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The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Thu, 22 Feb 2024 23:20:40 GMT2024-02-22T23:20:40ZHomogenization of size-dependent multiphysics behavior of nanostructured piezoelectric composites with energetic surfaces
http://hdl.handle.net/10985/22397
Homogenization of size-dependent multiphysics behavior of nanostructured piezoelectric composites with energetic surfaces
CHEN, Qiang; CHATZIGEORGIOU, George; MERAGHNI, Fodil; JAVILI, Ali
Surface piezoelectricity considering the extended Gurtin--Murdoch coherent interface model has been incorporated into the composite cylinder assemblage (CCA), generalized self-consistent method (GSCM), as well as the multiphysics finite-element micromechanics (MFEM), for simulating the size-dependent multiphysics response of nanoporous materials wherein interface
stress and electric displacement prevail. In the case of the CCA/GSCM model, the coherent interface model is implemented through the generalized Young--Laplace equations that govern the variation of the surface stress and the surface electric displacement. Three loading modes are utilized to identify the closed-form solutions for a complete set of Hill’s moduli, and piezoelectric
and dielectric constants. In the case of the MFEM, surface piezoelectricity is incorporated directly through additional surface energies associated with the elements that stretch along the interface. In order to assess the accuracy of the developed computational approaches, the generalized Kirsch problem under far-field transverse electric displacement loading is developed for recovering electric displacement concentration in the vicinity of the pore boundary. Homogenized properties are generated and critically examined for a broad variety of parameters and dimensions, predicted by the CCA/GSCM and MFEM methods. It is shown that all the predicted effective properties of these two families of homogenization techniques are similar except for the transverse shear moduli where they show marked differences that are reminiscent of what has been observed in the absence of surface electricity.
Sat, 01 Jan 2022 00:00:00 GMThttp://hdl.handle.net/10985/223972022-01-01T00:00:00ZCHEN, QiangCHATZIGEORGIOU, GeorgeMERAGHNI, FodilJAVILI, AliSurface piezoelectricity considering the extended Gurtin--Murdoch coherent interface model has been incorporated into the composite cylinder assemblage (CCA), generalized self-consistent method (GSCM), as well as the multiphysics finite-element micromechanics (MFEM), for simulating the size-dependent multiphysics response of nanoporous materials wherein interface
stress and electric displacement prevail. In the case of the CCA/GSCM model, the coherent interface model is implemented through the generalized Young--Laplace equations that govern the variation of the surface stress and the surface electric displacement. Three loading modes are utilized to identify the closed-form solutions for a complete set of Hill’s moduli, and piezoelectric
and dielectric constants. In the case of the MFEM, surface piezoelectricity is incorporated directly through additional surface energies associated with the elements that stretch along the interface. In order to assess the accuracy of the developed computational approaches, the generalized Kirsch problem under far-field transverse electric displacement loading is developed for recovering electric displacement concentration in the vicinity of the pore boundary. Homogenized properties are generated and critically examined for a broad variety of parameters and dimensions, predicted by the CCA/GSCM and MFEM methods. It is shown that all the predicted effective properties of these two families of homogenization techniques are similar except for the transverse shear moduli where they show marked differences that are reminiscent of what has been observed in the absence of surface electricity.Recursive multiscale homogenization of multiphysics behavior of fuzzy fiber composites reinforced by hollow carbon nanotubes
http://hdl.handle.net/10985/22398
Recursive multiscale homogenization of multiphysics behavior of fuzzy fiber composites reinforced by hollow carbon nanotubes
CHEN, Qiang; MERAGHNI, Fodil; CHATZIGEORGIOU, George
Fuzzy fibers are fibers enhanced in terms of multiphysics properties with radially oriented carbon nanotubes grown on their surface through the chemical deposition process. For the first time, this paper attempts to present two generalized zeroth-order asymptotic homogenization schemes aimed at identifying the homogenized and local response of fuzzy fiber-reinforced composites, accounting for both multiphysics piezoelectric effect and cylindrically orthotropic material behavior. The unit cell problems are solved using the multiphysics finite-volume and the multiphysics finite-element techniques, respectively. While the former approach is based on the strong form solution of the equilibrium and conservation equations in an averaged sense in the discretized domain, the latter is based on the minimization of the total potential energy over the entire unit cell. A recursive multiscale analysis algorithm is developed wherein homogenized moduli (or local fields) obtained from the homogenization (or localization) analysis at one scale are utilized in the calculation of homogenized moduli (or local fields) at the next scale. Numerical examples indicate that good agreement of the homogenized properties and local field distributions generated by the two approaches is observed hence confirming the accuracy of the new homogenization methods for fuzzy fiber composites with multiphysics behaviors.
