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1. Nonlinear Elasticity and Time Reversal Acoustics for Damage Detection and Localization Michele Griffa, Ph.D. EES-11 (Geophysics) Group Earth and Environmental Sciences (EES) Division Los Alamos National Laboratory MS D443, Los Alamos, New Mexico, 87545, USA and Bioinformatics and High Performance Computing Lab Biondustry Park of Canavese Colleretto Giacosa (Torino), 10010, Italy Email: mgriffa@lanl.gov Web site: http://www.lanl.gov/orgs/ees/ees11/geophysics/staff/griffa/griffa.shtml Personal Web site: http://www.calcolodistr.altervista.org/en/index_en.html UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

2. About myself ... • MS in Theoretical Physics (2003), University of Torino, Torino (Italy)‏ • Majors in Computational Physics and Applied Mathematics • Minors in Microelectronics and Cybernetics • Thesis field: Mathematical Biology and Biomechanics of Cancer Growth • Thesis title: “The Role of Mechanical Pressure, Cellular Adhesion and Apoptosis in the Growth of Multicellular Tumor Spheroids: Physical-Mathematical Modeling” • Ph.D. in Physics (2007), Polytechnic Institute of Torino, Torino (Italy)‏ • Majors in Condensed Matter Physics and Computational Physics • Minors in Biomechanics and Biomathematics • Thesis field: Elastodynamics, Nonlinear Elasticity, Ultrasound Imaging, NDE, High Performance Computing (Parallel Programming, Cluster Computing)‏ • Thesis title: “Modeling and Numerical Simulation of Elastic Wave Propagation for the Characterization of Complex Heterogeneous Materials” • Post Doc (since 2007), Nonlinear Elasticity/Time Reversal Team, EES-11 (Geophysics), Los Alamos National Laboratory, Los Alamos (USA)‏ • Research fields: Nonlinear Elasticity, Time Reversal Acoustics, Ultrasonic and Seismic Imaging, NDE, High Performance Computing (Parallel Programming and Cluster Computing)‏ UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

3. About myself ... Research Projects and Collaborations • Nonlinear Acoustics TEchniques for MIcro-Scale damage diagnostics (NATEMIS), European Science Foundation, 2000 - 2005 • Integrated Tool for In Situ Characterization of Effectiveness and Durability of Conservation Techniques in Historical Structures (DIAS), EU 5th Framework Program (FP5), 2002 - 2005 • Nonlinear Elastic Wave Spectroscopy for health monitoring of aircraft (AERONEWS), EU 6th Framework Program (FP6), 2004 - 2008 • Imaging by Time Reversal Mirrors, Los Alamos National Laboratory, LDRD (Institutional Program), Departmenf of Energy, 2006 - 2009 • Department of Physics, Polytechnic Institute of Torino: external collaborator • Center for the Development of a VIrtual Tumor (CVIT), Integrative Cancer Biology Program (ICBP), NCI-NIH, USA, 2004 - 2008 • Bioinformatics and High Performance Computing Lab, Bioindustry Park of Canavese: external collaborator • Aethia Power Computing Solutions, S.r.l. : external collaborator • Italian National Institute for Condensed Matter Physics, Parallel Computing Inititative UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

4. Non-Classical Non-Linear (NCNL) Elasticity: the origins General observation: “granular” geomaterials exhibit a peculiar set of nonlinear elastic behaviors, both in the quasi-static (stress-strain equation of state) and dynamic (wave propagation) regimes. Photomicrograph of a 30 m-thick slice of a Berea sandstone obtained by cross-polarized light. Grains with size from 50 to 200 m. R. Guyer, P.A.Johnson, Phys.Today 52 (4), 30-36 (1999)‏ Nonlinear elastic behaviour of “granular” geomaterials not describable by the “classical” theory of anharmonicity at finite strain amplitudes. UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

5. Quasi-Static Stress-Strain Eq. of State (EoS)‏ R. Guyer, P.A.Johnson, Phys.Today 52 (4), 30-36 (1999)‏ UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

6. Nonlinear Wave Mixing • Nonlinear wave mixing experiment: • intermediate amplitude sine-wave excitation at low frequency f1 (pump wave); • high-level amplitude excitation at high frequency f2 (probe wave); f2 >> f1 • the amplitude of the pump wave is increased. input: output: A special kind of nonlinear wave mixing: harmonics generation UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

