title: Abaqus/Python fixed seeding constraints
body: <p>I am working with Abaqus/Python for a finite element analysis. I've got the following problem: I have a 3D domain which consists of a 2D domain containing edges as well as circle segments and which is extuded in the third dimension. Now I want to mesh that domain with the constraint that only one element along the thickness direction has to be used. Following minimal example of an extruded quarter circle in Python code:</p>
  
  <pre><code>from abaqus import *
  from abaqusConstants import *
  import __main__
  
  # Sketch quarter circle
  s = mdb.models['Model-1'].ConstrainedSketch(name='__profile__', 
      sheetSize=50.0)
  g, v, d, c = s.geometry, s.vertices, s.dimensions, s.constraints
  s.setPrimaryObject(option=STANDALONE)
  
  s.ArcByCenterEnds(center=(0.0, 0.0), point1=(0.0, 5.0), point2=(5.0, 0.0),
      direction=CLOCKWISE)
  s.Line(point1=(0.0, 5.0), point2=(0.0, 0.0))
  s.Line(point1=(0.0, 0.0), point2=(5.0, 0.0))
  
  
  # Create part from sketch and extrusion in the depth
  p = mdb.models['Model-1'].Part(name='Part-1', dimensionality=THREE_D,
      type=DEFORMABLE_BODY)
  p.BaseSolidExtrude(sketch=s, depth=0.1)
  s.unsetPrimaryObject()
  session.viewports['Viewport: 1'].setValues(displayedObject=p)
  del mdb.models['Model-1'].sketches['__profile__']
  
  # Mesh
  # Global seeds
  p.seedPart(size=0.35, deviationFactor=0.1, minSizeFactor=0.1)
  # 'fixed' seeding constraint: only one element in thickness direction
  e = p.edges
  pickedEdges = e.findAt(((5.0, 0.0, 0.025), ), ((0.0, 5.0, 0.025), ), 
      ((0.0, 0.0, 0.025), ))
  p.seedEdgeByNumber(edges=pickedEdges, number=1, constraint=FIXED)
  
  # Generate mesh
  p.generateMesh()
  </code></pre>
  
  <p>In the last line, when I want to generate the mesh, the domain cannot be meshed because the 'fixed' seeding constraints cannot be honored. If I use</p>
  
  <pre><code>p.generateMesh(seedConstraintOverride=ON)
  </code></pre>
  
  <p>to generate the mesh, the domain can be meshed, but only with two elements in the thickness direction. Is there a way to mesh the domain with only one element in thickness direction? If not, why?</p>