Quantitative ultrasound is a modality that is used to evaluate bone quality. It is considered that the analysis of ultrasound guided wave propagating along cortical bone may be useful for the assessment of cortical bone quality. Because... more
Quantitative ultrasound is a modality that is used to evaluate bone quality. It is considered that the analysis of ultrasound guided wave propagating along cortical bone may be useful for the assessment of cortical bone quality. Because the frequency-dependent wavenumbers reflect the elastic parameters of the medium, high-resolution estimation of the wavenumbers at each frequency is important. We report an adaptive array signal processing method with a technique to estimate the numbers of propagation modes at each frequency using information theoretic criteria and the diagonal loading technique. The proposed method estimates the optimal diagonal loading value required for guided wave estimation. We investigate the effectiveness of the proposed method via simple numerical simulations and experiments using a copper plate and a bone-mimicking plate, where the center frequency of the transmit wave was 1.0 MHz. An experimental study of 4 mm thick copper and bone-mimicking plates showed t...
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In the 1950s, the effect of ultrasound stimulation on bone healing has been discovered. Nowadays, Low Intensity Pulsed Ultrasound Stimulation (LIPUS) is admitted to influence the mechanotransduction of bone. Nevertheless, despite a... more
In the 1950s, the effect of ultrasound stimulation on bone healing has been discovered. Nowadays, Low Intensity Pulsed Ultrasound Stimulation (LIPUS) is admitted to influence the mechanotransduction of bone. Nevertheless, despite a growing literature—cell cultures, animal models, and clinical studies—the underlying physical and biological mechanisms of LIPUS on bone healing are still misunderstood. Inspired from previous studies on the mechanotransduction induced by physiological loading, this work focuses on the effect of LIPUS on the osteocytes. These bone cells are thought to be the principal mechanosensors of bone. They are ubiquitous inside the bone matrix, immersed in the lacuno-canalicular network (LCN) filled with interstitial fluid (IF). The goal is to relate the ultrasound stimulation applied at the tissue scale, to the biological response at the cell scale. To tackle this question, two finite element models were implemented in the commercial software Comsol Multiphysics. ...
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Cementless implants have become widely used for total hip replacement surgery. The long-term stability of these implants is achieved by bone growing around and into the rough surface of the implant, a process called osseointegration.... more
Cementless implants have become widely used for total hip replacement surgery. The long-term stability of these implants is achieved by bone growing around and into the rough surface of the implant, a process called osseointegration. However, debonding of the bone–implant interface can still occur due to aseptic implant loosening and insufficient osseointegration, which may have dramatic consequences. The aim of this work is to describe a new 3D finite element frictional contact formulation for the debonding of partially osseointegrated implants. The contact model is based on a modified Coulomb friction law by Immel et al. (2020), that takes into account the tangential debonding of the bone-implant interface. This model is extended in the direction normal to the bone-implant interface by considering a cohesive zone model, to account for adhesion phenomena in the normal direction and for adhesive friction of partially bonded interfaces. The model is applied to simulate the debonding ...
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International audienc
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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or... more
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Biomechanics of the acetabular cup implant Influence of anisotropic bone properties on the biomechanical behavior of the acetabular cup implant: a multiscale finite element study Vu-Hieu Nguyen, Giuseppe Rosi, Salah Naili, Adrien Michel, Maria-Letizia Raffa, Romain Bosc, Jean-Paul Meningaud, Christine Chappard, Naoki Takano, Guillaume Haiat
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Abstract In this paper, we present a new approach to study Lamb-type waves of anisotropic elastic plates in a probabilistic framework. The study and analysis are carried out on an elastic plate whose randomly varied elastic properties in... more
Abstract In this paper, we present a new approach to study Lamb-type waves of anisotropic elastic plates in a probabilistic framework. The study and analysis are carried out on an elastic plate whose randomly varied elastic properties in the through-thickness direction. By introducing a stochastic model for quantitative description of heterogeneous elastic properties in the plate, the effect of material heterogeneity on Lamb modes may be investigated from a stochastic point of view. To the our best knowledge, this study is the first to investigate Lamb-type waves in a probabilistic framework. Different plate thicknesses are considered and associated dispersion curves are computed. A sensitivity study is performed, highlighting effect of the uncertainty of elasticity properties on the fluctuation of Lamb modes via phase velocities, energy velocities and modes shapes. Next, we discuss the relevance of introducing random media to identify branches associated with experimental dispersion curves.