7. Nonlinear Wave Mixing: an example • undamaged plexiglass: elastically linear and • isotropic • damaged plexiglass: elastically nonlinear, locally anisotropic damage due to cyclic loading → induction of pre-stress and change in the structure R.A. Guyer, P.A. Johnson, Nonlinear Mesoscopic Elasticity: Evidence for a New Class of Materials, Phys. Today 52 (4), 30-36, 1999. Classical Nonlinear Wave Mixing classical elastic behaviour <--> “atomic” elastic behaviour the macroscopic deformation properties depend only upon atomic and/or molecularscalesbonding and structure: classical elastic behaviour emerges from the microscopic scale UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

8. Nonlinear Wave Mixing: a more interesting example • harmonics generation and nonlinear wave mixing already in the undamaged state and at low strain • richer (“classical”) nonlinear frequency spectrum [P.A.Johnson, B.Zinszner and P.N.J.Rasolofosaon, J. Geophys. Res.101, p.11553 (1996)] [R.A. Guyer and P.A. Johnson, Physics Today 52, p.30 (1999)] UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

9. Nonlinear Wave Mixing: an even more interesting example 2nd order sidebands R.A. Guyer, P.A. Johnson, Nonlinear Mesoscopic Elasticity, Wiley, to be published f2 - f1 f2 f2 - 2f1 f2 + f1 f2 + 2f1 f1 not predicted by the classical theory of Nonlinear Elasticity but ... predicted in the framework of Nonclassical Nonlinear Elasticity UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

10. Nonclassical Nonlinear Elasticity: where does it come from ? • Which materials do exhibit such anomalous elastic behaviour ? porous aluminum powder soil (sieved, typical grain size 1 mm)‏ sandstone (typical grain size ~ 100 mm)‏ concrete ceramic UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

11. Nonclassical Nonlinear Elasticity: where does it come from ? • Which materials do exhibit such anomalous elastic behaviour ? typical structure: hard matrix made by many “grains” cemented together by “soft” inclusions (fluids, gels, or dislocation-based kinking bands)‏ • multi-phase materials • micro-structured materials • mesoscopic elasticity the “bond system” (set of soft inclusions) determines the presence and the level of nonclassical nonlinear elastic behavior • water saturation levels (Carmeliet and Van Den Abeele, 2002)‏ • mechanics of contact interfaces • phases and types of media constituting the “bond system” (neutron scattering experiments at LANL, Ten Cate and Darling, 2004-2007)‏ • nanoindentation and creation of dislocation-based kink bands (Barsoum et al., 2004-2008)‏ UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

12. Nonclassical Nonlinear Elasticity: where does it come from ? • Which materials do exhibit such anomalous elastic behaviour ? • pyrex containing cracks; • marble; • pearlite/graphite metal; • alumina ceramic; • sintered metal; • Perovskite ceramic; • quartzite; • damaged concrete; • metallic solids with interconnected dislocation networks, cracks or creeps; • nanoindented graphite, sapphire, layered semiconductors (in general MAX phases)‏ experimental evidence of nonclassical nonlinear elastic phenomenology in others materials only when damaged damage change in structure UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

13. Nonclassical Nonlinear Elasticity and NDE: damage detection looking for nonclassical nonlinear elastic behaviors as fingerprints of damage: damage detection Nonlinear Elastic Wave Spectroscopy (NEWS)‏ • K. Van Den Abeele et al., Res. Nondestr. Eval. 12, 17-42 (2000)‏ UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

14. Understanding and Exploiting Nonclassical Nonlinear Elasticity: modeling modeling and numerical simulations for supporting basic and applied experimental investigations need of a physical theory of NCNL Elasticity based on the knowledge of the micromechanics • NCNL elastic solids as a sub-category of Nonlinear Kinking Solids (Barsoum et al., 2004-2008)‏ • LISA modeling + Preisach-Mayergoyzphenomenological modeling UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

