Fatigue Material damage recorder

[ozgura]

Hi all,

I want to clarify some issues related with fatigue material damage recorder.
For fiber section elements, the argument that follows after "material" is actually the fiber number. It has nothing to do with the material tag. Indeed, you can use "fiber" instead of "material" in the recorder and you will get the same output. So in the following, 1) and 2) will give the same outputs which will be the damage index of the 1st fiber.

1) recorder Element -xml "Damage1.out" -time -ele 1 2 section 1 material 0.1 damage
2) recorder Element -xml "Damage2.out" -time -ele 1 2 section 1 fiber 0.1 damage

If you want to specify the fiber coordinates instead of fiber number, then you should add one more argument after "fiber" in the recorder such as:

3) recorder Element -xml "Damage3.out" -time -ele 1 2 section 1 fiber 0.1 0.1 damage

In recorder 3), the fiber which is close to the center of the element will be recorded as the coordinates are close to zero.

For a truss element, however, you have to specify the "material" in the recorder command without any tag. If you try to add a tag after "material", it won't work. In the following truss element recorder examples, only option 4) will work.

4) recorder Element -file Damage4.out -time -ele 1 material damage ==> works
5) recorder Element -file Damage5.out -time -ele 1 material $Mattag damage ==> doesn’t work
6) recorder Element -file Damage6.out -time -ele 1 damage ==> doesn’t work

Hope this helps.

[ozgura]

Note that, when fiber numbers are used in the recorder,in the xml output, the fiber locations are the same for the fiber numbers from 0.0 to 0.9, which are for the 1st fiber. Beginning from fiber number 1.0, it switches it to the 2nd fiber. So, for the fiber numbers in the recorder command, we can use integers beginning from zero. The maximum value should be "n-1", where n is the number of fibers in the cross section.

[SophieDecaen]

Hi,
Thanks for this precious information.
What does the 1 mean before "material" ?
So if I well understand the 0.1 refer to the fiber, if we want to know how is the behavior of all the fibers when there is a failure, what will be your advice ?

Thank you

[fmk]

element 1

[SophieDecaen]

Ok thanks,
I use this in a static analyse and it was workin gpretty well
but I use the same in a non linear analyse and I get realy wierd stuff it goes from very close to zero to something more important than 1, like 3 or 10 in just on step. It was not gradual...
I notice with the navigator, it is not exactly write the same. For instance,

recorder Element -xml "Damage2.out" -time -ele 1 2 section 1 fiber 0.1 0.1 $Mattag damage

Matag refering to the material of the element. Is it this kind of line I should use to get correctly the damage ?

Thank you for your help

[fmk]

that example is for a different element (disp beam column or force beam column (nonlinearbeamColumn)) or possiblky a truss that was created with a section as opposed to a uniaxial material.

[SophieDecaen]

I am sorry but I do use a nonlinearBeamColumn, and it gives me a number close to zero and the second after a number more important that one. My fatigue material is applied on a Steel02.
The thing is I don't understand how the damage recorder can go to a number bigger than 1 whereas it is kind of not possible by definition... and more over I expected something gradual like in the static analyze I can't get in a dynamic analyze.

Do you have an explanation ?
Thank you for your help.

[nilz]

Dears Ozgura and FMK,

How to determine the fiber numbers in a section?
desertemerland@yahoo.com

Sincerely yours