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Concept%20Modeling

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Title: DesignModeler Author: ANSYS, Inc. Last modified by: Ansys Created Date: 10/21/2002 1:39:10 AM Document presentation format: On-screen Show Company – PowerPoint PPT presentation

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Title: Concept%20Modeling


1
Concept Modeling
  • Chapter 6

2
Concept Modeling Contents
  • Concept Modeling
  • Creating Line Bodies
  • Modifying Line Bodies
  • Cross Sections
  • Cross Section Alignment
  • Cross Section Offset
  • Surfaces From Lines
  • Edge Joints
  • Workshop 6-1, Line and Surface Bodies

3
Concept Modeling Concept Modeling
  • The features in the Concept menu are used to
    create and modify line bodies and/or surface
    bodies which become FE beam or shell models.
  • To begin Concept Modeling, you can either
  • Create line or surface bodies using the features
    in the Draw toolbox to design a 2D sketch and/or
    generate a 3D model
  • Use the Import external geometry file feature
  • Line bodies can be created using the concept
    modeling tools
  • Lines from points
  • Lines from sketches
  • Lines from edges
  • Surface bodies can be created using the concept
    modeling tools
  • Surfaces from lines
  • Surfaces from sketches

4
Concept Modeling Creating Line Bodies
  • Lines From Points
  • Points can be any 2D sketch points, 3D model
    vertices or Point Feature (PF) points.
  • A point segment is a straight line connecting two
    selected points.
  • The feature can produce multiple Line Bodies,
    depending on the connectivity of the chosen point
    segments.
  • The Operation field allows Add or Add Frozen
    choices for line bodies.

5
Concept Modeling Creating Line Bodies
Example of Line From Points using 2d points
from a rectangular sketch. 2 points are chosen to
define a diagonal line body. The green line
indicates proposed line segment. Apply the
selection then Generate. The Line body is
displayed in blue.
Line Body
Point 1
Point 2
6
Concept Modeling Creating Line Bodies
  • Lines From Sketches
  • Line bodies created based on sketches and planes
    from faces
  • Multiple Line Bodies may be created depending on
    the connectivity of the edges within the base
    objects
  • Select sketches or planes in the feature tree
    then Apply in the detail window
  • Multiple sketches, planes, and combinations of
    sketches and planes can be used as the base
    object for the creation of line bodies

7
Concept Modeling Creating Line Bodies
  • Example of Lines From Sketches.
  • Sketch created as input for Line Body creation.
  • Lines From Sketches is chosen
  • Highlight sketch in tree
  • Apply as base object in Detail window

8
Concept Modeling Creating Line Bodies
  • Lines From Edges
  • Creates line bodies based on existing 2D and 3D
    model edges
  • Can produce multiple line bodies depending on the
    connectivity of the selected edges and faces
  • Can select edges and/or faces through two fields
    in the detail window then Apply

9
Concept Modeling Creating Line Bodies
  • Example of Lines From Edges. 3D solid created
    as input for Line Body creation.
  • Lines From Edges is chosen
  • Select faces on model. Face boundaries will
    become line bodies (alternately select 3d edges
    directly).
  • Apply as base object in Detail window
  • Note in this case 2 line bodies are created due
    to the edge connectivity.

10
Concept Modeling Modifying Line Bodies
  • Split Line Body
  • Splits line body edges into two pieces
  • Split location is controlled by the Fraction
    property (e.g. 0.5 split in half).
  • Example

11
Concept Modeling Cross Sections
  • Cross Sections
  • Cross sections are attributes assigned to line
    bodies to define beam properties in the FE
    simulation
  • In DM, cross sections are represented by sketches
    and are controlled by a set of dimensions
  • Note DesignModeler uses a different coordinate
    system for cross sections than the one used in
    the ANSYS environment (described later)

12
Concept Modeling Cross Sections
  • Cross sections are selected from the Concept menu
  • A cross section branch is inserted in the tree
    where each chosen cross section is listed

Concept menu
Display Tree
Cross Section menu
13
Concept Modeling Cross Sections
  • Highlight the cross section in the Tree to modify
    dimensions in the Details window

14
Concept Modeling Cross Sections
  • Dimension Editing
  • Cross section dimensions can be repositioned via
    a RMB and choosing Move Dimensions

15
Concept Modeling Cross Sections
  • Assigning a cross section to a line body
  • Highlight the line body in the Tree
  • A cross section property appears in the detail
    window
  • Click in this field and choose the desired cross
    section from the drop down list

16
Concept Modeling Cross Sections
  • A user integrated section can be defined in DM
  • The cross section is not sketched, rather the
    cross sections properties are placed in the
    details window
  • A Area of section.
  • Ixx Moment of inertia about the x axis.
  • Ixy Product of inertia.
  • Iyy Moment of inertia about the y axis.
  • Iw Warping constant.
  • J Torsional constant.
  • CGx X coordinate of centroid.
  • CGy Y coordinate of centroid.
  • SHx X coordinate of shear center.
  • SHy Y coordinate of shear center.