15. LISA (Local Interaction Simulation Approach)‏ for elastic wave propagation in solids beyond traditional FDTD (Finite Differences Time Domain)‏ for solving differential problems of Elastodynamics • Features: • based on a full displacement explicit FDTD scheme for solving PDEs; • exploitation of the mathematical correspondence between FDTD numerical discretization of PDEs and analogical modeling with discrete coupled systems (lumped-masses); mimetic scheme; • possibility of introducing in the model phenomenological “laws” of interactions between representative particles and/or special elastic behaviors of springs; • developed for modeling elastic wave propagation throughout highly heterogeneous materials, i.e. with a huge number of interfaces (M. Scalerandi, P.P. Delsanto et al., Naval Research Lab, USA, and Polytechnic Institute of Torino, Italy)‏ • modeling the physical role of interfaces in the wave propagation mechanism beyond simple reflection/refraction behavior ---> giving a physical “existence” to interfaces within the model UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

16. LISA-Spring Modeling Approach the importance of the mechanical behavior of the interstices constituting the “binding medium” grains <---> Kelvin-Voigt's viscoelastic bodies LISA-Spring modeling approach interstices/bond system poro-viscoelastic bodies with two possible sets of values for their parameters <--> two possible “states” modeling internal forces between interstices imposing constraints on the dynamics of the lateral sides of the interfaces dynamic switching between the two states during the wave propagation according to the comparison of a “control” parameterversus thresholds LISA modeling approach UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

17. LISA-Spring Modeling Approach • each interstice is an HEE (Hysteretic Elastic Elements), characterized by a bi-state dynamics triggered by the poro-elastic pressure P; • each HEE is characterized by the couple of threshold values for P, (Pc,Po)‏ • the whole specimen contains a huge amount of HEEs mapped into the Preisach-Mayergoyz plane (Pc,Po); • the overall elastic behavior of the whole specimen “emerges” from the local dynamics of the HEEs; • accounting for hysteretic strain-stress constitutive relations for “granular” materials geomaterials • M. Scalerandi, P.P. Delsanto, Phys. Rev. B 68 (6), 64107-1-9 (2003)‏ • M. Scalerandi et al., J. Acoust. Soc. Amer. 113 (6), 3049-59 (2003)‏ UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

18. Nonclassical Nonlinear Elasticity of Damaged Concrete In collaboration with M. Bentahar, R. El Guerjouma, GEMPPM UMR CNRS and INSA Lyon ≈168.2 KHz M. Bentahar, H. El Aqra, R. El Guerjouma, M. Griffa, M. Scalerandi, Phys. Rev. B 73, 014116 (2006)‏ UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

19. Nonclassical Nonlinear Elasticity of Damaged Concrete M. Bentahar, H. El Aqra, R. El Guerjouma, M. Griffa, M. Scalerandi, Phys. Rev. B 73, 014116 (2006)‏ linear regime linear regime • logarithmic-in-time recovery (slow dynamics)‏ • greater time recovey in the case of the damaged specimen UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

20. Nonclassical Nonlinear Elasticity of Damaged Concrete the problem of damage detection Two possible observables very sensitive to the damage state of a specimen (i.e. to the nonlinear nonclassical elastic behaviour): • linear (small excitation amplitude) Resonant Ultrasound Spectroscopy (RUS) measurements are already sensitive to the presence of damage (10% relative shift of the resonance frequency), but they always require a reference intact specimen ! • slope of the relative resonance frequency shift vs output peak amplitude • linear regime resonance frequency recovery time in slow dynamics • conditioning (small, reversible, changes of the elastic properties of the intersticial media even when a small amplitude perturbing wave is injected into the specimen) is at the basis of the fast and slow dynamics phenomenology ------> from the modeling of interstices elastic properties. • the validation of the model confirms the bases of its mathematical description of mechanisms for changes in elastic parameters of interstices, but the physical processes and components responsible for these changes must be discovered in order to develop a successful theory of NCNL Elasticity. UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

21. Nonclassical Nonlinear Elasticity and NDE the problem of damage localization LISA-Spring 2D simulation of elastic wave propagation in an Al sample with a linear inhomogeneity and a NCNL damage area (thin micro-crack)‏ A.S. Gliozzi, M. Griffa, M. Scalerandi, Efficiency of Time-Reversed Acoustics for Nonlinear Damage Detection in Solids, J. Acous. Soc. Amer. 120 (5), 2506-2517, (2006)‏ UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

