Boost Fertility New Invention Ups Success Rates.pdf
PhD Dissertation Defense
1. Modeling the PercussionModeling the Percussion
Response of LaminatedResponse of Laminated
Materials and Glass ColumnsMaterials and Glass Columns
through the use ofthrough the use of
Computational MethodsComputational Methods
Ian NievesIan Nieves
2. ObjectivesObjectives
• Damping and PercussionDamping and Percussion
• PeriometerPeriometer
• Modeling with Finite ElementModeling with Finite Element
Analysis (FEA)Analysis (FEA)
• Modeling Periometer TestingModeling Periometer Testing
Laminated Materials - DampingLaminated Materials - Damping
Glass Columns - DefectsGlass Columns - Defects
3. DampingDamping
• Energy dissipation during mechanical actionEnergy dissipation during mechanical action
• Intrinsic dampingIntrinsic damping: energy thermally: energy thermally
dissipated through microstructural changesdissipated through microstructural changes
• Damping a function of material structureDamping a function of material structure
U
D
π
η
2
= δη tan
'
"
==
E
E
4. Intrinsic Damping and TissueIntrinsic Damping and Tissue
RegenerationRegeneration
• Dominant paradigm of bone maintenance
(Mechanostat) = skeletal remodeling and
repair mediated by damping + dynamic
stresses
• Clinical studies implement damping in
prosthetics integration2
22
James C. Earthman, Cherilyn Sheets, J. Paquete, et al, Tissue EngineeringJames C. Earthman, Cherilyn Sheets, J. Paquete, et al, Tissue Engineering
in Dentistry,in Dentistry, Clin. Plastic Surg.Clin. Plastic Surg., Vol. 30, pp. 621 – 639, 2003, Vol. 30, pp. 621 – 639, 2003
22
James C. Earthman, Cherilyn Sheets, J. Paquete, et al, Tissue EngineeringJames C. Earthman, Cherilyn Sheets, J. Paquete, et al, Tissue Engineering
in Dentistry,in Dentistry, Clin. Plastic Surg.Clin. Plastic Surg., Vol. 30, pp. 621 – 639, 2003, Vol. 30, pp. 621 – 639, 2003
5. PercussionPercussion
• Generate mechanical pulses through impactGenerate mechanical pulses through impact
• Pulse parameters (intensity, duration, etc.)Pulse parameters (intensity, duration, etc.)
modified in situ through dampingmodified in situ through damping
• Pulsate mechanics similar to biologicalPulsate mechanics similar to biological
activities (Running, etc.)activities (Running, etc.)
*Bakos et al., Acta Veterinaria Hungarica (2003).
11. Modeling PercussionModeling Percussion
• Validate percussion responseValidate percussion response
• Elucidate mechanisms underlyingElucidate mechanisms underlying
responseresponse
• Predict facets of percussion profilePredict facets of percussion profile
• Taylor and refine detection capabilitiesTaylor and refine detection capabilities
• Facilitate construction of “PercussionFacilitate construction of “Percussion
Spectrum”Spectrum”
12. Finite Element Analysis (FEA)Finite Element Analysis (FEA)
Creates representations of geometryCreates representations of geometry
Uses geometry as template for networkUses geometry as template for network
(mesh) of discrete lattice points (nodes)(mesh) of discrete lattice points (nodes)
Nodes are vertices for line, planar orNodes are vertices for line, planar or
polyhedral elementspolyhedral elements
Uses Shape Functions to solve to produceUses Shape Functions to solve to produce
predictions of nodal (acceleration,predictions of nodal (acceleration,
displacement) and elemental (stress) resultsdisplacement) and elemental (stress) results
in response to inputs (initial and boundaryin response to inputs (initial and boundary
conditions)conditions)
13. ElementsElements
Idealized Hexagonal element used forIdealized Hexagonal element used for
virgin testing materials and full-scalevirgin testing materials and full-scale
Hexagonal elements in cylindricalHexagonal elements in cylindrical
probe with nodes adjacent toprobe with nodes adjacent to
accelerometeraccelerometer
14. Dytran vs.Dytran vs. MARCMARC
• Dytran specialized forDytran specialized for
ballistic modelingballistic modeling –– moremore
detailed resultsdetailed results
• Explicit solver –Explicit solver – ∆t∆tCritCrit
automatically calculatedautomatically calculated
• DYMAT 24 PiecewiseDYMAT 24 Piecewise
Linear PlasticityLinear Plasticity
(elastoplastic) material(elastoplastic) material
modelmodel
• Matrig rigid materialMatrig rigid material
model – only requiresmodel – only requires
mass inputmass input
• MARC capable of ballisticMARC capable of ballistic
modeling, specialized formodeling, specialized for
elastomeric analysiselastomeric analysis
• Implicit Solver -Implicit Solver - ∆t∆tCritCrit
calculated throughcalculated through
inspectioninspection
• Elastic Material modelElastic Material model
• Rayleigh damping modelRayleigh damping model
– intrinsic damping input– intrinsic damping input
DytranDytran MARCMARC
