equation difficulties

[oliebol]

Hey all,

I have some automation problems in IV 10.

In a sketch, I have an arc which I would like to dimension by its arclength, since this variable is my inputvalue.

However, Inventor doesn't seem to have arclength dimensions available in the sketch environment.

So I tried to solve my problem by using an equation which converts an arclength to it's corresponding arcsegment-angle. (in combination with the arcradius)

The mathematical expression for an arcsegment is:

arclength= PI/180*radius*angle, which is the same as:

Angle = (arclength *180 )/(3,141592 *radius )

What goes wrong in IV is that the angle variable is set to [deg] and it's formula has different units like [mm].

How can I make this equation work?


Thanks for your help.


Greetz,


Martin

Unigraphics NX4,NX3,NX2,R17
Inventor 10,9,8,7
Solid Edge 10,9,8
Solid Works 2000,98
Mechanical Desktop 4,3
Autocad 2004DX,2000,R14, R12
Teamcenter 9

 

[btrueblood]

Oliebol,

Not clear what the problem is - do you know angle and radius, such that you can solve for arclength? Your equations are set up to convert from degrees to radians (thus the pi and 180 terms), and if your radius is in mm, the equation calculates an arclength in mm.

 

[oliebol]

Hi btrueblood,

My main problem is that I don't know how to fill in the fields in my equation. when I fill in the value's of my formula manually, I receive the correct answer as result.

When I replace one value [ul] by a variable with for instance [mm], the equationline becomes redcolored which means the formula isn't solving.

For instance:
Angle = (arclength *180 )/(3,141592 *radius )
in value's it is:

Angle [deg] = (10000*180)/(3,141592 *100000)= 5,729 [deg]

when i replace the value 10000 by the variable Arclength [mm] with the same value it looks like

Angle [deg] = (Arclength [mm]*180)/(3,141592 *100000)= ?


Hope that makes it little more readible.


Unigraphics NX4,NX3,NX2,R17
Inventor 10,9,8,7
Solid Edge 10,9,8
Solid Works 2000,98
Mechanical Desktop 4,3
Autocad 2004DX,2000,R14, R12
Teamcenter 9

 

[btrueblood]

I assume you are using the "parameters list" in Inventor to actually define/name/set the variables? When doing so, you also set the default units (e.g. mm, degrees, km, etc.) for that variable. Thus delete the [mm] in your calculation for "angle", and you should get the right results, e.g.:

angle = arclength*180/3,141592/radius

If you are typing the equation into a sketch "edit dimension" box, delete the "angle =" part also.

 

[jozsef]

Hi Martin,

maybe you already solved this little issue... The only problem I can see in your equation is that "180": does Inventor know that's [deg]?

 

[oliebol]

hello Jozsef and Btrueblood,

Sorry for my late response. I forgot about my own thread

Equations are a bit tough to handle in IV. In order to use units correctly within an equation you sometimes have to use a little trick.

In my example above you see that I use a variable Arclength in my formula for Angle. Its unit are different so you have to correct this first to make it work.

Angle [deg] = (Arclength [mm]*180)/(3,141592 *100000)=

should become:

Angle [deg] = (Arclength [mm]/1mm *180)/(3,141592 *100000)=


Still it is not a very nice way to build formulae, but i'm still learning.


Thanks and greetz,


Martin

Unigraphics NX4,NX3,NX2,R17
Inventor 10,9,8,7
Solid Edge 10,9,8
Solid Works 2000,98
Mechanical Desktop 4,3
Autocad 2004DX,2000,R14, R12
Teamcenter 9