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Quantitative ultrasound are used to characterize and stimulate osseointegration processes at the bone-implant interface (BII). However, the interaction between an ultrasonic wave and the implant remains poorly understood. This study aims... more
Quantitative ultrasound are used to characterize and stimulate osseointegration processes at the bone-implant interface (BII). However, the interaction between an ultrasonic wave and the implant remains poorly understood. This study aims at investigating the sensitivity of the ultrasonic response to the microscopic and macroscopic properties of the BII and to osseointegration processes. The reflection coefficient R of the BII was modeled for different frequencies using a two-dimensional finite element model. The implant surface was modeled by a sinusoidal function with varying amplitude and spatial frequency and then by considering actual implant surface profiles. A soft tissue layer of thickness W was introduced between bone tissue and the implant in order to model non-mineralized fibrous tissue. For microscopic roughness, R is shown to increase from around 0.55 until 0.9 when k.W increases from 0 to 1 and to be constant for k.W>1. These results show that R depends on the proper...
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Bio‐sourced epoxy resins from resorcinol diglycidyl ether (RDGE) have been obtained by using cationic photopolymerization under UV‐light exposure. The photoinduced bulk resin samples were characterized by three‐point bending tests,... more
Bio‐sourced epoxy resins from resorcinol diglycidyl ether (RDGE) have been obtained by using cationic photopolymerization under UV‐light exposure. The photoinduced bulk resin samples were characterized by three‐point bending tests, dynamic mechanical analysis, as well as differential scanning calorimetry analysis, and thermogravimetric analysis. The influence of processing parameters, that is, reactant contents, UV irradiation time, and postcuring conditions on the thermomechanical behavior has been pointed out. For instance, the flexural modulus of the most performing materials reaches 4.1 GPa with the flexural strength and the glass‐transition temperature of around 105 MPa and 99°C, respectively. Interestingly, our optimized protocol has led to the synthesis of new bio‐based materials with more valuable thermal and mechanical properties than those of thermocured materials obtained from petroleum‐based commercial epoxy resins. Focus has been given on processing parameters to optimi...
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The stress distribution around endosseous implants is an important determinant of the surgical success but it remains difficult to be measured. So far, no method developed to determine the implant stability is sensitive to the loading... more
The stress distribution around endosseous implants is an important determinant of the surgical success but it remains difficult to be measured. So far, no method developed to determine the implant stability is sensitive to the loading conditions of the bone-implant interface (BII). The objective of this study is to investigate whether a quantitative ultrasound (QUS) technique may be used to retrieve information on compressive stresses applied to the BII. A dedicated acousto-mechanical device was conceived to compress 18 trabecular bovine bone samples onto coin-shaped implants and to measure the ultrasonic response of the BII during compression. The biomechanical behavior of the trabecular bone samples was modeled as Neo-Hookean. The reflection coefficient of the BII was shown to decrease as a function of the compressive stress during the elastic compression of the trabecular bone samples and during the collapse of the trabecular network, with an average slope of -4.82 GPa-1. Results...
