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To Create a Spinal Bend
1. Perform one of the following actions:
Select a spine for the bend, and then click Model > Engineering > Spinal Bend.
Click Model > Engineering > Spinal Bend. To select a spine, click the References tab, click the Spine collector, and select a chain.
To open the Chain dialog box, click Details.
To reverse the start point, click the arrow at the start point.
 • The spine must be C1 continuous (tangent). If the spine is not also C2 continuous (curvature continuous), the feature surfaces might not be tangent.• The plane that passes through the start point of the spine and is normal to the spine must intersect the original quilt or solid feature.
The Spinal Bend tab opens.
2. Click the Bend Geometry collector and select the geometry to bend.
To select a solid, click any surface. After the spinal bend is created, the original solid becomes invisible. However, you can still select it in the Model Tree.
To select a quilt, click the quilt. After the spinal bend is created, the original quilt remains visible.
3. Define the region to bend by selecting an option.
The bend region lies between the plane that passes through the start point of the spine and that is normal to the spine and axis at the curve start point, and a plane that is normal to the axis and that is determined using one of the following options. The bend region is defined relative to an axis that is tangent to the spine at the start point of the spine. —Bend the geometry from the start of the spine to the farthest point of the geometry to bend, in the direction of the axis. 1. Spine —Bend the geometry from the start of the spine to a specified depth, in the direction of the axis. Type or select a depth value from the start point. 1. Spine
2. Axis
3. Depth value to define bend region —Bend the geometry up to a selected reference. Select a plane that is perpendicular to the axis, or a point or a vertex. 1. Spine
2. Axis
3. Plane selected as reference to define bend region
4. To control properties of the cross section for the distribution of the mass property of a varying cross section along the spine, perform the following operations:
a. Click the Options tab, and under X-Section Property Control, select one of the following options:
Relation—Relation between the cross section properties. Type a relation in the Relations dialog box that opens. Type relations that define the symbol SEC_PROP on the left side of the equation as a function of the mass properties of the original quilt or solid cross sections. The right side of the relations can include any of the properties listed previously.
Area
Ixx, Ixy, or Iyy—Planar moments of inertia of the cross section in relation to the sketched coordinate system
Ixx at centroid, Ixy at centroid, or Iyy at centroid—Planar moments of inertia of the cross section in relation to a coordinate system at the centroid and with axes parallel to the specified coordinate system
Principal inertia 1—Greater planar principal moment of inertia
Principal inertia 2—Lesser planar principal moment of inertia
Centroid x—X-coordinate of the center of area of the cross section in relation to the sketched coordinate system
Centroid y—Y-coordinate of the center of area of the cross section in relation to the sketched coordinate system
b. To edit a relation, click Edit relation to open the Relations dialog box.
c. To enter Sketcher and create a coordinate system, click Sketch csys. Use the coordinate system in the calculation of cross section properties that require an origin and a direction. This coordinate system will be projected onto the plane of each cross section.
d. To control the cross section property, select one of the following types:
Linear—The section property varies linearly between the values at the start and end points of the spine.
Graph—The section property varies by the graph values between the values at the spine start and end points. Click the graph collector to select an existing graph feature. The graph must pass through the points (0, 0) and (1, 1) and must be monotonically non-decreasing (that is, with no horizontal tangent to the curve) in the interval 0 to 1.
Each cross section of the original quilt or solid is placed at the trajectory parameter (Trajpar) on the spine, according to the following formula:
G(Trajpar)=(F(p) - F(0)) / (F(p1) - F(p0))
The variables are as follows:
G()—If you selected Graph, this is the function defined by the reference graph feature. If you selected Linear, this is the function defined by trajpar itself (the identity function).
F()—The cross section property function defined by feature relations.
p—The properties of the original quilt or solid cross section (AREA, CENTROID_X, and so on).
p0, p1—The properties of the first and last cross sections.
5. To maintain the original length of the bend region after bending it, select the Lock Length check box.
6. Decide how to handle unbent geometry:
To remove the geometry that is outside of the bent region, select the Remove unbent geometry check box.
To reattach the geometry that is outside of the bent region to the bent region, clear the Remove unbent geometry check box.
7. Click .