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15.0 Release
Lecture 4:
Geometry Modeling
Introduction to ANSYS DesignModeler
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Overview
In this lecture we will learn about: • DesignModeler Concepts
• How to create a 3D geometry?
• How to modify/transform a geometry?
• Part Management
• Concepts in DM from meshing perspective
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Preprocessing Workflow
Sketches and Planes
Geometry Import Options
3D Operations
Bi-Directional
CAD/ Neutral
Geometry Cleanup and Repair
Automatic
Cleanup
Simplification,
Mid-surface,
Fluid Extraction
Extrude, Revolve,
Sweep, etc
3D Operations
Booleans,
Decompose, etc.
Import/ Geometry Creation
Geometry Modifications
Meshing Solver
Meshing Methods
Hybrid Mesh: Tet,
Prisms, Pyramids
Hexa Dominant,
Sweep meshing
Global Mesh Settings
Local Mesh Settings
Sizing, Controls,
etc.
Assembly
Meshing
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Body Types In DesignModeler
• Line body
– Has length and consists of points as lower entity
• Surface body
– Has surface area and consists of points & edges as lower entities
• Solid body
– Has volume and consists of points, edges & faces as lower entities
• Bodies are listed in the Tree Outline identified by default names and icons
Important DM Concepts
Surface body Line body Solid body
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Body States – Active
• Active bodies merge automatically with bodies in contact or overlapping.
– By default, DM creates Active bodies. To avoid active bodies or parts to merge together, use Add Frozen wisely.
– Frozen
• Frozen bodies remain independent
• Why to use Frozen bodies?
– If Meshing requires bodies to be decomposed
– If Solver requires different boundary & continuum conditions to be applied to different areas of the model
• “Unfreeze” can be used to Selectively convert Frozen bodies to Active State
Important DM Concepts
Active State: Single body after two feature creation operations
Frozen State: Two bodies (one frozen) after two feature operations
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Tools for creating new bodies or modifying existing bodies
– Used to create bodies
– Requires lower dimensioned geometry as base objects
– Result is a line/surface/solid body
– Applies blend/chamfer on edges/faces of existing bodies
– Used to modify existing bodies
– Results in modified or new bodies
– Quick creation of primitive shapes (without sketch)
3D Features
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Extrude Details • Geometry
– Can be a valid Sketch, selected face or Named Selection
• Operation
– Allows Add Material, Cut Material, Imprint Faces, Slice Material, Add Frozen
• Direction Vector
– Default option is Normal
• Other options are Reversed, Both-Symmetric and Both-Asymmetric
• Plane axes, geometric edges and faces can be used to specify direction
• Extent Type
– Fixed, Through All, To Next, To Faces, To Surface
Extrude
Sketch
Preview of the operation
Resultant body
Extent - Fixed
Extent - To Next
Direction - Symmetric
Direction - Asymmetric
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Options for Operation
• Add Material
– Creates new body and unites with existing active bodies in contact or overlap
• Add Frozen:
– An independent body is created, with separate faces and edges
• Cut Material:
– Create holes or modify existing bodies by removing material
• Imprint Faces:
– Imprints the sketch on the faces of existing body. This only works for Active bodies
• Slice Material:
– Slice out resultant body from the existing Frozen body Add Material Add Frozen Cut Material Imprint Faces Slice Material
Sketch
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Sweep Sweep Details • Selected profile is swept along selected path to
create bodies
• Profile
– Profile could be any sketch or entity to be swept
• Path
– Path could be a sketch or edge (open or closed)
• Alignment
– Path Tangent OR Global Axes
Profile
Path
Alignment - Path Tangent
Alignment - Global Axes
Swept Model
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Skin/Loft Details • Takes a series of profiles and creates a body
fitting through them
– All profiles must have the same number of edges
Skin/Loft Feature
Multiple sketches
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Thin Surface Details • Creates Thin Solid or Shell (Surface)
– Creation based on Selection Type; Faces to Keep/Faces to Remove/Bodies Only
– Faces to Keep: Selected faces used to form the thin solid or surface
– Faces to Remove: Unselected faces used
– Bodies Only: All faces used
– Specification of zero thickness will create a surface body (can specify offset)
– Direction for generation of thickness can be inward, outward or both (midplane)
Thin/Surface
Inward Outward Midplane
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Face Selection
Edge Selection
Fixed Radius Blend Details • Creates a blend of specified radius on
face/edges
Fixed Radius Blend
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Pattern Details • Creates multiple copies of selected features
in selected direction(s)
• Types of Pattern
– Linear, Circular and Rectangular
• Select Geometry (A Feature or bodies)
• Specify Direction, Axis, Offset/Angle, Copies
Pattern
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Body Transformation Tools • Contains 5 tools for transforming bodies
– Move
– Translate
– Rotate
– Mirror
– Scale
Body Tranformation
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• Creates a mirror image body reflected in selected plane
– Used for creating a full model from partial model which is Symmetrical
• Set Mirror Plane
• Select body/bodies to be mirrored
• Original body deletion controlled by ‘Preserve Bodies’ option
• Example – Mirroring car body in the XY Plane preserving the original
Body Transformation: Mirror
XY Plane
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• Moves and aligns selected bodies
• Select body or bodies
• Select option to Preserve Bodies
• Set Source and Destination Planes
• Example – Aligning two bodies using corresponding source and destination planes on each body respectively
Body Operation: Move
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Scale up : 2x
• Scale selected body or bodies
• Select body or bodies
• Set Scaling origin
– World Origin : Global coordinate origin
– Body Centroids: Centroid of the bodies selected
– Point: Selected Point
• Option to for Uniform or Non-uniform Scaling
Body Operation: Scale
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Body Operation Tools • Contains 6 tools for manipulating bodies
• Options vary depending on whether the bodies are Active or Frozen
• Cut Material is not available if all bodies are Frozen
Body Operation
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• To Slice out one body from the another body
Body Operation: Slice Material
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Tool Bodies
Intersect all bodies Union of all intersections Union of all intersections preserving input bodies
Unite, Subtract and Intersect • Unite: Merges two or more bodies
• Subtract: Target Body subtract Tool Body
• Intersection:
– Union of All Intersections: Regions shared by two or more Tool Bodies
– Intersection of All Bodies: Regions shared by all Tool Bodies
Boolean
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Slice Options • Slice By Plane
– Model is sliced by selected plane
• Slice Off Faces
– Selected faces are sliced off and separate bodies are created from them
• Slice Off Edges
– Selected edges are sliced off and separate bodies are created from them
• Slice by Surface
– Selected surface is used as a slicing tool to slice
• Slice by Edge Loop
– Selected edge loop is used as a slicing tool
‘Slice’ Operation under ‘Create’
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Suppressed
Suppressing Bodies
• Behaviour of Suppressed Body
– Will not be exported or transferred to other Workbench modules
– Not visible in Graphics view
– Identified by cross sign in Tree Outline
• How to Suppress or Unsuppress?
