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    Copyright 2006 ABAQUS, Inc.

    Meshing Imported and Native

    Geometry

    Lecture 7

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    Copyright 2006 ABAQUS, Inc.

    Introduction to ABAQUS

    L7.2

    Overview

    Introduction

    Dependent and Independent Part Instances

    Mesh Generation Techniques

    Enabling Various Meshing Techniques

    Mesh Compatibility

    Controlling Mesh Density and Gradation

    Parametric Modeling

    Assigning Element Types

    Checking Mesh Quality and Obtaining Mesh Statistics

    Workshop 8: Structured Hex Meshing: Pipe Creep Model

    Workshop 9: Free and Swept Meshing: Pump Model

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    Copyright 2006 ABAQUS, Inc.

    Introduction to ABAQUS

    L7.3

    Overview

    This lecture is intended to provide a brief overview of the meshing

    capabilities of ABAQUS/CAE.

    Meshing and partitioning is discussed further in the "ABAQUS/CAE:

    Geometry Import and Meshing" lecture notes.

    Specific issues relating to element selection criteria are discussed in

    Appendix 2 of these notes.

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    Copyright 2006 ABAQUS, Inc.

    Introduction

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    Copyright 2006 ABAQUS, Inc.

    Introduction to ABAQUS

    L7.5

    Introduction

    What is a mesh?

    Approximation of the geometry of the physical part model.

    Discretized geometry including many geometrically simple nodes and

    elements.

    Necessary for the finite element analysis program to perform a

    simulation. Defined by attributes that are features of the assembly.

    Features defined in the Mesh module will regenerate if you modify

    parameters of part or assembly features.

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    Copyright 2006 ABAQUS, Inc.

    Introduction to ABAQUS

    L7.6

    part geometry

    Discretized geometry

    nodes elements

    Introduction

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    Introduction to ABAQUS

    L7.7

    Introduction

    General capabilities of the Mesh module

    Allows you to mesh an assembly using various levels of automation and

    controls to suit the needs of your analysis

    Assign mesh attributes and set mesh controls to specify:

    Meshing technique

    Element shape

    Element type

    Mesh density

    Generate the mesh

    Query and verify the mesh for: Number of nodes and elements

    Element type

    Element quality

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    Dependent and Independent

    Part Instances

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    Introduction to ABAQUS

    L7.9

    Dependent and Independent Part Instances

    Concept of a part instance

    A part instance is a representation of the part in the assembly

    A part instance can either remain dependent on the original part or be

    designated independent of the original part

    Independent instances can be partitioned at the assembly level.

    Multiple independent instances of a given part can be partitionedeach according to its own requirements (mesh, loads, etc.)

    Each independent part instance must be meshed separately

    Dependent instances cannot be partitioned at the assembly level.

    All dependent instances of a given part share the same geometry as

    the original part.

    Thus, only the original part needs to be meshed

    Its dependent instances will inherit its mesh

    Any partitions must be made to the original part.

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    Introduction to ABAQUS

    L7.10

    Dependent and Independent Part Instances

    Misc.

    For either dependent or independent instances:

    Different attributes (loads, boundary conditions, etc.) and

    sets/surfaces can be created.

    All instances of a part must be either dependent or independent.

    No mixture is allowed for a given part.

    All orphan mesh instances must be dependent.

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    Introduction to ABAQUS

    L7.11

    Dependent and Independent Part Instances

    Part

    -Repair features

    -Shape features

    -Partitions

    -Seeds

    -Mesh techniques

    -Element types

    -Virtual topology

    -Mesh

    Part

    -Repair features

    -Shape features

    -Partitions

    -Virtual topology

    Dependent

    instance

    No mesh-related

    features allowed

    (The geometry and the

    mesh cannot be

    modified.)

    Mesh the

    part

    Independent

    instance

    -Partitions

    -Seeds

    -Mesh techniques

    -Element types

    -Virtual topology

    -Mesh

    Mesh the

    assembly

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    Introduction to ABAQUS

    L7.12

    Dependent and Independent Part Instances

    Choose Independent or

    Dependent when creatingpart instance

    Independent not allowed if:

    Part is meshed

    Dependent instances ofpart already exist

    Part is an orphan mesh

    Dependent not allowed if:

    Independent instances of

    part already exist

    Can easily convert between

    dependent and

    independent

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    Introduction to ABAQUS

    L7.13

    Dependent and Independent Part Instances

    Displaying parts or the

    assembly in the Mesh module

    Switch via context bar or

    model tree.

    All mesh module functions

    can be applied to parts.

    Native mesh display toggle

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    Mesh Generation Techniques

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    Introduction to ABAQUS

    L7.15

    Mesh Generation Techniques

    Free meshing

    Free meshing uses no preestablished mesh patterns, making it

    impossible to predict a free mesh pattern before creating the mesh.

    Element shape options available for free meshing two-dimensional

    regions:

    Quadrilateral (default) Can be applied to any planar orcurved surface.

    Quadrilateral-dominated Allows some triangular elements

    for transition.

    Triangular Can be applied to any planar or

    curved surface.

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    Introduction to ABAQUS

    L7.16

    quad mesh

    quad-dominated mesh triangular mesh

    Mesh Generation Techniques

    L 1

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    Introduction to ABAQUS

    L7.17

    Mesh Generation Techniques

    Element shape option

    available for free meshingthree-dimensional regions.

    Tetrahedralany

    geometry can be meshed

    with tetrahedral elements

    unless the mesh seedsare too coarse.

    L7 18

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    Introduction to ABAQUS

    L7.18

    Mesh Generation Techniques

    Swept meshing

    A mesh is created on one side

    of the region, known as the

    source side.

    The nodes of that mesh are

    copied, one element layer at a

    time, along the connectingsides of the region until the

    final side, known as the target

    side, is reached.

    The source and target sides

    are automatically located byABAQUS.

    source sidetarget side

    nodes copied from the

    source side to each element

    layer and to the target side

    L7 19

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    Introduction to ABAQUS

    L7.19

    Mesh Generation Techniques

    Two-dimensional swept meshes

    All-quad meshing of swept regions

    Planar or curved surfaces

    Quad-dominated meshing of degenerate revolved regions

    (Degenerate regions include the axis of revolution)

    Swept mesh Degenerate revolved mesh

    L7 20

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    Introduction to ABAQUS

    L7.20

    Mesh Generation Techniques

    Swept meshing (contd)

    Swept solid regions can be filled

    with:

    Hex meshes

    Hex-dominated meshes

    Wedge meshes

    General sweep paths allowed

    Generalized sweep path

    through the thicknessGeneralized sweep path

    follows the draft angle

    Extruded mesh

    sweep path:

    straight line

    Revolved mesh

    sweep path: arc

    L7 21

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    Introduction to ABAQUS

    L7.21

    Mesh Generation Techniques

    Requirements for sweep meshable

    regions Topological

    The source side may contain multiplefaces

    Target face and each connecting

    side must have only one face.

    Geometric

    Adjacent faces will be combined to

    form the source side only if the

    edge dihedral angles are not too far

    from 180

    Source Side

    Target Side

    Connecting side

    Not sweep meshable

    Sweep meshable

    L7 22

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    Introduction to ABAQUS

    L7.22

    Mesh Generation Techniques

    Structured meshing

    The structured meshing

    technique generates meshes

    using simpl