMAR]

first thanks TANSL for your reply
i know that ship loads is divided into static and dynamic loads one is from still water and ship weight and one is from ship motion, the bending moment i mean here is due to ship motion [pitch motion] do you have any idea about how to calculate it?

 

[TANSL]

I apologize because I have probably tried to explain things that you had not asked nor needed explanations.
I do not know how to calculate those forces of inertia, I've never done. But I have great faith in the rules of Classification Societies. Always give instructions and formulas for calculating these things. Check the ABS, I seem to remember having studies on these issues. I am attaching an ABS file speaking of these movements and efforts on container ships.
Good luck

 

[NAVMAR]

Thanks Tansl I work on it when i catch it i will proceed by posting it