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Biomechanical phenomena occurring at the bone–implant interface during the press-fit insertion of acetabular cup implants are still poorly understood. This article presents a nonlinear geometrical two-dimensional axisymmetric finite... more
Biomechanical phenomena occurring at the bone–implant interface during the press-fit insertion of acetabular cup implants are still poorly understood. This article presents a nonlinear geometrical two-dimensional axisymmetric finite element model aiming at describing the biomechanical behavior of the acetabular cup implant as a function of the bone Young’s modulus Eb, the diametric interference fit ( IF), and the friction coefficient µ. The numerical model was compared with experimental results obtained from an in vitro test, which allows to determine a reference configuration with the parameter set: μ* = 0.3, [Formula: see text], and IF* = 1 mm for which the maximal contact pressure tN = 10.7 MPa was found to be localized at the peri-equatorial rim of the acetabular cavity. Parametric studies were carried out, showing that an optimal value of the pull-out force can be defined as a function of μ, Eb, and IF. For the reference configuration, the optimal pull-out force is obtained f...
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Despite the unique mechanical strength and adhesion properties of epoxy resins, they still suffer from poor toughness and brittleness inducing poor resistance to cracks. Herein, we report an efficient method of synthesis of bioepoxy resin... more
Despite the unique mechanical strength and adhesion properties of epoxy resins, they still suffer from poor toughness and brittleness inducing poor resistance to cracks. Herein, we report an efficient method of synthesis of bioepoxy resin nanocomposites filled with highly exfoliated epoxy-grafted montmorillonite. The filled resin network was produced by covalent incorporation of a binary nanocomposite (MMT-PGMA) synthesized via in situ photoinduced polymerization of glycidyl methacrylate, into a Bioepoxy resin matrix to design a ternary nanocomposite (MMT-PGMA/Bioepoxy) and this in the presence of a green polyamine used as curing agent. The materials structure and morphology were characterized by FTIR, TGA, XRD, SEM, and TEM which show the key role of the MMT surface modification on its interfacial adhesion with the epoxy resin. The results showed that the clay interlayer d-spacing increases from 1.23 nm to more than 2.2 nm upon grafting of the polymer. The homogeneous solvent-free dispersion of hybrid cl...
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Ultrasonic responses probed from an axial transmission test (ATT) may provide useful information about material and structural properties of cortical bone. For the mathematical modeling of ultrasonic wave propagation in long bones, most... more
Ultrasonic responses probed from an axial transmission test (ATT) may provide useful information about material and structural properties of cortical bone. For the mathematical modeling of ultrasonic wave propagation in long bones, most of studies assumed an (visco-)elastic behavior for cortical bone tissue by neglecting the interstitial pressure in the pores presented within this material. Here, a functionally graded anisotropic poroelastic model is proposed for describing the behavior of long bones in the ultrasonic frequency range. The simulation of time-domain wave propagation can efficiently be carried out by using a semi-analytical finite element method. The proposed model allows us investigate the influence of the presence of the pores, as well as their distribution in a bone layer on the speed of sound propagated in a cortical bone layer coupled with the marrow and the soft tissue. The effects of emitted signal’s frequency will also be examined.
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Although endosseous implants are widely used in the clinic, failures still occur and their clinical performance depends on the quality of osseointegration phenomena at the bone-implant interface (BII), which are given by bone ingrowth... more
Although endosseous implants are widely used in the clinic, failures still occur and their clinical performance depends on the quality of osseointegration phenomena at the bone-implant interface (BII), which are given by bone ingrowth around the BII. The difficulties in ensuring clinical reliability come from the complex nature of this interphase related to the implant surface roughness and the presence of a soft tissue layer (non-mineralized bone tissue) at the BII. The aim of the present study is to develop a method to assess the soft tissue thickness at the BII based on the analysis of its ultrasonic response using a simulation based-convolution neural network (CNN). A large-annotated dataset was constructed using a two-dimensional finite element model in the frequency domain considering a sinusoidal description of the BII. The proposed network was trained by the synthesized ultrasound responses and was validated by a separate dataset from the training process. The linear correlation between actual and estimated soft tissue thickness shows excellent R2 values equal to 99.52% and 99.65% and a narrow limit of agreement corresponding to [ -2.56, 4.32 μm] and [ -15.75, 30.35 μm] of microscopic and macroscopic roughness, respectively, supporting the reliability of the proposed assessment of osseointegration phenomena.