22. Nonclassical Nonlinear Elasticity and NDE the problem of damage localization LISA-Spring 2D simulation of elastic wave propagation in an Al sample with a linear inhomogeneity and a NCNL damage area (thin micro-crack)‏ A.S. Gliozzi, M. Griffa, M. Scalerandi, Efficiency of Time-Reversed Acoustics for Nonlinear Damage Detection in Solids, J. Acous. Soc. Amer. 120 (5), 2506-2517, (2006)‏ UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

23. Nonclassical Nonlinear Elasticity and NDE the problem of damage localization Inserisci qui l'ultimo snapshots dal movie precedente • weak scattering by the linear inhomogeneity • even more weak scattering by the very thin NCNL feature (the damage region)‏ how to solve the inverse scattering problem and localize (image) selectively the different types of defects (linear and nonlinear) ? UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

24. Imaging by Time Reversal Acoustics M. Fink, Scientific American 281 (5), 91-97 (1999)‏ UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

25. general linear Elastodynamics wave equation covariance in respect of t --> -t P. Roux, B. Roman, M. Fink, Time Reversal in an ultrasonic waveguide, Appl.Phys.Lett. 70 (14), 1811-1813 (1997)‏ • spatial retro-focusing; • temporal compression; • multiple reflections subtitute TR transducers; • spatial informationconverted into temporal information; A. Derode, P. Roux, M. Fink, Robust Acoustic Time Reversal with High-Order Multiple Scattering, Phys.Rev.Lett 75 (3), 4206-4210 (1995)‏ UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

26. Nonclassical Nonlinear Elasticity and NDE the problem of damage localization TR-NEWS: Time Reversal + Nonlinear Elastic Wave Spectroscopy • insonify the specimen (forward propagation, FP)‏ • collect the signals at the Time Reversal Mirror • apply NEWS signal processing to enhance the nonlinear scatterer contribution • time reverse and rebroadcast into the specimen the signals • perform the TR backward propagation, experimentally for surface damage detection, in silico for 3D embedded UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

27. The problem of damage localization TR backward propagation with removal of the base-line (reflections from the boundaries and contribution of the inspection sources): focusing at the linear scatterer location A.S. Gliozzi, M. Griffa, M. Scalerandi, Efficiency of Time-Reversed Acoustics for Nonlinear Damage Detection in Solids, J. Acous. Soc. Amer. 120 (5), 2506-2517, (2006)‏ UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

28. TR-NEWS imaging: simulation test TR backward propagation with removal of the base-line + NEWS filtering: focusing at the nonlinear scatterer location only A.S. Gliozzi, M. Griffa, M. Scalerandi, Efficiency of Time-Reversed Acoustics for Nonlinear Damage Detection in Solids, J. Acous. Soc. Amer. 120 (5), 2506-2517, (2006)‏ UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

29. TR-NEWS imaging of surface micro-cracks: experimental results Sources: broadband -- hammer tap (excite 4 kHz)‏ probe – 204 kHz, toneburst (200 cycles, sin2 envelope)‏ T.J. Ulrich et al., Phys. Rev. Lett. 98, 104301 (2007)‏ UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA

30. 3D TR imaging UNCLASSIFIED UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA Operated by Los Alamos National Security, LLC for NNSA

31. Additional information • LANL Nonlinear Elasticity Web site • http://www.lanl.gov/orgs/ees/ees11/geophysics/nonlinear/nonlinear.shtml • LANL Time Reversal Acoustics in solid media Web site: • http://www.lanl.gov/orgs/ees/ees11/geophysics/timerev/timerev.shtml B.E. Anderson, M.Griffa, C. Larmat, T.J. Ulrich, P.A. Johnson, Acoustics Today 4 (1), 5-16 (2008)‏ UNCLASSIFIED UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA Operated by Los Alamos National Security, LLC for NNSA

32. Thanks a lot for your attention UNCLASSIFIED UNCLASSIFIED LAUR 2008-XX-XX Operated by Los Alamos National Security, LLC for NNSA Operated by Los Alamos National Security, LLC for NNSA