parametric ecuation f(x) in intervals definition

[sara1234123]

Hello everybody.
Since 3 days I am traying something as ''easy'' as drawing a line that follow a given ecuation. Every body tells me taht with catia it should be easy and quick, but I think it is imposible.

the function of my line is:
f(x) = 0 , -100<x<-50
f(x) = h/2 * (cos (2*pi*x/l)+1) , -50<x<50
f(x) = 0 , 50<x<100

where h and l area parametres in have already introduced and x should be values (betwen -100 and 100) and f(x) is the y coordenate.

So far i have created my parametres and I tried to create laws, (fog) which i was able to introduce parametres. The problem is that the law gives to x only values betwen 0 and 1 and I do not know how to tell to the program, please, calculate values of y, taken for x values between -100 and 100!!!

Anybody has any idea? Would be very nice to get a clue how to do this!!
Thanks!
Sara.

 

[Azrael]

I don't know which steps you already have done. I will present a workflow that I would try. When using law (fog)you can in the law editor setup if statements, so in this case I would try:

if -100<x<-50
{
y = 0
}

if -50<x<50
{
y = h/2 * (cos (2*pi*x/l)+1)
}

if 50<x<100
{
y = 0
}

Considering yout -100 to 100 issue, I would actually introduce two new parameters, say A and B, that I create a curve with and also use those parameters in the law statements. ( if A<x<-50 and if 50<x<B)

Use parallel curve and chose the line and the law option to create the wanted curve

 

[sara1234123]

Hello. Thanks for your answer.
I have tried what you told me. but the law editor does not let me to write ''-50<x<50'' gives me error once and again.

After trying everything and reading in the forum, I choosed the option of creating my curve in excel and with a macro export all the points to catia, and then create a spline that joint those points.

It works, but for me is not the perfect solution, since i would like to have a total parametric model in catia. I still think that it is not possible

 

[Azrael]

which release are you using?

 

[sara1234123]

V5 r 18

 

[jackk]

Sara,

once you have this equation defined in CATIA, what will you use it for?

what are typical values for H and L ?

 

[Azrael]

Don't have R18 but I will give it a go on R21. Could you explain what it is for and as Jackk wonder so do I, what values are to be expected for H and L? It's important to undertand how it will be used because you are merging three equations, two linear and a wave form, which will render in an abvious issue that the result may be non-continous.

 

[Azrael]

Didn't got the interval working... either I did something wrong or a limitation? so I created the reference curve for parallel curve function as the interval. But as you see the three different curves have gaps and even if I got the equations set to work I would got problems with the vertical line missing. If you could fill in the blanks about usage I maybe could find another way.

 

[sara1234123]

Hello boys
Yes, this is exactly what happens to me.
The reason for this is that CATIA considers that the values of x are going from 0 to 1 and gives values to the parametre x and calculates y.
there is no way to tell that x goes from a number to antoher. it is allways 0 to 1!

But anyway, I like your way to define the flate lines.

@ Jackk and Azrael, typical values for l=100 and =20mm