Table Formulas

[LtSnikch]

Hello there,

I am relatively new to MSC Marc / Mentat and I'm having some difficulties applying a load using a spatial distribution.
Since the load is dependent on the nodes' x0 and y0 coordinates, I attempted to apply the load using a table, containing 2 independent variables (x0, and y0).

Unfortunately, the analytical description of the load results in a formula far too large for the formula editor, resulting in 'ERROR: Formula too long!'
To circumvent this, I split the formula up in seperate parts, defining each part as a paramter (for example: P1, P2 and P3(P1,P2)) and combining them in the formula entry (P3*dsin(15)). This results in a correct evaluation when creating the table's formula.

However, after creating the loadcase and running the corresponding job, I get the following errors at these combined formulas:
*** - error - expression cannot be evaluated

I'm not sure whether the program just doesn't transmit the defined parameters to the job, and therefore being unable to solve the formula P3*dsin(15) since P3 is unknown.
Or perhaps that the combined formula is still too long to evaluate. Either way the formula is too long and I'm not sure how to go about this (tried using table multiplication but unfortunately this is not possible with the current formula).
Anyone got any ideas on how I may be able to enter longer formulas for the tables, or how to use the correct parameters in the solver if this is the issue?

Thanks for any pointers!

Gr,
Lt

 

[Itap]

Maybe you can use a usersubroutine like FORCEDT.

 

[LtSnikch]

Hi Itap, thanks for the reply.
I'll have to look into writing user subroutines but from what I've found I'm afraid that's got to be the way to go about it.
Does anyone have a reference to writing these subroutines perhaps? Would help a great deal.
Thanks again

 

[hezhj2000]

There are some examples with user subroutines. Check User Manual Volume 5. For your problem, you might also want to use some other tools to create a table externally, and import it into Mentat. In this way, you are not providing an analytical expression, but a discrete table.

 

[hezhj2000]

Forgot to mention, you need to have Intel Fortran to use user subroutines.