Embed Size (px)
Citation preview
Exporting
TexGen Models
for Simulation
Dr Louise Brown
Download TexGen Executable for Windows
https://sourceforge.net/projects/texgen/
Use the Files tab to access different versions and
installation files with and without bundled Python
Code on GitHub
Source code is stored on GitHub
https://github.com/louisepb/TexGen
Bugs/issues can be reported here:
https://github.com/louisepb/TexGen/issues
Sample scripts are here:
https://github.com/louisepb/TexGenScripts
Instructions for compiling from source for both Windows and Linux are here:
http://texgen.sourceforge.net/index.php/Compiling_from_Source
TexGen Forum
Queries about TexGen can be directed via the
TexGen forum
http://texgen.sourceforge.net/phpBB3/index.php
This is also a useful source of information and gives
a record of queries and discussion by other TexGen
users
TexGen Geometric Textile Modelling Software
Fibre/Micro-Scale
Unit Cell/Meso-Scale
Component/Macro-Scale
Generate textile geometry using TexGen GUI or script
Automatically generate 2D and 2D sheared textiles
3D wizard generates idealised 3D textiles
Refinement of orthogonal weave to simulate compaction
Generate mesh and input files for FEA or CFD to predict material properties
Micro-scale FEA simulations or analytical methods determine yarn properties
Composite material properties extracted from meso-scale predictions are used to model structural components
Preparing
models for
export
Create Yarns
Nodes
Interpolated yarn path
Cross-section
Building Yarns
1. Generates yarn path using specified interpolation function• Creates a set of slave nodes along the interpolated path at
the specified resolution2. Generates cross-sections for each slave node, interpolating
between specified cross-sections where necessary3. Generates surface by joining points on adjacent cross-section
Slave nodes
Set Resolution
Yarn.SetResolution function assigns number of section points and, optionally, number of slave nodes
SetResolution(20)20 section points, automatic calculation of number of slave nodes
SetResolution(40)
SetResolution(40,20)40 slave nodes, 20 section points
Yarn Repeats and Domain
Yarn repeats allow a given yarn section to be repeated as
specified by a set of vectors (in theory, allowing an infinite
textile)
The domain restricts the model to a specific region
• Specified by a set of convex planes
• Typically, but not always, the unit cell
• For a composite the domain gives the volume to be exported as matrix elements
Material Properties
Volume Fraction
To export element volume fractions set up yarn properties, either for
whole textile (all yarns same) or individual yarns
Modeller -> Assign Yarn Properties
Requires
Total fibre area
Or
Fibre density and yarn linear density
Or
Fibre diameter and number of fibres per yarn
Mechanical properties
Select required yarns then Modeller -> Assign Yarn Properties
to set Young’s modulus, Shear modulus, Poisson’s ratio and
coefficient of thermal expansion
Select Modeller -> Assign Matrix Properties to set matrix properties
Saving TexGen
models
Save File Format
• tg3 file – basically a renamed xml file
• Three versions containing different levels of data
• Minimal – textile data only (generated by the
weave classes)
• Standard – textile and yarn data
• Full – textile, yarn and mesh data
TexGen as a Pre-
processor for
Generating
Textile Models
Simulations for
prediction of
mechanical properties
Workflow for finite element elastic analysis
Material properties for yarn fibres and
matrix (manufacturer data)
Micro-scale simulation for yarn material properties
TexGen geometry model (.TG3) file
TexGen export of Abaqus input (.INP)
file
Customisation of .INP file
Abaqus simulations
* Elastic* Thermo-mechanical* (Damage)
Abaqus script for result file (.ODB)
exploitation.
RVE material properties
Reporting of results:
* Material properties
* Stress fields* Strain fields
• http://texgen.sourceforge.net/index.php/Extraction_of_Material_Properties_using_Voxel_Meshing_and_Abaqus
Evaluation of yarn component properties: FE Analysis
Example results:
Fibre properties (HTS40 F13)
Input yarn material properties: 7micron fibre at 76% vol. UD hexagonal packing
E1 E2 E3 v13 v12 v32 G12 G23 G31
183.1 9.67 9.67 0.23 0.23 0.43 5.66 3.37 5.66
Ex ν
Fibre 238.6 0.20
Resin 3.1 0.35
Finite element analysis for calculation of elastic properties for composite (impregnated yarns)Example shows:• hexagonal packing of filaments:• six load cases of a single filament
(+ resin) unit cell model
Evaluation of yarn component properties: Analytical method
• TexGen exports include .eld file
• Local volume fraction for each element
• Based on fibre area etc as specified earlier
• Use an Abaqus UMAT subroutine to compute
properties for each element
• chamis_model_final.for in Utitlities folder in
TexGen installation
• Specify raw fibre and matrix properties
• Uses the Chamis micromechanical model• Chamis CC. Mechanics of Composite-Materials -
Past, Present, and Future. J Compos Tech Res. 1989;11(1):3-14.