Sat, 01 Jan 2022 00:00:00 GMThttp://hdl.handle.net/10985/223982022-01-01T00:00:00ZCHEN, QiangMERAGHNI, FodilCHATZIGEORGIOU, GeorgeFuzzy fibers are fibers enhanced in terms of multiphysics properties with radially oriented carbon nanotubes grown on their surface through the chemical deposition process. For the first time, this paper attempts to present two generalized zeroth-order asymptotic homogenization schemes aimed at identifying the homogenized and local response of fuzzy fiber-reinforced composites, accounting for both multiphysics piezoelectric effect and cylindrically orthotropic material behavior. The unit cell problems are solved using the multiphysics finite-volume and the multiphysics finite-element techniques, respectively. While the former approach is based on the strong form solution of the equilibrium and conservation equations in an averaged sense in the discretized domain, the latter is based on the minimization of the total potential energy over the entire unit cell. A recursive multiscale analysis algorithm is developed wherein homogenized moduli (or local fields) obtained from the homogenization (or localization) analysis at one scale are utilized in the calculation of homogenized moduli (or local fields) at the next scale. Numerical examples indicate that good agreement of the homogenized properties and local field distributions generated by the two approaches is observed hence confirming the accuracy of the new homogenization methods for fuzzy fiber composites with multiphysics behaviors.Extended Mean-Field Homogenization of Viscoelastic-Viscoplastic Polymer Composites Undergoing Hybrid Progressive Degradation Induced by Interface Debonding and Matrix Ductile Damage
http://hdl.handle.net/10985/19602
Extended Mean-Field Homogenization of Viscoelastic-Viscoplastic Polymer Composites Undergoing Hybrid Progressive Degradation Induced by Interface Debonding and Matrix Ductile Damage
CHEN, Qiang; CHATZIGEORGIOU, George; MERAGHNI, Fodil
In this contribution, a probabilistic micromechanics damage framework is presented to predict the macroscopic stress-strain response and progressive damage in unidirectional glass-reinforced thermoplastic polymer composites. Motivated by different failure modes observed experimentally, the damage mechanism in the vicinity of the fibers (namely, the interphase) is characterized by initiating and growing voids. The mechanisms can be formulated through a Weibull probabilistic density function. In contrast, the ductile progressive degradation of matrix initial stiffness is analyzed via the continuum damage theory. To accommodate different damage mechanisms in the matrix and the interphase, a three-phase Mori-Tanaka (MT) method and transformation field analysis approach (TFA) are established within a unified framework that allows simulation of both ductile and discrete damages in different phases. Moreover, the rate-dependent viscoelastic and viscoplastic response of the polymer matrix phase is modelled through a phenomenological model consisting of four Kelvin-Voigt branches and a viscoplastic branch under the thermodynamics framework. The reliability and efficiency of the modified mean-field damage model, based on TFA and Mori-Tanaka scheme, are assessed by comparing the simulated stress-strain response against full-field Abaqus simulations under both unidirectional and multiaxial nonproportional loading paths at different loading rates. The developed model provides an efficient alternative to the finite-element based full-field homogenization schemes or other mean-field micromechanics techniques that may be compared, as well as a framework for a potential extension of the theory for simulating damage evolution in composites with random reinforcement orientations.
