Why coords are not nodes in process "DFlux" ?

[truongthinhs]

I am working with Dflux in BODY FLUX. I have data file with coordinates of nodes and values of flux at the nodes. I write the subroutine "Dflux" to read data, then I defined that coordinates at nodes are not equal with COORDS(3)(Integration point) getting from modeling.
Ex: I meshed model with length = 5 (mm).
Point node cordinate: (50, 50, 45), but the integation point: (49,49,44).

Now I dont know what I do. Do You help me? Thanks

 

[xerf]

Maybe you should try to find a good fitting function based on the values you have.

 

[truongthinhs]

Dear Xerf.

I have read your reply. I have just worked at Abaqus in some days. I dont know much about it. Please, decribe clearly. Abaqus gives data of element nodes. They differ from nodes processing in Body Flux (Subroutine DFLUX). What do I do now?
where Can I read or find Fitting Function?

Thank Xerf very much!

Sincerely!

 

[xerf]

If you have a field of values at nodes and you need the values of the field at integration points for a user subroutine you have to use interpolation to approximate the values at the integration points. One solution is to create a function: either an interpolation function or fitting function based on the values at nodes.

This has nothing to do with ABAQUS.

How to construct interpolation functions and fitting functions is described in common textbooks on numerical analysis , numerical methods etc.

A simple 1D example: if you have the values v1, v2 at 2 points x1 and x2 respectively and you are interested in the value v at a point x, with x1<x<x2, then you can interpolate linearly between the values v1 and v2.

The same approach can be used for 2D, 3D.

 

[truongthinhs]

Thanks Xerf!