You can create a blended surface, that is a surface between two
wireframe elements, taking a number of constraints into account, such as tension,
continuity, and so forth.
Before you begin: Create a 3D shape containing open or closed curves.
Create a Blend Between Curves
You can
create a blended surface between curves.
From the Surface
section of the action bar, click Blend
.
The Blend Definition dialog box
appears.
Successively select the first curve and its support, then
the second curve and its support.
These can be surface edges, or any curve.
In the Basictab, set the continuity type.
It defines the continuity connection between the newly created
surface and the curves on which it lies. The illustration above, shows the
Tangency continuity, and the following
illustrations show the Point and
Curvature continuity types:
Select the Trim first support/Trim second support
check boxes,
on one or both support surfaces to trim them by the curve and assemble
them to the blend surface:
By default, the blend surface borders are tangent to the support
surface borders.
You can also specify whether and where the blend boundaries must be
tangent to the supports boundaries:
Both extremities: the tangency constraint applies at both ends of
the curve.
None: the tangency constraint is disregarded.
Start extremity only: the tangency constraint
applies at the start endpoint of the curve only.
End extremity only: the tangency constraint
applies at the end endpoint of the curve only.
The Start and End extremities are defined according to the arrows in the
blended surface's preview.
In the Tensiontab, define the tension type.
It defines the tension of the blend at its limits. It can be
Constant or Linear, and
can be set for each limit independently. A third tension type is available:
S Type. It enables to set a variable tension.
Important:
If you select any of the tension types in the
list, the Default option is cleared.
Click OK to create the blended
surface.
The surface (identified as Blend.xxx) is
added to the tree.
Create a Blend Between Closed Contours
You can create blend surface between closed contours.
Click Blend
.
The Blend Definition dialog box appears.
Successively select two contours.
Click Preview.
The surface to be generated is twisted.
To
avoid this you need to define a closing point.
Important:
By
default, the system detects and highlights a vertex on each curve that
can be used as a closing point, or it creates an extremum point (you can
also manually select another one if you want).
Warning:
This capability only applies to closed curves.
In the Closing Pointstab, right-click in the First
closing point box and select Create
Projection.
The Projection Definition dialog box appears.
Select the closing point on the second contour, then the first curve onto
which the point is to be projected.
Click OK in the Projection
Definition dialog box.
Click OK in the Blend
Definition dialog box to create the blended surface.
The surface (identified as
Blend.xxx) is added to the tree.
Create a Coupling Blend
You can create a blend surface between a coupling.
Click Blend
.
The Blend Definition dialog box appears.
Select the elements to be blended and click
Preview.
Select the Coupling / Spinetab and define the coupling type.
Ratio: the curves are coupled according to
the curvilinear abscissa ratio.
Tangency : the curves are coupled
according to their tangency discontinuity points. If they do not
have the same number of points, they cannot be coupled using
this option.
Tangency then curvature: the curves are
coupled according to their tangency continuity first then
curvature discontinuity points. If they do not have the same
number of points, they cannot be coupled using this option.
Vertices: the curves are coupled
according to their vertices. If they do not have the same number
of vertices, they cannot be coupled using this option.
Spine: the curve are
coupled using a spine curve. This curve can either be a new curve or
one of the curves already specified. If no spine is explicitly
selected, the first curve is used as the default one. Here is how
the blended surface is computed using this coupling mode: at any
given point on the spine, a plane normal to the spine is first
computed then coupling points corresponding to the intersection of
this plane with the limit curves are computed. The blended surface
corresponds to the set of lines created with the coupled points.
This construction is similar to the one used when creating swept surfaces using a linear profile
and two guide curves. In the
Spine box, select the spine curve. When
using this option, the Display coupling curves option is disabled
and any manual coupling is removed.
Avoid Twists: The coupling points are
automatically computed hence avoiding possibilities of twisted
geometry. When using this option, the Display coupling
curves option is disabled, as well as the manual
coupling and developable modes.
Important:
The Spine box is enabled
only when selecting the Spine coupling type.
Double-click in the coupling list or select Add in
the context menu and manually select a point on the
first section.
The Coupling dialog box appears.
Select a corresponding coupling point on each section.
The Coupling dialog box is updated
consequently, and the coupling curve is previewed, provided the
Display coupling curves option is active. When a
coupling point has been defined on each section, this dialog box
automatically disappears.
Click OK in the Blend Definition dialog box to
create the blended surface.
The surface (identified as Blend.xxx) is
added to the tree.
Create a Ruled Developable Surface
You can create a blend surface by defining the start and end connection
points.
Click Blend
.
The Blend Definition dialog box appears.
Successively select the first curve, then the second curve.
Warning:
They cannot form closed contour.
In the Developabletab, select the Create a ruled
developable surface check box.
The Start and End lists are
enabled.
The options available under the Start drop-down
list are:
Connect Both Extremities: connects the
extremities of both curves.
First Curve Origin: lets you to free the
first curve origin.
Free Second Curve Origin: lets you to
free the second curve origin.
The options available under the End list are:
Connect Both Extremities: connects the
extremities of both curves
First Curve End: lets you free the first
curve end.
Free Second Curve End: lets you free the
second curve end.
Important:
The icons depicting the chosen options are
represented in the work area as follows:
: indicates that both extremities are connected.
: indicates that the first curve origin/end is free.
: indicates that the second curve origin/end is free. You can
click on the icons to change the options.
Click Preview.
The maximum value of the Gaussian curve appears in the work area.
Click OK to generate the ruled developed
surface.
The surface (identified as Blend.xxx) is
added to the tree.
Define Smooth Parameters
You can define the smoothing parameters on the blend surface.
In the Smooth parameters area, select the:
Angular Correction check box to smooth the
blending motion along the reference guide curves. This may be
necessary when small discontinuities are detected with regards to
the spine tangency or the reference guide curves' normal. The
smoothing is done for any discontinuity which angular deviation is
smaller than the input value, and therefore helps generating better
quality for the resulting blended surface. Over 0.01 degree, the
smoothing is cancelled. By default, the angular correction is set to
0.5 degree.
Deviation check box to smooth the blending
motion by deviating from the guide curve(s). A smoothing is
performed using correction default parameters in tangency and
curvature. By default, the deviation is set to 0.001mm.
Important:
Selecting a support is not compulsory.
You can create closing points using the context menu directly on one of the
selected curves, providing no closing point already exists.
Use the Replace,
Remove or
Reverse buttons, to manage the
selected elements (curves, support, closing and coupling
points).
You can use the context menu on the texts displayed on
the geometry to set the continuities, trim the supports or
manage the curves and support in general.