Dependent equations

[BPP]

Hello everyone.

I want to express a set of equations as a function of some variables, to evaluate the results according to different input data.

PD: attached the spreadsheet with what I intend to do.

Thanks in advance.

[Werner_E]

One possible way to wade through the problem is to disable the green definitions at the top - you'll get alot of red errors now.

Now go through the whole sheet and wherever you encount an error, turn is into a function of the appropriate arguments, beginning with A.beam(d.beam):=...

When it comes to the solveblocks, instead of

you could use something like

WE

[BPP]

Thanks for the help Werner

I tried to do what you told mebut appear errors and can not find the solution 

[AlanStevens]

Perhaps the attached will help (though there is probably an error in it somewhere!)

Alan

[Werner_E]

> (though there is probably an error in it somewhere!)

Yes, the solve block (function R.AB) doesn't do its job and simply returns the guess values (100 N).

The same is true if we delete the superfluous second line using "Find" in Bryans sheet, which throws the first error in his sheet.

I thought that the reason may be the range variable created in a function and used to sum up. But obviously thats not the case.

I also wonder why a solve block is used as the second equation can directly be solved for R.Ay.

WE

[AlanStevens]

"Yes, the solve block (function R.AB) doesn't do its job and simply returns the guess values (100 N)."

That's odd.  It doesn't do that for me.  Here are the values before and after calling the solve block:

It is odd that both returned values are the same though (or is it?).

Alan

[Werner_E]

> That's odd.  It doesn't do that for me.

Nor does it for me when I tried just now. Don't know why I thought that I get the guesses. Maybe I was in the wrong file - had opened all of them (original, mine and yours) at the same time.

But now I see the very same results your screenshot shows.

> It is odd that both returned values are the same though (or is it?).

Seems to be the nature of the equations involved. I also get identical results for both variables in my sheet where I calculate them directly without the solve block.

Beneath the solve block the definition of function Q uses R.Ay and that would use the guess value. Should be replace by the appropriate function R.Ay(..).

Werner

[AlanStevens]

"Beneath the solve block the definition of function Q uses R.Ay and that would use the guess value. Should be replace by the appropriate function R.Ay(..)."

You are right.  Attached is the corrected file.  (Can't say it makes any more sense to me though!)

Alan

[Werner_E]

I worked from Alans sheet and got rid of the solve block, calculating Ra and Rb directly.

Not sure if the rest is correct and which function to maximize.

WE

P.S.: Still not sure why the solve block failed, though.

[BPP]

I made a few small changes in the spreadsheet of "Alan" and get the correct results in some equations.

But when evaluating the last equations, continuos the failure

[Fred_Kohlhepp]

I corrected your moment equation (summing moments at B, but concentrated loads were relative to A)

If you arrange your function definitions below the constant inputs, you don't have to put those constants in as variables in the functions.

[BPP]

Following the advice of each of you I think I've managed to get what I needed, thank you very much to all for the help.