Displacement dependent surface pressure/traction

[ebdoep22]

I need to be able to model pressure loads on a surface which change with displacement. As a simple example imagine a cantilever beam with tip load which does not change pushing down. This motion is resisted by a pressure load on the bottom surface which is a function of displacement in the y-direction. For instance the pressure load could be press=Y^3 so initially there is no pressure on the bottom surface, but once it is displaced the pressure would increase cubic with y-dir displacement, and an equilibrium would be found between the tip load down and variable pressure surface up. In a away this would be like attaching a nonlinear spring, but continuously across the surface.

I know how to apply a distributed load on a surface using an expression and surface tractions, but it only evaluates the surface position at the beginning of the step and does not change the applied surface as the structure deforms.

 

[burningDiesel]

You can look into the DLOAD user subroutine, it has the current COORDS as variable, so you can use that one for position

 

[ebdoep22]

So I see that DLOAD does contain COORDS which seem to update to the current position in a nonlinear analysis, this is what I need. However is there a way to do this in CAE? I know I can apply a pressure load and specify User-Defined in CAE, which it then says that a DLOAD routine must be attached. I am confused on how it expects me to do this?

 

[burningDiesel]

You need to write the DLOAD subroutine in fortran and run it together with the simulation (eg user=dload.f)

 

[ebdoep22]

Is there an example of this somewhere? I know some about CAE and the Abaqus Python script but nothing about Fortran. I find it a little hard to believe with all that CAE can do, you can't setup a simple displacement dependent pressure force. This is kind of a first order effort at a fluid structures interaction problem, where the more something deflects in a flow that more surface pressure there is.

 

[ebdoep22]

So after doing some more research is does look like DLOAD or DSLOAD is my best option. But what I can't figure out is where do I find the correct FORTRAN compiler, apparently everyone is saying Abaqus is really picky about it, I am using 6.12.

 

[ebdoep22]

Are there any free compilers that work with Abaqus? Any help is appreciated.

 

[burningDiesel]

you can use gcc/gfortran , you have to edit your .env file after. Google knows how