Wed, 01 Jan 2020 00:00:00 GMThttp://hdl.handle.net/10985/196022020-01-01T00:00:00ZCHEN, QiangCHATZIGEORGIOU, GeorgeMERAGHNI, FodilIn this contribution, a probabilistic micromechanics damage framework is presented to predict the macroscopic stress-strain response and progressive damage in unidirectional glass-reinforced thermoplastic polymer composites. Motivated by different failure modes observed experimentally, the damage mechanism in the vicinity of the fibers (namely, the interphase) is characterized by initiating and growing voids. The mechanisms can be formulated through a Weibull probabilistic density function. In contrast, the ductile progressive degradation of matrix initial stiffness is analyzed via the continuum damage theory. To accommodate different damage mechanisms in the matrix and the interphase, a three-phase Mori-Tanaka (MT) method and transformation field analysis approach (TFA) are established within a unified framework that allows simulation of both ductile and discrete damages in different phases. Moreover, the rate-dependent viscoelastic and viscoplastic response of the polymer matrix phase is modelled through a phenomenological model consisting of four Kelvin-Voigt branches and a viscoplastic branch under the thermodynamics framework. The reliability and efficiency of the modified mean-field damage model, based on TFA and Mori-Tanaka scheme, are assessed by comparing the simulated stress-strain response against full-field Abaqus simulations under both unidirectional and multiaxial nonproportional loading paths at different loading rates. The developed model provides an efficient alternative to the finite-element based full-field homogenization schemes or other mean-field micromechanics techniques that may be compared, as well as a framework for a potential extension of the theory for simulating damage evolution in composites with random reinforcement orientations.Extended mean-field homogenization of unidirectional piezoelectric nanocomposites with generalized Gurtin-Murdoch interfaces
http://hdl.handle.net/10985/23082
Extended mean-field homogenization of unidirectional piezoelectric nanocomposites with generalized Gurtin-Murdoch interfaces
CHEN, Qiang; CHATZIGEORGIOU, George; MERAGHNI, Fodil
This paper presents for the first time an extended Mori-Tanaka approach aimed at identifying the little-explored piezoelectric response of unidirectional nanoporous composites with energetic surfaces. The interface is simulated using the generalized Gurtin-Murdoch coherent interface model considering nonvanishing in-plane surface stress and surface electric displacement. The analytical solutions for Eshelby’s inhomogeneity problems are obtained by solving four systems of equations, generated from the known macroscopic electromechanical loading conditions. The dilute concentration tensors for the fiber and energetic surface are evaluated exactly for coupled electromechanical fields, which are then utilized in the extended multiphysics Mori-Tanaka homogenization scheme. The reliability and accuracy of the extended theory are demonstrated through an extensive comparison with the predictions of the composite cylinder assemblage (CCA), the generalized self-consistent method (GSCM), as well as the finite-element (FE) homogenization technique. New results generated in this work demonstrate that, except for the transverse shear
modulus, the extended Mori-Tanaka, CCA, and FE provide indistinguishable results under axisymmetric, axial shear, and electric loading, even at high volume fractions and small pore sizes where the surface piezoelectric effects are significant.
Thu, 01 Dec 2022 00:00:00 GMThttp://hdl.handle.net/10985/230822022-12-01T00:00:00ZCHEN, QiangCHATZIGEORGIOU, GeorgeMERAGHNI, FodilThis paper presents for the first time an extended Mori-Tanaka approach aimed at identifying the little-explored piezoelectric response of unidirectional nanoporous composites with energetic surfaces. The interface is simulated using the generalized Gurtin-Murdoch coherent interface model considering nonvanishing in-plane surface stress and surface electric displacement. The analytical solutions for Eshelby’s inhomogeneity problems are obtained by solving four systems of equations, generated from the known macroscopic electromechanical loading conditions. The dilute concentration tensors for the fiber and energetic surface are evaluated exactly for coupled electromechanical fields, which are then utilized in the extended multiphysics Mori-Tanaka homogenization scheme. The reliability and accuracy of the extended theory are demonstrated through an extensive comparison with the predictions of the composite cylinder assemblage (CCA), the generalized self-consistent method (GSCM), as well as the finite-element (FE) homogenization technique. New results generated in this work demonstrate that, except for the transverse shear
modulus, the extended Mori-Tanaka, CCA, and FE provide indistinguishable results under axisymmetric, axial shear, and electric loading, even at high volume fractions and small pore sizes where the surface piezoelectric effects are significant.Combination of mean-field micromechanics and cycle jump technique for cyclic response of PA66/GF composites with viscoelastic–viscoplastic and damage mechanisms
http://hdl.handle.net/10985/23081
Combination of mean-field micromechanics and cycle jump technique for cyclic response of PA66/GF composites with viscoelastic–viscoplastic and damage mechanisms
CHEN, Qiang; CHATZIGEORGIOU, George; ROBERT, Gilles; MERAGHNI, Fodil
An accelerated micromechanics framework based on the extended Mori–Tanaka transformation field analysis (TFA) and cycle jump technique is proposed to predict the homogenized response of short glass fiber-reinforced polyamide 66 composites (PA66/GF) under a large number of loading cycles (> 100,000 cycles). The extended theory accounts for microscopic viscoelastic–viscoplastic and damage mechanisms, and realistic microstructures induced by the injection molding process. Toward this end, a number of training cycles are first conducted using the extended Mori–Tanaka TFA to obtain the global evolution functions of material state-dependent variables (SDVs) for each phase. These SDVs are extrapolated linearly to a certain jump length with the help of global evolution functions such that direct numerical simulation of the cycles during this interval can be skipped, leading to a large computational cost reduction. After the cycle jump, a set of complete cycles are performed based on the extrapolated SDVs using the Mori–Tanaka TFA simulation to re-establish the global evolution functions. The implementation of the cycle jump procedure is facilitated by introducing an extrapolation control function to allow adaptive jump size control as well as to minimize the extrapolating error. The capabilities of the extended theory with the cycle jump technique have been validated extensively vis-à-vis cycle-by-cycle benchmark calculations under various loading conditions. It has been further verified with the experimental results of actual PA66/GF composites under high-cycle loading beyond which the cycle-by-cycle simulations can achieve.