17
Concept Modeling Cross Section Alignment
  • As shown below in DesignModeler the cross section
    lies in the XY plane
  • Cross section alignment is defined by
  • A local or cross section Y direction
  • Default alignment is with the global Y direction
    unless that would result in an invalid alignment
    in which case Z is used
  • Note In the ANSYS Classic Environment, the cross
    section lies in the YZ plane and uses the X
    direction as the edge tangent. This difference in
    orientation has no bearing on the analysis.

18
Concept Modeling Cross Section Alignment
  • A color code is used to indicate cross section
    status for line bodies
  • Violet no cross section assigned
  • Black cross section assigned with valid
    alignment
  • Red cross section assigned with invalid
    alignment
  • The line body icons in the tree have similar
    visual aids
  • Green cross section assigned with valid cross
    section alignment
  • Yellow no cross section assigned or default
    alignment
  • Red invalid cross section alignment

19
Concept Modeling Cross Section Alignment
  • Checking alignment can be done graphically using
    the View menu
  • Choose Show Cross Section Alignments
  • Green arrow Y, blue arrow edge tangent of
    cross section
  • Or choose Cross Section Solids

Y
Edge Tangent
20
Concept Modeling Cross Section Alignment
  • Because a default alignment is chosen cross
    section orientation will almost always need to be
    modified. There are 2 methods for cross section
    alignment, selection and vector
  • The selection method uses existing geometry
    (edges, points, etc.) as alignment reference
  • The vector method uses input according to X, Y, Z
    coordinate directions
  • For either method a rotation angle can be input
    and/or the orientation reversed

Selection Method
Vector Method
21
Concept Modeling Cross Section Alignment
  • Modifying the cross section orientation by
    vector

Switch to Vector alignment mode
Enter the desired coordinate values
Enter rotation angle if desired
Reverse orientation if desired
22
Concept Modeling Cross Section Alignment
  • Modifying the cross section orientation by
    selection (several examples follow)
  1. Select the line body to be aligned in graphics
    window
  1. Select the geometry to be used for alignment
  1. With Selectionmethod active click in the
    alignment field

23
Concept Modeling Cross Section Alignment
Alignment using lines or axes.
Line chosen for alignment
Y
Edge Tangent
Axis chosen for alignment
Y
Edge Tangent
24
Concept Modeling Cross Section Alignment
Alignment using face normal.
Edge Tangent
Y
Alignment Faces
Y
Edge Tangent
25
Concept Modeling Cross Section Alignment
Alignment using sketch points. Note the order
of point selection determines cross section
alignment.
1
2D points
2
Y
Selected Line Body
Edge Tangent
26
Concept Modeling Cross Section Offset
  • Cross Section Offset
  • After assigning a cross section to a line body,
    the Detail property allows users to specify the
    type of offset to use with the cross section
  • Centroid The cross section is centered on the
    line body according to its centroid (default)
  • Shear Center The cross section is centered on
    the line body according to its shear center
  • Note the graphical display for centroid and shear
    center appear the same however, when analyzed,
    the shear center is used
  • Origin The cross section is not offset and is
    taken exactly as it appears in its sketch
  • Examples next page

27
Concept Modeling Cross Section Offset
Origin offset (no offset)
Line Body
Line Body with cross section displayed
Centroid/Shear Center offset
28
Concept Modeling Surfaces From Lines
  • Surfaces From Lines
  • Creates surface body using line body edges as the
    boundary
  • Line body edges must form non-intersecting closed
    loops
  • Each closed loop creates a frozen Surface Body
  • The loops should form a shape such that a simple
    surface can be inserted into the model
  • Planes, cylinders, tori, cones, spheres and
    simple twisted surfaces
  • Details window
  • Flip surface normals
  • Input thickness which will be transferred to the
    FE model

29
Concept Modeling Surfaces From Lines
  • Notes on surface from lines
  • A line body with no cross section can be used to
    tie together surface models. In this case the
    line body acts merely as a mechanism to insure a
    continuous mesh at the surface boundaries.