19. Initial and Boundary ConditionsInitial and Boundary Conditions
for Rigid Probe and Glass Columnsfor Rigid Probe and Glass Columns
20. Material ParametersMaterial Parameters
Material
Model
Material E (KPa) ρ (kg/mm3
) ν σys (KPa) Code
DYMAT 24
Steel 1.93108
8.00x10-6
0.30 4.40x104
Dytran
Al 6061 7.00x107
2.70x10-6
0.35 3.95x105
PTFE 5.00x105
2.10x10-6
0.40 9.00x104
Glass 7.03x107
2.47x10-6
0.22 6.90x104
PMMA 3.30x106
1.19x10-6
0.37 1.07x105
PLGA 3.50x106
1.19x10-6
0.40 4.4x104
Elastic
Steel 1.93108
8.00x10-6
0.30
MARC
Al 6061 7.00x107
2.70x10-6
0.35
PTFE 5.00x105
2.10x10-6
0.40
Glass 7.03x107
2.47x10-6
0.22
PMMA 3.30x106
1.19x10-6
0.37
PLGA 3.50x106
1.19x10-6
0.40
21. Intrinsic Damping in MARCIntrinsic Damping in MARC
Material Al PTFE PMMA
η 0.0003 0.1038 0.0400
• Rayleigh Damping Function: C = αM + (β+gt)K, MRayleigh Damping Function: C = αM + (β+gt)K, M
= Mass Matrix, K = Stiffness Matrix, C = Damping= Mass Matrix, K = Stiffness Matrix, C = Damping
MatrixMatrix
• Damping is proportional to stiffness and massDamping is proportional to stiffness and mass
• Stiffness Matrix Factor(Stiffness Matrix Factor(β) = 2(η)/π(lowest modalβ) = 2(η)/π(lowest modal
frequency(Hz))frequency(Hz))
• η = Loss Coefficientη = Loss Coefficient
• Modal frequency material specific, derivedModal frequency material specific, derived
through MARC modal analysisthrough MARC modal analysis
23. 3.175 mm thick Al Monolith: Results3.175 mm thick Al Monolith: Results
Stepped ProbeStepped Probe
Stepped Probe: MARCStepped Probe: MARC
Cylindrical Probe: DytranCylindrical Probe: Dytran
Cylindrical Probe:Cylindrical Probe:
DytranDytran
Cylindrical Probe: MARCCylindrical Probe: MARC
24. Size Effects: 500 x 500 x 3.175 mm Al MonolithSize Effects: 500 x 500 x 3.175 mm Al Monolith
and 27 gram Probeand 27 gram Probe
k
m
T =
27 gram Probe27 gram Probe 500 mm x 500 mm x 3.175 mm Monolith500 mm x 500 mm x 3.175 mm Monolith
25. Al – PTFE Scaffolds withAl – PTFE Scaffolds with
Rigid ProbeRigid Probe
26. Al – PTFE Scaffolds withAl – PTFE Scaffolds with
Stepped Probe and IntrinsicStepped Probe and Intrinsic
DampingDamping
27. 3.175 PTFE: 3.175 Al3.175 PTFE: 3.175 Al 1.58 PTFE: 3.175 Al1.58 PTFE: 3.175 Al
28. PMMA Scaffold with IntrinsicPMMA Scaffold with Intrinsic
DampingDamping
Scaffold and ProbeScaffold and Probe Layer with DefectLayer with Defect
29. PMMA Scaffold with IntrinsicPMMA Scaffold with Intrinsic
Damping: Origin of ShoulderDamping: Origin of Shoulder
Intrinsic DampingIntrinsic Damping No Intrinsic DampingNo Intrinsic Damping
30. PLGA Scaffold: Mesh re-Enforcement andPLGA Scaffold: Mesh re-Enforcement and
Stress AttenuationStress Attenuation
1
J. Calvert, L. Weiss, New Frontiers in Bone Tissue
Engineering, Clin. Plast. Surg., Vol. 30, pp. 641 – 648,
2003
• PLGA demonstrated toPLGA demonstrated to
stimulate bonestimulate bone
and vascular regenerationand vascular regeneration11
Re-enforcedRe-enforced
VirginVirgin
31. Glass DefectGlass Defect
0.2 mm0.2 mm
Glass used to model rigid biological materials:Glass used to model rigid biological materials:
bone, enamel, etc.bone, enamel, etc.
32. Cylindrical Probe and Glass ControlCylindrical Probe and Glass Control
MARCMARC
DytranDytran
33. Stepped Probe and Glass Control:Stepped Probe and Glass Control:
Acceleration ResultsAcceleration Results
T ≈ 0.18 msecT ≈ 0.18 msec
T ≈ 0.25 msecT ≈ 0.25 msec
T ≈ 0.25 msecT ≈ 0.25 msec
MARCMARC
DytranDytran
41. Glass Controls: FEA vs. Percussion
Y–AxisAcceleration(mm/secY–AxisAcceleration(mm/sec22
)
Time (sec)Time (sec)
Glass control acceleration accurately modeled with stepped probe
42. Cracked Glass : FEA vs. Percussion
Y–AxisAcceleration(mm/secY–AxisAcceleration(mm/sec22
)
Y–AxisAcceleration(mm/secY–AxisAcceleration(mm/sec22
)
Y–AxisAcceleration(mm/secY–AxisAcceleration(mm/sec22
)
Time (sec)Time (sec) Time (sec)Time (sec)
Time (sec)Time (sec)
43. Crack Stresses (KPa)
Semi-circular crack withSemi-circular crack with
square edgesquare edge
Semi-
circular
crack
with
round
edge
Wedge-formWedge-form
crackcrack
with roundwith round
edgeedge
45. Summary
• FEA can elucidate mechanical origin of probeFEA can elucidate mechanical origin of probe
signalssignals
• FEA – based modeling can accurately modelFEA – based modeling can accurately model
defect detection in rigid materialsdefect detection in rigid materials
• FEA can qualitatively evaluate energyFEA can qualitatively evaluate energy
dissipation in biomedical scaffoldsdissipation in biomedical scaffolds
• Modeling indicates dependence ofModeling indicates dependence of
Periometer function on interference effectsPeriometer function on interference effects
• Further modeling – experimental is requiredFurther modeling – experimental is required
to refine intrinsic damping modelingto refine intrinsic damping modeling
