How to create correct geometry of coil in Abaqus/CAE?

[mikechy]

Hi,
I try to create a spiral coil (fraction of it) with such parameters:
springRad = 3.835
wireRad = 0.2
helixAngle = 78.2
numTurns = 0.25 (can be any)
and therefore pitch = 2*pi*springRad/tan(helixAngle*pi/180)
by
p.BaseSolidRevolve(angle=numTurns*360.0,
flipPitchDirection=OFF, flipRevolveDirection=OFF, moveSketchNormalToPath=ON
, pitch=pitch, sketch=sketch).
When I drawn a circle centered on (springRad, 0.0), the measured spiral angle is 78.769646, which is not right. In addition, in the reverse calculation, the spring radius is 4.035, which is also incorrect.
If one draw a circle centered on (springRad+wireRad, 0.0), then the angle will be exactly the same as you would like (but the radius is wrong!).
The question is how to create a helical coil with right and desirable both pameters: springRad and helixAngle in Abaqus/CAE? Thanks.

 

[mikechy]

Below is Python code for creating the described springs, maybe this will clarify my question:

from abaqus import *
from abaqusConstants import *

springRad = 3.835
wireRad = 0.2
helixAngle = 78.2
pitch = 2*pi*springRad/tan(helixAngle*pi/180)
numTurns = 0.25

# Correct spring radius but wrong helical angle
sketch1 = mdb.models['Model-1'].ConstrainedSketch(name='__profile__', sheetSize=200.0)
sketch1.ConstructionLine(point1=(0.0, -100.0), point2=(0.0, 100.0))
sketch1.FixedConstraint(entity=sketch1.geometry[2])
sketch1.ArcByCenterEnds(center=(springRad, 
    0.0), direction=CLOCKWISE, point1=(springRad-wireRad, 0.0), point2=(springRad+wireRad, 0.0))
sketch1.ArcByCenterEnds(center=(springRad, 
    0.0), direction=COUNTERCLOCKWISE, point1=(springRad-wireRad, 0.0), point2=(springRad+wireRad, 0.0))
p1 = mdb.models['Model-1'].Part(dimensionality=THREE_D, name='Part-1', type=
    DEFORMABLE_BODY)
p1.BaseSolidRevolve(angle=numTurns*360.0, 
    flipPitchDirection=OFF, flipRevolveDirection=OFF, moveSketchNormalToPath=ON
    , pitch=pitch, sketch=sketch1)
del sketch1

# Correct helical angle but wrong spring radius
sketch2 = mdb.models['Model-1'].ConstrainedSketch(name='__profile__', sheetSize=200.0)
sketch2.ConstructionLine(point1=(0.0, -100.0), point2=(0.0, 100.0))
sketch2.FixedConstraint(entity=sketch2.geometry[2])
sketch2.ArcByCenterEnds(center=(springRad+wireRad, 
    0.0), direction=CLOCKWISE, point1=(springRad+wireRad-wireRad, 0.0), point2=(springRad+wireRad+wireRad, 0.0))
sketch2.ArcByCenterEnds(center=(springRad+wireRad, 
    0.0), direction=COUNTERCLOCKWISE, point1=(springRad+wireRad-wireRad, 0.0), point2=(springRad+wireRad+wireRad, 0.0))
p2 = mdb.models['Model-1'].Part(dimensionality=THREE_D, name='Part-2', type=
    DEFORMABLE_BODY)
p2.BaseSolidRevolve(angle=numTurns*360.0, 
    flipPitchDirection=OFF, flipRevolveDirection=OFF, moveSketchNormalToPath=ON
    , pitch=pitch, sketch=sketch2)
del sketch2

Hope there is someone who can answer to my question. Thanks.