• Details of use -http://texgen.sourceforge.net/index.php/Abaqus_UMAT_Subroutine_for_Calculation_of_Localised_Yarn_Properties
********************
*** ELEMENT DATA ***
********************
** Element data stored as a depvars
** 1 - Yarn Index (-1 for matrix, first yarn starting
at 0)
** 2/3 - Location (x and y cross-section coordinates of
element relative to yarn centreline)
** 4 - Volume fraction
** 5 - Distance of element from the surface of the yarn
(for yarn elements only, distance is negative)
1, -1, 0, 0, 0, 0
2, -1, 0, 0, 0, 0
…
23, 2, 2.77556e-17, -0.049, 0.75, -0.000999952
…
28, 0, -2.77556e-17, -0.049, 0.73, -0.000999952
Workflow for finite element elastic analysis
Material properties for yarn fibres and
matrix (manufacturer data)
Micro-scale simulation for yarn material properties
TexGen geometry model (.TG3) file
TexGen export of Abaqus input (.INP)
file
Customisation of .INP file
Abaqus simulations
* Elastic* Thermo-mechanical* (Damage)
Abaqus script for result file (.ODB)
exploitation.
RVE material properties
Reporting of results:
* Material properties
* Stress fields* Strain fields
• http://texgen.sourceforge.net/index.php/Extraction_of_Material_Properties_using_Voxel_Meshing_and_Abaqus
ABAQUS Voxel Export
• Generates a mesh of hex elements• Assigned to yarn or matrix based on the centre point of the element
• Periodic boundary conditions and steps for extraction of material properties• Based on the paper: Unit cells for micromechanical analyses of particle-
refined composites , Shuguang Li, Anchana Wongsto, Mechanics of Materials 36(2004) 543-572
• All ABAQUS exports include additional .ori and .eld files containing element orientation, fibre volume fraction and yarn information.
• Calculated for the centre point of the element
Create ABAQUS Voxel File
GUI: Select File -> Export -> ABAQUS File -> ABAQUS Voxel File
Number of voxels required in the x, y and z directions
Output yarns, matrix or both
Element type: C3D8R or C3D8
Boundary conditions
Python script
Periodic BCs: Material Continuum
• “Correct” BC approach of Li and Wongsto
• Full 3D boundary conditions: infinitely repeating 3D continuum
• Not true for tests!
Periodic BCs: Single Layer RVE
• “Untie” the through-thickness constraints
• Represents repeating units only in-plane, free surfaces top and bottom
• Differences in results actually insignificant
Workflow for finite element elastic analysis
Material properties for yarn fibres and
matrix (manufacturer data)
Micro-scale simulation for yarn material properties
TexGen geometry model (.TG3) file
TexGen export of Abaqus input (.INP)
file
Customisation of .INP file
Abaqus simulations
* Elastic* Thermo-mechanical* (Damage)
Abaqus script for result file (.ODB)
exploitation.
RVE material properties
Reporting of results:
* Material properties
* Stress fields* Strain fields
• http://texgen.sourceforge.net/index.php/Extraction_of_Material_Properties_using_Voxel_Meshing_and_Abaqus
Run Abaqus Simulation
Voxel mesh viewed in ABAQUS
• Export generates 3 files: .inp, .eld, ori
• Copy files into Abaqus working folder
• Start Abaqus Command
• Type abaqus job=Filename (without extension)
• Equations in boundary conditions which match multiple node
sets mean .inp file must be run from command line
Extract Material Properties from ODB File
• Use files dataHandling.py and effectiveMatPropRVE,py to
extract material properties from ODB file
• Use dataHandlingInPlane for SingleLayerRVE
• File are in Python->libxtra->TexGen folder of TexGen
installation
• Set up files following steps in http://texgen.sourceforge.net/index.php/Extraction_of_Material_Properties_using_Voxel_Meshing_and_Abaqus
• Open .odb file in Abaqus CAE
• Select File->Run Script..
• Select effectiveMatPropRVE.py
• Dialog is displayed with properties calculated
• Results also saved in .rpt file
Octree Voxel Mesh with Smoothing
• Select Octree Refinement in Voxel Mesh Options dialog
• Only implemented for single layer RVE boundary conditions
• Use via Python script:
http://texgen.sourceforge.net/index.php/Using_Octree_Refineme
nt_and_Mesh_Smoothing
Matveev, M. Y., Brown, L. P., & Long, A. C. (2020). Efficient meshing technique for textile composites unit
cells of arbitrary complexity. Composite Structures, 254, https://doi.org/10.1016/j.compstruct.2020.112757
Periodic BCs: Staggered (Reduced Domain)
• It is possible to take advantage of
symmetry in the unit cell to reduce its
size and, in turn, computational cost
• Staggered boundary condition
assumes an x offset
• X-offset box is enabled when selected
Unit cellHalf of the
unit cell
Periodic BCs: Sheared and Rotated Domains
L P Brown, X Zeng, A C Long, R Brooks, I A Jones. “Predicting the coefficient of expansion for textile composites based on a unit cell approach”, Proc. 11th Int. Conf. on Textile Composites (TexComp-11), Leuven, Sept 2013.
