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• Experimental longitudinal tensile stress–strain curves fluctuated obviously before final failure. • Micromechanical model considers the dispersions of fiber strength and spatial distributions. • Predicted stress–strain curves agree well with experiments in modulus, initial failure and final failure. • Simulations show the progressive failure process of fibers before the final failure of the unidirectional composite. Longitudinal tensile failure prediction has always been the focus of research on unidirectional (UD) Carbon Fiber Reinforced Polymer (CFRP). In this paper, the longitudinal tensile tests of unidirectional T800 grade carbon fiber reinforced epoxy resin composite were carried out first. The experimental stress–strain curves show that there are obvious progressive damages before the final failures of the specimens. However, this phenomenon is usually neglected in most of the existing investigations and tests to only obtain elastic modulus and ultimate strength. Thus, a Representative Volume Element (RVE) model based on micromechanics was established using finite element method, considering the randomness of fiber spatial distribution and fiber strength. The tensile strength of fiber monofilaments was assumed to follow a statistical two-parameter Weibull distribution. The failure process of UD composite under longitudinal tensile load was simulated by explicit finite element method. The stress–strain curves obtained by simulation are in good agreement with the experimental results. Finally, the influence of different boundary conditions on the calculation of the RVE was studied. It is found that the final failure strengths of the RVE with uniform displacement boundary conditions are similar to the case of periodic boundary conditions, while the former has higher computational efficiency. [ABSTRACT FROM AUTHOR]

• Micromechanics-based ANN establishes structure-property linkage under humid ageing. • Framework to generate artificial RVE with random fibre distribution is developed. • Effective approach is developed to process physical descriptors from microstructure images. • ANN established relation between transverse modulus and geometry, property, and environment. • Contribution of microstructure morphology and humid condition on FRP degradation is investigated. This paper proposes an innovative micromechanics-based artificial neural network (ANN) method to efficiently investigate the transverse modulus of unidirectional fibre/epoxy composites under humid conditions. In this research, a novel approach is developed to establish relations between the geometrical, mechanical, and environmental properties of the microstructure and the material's performance under transverse tension. A framework is developed to artificially generate periodic representative volume elements (RVEs) while taking into account the interphase region between fibre and matrix. The RVEs are analysed by the finite element method to obtain the transverse moduli of composites. Two-point correlation functions and principal component analysis techniques are applied to extract and compress statistical information from microstructure images. A database establishment framework is developed to create three batches of data with 1000, 2000, and 3000 sizes. An ANN-based prediction framework is developed by integrating 10-fold cross-validation and Bayesian optimisation to optimise the neural network architecture and establish an efficient structure-property linkage under the influence of humid conditions. The prediction results demonstrate the efficiency of ANN in mapping microstructural data to an effective transverse modulus. A parametric study by ANN reveals the role of microstructure geometrical features and humid environmental parameters on the transverse performance of the composite. [ABSTRACT FROM AUTHOR]

In this study, a novel multiscale analysis technique is presented for predicting the mechanical behavior of 3D woven composites. To this end, the model of the representative unit cell (RUC) is generated using SOLIDWORKS computer-aided design package by taking the optical microscopic images as a reference. The fiber volume fractions (FVF) of the impregnated yarns are calculated using the roving parameters and the dry fiber density for each tow separately. Homogenized properties are obtained by utilizing the finite element analysis (FEM) software ABAQUS. The proposed method simplifies the meso -modeling process of 3D woven composites as it does not require CT scanning for geometry generation or sophisticated localized fiber volume fraction measurements. The verification of the current model is carried out both in the meso scale where the RUC surface strains are compared with DIC results and in the macro scale where tensile and flexural tests are simulated and compared with the experiments. Finally, the applicability of this method is demonstrated through an assessment study of the 3D woven composites as facesheets in thick sandwich structures in an isogeometric refined zigzag framework. [ABSTRACT FROM AUTHOR]