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Finite element procedures for nonlinear structures in moving coordinates. Part II:
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The technique of non-invasive cortical bone quality assessment using ultrasound axial transmission has attracted considerable attention. Estimating the phase velocity and the attenuation of the absorbing plate will assist the assessment.... more
The technique of non-invasive cortical bone quality assessment using ultrasound axial transmission has attracted considerable attention. Estimating the phase velocity and the attenuation of the absorbing plate will assist the assessment. Among several techniques proposed for these purposes, many employ either a thresholding process or a peak search process. The thresholding process uses the intensity of the guided wave to distinguish the noise from the signal, but may dismiss weak intensity modes. The peak search process extracts the phase velocity and attenuation from the estimated intensity in the frequency and wavenumber domains; however, this process costs a large computational load. To overcome these difficulties, we propose a novel algorithm that uses an adaptive beamforming technique.
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The evaluation of implant stability is an important task for dentists. The long-term stability of a dental implant is dependent on the quality of bone tissue surrounding it. In this context, difficulties are mostly due to the complexity... more
The evaluation of implant stability is an important task for dentists. The long-term stability of a dental implant is dependent on the quality of bone tissue surrounding it. In this context, difficulties are mostly due to the complexity of newly formed bone tissue (a complex, anisotropic, porous-viscoelastic medium in constant remodeling) but also to the boundary conditions at the bone-implant interphase. In particular, multiple parameters affect primary and secondary stability, as bone quality, bone density or amount of bone in contact with the implant. In this framework, ultrasound based techniques have already been proven to be effective in the qualitative and quantitative evaluation of primary and secondary stability of dental implants. The ultrasonic response of the implant depends on the microstructure, mechanical properties and geometry of the boneimplant system. Major questions are: how each of these properties leaves a specific signature on the signal, and how the informati...
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Les techniques de mesures quantitatives par ultrasons sont non-destructives et a ce titre sont interessantes pour determiner les caracteristiques mecaniques et/ou geometriques de l'os in vivo ou in vitro. La mesure est basee sur... more
Les techniques de mesures quantitatives par ultrasons sont non-destructives et a ce titre sont interessantes pour determiner les caracteristiques mecaniques et/ou geometriques de l'os in vivo ou in vitro. La mesure est basee sur l'estimation de vitesses et d'attenuations des ondes qui se sont propagees dans le tissu osseux. Cependant, l'interpretation des resultats est difficile du fait de la complexite de ce tissu lequel est elastique, poreux, anisotrope et heterogene. Par exemple, en utilisant la technique de transmission transverse in vitro, des etudes theoriques et experimentales ont montre que le comportement des ondes dans l'os spongieux, aussi appele trabeculaire, depend fortement de l'angle entre la direction d'emission des ondes et l'orientation des trabecules lesquelles constituent la microstructure de ce tissu. Les etudes realisees in vitro sur l'os trabeculaire supposent que l'echantillon osseux est un materiau orthotrope dont les ...
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A new numerical tool, called DEEPLINES , has been developed by IFP and Principia RD to perform dynamic analyses of Floating Production Systems. This Finite-Element program may either deal with flexible risers, rigid risers, umbilicals and... more
A new numerical tool, called DEEPLINES , has been developed by IFP and Principia RD to perform dynamic analyses of Floating Production Systems. This Finite-Element program may either deal with flexible risers, rigid risers, umbilicals and mooring lines individually or take into account the coupled behaviour of these connections and their floating support. For the analysis of rigid risers, the implementation of elastoplastic material laws is presented in this paper. As an illustration, the case of reeled pipes is examined through a preliminary calculation of residual stresses due to the reeling process. Catenary configurations are then subsequently calculated using the results of the previous calculations, and comparisons are made between the response of classical and reeled pipes. Results show that according to the loading amplitude, residual stresses have an initial influence on the structure behaviour, but this influence may vanish after several loading cycles. Situations are then...