• Create sheared textile with sheared domain in 2D wizard
• Select sheared domain boundary conditions
• Parallepiped voxel mesh is created
Conformal Mesh
Volume MeshGUI: Select File -> Export -> Volume Mesh• Tetrahedral elements• Save as ABAQUS .inp file or .vtu• Works best for 2D weaves• Seed size – used for triangulation of
top surface• Merge Tolerance – any gap between
yarns smaller than this tolerance will be merged to avoid bad quality elements
Flow simulation
using TexGen and
CFX
Exporting volume mesh from TexGen
1.a This controls the number of element nodes. Linear results in 4 noded tetrahedrons while Quadratic results in 10 noded tetrahedrons.
1.b Option for Quadratic meshing only.
1.c Create the matching meshes on opposite faces to ensure periodic interface.
1.f Any gap between yarns smaller than this tolerance will be merged to avoid bad quality elements.
1.e Controls the mesh density and it approximates the edge length of elements.
1.d Sets up periodic boundary conditions. Select None.Creates nodes, elements, element sets and materials
Open a TexGen model ready in TexGen window. Click “File -> Export -> Volume Mesh…”, a dialog window appears as below. Once the parameters are set and click ok, a volume mesh file is created, either in .vtu or .inp format.
Importing mesh to CFX and running the simulation
Import tetrahedral or voxel meshes using either method below:
• VTK import – use the CFXImportVTK file in the Utilities folder of
the TexGen installation
• .vtu file includes point/cell data including yarn index,
orientation, volume fraction etc
• .vtu file can be viewed in Paraview
• .inp import – follow the instructions given on the ANSYS/CFX
Export page on the TexGen website
Follow the steps in the Flow simulation using TexGen and CFX
tutorial on the TexGen website
Fabric permeability
TexGen unit cell model CFD simulation of steady-state Stokes flow
Determine in-plane and through-thickness permeabilities from prescribed pressure gradients and calculated average flow velocities
Impregnating resin flow in composites processing is described by homogenisation of local flow through pore spaces in the textile unit cell
generation of voxel mesh
(streamlines for flow along warp direction)
(Ansys CFX)
X Zeng, L P Brown, A Endruweit, M Matveev, and A.C. Long, Geometrical modelling of 3D woven reinforcements for polymer composites: Prediction of fabric permeability and composite mechanical properties. Composites Part A, 2014. 56(0): p. 150-160.
Tetgen Mesh Export
GUI: Select File -> Export -> Tetgen Mesh
• Uses Tetgen library• Parameters - http://wias-
berlin.de/software/tetgen/switches.html
• Tetrahedral elements
• Save as ABAQUS .inp file• Creates .ori and .eld files• Exports nodes, elements, element
sets• Save as VTK .vtu file
• Saves extra data in properties
• May need to introduce gap between yarns for export to be successful
• Set resolution can be used to change the surface mesh which is used as input for the tetgen mesh generator
Dry fibre export
Volume Mesh
• Conformal mesh using hex and wedge elements
• Generates mesh based on section points and number of slave nodes (ie yarn resolution)
• Section mesh based on section points• Corresponding points in adjacent section
meshes joined to form volume mesh
• View using Render Textile Volume
Section mesh based
on section points
ABAQUS Dry Fibre Export
GUI: Select File -> Export -> ABAQUS Dry Fibre File• Uses volume mesh• Sets up Explicit analysis• Specify deformation• Add compression plates• Correction for small intersections
• Regenerate mesh redistributes section mesh and saves in original textile
• Uses weave pattern information to generate contact surfaces
Interference points Corrected mesh
Deformation Simulation
• TexGen dry fibre export generates conformal mesh and .inp
for ABAQUS/Explicit simulation
• Used ABAQUS General Contact algorithm
Unit cell with periodic boundary conditions
3x3 unit cell, unconstrained in x direction
Geometry Export
Geometry Export: STEP and IGES files
The geometry alone can be exported in IGES, STEP or
stl format. No orientations, volume fractions or properties
are exported.
GUI: Select File -> Export -> IGES Fileor -> STEP File
• This option uses the OpenCASCADE library. • The ‘Smooth’ option may be unsuccessful for more
complex geometries• ‘Faceted’ option uses the surface mesh
• Use Rendering->X-Ray to view what is generated• ‘Join Yarn Sections’ will remove joins at repeat
boundaries but is much slower
Geometry Export: Surface Mesh
.vtu surface mesh
displayed in Paraview
GUI: Select File -> Export -> Surface Mesh• Exports the surface mesh as displayed by Rendering -> X-Ray• Export with or without the domain
• VTK unstructured grid file (.vtu)
• ASCII or binary STL file (.stl or .stlb)
• SCIRun file (.pts)
Any Questions?
