Parametric Equation

[Tvvilight]

Hi!

How can I make a parametric equation in NX.
I'm using NX6. First, I defined a constant expression, named 't' and set to 0. Then I defined an equation like this:

yt=sin(t*pi())-cos(t*pi())*t*pi()

where the type of 'yt' is length.
I want to create a point with Y component value which is calculated by yt function, since the values of 't' will be 0, 0.1, 0.2, 0.3 and 0.4. Hence, I want NX to calculate it automatically. For example, for t=0.4, it would calculate the yt(0.4).
Please tell me how to do this in NX.
Thanks in advance.

And, by the way, Merry Christmas... ;-)

 

[jerry1423]

What are the units of yt and t?

 

[Tvvilight]

The type of 't' is constant, so it has no unit. The type of 'yt' is length and its unit is mm.

 

[man2007]

You need to use Tools->Expressions... for entering the equations like t=0 and yt=sin(t*pi())-cos(t*pi())*t*pi()

As the value of t changes, yt will be recalculated, to change the location of the point.

You can create law curve by using t, yt along with xt & zt.

 

[Tvvilight]

Thanks, but I want to create 5 points with the 't' values 0, 0.1, 0.2, 0.3, and 0.4; Not a curve, and the values of variable 't' will be only these numbers. I mean in Point creation window, in the Y field, I put a formula like yt(0.4) or something else, I don't know; However, I found a function called ug_fieldVarAt() that maybe will answer my question. If so, how? Anyone has worked with this function..?
Thanks a lot...

 

[JohnRBaker]

Not sure what it is that you're trying to accomplish. Are you talking about linking an expression to some external 'data source' which will supply the value of 't'? Or are you talking about allowing the user to enter the value of 't', but limit him to one of the 5 predefined values? Also what do we use for the value of X and Z since a Point require 3 variables?

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

To an Engineer, the glass is twice as big as it needs to be.

 

[Tvvilight]

I'm talking about entering these 5 values myself. Otherwise, I have to define new expressions for each point! Namely, yt1, yt2 & ... for point1, point2, ...

Also, these points are gonna be located on YC-ZC plane. The other one is:

zt=cos(t*pi())+sin(t*pi())*t*pi()

And what about that function I mentioned?

 

[Tvvilight]

By the way, if this can be accomplished by external data source, not entering by myself, then please explain it...
Thanks in advance...

 

[cowski]

Are you defining the equations so that you can easily enter a large number of points? Do the points need to be controlled by expressions for some purpose? Or do you have a file containing point data that you just need to import? Perhaps if we better understand your end goal we will be able to provide better help.

If you have a file with point data you can import that into NX, see thread561-181530 for an example (it is a fairly easy process though not intuitive). It seems like we have had a more recent (and thorough) discussion on importing points, but my searching has not hit on the right key words.

 

[cowski]

Here's the other thread I was thinking about:
thread561-225071.

 

[Tvvilight]

Thank you cowski; Yes, the points need to be controlled by expressions (or by functions which mentioned) and there are only 5 points. My intention is not to make new expressions for each point, 'cause for example, for point3 the 't' value would be 0.2 and for point5 the 't' value would be 0.4...
I'm trying to know that,
is there any way to calculate those 'yt' and 'zt' values automatically by NX Application or I have to make new expressions and assign the values of 't' for each of them like this?

t3=0.2
yt3=yt=sin(t3*pi())-cos(t3*pi())*t3*pi()
zt3=cos(t3*pi())+sin(t3*pi())*t3*pi()

and

t5=0.4
yt5=sin(t5*pi())-cos(t5*pi())*t5*pi()
zt5=cos(t5*pi())+sin(t5*pi())*t5*pi()

and etc...

By the way, I can do this in CATIA via yt.Evaluate() function in Law Editor window.

 

[cowski]

To the best of my knowledge you cannot make a 'user defined function' for use in an expression. When you use the parametric equations based on 't', the value of 't' varies from 0 to 1 and all the values are passed to the parametric equation. The result is a curve, you cannot feed it individual values to get points.

What if you use the parametric equations to define a curve then space datum planes along the curve (possibly controlled by expressions) then your points would be the intersection(s) of the datum planes and the curve?

 

[Tvvilight]

Thanks, but it doesn't make any difference. 'cause you have to control those planes with 'yt' and 'zt' functions again! Unless you have another idea...

Also, please someone explain the ug_fieldVarAt() function in NX6. There's no example of this in the Documentation...

 

[Tvvilight]

I solved the problem by myself. Thank everyone...

 

[JohnRBaker]

Well!!! Tell us what you did to solve the problem, eh?

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

To an Engineer, the glass is twice as big as it needs to be.

 

[Tvvilight]

I'll post a helpful tip relating to the subject of this topic soon... ;-)