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Poroelastic materials are well known to possess exclusive properties for sound absorption. However, tuning their properties for achieving the better acoustic performance is not an easy experimental tasks which can be significantly... more
Poroelastic materials are well known to possess exclusive properties for sound absorption. However, tuning their properties for achieving the better acoustic performance is not an easy experimental tasks which can be significantly improved by mathematical modelling. In this work we exploit the homogenization procedure to determine the effective properties of an air-saturated material with microstructure. These properties are then used to solve an acoustic problem with the final objective of finding the optimal design microstructural parameters for the highest acoustic absorption. The microstructure of a material is formed by the translation of a unit cell. We study certain topologies of a unit cell to verify their effects on the optimization results. Moreover, we consider different types of a skeleton material (perfectly rigid, stiff and soft frames) and demonstrate the influence of the material properties on the optimal design parameters. Particularly, the effective elastic propert...
This paper deals with modeling of the ultrasound axial transmission technique for in vivo cortical long bone which is known as being a anisotropic solid medium with functionally graded porosity. The bone is modeled as an anisotropic... more
This paper deals with modeling of the ultrasound axial transmission technique for in vivo cortical long bone which is known as being a anisotropic solid medium with functionally graded porosity. The bone is modeled as an anisotropic poroelastic medium using the Biots theory. We develop a hybrid spectral/finite element formulation to obtain the time-domain solution of ultrasonic waves propagating in a poroelastic plate immersed two fluid halfspaces. The numerical method is based on a combined Laplace-Fourier transform which solves the problem in the frequency-wavenumber domain. In the spectral domain, as radiation conditions may be exactly introduced in the infinite fluid halfspaces, only the heterogeneous solid layer needs to be analyzed using finite element method. Several numerical tests are presented showing very good performances of the proposed approach. A preliminary study on the FAS (First Arrived Signal) velocities computed by using equivalent elastic and poroelastic models...
Resonance frequency analyses (RFA) and quantitative ultrasound (QUS) methods have been suggested to dental assess implant stability. The aim of this study was to compare the results obtained using these two techniques in vitro and in... more
Resonance frequency analyses (RFA) and quantitative ultrasound (QUS) methods have been suggested to dental assess implant stability. The aim of this study was to compare the results obtained using these two techniques in vitro and in vivo. Implants were inserted in bone phantoms with different values of density and cortical thickness to assess the effect of bone quality on the ultrasonic indicator (UI) and on the ISQ values. 81 identical implants were inserted in the iliac crests of 11 sheep. The QUS and RFA measurements were realized after different healing times. ISQ values increase and UI values decrease when i) the bone density and ii) cortical thickness increase. The error realized on the estimation of the trabecular density (respectively cortical thickness) with the QUS device is around 4 (respectively, 8) times lower compared to that made with the RFA technique. The error made on the estimation of the healing time using the QUS technique was 10 times lower than using the RFA ...
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This study has developed novel fully bio-based resorcinol epoxy resin–diatomite composites by a green two-stage process based on the living character of the cationic polymerization. This process comprises the photoinitiation and... more
This study has developed novel fully bio-based resorcinol epoxy resin–diatomite composites by a green two-stage process based on the living character of the cationic polymerization. This process comprises the photoinitiation and subsequently the thermal dark curing, enabling the obtaining of thick and non-transparent epoxy-diatomite composites without any solvent and amine-based hardeners. The effects of the diatomite content and the compacting pressure on microstructural, thermal, mechanical, acoustic properties, as well as the flame behavior of such composites have been thoroughly investigated. Towards the development of sound absorbing and flame-retardant construction materials, a compromise among mechanical, acoustic and flame-retardant properties was considered. Consequently, the composite obtained with 50 wt.% diatomite and 3.9 MPa compacting pressure is considered the optimal composite in the present work. Such composite exhibits the enhanced flexural modulus of 2.9 MPa, a sa...