2 Surface Bodies
Result is continuous FE mesh at surface interface
Line Body (no cross section)
30
Concept Modeling Surfaces From Sketches
  • Surfaces From Sketches
  • Creates surface bodies using sketches as
    boundaries (single or multiple sketches are OK)
  • Base sketches must be closed profiles which are
    not self intersecting
  • May choose to Add or Add Frozen operations
  • Can reverse normal direction No in orient with
    plane normal field
  • Can enter thickness which will be used in
    creating the FE model

31
Concept Modeling Surfaces From Sketches . . .
2 ways to identify sketch for operation Click in
the Base Objects field
Select the desired sketch from the tree then
Apply
Select a portion of the desired sketch in the
graphics window then Apply
32
Concept Modeling Edge Joints
  • Edge Joints are the glue that holds together
    surface bodies that have been joined and concept
    models where beams and surfaces connect. Each
    time you create a Joint, Lines From Edges, or
    Surfaces From Lines feature, edge joints are
    implicitly created in DM

33
Concept Modeling Edge Joints
  • Edge Joints can be viewed by turning on the Edge
    Joints option in the View menu
  • Edge joints are displayed in either blue or red.
  • Blue edge joint is contained in properly defined
    multi-body part
  • Red edge joint not grouped into the same part

34
Workshop 6-1, Line and Surface Bodies
  • Goals
  • Create a sketch representing beams used to
    stiffen a panel.
  • Create a line body from the sketch.
  • Choose a beam cross section to be used and assign
    it to the line body.
  • Create a surface model representing the panel.
  • gtFilegtNew, or Start Page
  • Choose to create new geometry
  • At the prompt, set the length unit to millimeter

35
Workshop 6-1, Line and Surface Bodies
  • Create a rectangle
  • Sketch gt Rectangle
  • Place the cursor near the origin until P
    appears, click then drag to define the rectangle
  • Click gtLook At gtZoom to Fit tool buttons,
    and Triad ISO Ball as desired.

36
Workshop 6-1, Line and Surface Bodies
Dimension the rectangle 600X300 mm as
shown Sketch gt Dimension gt General Horizontal
600 mm Vertical 300 mm Fit the sketch and move
dimensions as necessary Sketch gt Dimension gt
Move
37
Workshop 6-1, Line and Surface Bodies
  • Add 2 vertical lines and dimension as shown
  • Sketch gt Draw gt Line
  • Place the cursor near the top line until the C
    coincidence constraint appears. Move the cursor
    to the bottom line until the C appears and a
    V indicating a vertical constraint.
  • Repeat for second line
  • Apply horizontal dimensions as shown.
  • Sketch gt Dimension gt Horizontal
  • Adjust Details so all dimensions are as
    indicated

38
Workshop 6-1, Line and Surface Bodies
  • Create a Line Body from Sketch1
  • Main Menu gt Concept gt Lines From Sketches
  • Select Sketch1 from the Tree (click the
    near the XYPlane to expand that branch if
    necessary) and gtDetailsgtApply it as the base
    object
  • Click gtGenerate

39
Workshop 6-1, Line and Surface Bodies
Select a rectangular tube type cross
section Main Menu gt Concept gt Cross Section gt
Rectangular Tube After selection, the cross
section is displayed with its dimensions. In
this case we will use the default dimensions.
If desired the cross section Details can be
changed to modify the cross section.
40
Workshop 6-1, Line and Surface Bodies
  • With a cross section selected we now need to
    associate it with our line body.
  • Highlight the line body in the tree and the
    details shows that no cross section is yet
    associated with it.
  • tree gt 1 Part, 1 Body gt Line Body (at bottom
    of tree)
  • Click in the Cross Section field
  • Choose RecTube1 from the drop down list

41
Workshop 6-1, Line and Surface Bodies
After assigning the cross section to the line
body the default display shows the line body with
its cross section alignment (see right). We can
also display the beam with the cross section
displayed as a solid. Main Menu gt View gt Show
Cross Sections Solids
42
Workshop 6-1, Line and Surface Bodies
  • The next step is to create the surfaces between
    the beams. These surfaces will be shell meshed in
    the FE simulation.
  • Main Menu gt Concept gt Surfaces From Lines
  • Hold the control key and select the 4 lines shown
    at right.
  • (or can hold down LMB and sweep mouse over lines
    to be group selected)
  • gtApply

43
Workshop 6-1, Line and Surface Bodies
12. gtGenerate the Surface Body. Note a frozen
surface body is created, bounded by the selected
lines Repeat the previous steps to create two
more surface bodies gtGenerate as necessary
44
Workshop 6-1, Line and Surface Bodies
The final modeling operation is to place all the
bodies into a single part (multi-body part).
We must do this to insure that, when meshed,
each boundary recognizes its neighbor resulting
in a continuous mesh. Set the Selection Filter
to Bodies. In the graphics window right
mouse click and choose gtSelect All
45
Workshop 6-1, Line and Surface Bodies
With all bodies selected, again right click in
the graphics window and choose Form New
Part. By examining the Tree notice a single
part has been formed which contains 4 bodies.
46
Workshop 6-1, Line and Surface Bodies
  • Shown here we have moved to a Simulation
    environment in Workbench and meshed the
    geometry.
  • By grouping all bodies into a common (single)
    part, nodal connectivity is insured.
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