Sun, 01 Jan 2023 00:00:00 GMThttp://hdl.handle.net/10985/230812023-01-01T00:00:00ZCHEN, QiangCHATZIGEORGIOU, GeorgeROBERT, GillesMERAGHNI, FodilAn accelerated micromechanics framework based on the extended Mori–Tanaka transformation field analysis (TFA) and cycle jump technique is proposed to predict the homogenized response of short glass fiber-reinforced polyamide 66 composites (PA66/GF) under a large number of loading cycles (> 100,000 cycles). The extended theory accounts for microscopic viscoelastic–viscoplastic and damage mechanisms, and realistic microstructures induced by the injection molding process. Toward this end, a number of training cycles are first conducted using the extended Mori–Tanaka TFA to obtain the global evolution functions of material state-dependent variables (SDVs) for each phase. These SDVs are extrapolated linearly to a certain jump length with the help of global evolution functions such that direct numerical simulation of the cycles during this interval can be skipped, leading to a large computational cost reduction. After the cycle jump, a set of complete cycles are performed based on the extrapolated SDVs using the Mori–Tanaka TFA simulation to re-establish the global evolution functions. The implementation of the cycle jump procedure is facilitated by introducing an extrapolation control function to allow adaptive jump size control as well as to minimize the extrapolating error. The capabilities of the extended theory with the cycle jump technique have been validated extensively vis-à-vis cycle-by-cycle benchmark calculations under various loading conditions. It has been further verified with the experimental results of actual PA66/GF composites under high-cycle loading beyond which the cycle-by-cycle simulations can achieve.Fully-coupled electro-magneto-elastic behavior of unidirectional multiphased composites via finite-volume homogenization
http://hdl.handle.net/10985/19876
Fully-coupled electro-magneto-elastic behavior of unidirectional multiphased composites via finite-volume homogenization
CHEN, Qiang; CHEN, Weiqiu; WANG, Guannan
The effective and localized electro-magneto-elastic behavior of periodic unidirectional composites is investigated in this work. Instead of adopting the classical micromechanics models or variational principle-based finite-element (FE) techniques, the finite-volume direct averaging micromechanics (FVDAM) is extended to fulfill this task by incorporating fully-coupled electro-magneto-elastic constitutive relations. Consistent with the mathematical homogenization theories, the mechanical displacements and electric/magnetic potentials are partitioned using two-scale expansion involving the macroscopic and fluctuating contributions. The generalized local stiffness matrices are constructed explicitly by relating the surface-averaged tractions, electric displacements, and magnetic inductions to the surface-averaged mechanical displacements and electric/magnetic potentials, followed which the continuity and periodic boundary conditions are applied. The homogenized coefficients and localized stress, electric/magnetic field distributions are validated extensively against the exact generalized Eshelby solution and an in-house FE program, as well as the experimental measurements, where perfect agreements are observed for all cases. The efficiency and convergence of the proposed multiphysics FVDAM (MFVDAM) are tested by comparing the execution time and localized fields as a function of mesh discretization, with the multiphysics FE (MFEM) results as references. Besides, the MFVDAM is encapsulated into the particle swarm optimization algorithm to deduce the optimal fiber volume fraction at which maximum magnetoelectric coupling effect may occur in the composite system with piezomagnetic ceramics reinforced with piezoelectric unidirectional fibers.