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This paper presents for the first time an eco-friendly combination of cationic photopolymerization and the solid template technique to obtain macroporous epoxy resins from resorcinol diglycidyl ether (RDGE) with defined cell size and... more
This paper presents for the first time an eco-friendly combination of cationic photopolymerization and the solid template technique to obtain macroporous epoxy resins from resorcinol diglycidyl ether (RDGE) with defined cell size and distribution. The polymerization was performed by cationic polymerization under UV irradiation in the presence of NaCl particles template sintered through the spark plasma sintering process (SPS). After removal of NaCl by water, a porous material with interconnected pores was obtained. The influence of processing parameters, i.e., reactant contents, UV irradiation time, and post-curing conditions on the reticulation achievement and the thermomechanical behavior have been pointed out. Mechanical, physical, acoustic and morphological properties were deeply investigated. For instance, the specific compressive modulus is of 50.9 MPa cm3.g−1 for a density of 0.224 g.cm−3 and the glass transition is around 137 °C, which makes this system an interesting alternative for sustainable building materials.
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Abstract Understanding dispersion relations and wave mode shapes is vital in nondestructive control of dynamic behaviors of poroelastic composites. In the framework of semi-analytical finite element (SAFE) method, this paper presents two... more
Abstract Understanding dispersion relations and wave mode shapes is vital in nondestructive control of dynamic behaviors of poroelastic composites. In the framework of semi-analytical finite element (SAFE) method, this paper presents two numerical approaches so-called semi-analytical isogeometric Galerkin (SAIGA-G) and semi-analytical isogeometric collocation (SAIGA-C) for computing dispersion of guided-waves in anisotropic poroelastic plates immersed in acoustic fluids. Biot’s theory was used for describing the dynamic behavior of anisotropic poroelastic material. Assuming the structures is homogeneous along its axial direction, the Non-Uniform Rational B-splines (NURBS) was successful employed in procedures using isogeometric Galerkin and collocation methods. The numeral studies showed that the SAIGA-G method using high continuity NURBS basis allowed to significantly improve the accuracy as well as the convergence rate of the wave dispersion solutions in compared with the conventional SAFE method, which used Lagrange basis functions. Otherwise, the SAIGA-C method was shown to have similar performance in terms of accuracy to the SAFE method.
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Abstract Material and structural non-destructive evaluations using guided-wave (GW) testing techniques rely on the knowledge of wave dispersion characteristics. When studying coupled fluid–solid waveguides having complex geometries using... more
Abstract Material and structural non-destructive evaluations using guided-wave (GW) testing techniques rely on the knowledge of wave dispersion characteristics. When studying coupled fluid–solid waveguides having complex geometries using the semi-analytical finite element (SAFE) method, an excessive computational effort may be required, especially at high-frequency ranges. In this paper, we show the robustness of an efficient computational approach so-called the semi-analytical isogeometric analysis (SAIGA) for computing the wave dispersion in 3D anisotropic elastic waveguides coupled with acoustic fluids. This approach is based on the use of Non-Uniform Rational B-splines (NURBS) as the basis functions for the geometry representation as well as for the approximation of pressure/displacement fields. The obtained results are compared with the ones derived from using the conventional SAFE method which uses Lagrange polynomials. It is shown that for computing the dispersion of GWs, using SAIGA leads to a much faster convergence rate than using the conventional SAFE with the same shape function’s order. For hollow prismatic structures immersed in fluids, using high-order NURBS ( e.g, p = 8 ) is particularly efficient as it only requires a few elements to achieve solutions having the same precision as the ones obtained by SAFE which requires up to five times of number of DOFs. Moreover, the continuity of normal displacement at fluid–solid interfaces could be significantly improved thanks to the smoothness feature of NURBS, showing the advantage of SAIGA over SAFE in the evaluation of the shape modes of GWs in coupled fluid–solid systems.
