axially varying pressure load - Help please

[mvp23]

Hi , I have my problem described along with a figure (see attached) .

I was told to assume a linear profile for the pressure distribution and based on the values of pressure at the trailing edge ( 0 pa) and leading edge(1000 pa) , I obtained an expression for the pressure distribution .

pressure distribution = 1543.9 * Y (Y is along the length).

So , when I created my Analytic Field (named Axial_pressure) , I entered 1543.9 * Y in the expression field.

The problem I face is when I apply the Load.
I select '(A)Axial_pressure' from the drop down list and then I don't know what value to enter for Magnitude.

Any help on this topic will be appreciated.

Thank you

 

[tetmesh]

I am working with a non-uniform pressure as well. I understand the "Magnitude" field to be a linear multiplier, basically. If the pressure value is correct in the distribution equation/specification, a magnitude of 1 should suffice. I think. Maybe someone could confirm this.

I have operated under that assumption and the data check passes but the job fails when Abaqus looks for a user-subroutine (DLOAD or DVLOAD). The load editor has all of the information I need to describe the non-uniform field and the pressure vector graphics are correct. That leads me to believe the pressure is alrady defined and a user sub-routine is not actually necessary. Is a sub-routine necessary if the distribution, magnitude and amplitude are defined in CAE as by the original poster? Could the requirement for a sub-routine be left over from code before the CAE method of pressure distribution was available? Thank you.

 

[mvp23]

tetmesh ,

I did not include a user sub-routine when I ran my non uniform pressure analysis.

1. Using the given values of pressure at the leading and trailing edges I obtained a pressure distribution.

2. I created an analytic field based on this pressure distribution.

3. When I apply my load , I reference this analytic field and hence abaqus doesn't ask me to include the DLOAD sub-routine.

4. However , if you directly try to create a 'user defined' load , then you might see a small note appear below the Magnitude box that says " include DLOAD subroutine ".

5. I do not know which is the acceptable method though.

Appreciate your help testmesh