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svantevid1-Visitor
1-Visitor
June 27, 2018
Solved

Logarithmic spiral with equation

  • June 27, 2018
  • 1 reply
  • 3064 views

I'm trying to create a Logarithmic spiral in Creo. I used the equation bellow, but the "shape" of the curve I get is not correct (I compared it to a curve from Graph software and calculations of intersection properties with a circle with 129,4mm diameter). 

 

Equation in Creo:

a=1
b=0.3
x=a*exp(b*t)*cos(t*360)
y=a*exp(b*t)*sin(t*360)
z=0

 

Screenshot from Creo:

https://i.imgur.com/tWBBViU.png

Screenshot from Graph software:

https://i.imgur.com/4FsrHMf.png

 

Does anyone know why I cannot get the correct shape? I also tried with polar (cylindrical) csys and get the same results.

 

Best answer by MartinHanak

Hi,

 

use following equations

a=1
b=0.3
n=4
x=a*exp(b*t*2*pi*n)*cos(t*360*n)
y=a*exp(b*t*2*pi*n)*sin(t*360*n)
z=0

 

Note:

In Graph software sin() an cos() functions use values in radians. In Creo sin() an cos() functions use values in degrees.

1 reply

M
MartinHanak24-Ruby IIIAnswer
24-Ruby III
June 27, 2018

Hi,

 

use following equations

a=1
b=0.3
n=4
x=a*exp(b*t*2*pi*n)*cos(t*360*n)
y=a*exp(b*t*2*pi*n)*sin(t*360*n)
z=0

 

Note:

In Graph software sin() an cos() functions use values in radians. In Creo sin() an cos() functions use values in degrees.

S
svantevid1-VisitorAuthor
1-Visitor
June 27, 2018

Martin, thank you very much!

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