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Bone substitutes can be used for pre-implant surgery in presence of volumetric bone defects. In this context, the ultrasound characterization of the bone substitute is a key issue. To this end, we model the implant as a 3D porous... more
Bone substitutes can be used for pre-implant surgery in presence of volumetric bone defects. In this context, the ultrasound characterization of the bone substitute is a key issue. To this end, we model the implant as a 3D porous structure and we study its ultrasonic behavior. In the framework of artificial bone substitutes, microstructured scaffolds are widely used. In the literature, several geometrical configurations have been tested: among them, the gyroid-shaped scaffolds turn out to be an excellent choice, thanks to its ability to reproduce the behavior and the porous structure of trabecular bone. This study is focused on the mechanical modelling and numerical validation of wave propagation in a porous implant substitute. In particular, 3D finite-difference time-domain (FDTD) simulations were performed on a gyroid-shaped scaffold of saturated with water to validate the continuum mechanical model. Ultrasound excitations at different central frequencies were used in order to investigate the frequency-dependent behavior phase and group velocities.Bone substitutes can be used for pre-implant surgery in presence of volumetric bone defects. In this context, the ultrasound characterization of the bone substitute is a key issue. To this end, we model the implant as a 3D porous structure and we study its ultrasonic behavior. In the framework of artificial bone substitutes, microstructured scaffolds are widely used. In the literature, several geometrical configurations have been tested: among them, the gyroid-shaped scaffolds turn out to be an excellent choice, thanks to its ability to reproduce the behavior and the porous structure of trabecular bone. This study is focused on the mechanical modelling and numerical validation of wave propagation in a porous implant substitute. In particular, 3D finite-difference time-domain (FDTD) simulations were performed on a gyroid-shaped scaffold of saturated with water to validate the continuum mechanical model. Ultrasound excitations at different central frequencies were used in order to investigate the frequency-...
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Abstract We consider fluid-saturated poroelastic media whose the mechanical response is governed by the Biot model relevant to a mesoscopic scale. Assuming the material properties being described by periodic functions, to analyze wave... more
Abstract We consider fluid-saturated poroelastic media whose the mechanical response is governed by the Biot model relevant to a mesoscopic scale. Assuming the material properties being described by periodic functions, to analyze wave propagation in such heterogeneous and anisotropic media, we derive a formulation based on the Floquet-Bloch (FB) wave decomposition which enables to analyze waves within the whole first Brillouin zone associated with the periodic structure. The wave dispersion results obtained by the FB approach are compared with those computed using a model derived by the homogenization based on the asymptotic analysis with respect to the scale parameter. As another new ingredient, the homogenized model is extended to describe media saturated simultaneously by multiple different fluids, so that the model involves new permeability tensors and differs in structure from the model derived earlier. The dispersion analysis by the FB approach leads to a cumbersome quadratic eigenvalue problem to be solved for complex wave numbers. We suggest an efficient filtration strategy to identify the principle propagating modes (the fast and slow compressional waves and the shear waves). For comparison with results of the FB transformation applied at the mesoscopic heterogeneity scale, the homogenized model responses are reconstructed using the corrector results of the homogenization with fixing a finite scale. Numerical examples illustrate very good correspondence of the dispersion results, as computed by both the approaches.
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Quantitative ultrasound can be used to characterize the evolution of the bone-implant interface (BII), which is a complex system due to the implant surface roughness and to partial contact between bone and the implant. The determination... more
Quantitative ultrasound can be used to characterize the evolution of the bone-implant interface (BII), which is a complex system due to the implant surface roughness and to partial contact between bone and the implant. The determination of the constitutive law of the BII would be of interest in the context of implant acoustical modeling in order to take into account the imperfect characteristics of the BII. The aim of the present study is to propose an analytical effective model describing the interaction between an ultrasonic wave and a rough BII. To do so, a spring model was considered to determine the equivalent stiffness K of the BII. The stiffness contributions related (i) to the partial contact between the bone and the implant and (ii) to the presence of soft tissues at the BII during the process of osseointegration were assessed independently. K was found to be comprised between 1013 and 1017 N/m3 depending on the roughness and osseointegration of the BII. Analytical values of the reflection and transmission coefficients at the BII were derived from values of K. A good agreement with numerical results obtained through finite element simulation was obtained. This model may be used for future finite element bone-implant models to replace the BII conditions.