Fri, 01 Jan 2021 00:00:00 GMThttp://hdl.handle.net/10985/198762021-01-01T00:00:00ZCHEN, QiangCHEN, WeiqiuWANG, GuannanThe effective and localized electro-magneto-elastic behavior of periodic unidirectional composites is investigated in this work. Instead of adopting the classical micromechanics models or variational principle-based finite-element (FE) techniques, the finite-volume direct averaging micromechanics (FVDAM) is extended to fulfill this task by incorporating fully-coupled electro-magneto-elastic constitutive relations. Consistent with the mathematical homogenization theories, the mechanical displacements and electric/magnetic potentials are partitioned using two-scale expansion involving the macroscopic and fluctuating contributions. The generalized local stiffness matrices are constructed explicitly by relating the surface-averaged tractions, electric displacements, and magnetic inductions to the surface-averaged mechanical displacements and electric/magnetic potentials, followed which the continuity and periodic boundary conditions are applied. The homogenized coefficients and localized stress, electric/magnetic field distributions are validated extensively against the exact generalized Eshelby solution and an in-house FE program, as well as the experimental measurements, where perfect agreements are observed for all cases. The efficiency and convergence of the proposed multiphysics FVDAM (MFVDAM) are tested by comparing the execution time and localized fields as a function of mesh discretization, with the multiphysics FE (MFEM) results as references. Besides, the MFVDAM is encapsulated into the particle swarm optimization algorithm to deduce the optimal fiber volume fraction at which maximum magnetoelectric coupling effect may occur in the composite system with piezomagnetic ceramics reinforced with piezoelectric unidirectional fibers.Hybrid Hierarchical Homogenization Theory for Unidirectional CNTs-Coated Fuzzy Fiber Composites Undergoing Inelastic Deformations
http://hdl.handle.net/10985/20720
Hybrid Hierarchical Homogenization Theory for Unidirectional CNTs-Coated Fuzzy Fiber Composites Undergoing Inelastic Deformations
CHEN, Qiang; CHATZIGEORGIOU, George; MERAGHNI, Fodil
A new hybrid homogenization approach is proposed for simulating the homogenized and local response of unidirectional fuzzy fiber nanocomposites undergoing inelastic deformations. Fuzzy fiber composites are hierarchical reinforcing structures where the fibers coated with radially aligned carbon nanotubes (CNTs) are embedded in the matrix. In this spirit, the fuzzy fiber composites are modeled as a three-scale medium. At the microscale, the CNTs-reinforced matrix is homogenized as nanocomposite interphase (NCP) attached to the main fiber via the asymptotic expansion homogenization (AEH). At the mesoscale, an intermediate equivalent fiber that substitutes for the NCP and the main fiber is constructed using the composite cylinder assemblage (CCA) and the transformation field analysis (TFA) techniques. At the macroscale, homogenization of the equivalent fiber and the surrounding matrix is handled by AEH which yields the effective response of the whole fuzzy fiber composites. The new technique facilitates accurate and efficient studies of the inelastic deformation mechanisms of periodic fuzzy fiber arrays with single or multiple inclusions under biaxial and triaxial loading conditions, eliminating exhausting interphase mesh discretizations encountered in the classical full-field homogenization. An added advantage is that the proposed theory captures the fiber-fiber interaction neglected in the classical CCA-TFA, an issue that leads to the exceptionally stiff post-yielding stress-strain response common in the mean-field micromechanics approaches.