• A two-scale homogenization scheme is developed for hybrid fiber composites with viscoelastic matrices. • Improvement of blocked stress but diminishment of free strain is elucidated. • Viscoelastic effect is significant on magnetoelastic response although the polymer matrix had been reinforced by stiff fillers. • Magnetoelastic responses shows the different degrees of the dependency on phase concentrations, boundary conditions, loading rate, prestress, and temperature. This study examines the overall magnetoelastic responses of unidirectional fiber composites constructed by magnetostrictive fibers embedded in viscoelastic polymer matrices that had been reinforced by stiff fillers. In some polymer-based fiber composites, modifying polymer's property by infiltrating particulate fillers is necessary. To design such hybrid composite systems with magnetoelastic coupling, it requires a detailed understanding of aggregate responses. In this study, we formulate a composite constitutive model based on a two-scale homogenization scheme for effective coupled viscoelastic and magnetoelastic responses for hybrid fiber composites. We first verify the validity of the model by comparing the predictions with experimental results available in literatures. We next investigate the performance of a hybrid composite in light of blocked stress and free strain which are two common factors of characterizing sensors and actuators. We finally elucidate how viscoelastic polymer matrices affect the overall magnetoelastic responses and Δ E -effect phenomenon in terms of some critical parameters such as phase concentrations, loading rates, prestresses and temperatures. The findings of this study serve as a preliminary guidance for the rational design of hybrid magnetostrictive composite materials. The proposed mathematics model can further integrate into a finite element framework for composite structure analysis. [ABSTRACT FROM AUTHOR]

This study presents numerical investigations into the progressive damages in unidirectional carbon fiber reinforced plastics using computational micromechanics with an image-based periodic representative volume element (RVE). This RVE modeling approach combines the methodologies of image-based RVE and artificial periodic RVE to reflect the actual fiber packing while retaining geometrical periodicity. For high-fidelity modeling, the RVE model is prepared with more than 200 carbon fibers extracted from X-ray computed tomography images. Both homogenization simulation for elastic properties and unidirectional loading simulations for plastic and fracture properties are carried out. The constitutive model parameters are identified and verified by comparing the experimental and predicted effective (spatially averaged) elastic and plastic properties, and ultimate strength. Then, with the identified parameters, the local damage initiation and propagation mechanism, and their influence on the macroscopic nonlinear stress–strain behaviors are discussed. Finally, the influences of fiber packing on the prediction accuracy of computational micromechanics are discussed by comparing the results between the proposed image-based RVE and simple RVEs with the square and hexagonal arrays. [ABSTRACT FROM AUTHOR]

We present an isogeometric homogenization theory (IGH) for efficiently identifying homogenized and local creep and relaxation response of linearly viscoelastic polymer composites with different microstructural parameters. The principal idea is to construct exact geometric representations of both two- and three-dimensional unit cell microstructures for periodic materials by utilizing multiple conforming NURBS patches that are also employed for the displacement field interpolation function at the local scale. The IGH-based unit cell formulation is then converted to the viscoelastic solution with the Laplace-Carson space parameters via the correspondence principle. Subsequently, we leverage the Zakian formula to reverse the transformed IGH solution and obtain the homogenized creep and relaxation response of the composite in the original time space. The modelling and predictive capabilities of the IGH theory have been extensively validated vis-à-vis the elasticity-based and conventional finite-element homogenization techniques, and the advantages of the proposed technique over the reference techniques were demonstrated. [ABSTRACT FROM AUTHOR]