– Select the body to be suppressed, right click and select “Suppress Body”
– Select the body/bodies to be unsuppressed, right click and select “Unsuppress Body”
• Please note: Suppressing & unsuppressing bodies may change some features in tree, wherever they were used.
Suppression
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Hiding Geometry
• Behaviour of Hidden Bodies
– In Tree Outline, Hidden body is identified by transparent “tick-mark” sign
– Hidden bodies are transferred to other Workbench modules and can also be exported
• Useful when working with complex models
• How to Hide or Unhide?
– Select the body or face to hide, right click and select “Hide Body” OR Press F9
– Right click “Show Body” to restore view
Visibility
Hidden
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What are Named Selections?
• Any number of entities grouped together under one name
• These can be used to:
– Group Entities together for display purposes
– Define boundary conditions
– Apply Mesh Settings
– Define Meshing Order
• Can be created using one of two ways
– Select an entity or a group of entities, click RMB, select ‘Named Selection’ from the context menu or…
– Select an entity or a group of entities, click on Tools menu and select ‘Named Selection’
• Named Selections can be assigned to groups points, lines, surfaces or solids.
Named Selections
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Working with Parts
• By default, DM places each body into one part by itself
• Single-body parts : Individual parts are meshed separately
– Non-conformal mesh at interface
• Multi-body part : Two or more bodies in a single part
– Conformal mesh at interface if Shared Topology set to “Automatic”
• Bodies can be grouped into a part in 2 ways :
– Select bodies. Click RMB and select Form New Part
– Select bodies. Go to Tools Form New Part
Single and Multi-Body Parts
Single-body Parts Multi-body Parts
All bodies in a single part
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• Case 1: In DM: 3 parts, 3 bodies consisting of 3 solids
• Result of transferring this geometry to Meshing
– Contains: 3 solids, 3 bodies
– Each solid is meshed independently
– Nodes are not shared and do not line-up
– No connection between the 3 mesh regions for fluid flow and/or heat transfer
– Contact pairs are automatically created between parts/bodies in ANSYS Mechanical to transfer loads
Single and Multi-Body Parts
DM Mesh
DM
Mesher
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• Case 2: In DM: 1 multi-body part, 3 bodies/solids
• Result of transferring this geometry for Meshing
– Contains: 1 multi-body part, 3 bodies/solids
– Each solid meshed independently but node connectivity among solids is preserved
– Contains internal face which can be used for Post Processing
– No contact pair is created in ANSYS Mechanical
Single and Multi-Body Parts
DM Mesh
DM
Mesher
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• Shared Topology can be completed manually using
• Uses of Shared Topology – For getting Conformal mesh
– Imprinting for Contacts or Interface definition
• Options – For generating a conformal mesh for a Multibody Part, Shared Topology
needs to be completed with “Automatic” setting
– If conformal mesh is not required between two bodies in Part, but imprints of faces of one body on other are required (for defining contacts in Mechanical or Interface in Fluent), Shared Topology needs to be completed with “Imprint” setting
– For non-conformal, non-imprinted mesh on a body, Shared Topology setting needs to be kept “None”
Shared Topology
Shared Topology can be set through its Form
OR Shared Topology can be set for individual Part manually
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Custom Shared Topology
• This option allows users to Selectively keep some bodies disconnected within same Part
• For Example: T-Joint formed by Two plates Welded Together
• Objective: To Make mesh conformal between Weld and Both Plates, but mesh should be non-conformal between plates
Non-conformal
Here Weld 1
Plate 2
Weld 2
Plate 1
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Custom Shared Topology: Steps
• Form a part with all four bodies and Keep Shared Topology “Automatic” for Part
• For One of the plates (blue one), keep Custom setting of Shared Topology to None
– This will keep plate disconnected with remaining bodies, even when in same Part
• Use Connect operation Post Shared Topology to connect this body to both welds
Geometry Connectivity after Shared Topology
Black line here shows disconnected faces
Non-conformal mesh between two plates Conformal everywhere else
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Summary
What have we learnt in this session?
• Important Concepts in DM such as Body Types & Body States
• 3D modelling tools in DM
• Geometry Transformation tools
• Visibility, Suppression and Part Management
• Conformal Meshing and Shared Topology
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Workshop 4.1 – Modeling