Fri, 01 Jan 2021 00:00:00 GMThttp://hdl.handle.net/10985/207202021-01-01T00:00:00ZCHEN, QiangCHATZIGEORGIOU, GeorgeMERAGHNI, FodilA new hybrid homogenization approach is proposed for simulating the homogenized and local response of unidirectional fuzzy fiber nanocomposites undergoing inelastic deformations. Fuzzy fiber composites are hierarchical reinforcing structures where the fibers coated with radially aligned carbon nanotubes (CNTs) are embedded in the matrix. In this spirit, the fuzzy fiber composites are modeled as a three-scale medium. At the microscale, the CNTs-reinforced matrix is homogenized as nanocomposite interphase (NCP) attached to the main fiber via the asymptotic expansion homogenization (AEH). At the mesoscale, an intermediate equivalent fiber that substitutes for the NCP and the main fiber is constructed using the composite cylinder assemblage (CCA) and the transformation field analysis (TFA) techniques. At the macroscale, homogenization of the equivalent fiber and the surrounding matrix is handled by AEH which yields the effective response of the whole fuzzy fiber composites. The new technique facilitates accurate and efficient studies of the inelastic deformation mechanisms of periodic fuzzy fiber arrays with single or multiple inclusions under biaxial and triaxial loading conditions, eliminating exhausting interphase mesh discretizations encountered in the classical full-field homogenization. An added advantage is that the proposed theory captures the fiber-fiber interaction neglected in the classical CCA-TFA, an issue that leads to the exceptionally stiff post-yielding stress-strain response common in the mean-field micromechanics approaches.Electromechanical response of multilayered piezoelectric BaTiO3/PZT-7A composites with wavy architecture
http://hdl.handle.net/10985/19877
Electromechanical response of multilayered piezoelectric BaTiO3/PZT-7A composites with wavy architecture
TU, Wenqiong; CHEN, Qiang
Electromechanical laminated composites with piezoelectric phases are increasingly being explored as multifunctional materials providing energy conversion between electric and mechanical energies. The current work explores thus-far undocumented combined microstructural effects of amplitude-to-wavelength ratio, volume fraction, poling direction of piezoelectric phases on both the homogenized properties and localized stress/electric field distributions in multilayered configurations under fully coupled electro-mechanical loading. In particular, the Multiphysics Finite-Volume Direct Averaging Micromechanics (FVDAM) and its counterpart, an in-house micromechanical multiphysics finite-element model, are utilized to investigate the homogenized and localized responses of wavy multilayered piezoelectric BaTiO3/PZT-7A architectures. These two methods generate highly agreeable results. Moreover, we critically examine the convergence of the finite-volume and finite element-based approaches via the Average Stress Theorem and Average Electric Displacement Theorem. The comparison shows the finite volume-based approach possesses a better numerical convergence. This study illustrates the FVDAM’s ability toward the analysis and design of engineered multilayered piezoelectric materials with wavy architecture.
Fri, 01 Jan 2021 00:00:00 GMThttp://hdl.handle.net/10985/198772021-01-01T00:00:00ZTU, WenqiongCHEN, QiangElectromechanical laminated composites with piezoelectric phases are increasingly being explored as multifunctional materials providing energy conversion between electric and mechanical energies. The current work explores thus-far undocumented combined microstructural effects of amplitude-to-wavelength ratio, volume fraction, poling direction of piezoelectric phases on both the homogenized properties and localized stress/electric field distributions in multilayered configurations under fully coupled electro-mechanical loading. In particular, the Multiphysics Finite-Volume Direct Averaging Micromechanics (FVDAM) and its counterpart, an in-house micromechanical multiphysics finite-element model, are utilized to investigate the homogenized and localized responses of wavy multilayered piezoelectric BaTiO3/PZT-7A architectures. These two methods generate highly agreeable results. Moreover, we critically examine the convergence of the finite-volume and finite element-based approaches via the Average Stress Theorem and Average Electric Displacement Theorem. The comparison shows the finite volume-based approach possesses a better numerical convergence. This study illustrates the FVDAM’s ability toward the analysis and design of engineered multilayered piezoelectric materials with wavy architecture.Deep learning in heterogeneous materials: Targeting the thermo-mechanical response of unidirectional composites
http://hdl.handle.net/10985/19895
Deep learning in heterogeneous materials: Targeting the thermo-mechanical response of unidirectional composites
CHEN, Qiang; TU, Wenqiong; MA, Meng
In this communication, a multi-task deep learning-driven homogenization scheme is proposed for predicting the effective thermomechanical response of unidirectional composites consisting of a random array of inhomogeneity. Toward this end, 40 000 repeating unit cells (RUCs) comprising an arbitrary number of locally irregular inclusions are generated over a wide range of fiber volume fractions. The finite-volume direct averaging micromechanics is then employed to evaluate the homogenized thermo-mechanical moduli of each RUC. Subsequently, a two-dimensional deep convolution neural network (CNN) is constructed as a surrogate model to extract the statistical correlations between the RUC geometrical information and the corresponding homogenized response. The RUC images together with their homogenized moduli are divided into two datasets in a ratio of 9:1 with the former part used for training the CNN model and the latter part used for verification. The results presented in this contribution demonstrate that the deep CNN predictions exhibit remarkable correlations with the theoretical values generated by the finite-volume micromechanics, with a maximum relative prediction error of less than 8%, providing good support for the data-based homogenization approach.