Abstract Fiber reinforced polymer matrix composites are increasingly being used to fabricate energy-absorbing aerospace structural components susceptible to impact loading, such as jet engine containment structures subjected to blade-out events. The development and certification of such structures necessitates a detailed understanding of the dynamic behavior of the constituent materials, particularly the strain rate, temperature, and pressure dependent polymer matrix, and their complex interaction. As the rate of deformation increases, the thermodynamic condition transitions from isothermal to adiabatic. The conversion of plastic work to heat causes local adiabatic heating in the polymer matrix, but the rapid nature of impact events does not allow sufficient time for heat to dissipate; ballistic impact events can therefore be regarded as fully adiabatic. Local adiabatic heating can significantly affect the high rate deformation response if thermal softening effects outweigh strain and strain rate hardening effects and therefore, must be explicitly modeled at the appropriate length scale. In this paper, an existing isothermal viscoplastic strain rate and pressure-dependent polymer constitutive formulation is extended to nonisothermal conditions by modifying the inelastic strain rate tensor components to explicitly depend on temperature based on the Arrhenius equation for nonisothermal processes. A methodology based on shifting neat resin dynamic mechanical analysis data is utilized to determine the polymer elastic properties over a range of strain rates and temperatures. Temperature rises due to the conversion of plastic work to heat are computed, assuming adiabatic conditions. It is demonstrated that the modified polymer constitutive model is capable of capturing strain rate and temperature dependent yield as well as thermal softening associated with the conversion of plastic work to heat at high rates of strain. The nonisothermal polymer constitutive model is then embedded within the Generalized Method of Cells micromechanics framework to investigate the manifestation of matrix thermal softening, due to the conversion of plastic work to heat, on the high strain rate response of a T700/Epon 862 unidirectional composite. Adiabatic model predictions for high strain rate composite longitudinal tensile, transverse tensile, and in-plane shear loading are presented. Results show a substantial deviation from isothermal conditions; significant thermal softening is observed for matrix dominated deformation modes (transverse tension and in-plane shear), highlighting the importance of accounting for local adiabatic heating in the polymer matrix in the high strain rate analysis of polymer matrix composite structures. [ABSTRACT FROM AUTHOR]

Abstract Experimental results on metal-matrix composites (MMCs) with inhomogeneous reinforcement distribution confirmed the enhancement of the mechanical properties. Here three-dimensional network architecture, formed by particle- and rod-shaped SiC, was modeled and the effect of network structure on the strength and fracture was numerically investigated. The present specific network structural design enhances the 10 vol% SiC/Al composite, leading to a higher elastic modulus and yield stress in SiC rod /Al and SiCp/Al composite. The enhanced strength is attributed to the high load-transfer efficiency in the network composites: SiC walls parallel to the load direction carries a stress of 750–1000 MPa in SiCp/Al network composite, which is close to stress level of perpendicular SiC wall in SiC rod /Al network composite, and are higher than that in homogeneous composite (500 MPa). In SiCp/Al network composite, the main crack initiates in perpendicular SiC wall and then deflects to the matrix alloy, while the main crack initiates by rods fracture and propagates through perpendicular SiC walls in the SiC rod /Al network composite. The main crack is generated much earlier in SiCp/6061Al than in SiC rod /Al composites. [ABSTRACT FROM AUTHOR]

Abstract A numerical micromechanics study is performed to investigate the effect of using graphene nanoplatelets (Gnp) with theoretical maximum properties and reduced graphene oxide (rGOnp) on the mechanical properties and damage mechanism of graphene based nanocomposites. Here we consider brittle matrix cracking and interface debonding as the main damage mechanisms. The results showed that the competition between both mechanisms is affected by nanoplatelets/matrix modulus-mismatch, volume fraction, interface strength and orientation. Gnp showed improved modulus, however, with inferior strength and fracture strain compared to rGOnp. This is due to the large modulus-mismatch of Gnp, which resulted in increasing the stress concentration, matrix cracking and coalescing at lower loads. On the other side, the lower stress concentration of rGOnp allowed for higher load accumulation and increased interface debonding. Applying stronger interface properties was found to suppress the interface debonding, improving strength and fracture strain. Further, aligned nanoplatelets lead to a simultaneous improvement in modulus, strength and fracture strain. This is due to the improved load transfer and activation of toughening mechanisms observed for bioinspired nacre like structures. [ABSTRACT FROM AUTHOR]

Abstract Three dimensional (3D) finite element analysis along with a damage model based on kinetic theory of fracture (KTF) are used to determine the onset of fatigue crack initiation in unidirectional carbon fiber reinforced composites. In addition, the Multicontinuum theory (MCT) and micromechanics are employed separately to enable the assessment of the stress state distribution at the length scale level of the constituents. While the MCT is implemented in the macroscale model formulation, micromechanical analysis of a representative unit cell has been also developed to capture the stress field in the micro length scale level. An ABAQUS™ user material (UMAT) subroutine has been developed and used for implementing the formulation. Numerical examples of various tests including tension, three point bending, four point bending, and short beam shear test of a unidirectional (UD) laminate are considered and the results are compared against actual test data. A detailed discussion, challenges and future plans on the applicability of the KTF are concluding this work. [ABSTRACT FROM AUTHOR]