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Abstract We present in this paper a combined technique of long short-term memory and hidden Markov model to prediction problems of crack propagation in engineering. The primary advantage of the hidden Markov model is that the ability to... more
Abstract We present in this paper a combined technique of long short-term memory and hidden Markov model to prediction problems of crack propagation in engineering. The primary advantage of the hidden Markov model is that the ability to learn with less information, in other words, its future states do not depend on past ones, based only on the present state. We use long short-term memory to train data, and output consequences improved by adding predicted different changes that are computed by hidden Markov model. Applying this combined method to numerical examples of forecasting crack propagation of singled-edge-notched beam forced by 4-point shear, crack-height growth in Marcellus shale under the hydraulic fracturing and deformations of dam structures made from fiber reinforced concrete material is addressed. The tests were carried out with many different sizes of experimental data. It was found that a combined long short-term memory - hidden Markov model results in more accurate solution than only using long short-term memory, especially in the case of the dataset that is lack of information.
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Ultrasound techniques can be used to characterize and stimulate dental implant osseointegration. However, the interaction between an ultrasonic wave and the implant-bone interface (IBI) remains unclear. This study-combining experimental... more
Ultrasound techniques can be used to characterize and stimulate dental implant osseointegration. However, the interaction between an ultrasonic wave and the implant-bone interface (IBI) remains unclear. This study-combining experimental and numerical approaches-investigates the propagation of an ultrasonic wave in a dental implant by assessing the amplitude of the displacements along the implant axis. An ultrasonic transducer was excited in a transient regime at 10 MHz. Laser interferometric techniques were employed to measure the amplitude of the displacements, which varied 3.2-8.9 nm along the implant axis. The results demonstrated the propagation of a guided wave mode along the implant axis. The velocity of the first arriving signal was equal to 2110 m.s-1, with frequency components lower than 1 MHz, in agreement with numerical results. Investigating guided wave propagation in dental implants should contribute to improved methods for the characterization and stimulation of the IBI.
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Ultrasound techniques can be used to characterize and stimulate dental implant osseointegration. The acoustical energy transmitted to the bone-implant interface is an important parameter that must be controlled for both applications,... more
Ultrasound techniques can be used to characterize and stimulate dental implant osseointegration. The acoustical energy transmitted to the bone-implant interface is an important parameter that must be controlled for both applications, since it should be sufficiently low to avoid damaging the surrounding tissues, but sufficiently high for stimulation purposes to enhance bone growth. However, the interaction between an ultrasonic wave and a dental implant remains unclear. The objective of this study combining experimental, analytical and numerical approaches is to investigate the propagation of an ultrasonic wave in a dental implant by assessing the amplitude of the displacements along the implant axis. An ultrasonic transducer was excited in transient regime at 10 MHz. Laser interferometric techniques were employed to measure the amplitude of the displacements, which varied between 5 and 12 nm according to the position. The results show the propagation of a guided wave mode along the implant axis with a velocity of first arriving signal equal to 2110 m s−1 and frequency components lower than 1 MHz, which was confirmed by the analytical and numerical results. This work paves the way to improve techniques for the characterization and stimulation of the bone-implant interface.Ultrasound techniques can be used to characterize and stimulate dental implant osseointegration. The acoustical energy transmitted to the bone-implant interface is an important parameter that must be controlled for both applications, since it should be sufficiently low to avoid damaging the surrounding tissues, but sufficiently high for stimulation purposes to enhance bone growth. However, the interaction between an ultrasonic wave and a dental implant remains unclear. The objective of this study combining experimental, analytical and numerical approaches is to investigate the propagation of an ultrasonic wave in a dental implant by assessing the amplitude of the displacements along the implant axis. An ultrasonic transducer was excited in transient regime at 10 MHz. Laser interferometric techniques were employed to measure the amplitude of the displacements, which varied between 5 and 12 nm according to the position. The results show the propagation of a guided wave mode along the implant axis with a vel...