The finite element muscle modelling cookbook AND THE IMPORTANCE OF FIBRES C. Antonio Sánchez* Dept...
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- The finite element muscle modelling cookbook AND THE IMPORTANCE
OF FIBRES C. Antonio Snchez* Dept of Elec & Comp Eng University
of British Columbia Vancouver, BC, Canada antonios@ece.ubc.ca John
E. Lloyd Dept of Elec & Comp Eng University of British Columbia
Vancouver, BC, Canada lloyd@cs.ubc.ca *presenting author
- Slide 2
- Finite Element(FE) Muscle Models Extensor Carpi Radialis Longus
Masseter
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- FE Muscle Models Term Stress tensor Strain tensor Strain-energy
density Fibre direction/activation Volumetric Mesh Fibre Field(s)
Constitutive Law (Blemker, 2005)
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- Fibre Geometries Fibre templates (Blemker & Delp,
2005)Digitized Fibres (Ravichandiran et al., 2009)
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- Fibre Geometries Digitized Template Point-to-Point (Axial)
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- Fibres matter! 45 Digitized Template Point-to-Point
(Axial)
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- Fibres matter! Axial has same force-length relationship
Template force is scaled 1.46x
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- Fibre-Rich FE Muscle Target surface geometry Template
volumetric mesh Fibre geometry Ingredients Directions 1.Create
Volumetric Mesh Register template to target Recondition elements
2.Register Fibre Field Wrap fibres with surface Register to target
3.Assign element properties Extract directions from fibres
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- 3.Assign element properties Extract directions from fibres
2.Register Fibre Field Wrap fibres with surface Register to target
Fibre-Rich FE Muscle Target surface geometry Template volumetric
mesh Fibre geometry Ingredients Directions 1.Create Volumetric Mesh
Register template to target Recondition elements
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- Volumetric Meshes Muscles are highly deformable Structured
hexahedral meshes preferred Most are hand-crafted International
Union of Physiological Sciences (IUPS) Physiome Project Collection
of template meshes Register template shapes to target geometry
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- Volumetric Meshes PoorGood Element ConditioningDeformable
Registration
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- 3.Assign element properties Extract directions from fibres
1.Create Volumetric Mesh Register template to target Recondition
elements 2.Register Fibre Field Wrap fibres with surface Register
to target Fibre-Rich FE Muscle Target surface geometry Template
volumetric mesh Fibre geometry Ingredients Directions
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- Fibre Registration (Lee et al., 2012)
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- Fibre Registration Video courtesy of Benjamin Gilles, INRIA
Grenoble (Gilles et al., 2007)
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- 2.Register Fibre Field Wrap fibres with surface Register to
target 1.Create Volumetric Mesh Register template to target
Recondition elements Target surface geometry Template volumetric
mesh Fibre geometry Ingredients 3.Assign element properties Extract
directions from fibres Fibre-Rich FE Muscle Directions
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- Extracting Orientations Evaluated at integration points Find
fibres in neighbourhood
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- Extracting Orientations Evaluated at integration points Find
fibres in neighbourhood
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- Finite Element(FE) Muscle Models Extensor Carpi Radialis Longus
Masseter
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- AND THE IMPORTANCE OF FIBRES ?
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- Preliminary simulations What level of detail is important?
Axially along muscle Minimal set of templates Fibres typically run
between tendon sheets Are there important intricacies? Simulation:
Isometric contraction Generic muscle properties Ignored tendon
component
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- Fibre Geometries Digitized Template Point-to-Point (Axial)
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- Extensor Carpi Radialis
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- Flexor Digitorum Superficialis
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- Axial force scaled 1.12x Template force is scaled 1.26x
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- Implications and Future Work Implications: Might not be
sufficient to use simple templates Geometric deformation is
sensitive to fibre orientations Questions to answer: How much
detail is enough? Can fibres be registered between subjects? Future
Work: Include tendon structures Accurate attachment sites Mesh-Free
Implementation
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- EXTRA SLIDES