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Nonuniform Load

Nonuniform Load

Nonuniform Load

(OP)
Hi
Does anyone know how to apply a nonuniform load (triangular loadings) on the surface.

RE: Nonuniform Load

Use Subroutine DLOAD

RE: Nonuniform Load

Or for a simpler method, use ABAQUS/CAE V6.6 (which was released about 5 months ago). You can provide a Python expression as your "Analytical Field" and then use this as the spatial distribution for the load.

RE: Nonuniform Load

(OP)
Hi
I looked in the documentation how to use DLOAD under subroutine option, but I still didn't quite understand how to write that subroutine.  Can you help me to start with this DLOAD subroutine, for example, you have a square box 1 x 1 meter and nonuniform loadings will be applied on the right side of the box. Let the top be the reference surface starts at zero height and the bottom surface is 1 meter down.  Thus at zero height the pressure will be 0, as the depth increases the pressure at 1 meter depth will be 18 kPa.  So the pressure is function of depth.

Thank you very much

RE: Nonuniform Load

Presmably you don't have 6.6?

This is your model, with pressure varying from 0, at y=0, to 18 model units, at y=-1 model distance, on the RHS of the model. Let's say that is side 2 of the elements on that RHS.
            Origin
            o--------------           press= 0
            |               |     <-
            |               |     <--
            |               |     <---
            |               |     <----
y=-1      --------------    <-----  press=18

So you need in your inp file

*DLOAD, OP=MOD
ELOAD , P2NU, 0.0

which according to the manual "applies a nonuniform pressure on face n with magnitude supplied via user subroutine DLOAD". Here 'ELOAD' is an element set of elements adjoining that RHS.
Here is your subroutine DLOAD:

      SUBROUTINE DLOAD (F,KSTEP,KINC,TIME,NOEL,NPT,LAYER,KSPT,
     1 COORDS,JLTYP,SNAME)
C
      INCLUDE 'ABA_PARAM.INC'
C
      DIMENSION TIME(2), COORDS (3)
      CHARACTER*80 SNAME
      Y = COORDS(2)
C Interpolate to find distributed load according to y:
      F = -18*Y
      RETURN
      END
    

RE: Nonuniform Load

(OP)
Hi

Thank you very much for your help mrgoldthorpe....
I really appriciated that

Akadet

RE: Nonuniform Load

(OP)
Hi mrgoldthorpe

I just got abaqus 6.6-3 yesterday, and I tired to use analysis field to create nonuniform load.  In the analysis field, the math equation would be Y*-18 to have pressure varying with depth from 0 to -1, but how do you define your magnitude when you select the right side of the rectangle box and pressure and spatial field.  How would abaqus know that is pressure = Y*-18 and how about the magniture just use 1.

RE: Nonuniform Load

akadet,

I'm not sure what you tried, but it should be pretty easy:
1. Create your analytical field (Field-1) and the expression should be Y*(-18.0)
2. Create a pressure load on the appropriate face with magnitude 1 and in the "distribution" pull-down select "Field-1"

The magnitude (=1)that you provide will by factored by the value of the expression at the given local value of Y.

(There is no need for user subroutines with this method)

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