Abstract We use three micromechanics approaches, namely, the method of cells (MoCs), the Fourier series approach (FSA) and the transformation field analysis (TFA) to delineate the sensitivity of their predictions to changes in the unit cell configuration. The three approaches are formulated to have identical final expressions relating the local sub-cell strains to the homogenized strains in the unit cell. The cubic-edge, the hexagonal close-packed and the cubic-diagonal unit cell configurations are employed to study the elasto-plastic response of a Boron-Aluminum fiber reinforced composite under transverse loading, and compare present results with Brockenbrough et al.'s findings who used the finite element method. The elasto-plastic response predicted from the cubic-edge unit-cell shows the most hardening while that from the cubic-diagonal unit-cell the least hardening. Of the three approaches employed, the elasto-plastic response predicted by the MoCs is closest to that of Brockenbrough et al. The effect of fiber cross section on the elasto-plastic response analyzed using only the TFA approach is found to be significant for both elastic constants and plastic hardening. [ABSTRACT FROM AUTHOR]

Abstract This study proposed two new micromechanics models to predict the effective properties of multiferroics composites with spring-type imperfect interfaces. The first model is a full field micromechanics scheme based on the mechanics of structure genome, a multiscale constitutive modeling framework, recently discovered to unify the micromechanics and the structural mechanics. The second model is a mean field micromechanics approach that extends the Mori-Tanaka scheme using the concept of the interior and exterior-point Eshelby tensors to multiferroics composites. The imperfect interface model assumes that the normal components of the fluxes (stress, electric displacement and magnetic flux) are continuous across the interface, whereas the potential fields (displacement, electric potential and magnetic potential) suffer interfacial jumps proportional to the normal components of the fluxes. In contrast to multiferroics composites with perfect contact conditions, the effective properties formulations show the dependence on the size of the reinforcements. Numerical examples of fibrous multiferroics composites are used to demonstrate the robustness and accuracy of the proposed micromechanics theories. The size-dependency of the overall properties shows the importance of imperfect interfaces in predicting the effective properties of multiferroics composites. [ABSTRACT FROM AUTHOR]

Abstract Matrix behavior is expected to widely influence the impact response of composites, but detailed conclusions in the case of thermoplastic laminates are still needed. In this paper, we investigated the effect of using either ductile homopolymer PP or less-ductile impact copolymer PP matrices on the low-velocity impact responses of continuous glass fiber-reinforced polypropylene (PP) laminate. These PP types represent two variants in the same family of thermoplastic matrix. A thorough experimental campaign was first performed to provide the tensile properties (for PP and glass/PP) and fracture toughness (Mode-I and Mode-II, glass/PP only) of the employed materials. Then, low-velocity impact tests where the energy levels are ranging from 12 to 30 J were performed. Using ductile PP in glass/PP laminates reduces the energy dissipated during impact as well as the impact damage area. The effect of selected stacking sequences on the resistance to impact was also studied as a way to reveal the difference between ductile and less-ductile glass/PP. Stacking sequence with thin plies shows better impact properties than other sequences regardless of the matrix ductility, which can be explained by micromechanics for both grades of material. Finally, as quasi-static indentation (QSI) is usually used to quickly access the resistance of laminates towards out-of-plane impact, we systematically compared our impact results with QSI results. We found that the prospective use of QSI in forecasting impact properties and damage is very limited in glass/PP composite due to strain-rate sensitivity. [ABSTRACT FROM AUTHOR]

Abstract Fiber reinforced polymers (FRPs) subjected to mode I fracture show important toughening due to the development of large scale bridging (LSB). Experimental studies of this phenomenon in unidirectional carbon/epoxy laminates using double cantilever beam specimens, demonstrate important differences in R-curve response for inter- and intralaminar fracture. Post fracture observation of composite's cross-section pointed out dissimilar fiber bundle size and shape, as the main origin of their differences. In the present paper, representative volume elements with the composite's constituents, based on the actual material microstructure, and homogenized 2D finite element models were developed to study the effects of microstructure on the first stage of damage leading to LSB development in carbon/epoxy composites under mode I fracture. The differences between inter- and intralaminar fracture were investigated along with the influence of fiber dispersion and the presence of interply and intraply resin-rich zones. The numerical simulations captured different microcrack morphologies for inter- and intralaminar fracture, supporting the experimental observations, while parametric studies showed the influence of the microstructure in the formation of LSB. In particular, fiber dispersion within a ply and resin rich zone between plies play significant roles in mode I fracture and can be used to control toughening mechanisms in FRPs. [ABSTRACT FROM AUTHOR]