Wed, 01 Jan 2020 00:00:00 GMThttp://hdl.handle.net/10985/198952020-01-01T00:00:00ZCHEN, QiangTU, WenqiongMA, MengIn this communication, a multi-task deep learning-driven homogenization scheme is proposed for predicting the effective thermomechanical response of unidirectional composites consisting of a random array of inhomogeneity. Toward this end, 40 000 repeating unit cells (RUCs) comprising an arbitrary number of locally irregular inclusions are generated over a wide range of fiber volume fractions. The finite-volume direct averaging micromechanics is then employed to evaluate the homogenized thermo-mechanical moduli of each RUC. Subsequently, a two-dimensional deep convolution neural network (CNN) is constructed as a surrogate model to extract the statistical correlations between the RUC geometrical information and the corresponding homogenized response. The RUC images together with their homogenized moduli are divided into two datasets in a ratio of 9:1 with the former part used for training the CNN model and the latter part used for verification. The results presented in this contribution demonstrate that the deep CNN predictions exhibit remarkable correlations with the theoretical values generated by the finite-volume micromechanics, with a maximum relative prediction error of less than 8%, providing good support for the data-based homogenization approach.Physically informed deep homogenization neural network for unidirectional multiphase/multi-inclusion thermoconductive composites
http://hdl.handle.net/10985/23502
Physically informed deep homogenization neural network for unidirectional multiphase/multi-inclusion thermoconductive composites
JIANG, Jindong; WU, Jiajun; CHEN, Qiang; CHATZIGEORGIOU, George; MERAGHNI, Fodil
Elements of the periodic homogenization framework and deep neural network were seamlessly connected for the first time to construct a new micromechanics theory for thermoconductive composites called physically informed Deep Homogenization Network (DHN). This method utilizes a two-scale expansion of the temperature field of spatially uniform composites in terms of macroscopic and fluctuating contributions. The latter is estimated using deep neural network layers. The DHN is trained on a set of collocation points to obtain the fluctuating temperature field over the unit cell domain by minimizing a cost function given in terms of residuals of strong form steady-state heat conduction governing differential equations. Novel use of a periodic layer with several independent periodic functions with adjustable training parameters ensures that periodic boundary conditions of temperature and temperature gradients at the unit cell edges are exactly satisfied. Automatic differentiation is utilized to correctly compute the fluctuating temperature gradients. Homogenized properties and local temperature and gradient distributions of unit cells reinforced by unidirectional fiber or weakened by a hole are compared with finite-element reference results, demonstrating remarkable correlation but without discontinuities associated with temperature gradient distributions in the finite-element simulations. We also illustrate that the DHN enhanced with transfer learning provides a substantially more efficient and accurate simulation of multiple random fiber distributions relative to training the network from scratch.
Mon, 01 May 2023 00:00:00 GMThttp://hdl.handle.net/10985/235022023-05-01T00:00:00ZJIANG, JindongWU, JiajunCHEN, QiangCHATZIGEORGIOU, GeorgeMERAGHNI, FodilElements of the periodic homogenization framework and deep neural network were seamlessly connected for the first time to construct a new micromechanics theory for thermoconductive composites called physically informed Deep Homogenization Network (DHN). This method utilizes a two-scale expansion of the temperature field of spatially uniform composites in terms of macroscopic and fluctuating contributions. The latter is estimated using deep neural network layers. The DHN is trained on a set of collocation points to obtain the fluctuating temperature field over the unit cell domain by minimizing a cost function given in terms of residuals of strong form steady-state heat conduction governing differential equations. Novel use of a periodic layer with several independent periodic functions with adjustable training parameters ensures that periodic boundary conditions of temperature and temperature gradients at the unit cell edges are exactly satisfied. Automatic differentiation is utilized to correctly compute the fluctuating temperature gradients. Homogenized properties and local temperature and gradient distributions of unit cells reinforced by unidirectional fiber or weakened by a hole are compared with finite-element reference results, demonstrating remarkable correlation but without discontinuities associated with temperature gradient distributions in the finite-element simulations. We also illustrate that the DHN enhanced with transfer learning provides a substantially more efficient and accurate simulation of multiple random fiber distributions relative to training the network from scratch.