# relations

#### rajneesh

##### New member
I am not able to utilize the full functionality of using relations in pro/e apart from setting dimensional relations.

If anyone can send me some models or tutorials or sitelinks explaining the advanced usage of relations.

my email id is :

[email protected]

#### rajneesh

##### New member
for jason this time,

jason it seems that they are not able to explain use of relations in part and assembly modelling. i request you to please help me understand them in detail.

#### dougr

##### New member
Relations are used to set up relationships/dependencies between different dimensions.

As assemblies tend to have only a few dimensions, relations ten to be of limited use here so they are only really useful in part mode.

There is extensive information in your help guides, you may want to search on some terms:

relations

system parameters

parameters

You can also enter constants and expressions like:

pi()

r1*sin(theta)

Again, just take the time to look thru your help..

#### rajneesh

##### New member
is it possible to create a parametric 3d datum curve using relations? please explain how.

#### dougr

##### New member
You can create a datum-curve from equation...

#### Rajesh

##### New member
Create datum-curves from equation as follows (of course there are many more)

1. ELLIPTICAL CURVE

Cartesian coordinate system

XOR = 'overall size in y'

YOR = 'overall size in x'

x = XOR / 2 * cos ( t * 360)

y = YOR / 2 * sin ( t * 360)

z = 0

2. SPIRAL CURVE

Cylindrical Coordinate system

TURNS='number of turns'

r= IR + t * (OR-IR)

theta=t * 360 * TURNS

z=0

3. Wavy Spiral

change z to z='size of wave'*sin(360*t*'no of waves')

4. Helical Curve

Cylindrical coordinate system

r=IR + t * (IR-OR)

theta=t * 360 * 'no of turns'

z='height' * t (or pitch * no of turns * t)

o Helical Curve

Cartesian coordinate system

x = XOR * cos (t * 360 * 'no of turns')

y = YOR * sin (t * 360 * 'no of turns')

z = t * 'height'

o TAPERED HELIX

change r to r= IR+t*(OR-IR)

o WAVY HELIX

change z to z='height' * t + 'size of wave' * sin(360 * t * 'no of waves')

1. ELLIPTICAL HELIX

Cartesian coordinate system

XOR = 'overall size in y'

YOR = 'overall size in x'

x = XOR * cos ( t * 360 * 'no of turns')

y = YOR * sin ( t * 360 * 'no of turns')

z = 'height' * t

2. WAVY CIRCLE

Cylindrical Coordinate system

theta=t * 360 * TURNS

t='size of wave' * sin(360 * t * 'no of waves')

3. Weird Curve

Spherical Coordinate System

rho=360*8*t

theta=360*t*4

phi=-360*t*8

4. Astroid

Cartesian Coordinate System

x=10*cos(t*360)^3

y=10*sin(t*360)^3

z=0

5. Cochleoid

Cylindrical Coordinate system

theta=5*t*360+.01

a=1

r=a*sin(theta)/theta

z=0

6. Epicycloid

Cartesian Coordinate System

a=8

b=5

x=(a+b)*cos(t*360*8)-b*cos((a/b+1)*t*360*8)

y=(a+b)*sin(t*360*8)-b*sin((a/b+1)*t*360*8)

z=0

7. Witch of Agnesi

Cartesian Coordinate System

a=100

x=a*(10*(t-0.5))

y=a/(1+(10*(t-0.5))^2)

z=0

8. Hypocycloid

a&n are variables

a=10

n=10

x = n*a*cos(theta) + a*cos(n*theta)

y = n*a*sin(theta) - a*sin(n*theta)

9. Rose

theta=t*360

p=2

q=1

r=Cos(p/q*theta)