Abstract Here, a new Integrated Micro/Macro (IMM) approach is proposed to consider the impact of debonding and its induced matrix cracking on the macro response of composite laminates. To this purpose, a new micromechanics formulation based on complex variable elasticity is developed to calculate the stress and displacement fields along the perfect/imperfect bonded interface between rigid inclusion (fiber) and matrix under general remote stresses. Then, by employing strength based and Griffith failure energy criteria, the initiation and growth of debonding angle will be examined respectively. To obtain the stiffness degradation due to debonding formation, the shadow of the interfacial cracks in different directions is employed. The obtained stiffness reductions are employed to develop new relations for the calculation of damage parameters. The damage parameters are dependent on the terms of the debonding angle, radius and volume fraction of inclusion. Then, by the implementation of the impact of the diffusion debonding using the proposed damage parameters into ANSYS commercial software via a developed IMM code, the precision of the methodology on the modeling of the mentioned damage mechanisms is assessed by comparison with the available experimental results. The matching between the proposed method and experiments implies that IMM approach provides a reliable tool to the precise prediction of the nonlinear response of composite laminates containing an open hole due to the debonding initiation and propagation. [ABSTRACT FROM AUTHOR]

Abstract A numerical framework for the determination of the damage, the stress and the inelastic strain field induced by the curing process for unidirectional carbon/epoxy composite material is proposed. The approach integrates a network model for the estimation of the matrix shrinkage and elastic properties evolution during curing with damageable elasto-plastic constitutive equations. Simulations of the curing process and of the cured material transverse mechanical response are carried out. A sensitivity study is realised for different volume fractions and matrix tensile strengths for single fiber models. Analyses of Representative Volume Elements (RVEs) with randomly distributed fibers are also performed and a comparison with the ideally cured version of the same model is used to highlight the importance of considering the curing process effects in micromechanical models. The proposed framework, with a proper calibration of the constituents, contributes to the enhancement of the fidelity of numerical micromechanics for this class of materials. [ABSTRACT FROM AUTHOR]

Abstract The vibration response of a functionally graded graphene nanoplatelet reinforced composite (FG-GPLRC) beam under two successive moving masses is investigated in the current study. The weight fraction of graphene nanoplatelets (GPLs) is assumed to vary continuously and smoothly in the thickness direction. The modified Halpin–Tsai micromechanics model is used to evaluate the effective Young's modulus of the FG-GPLRC beam. A new high order shear deformation theory (HSDT) is proposed for the structural behavior analysis of FG-GPLRC beams. The proposed theory assumes nonlinear distribution of transverse shear stresses and satisfies the traction-free boundary conditions at the bottom and top surfaces of the beam and hence, a shear correction factor is not required. A generalized closed-form solution methodology of the Navier-type is implemented to ensure the validity and efficiency of the present theory for the free vibration and dynamic response of the beam. The Newmark- β method is adopted to obtain the response of the tube in time domain. Two successive moving masses are considered as the moving load acting on the beam. A parametric study is performed to investigate the effects of GPL weight fraction, distribution pattern, and distance between the two masses on the vibration responses of the beam. [ABSTRACT FROM AUTHOR]

Abstract Failure prediction for composite materials is still a major area of interest within both the academic literature and the composite industry. This paper presents a modelling and experimental framework which has been developed for the application of Strain Invariant Failure Theory (SIFT), but which can be adapted to other failure prediction methods if required. SIFT is set of physics-based failure criteria developed to predict the onset of irreversible deformation of glassy polymers. The paper provides an overview of the available evidence for SIFT and provides a complete methodology for applying SIFT to predict the onset of failure in a composite component. Fundamental to the method presented is a modular and hierarchical dehomogenisation procedure; allowing for the evaluation of stress and strain state variables within the constituent components of the composite. Due to the constant evolution of composite characterisation techniques, the method presented in this paper is designed to be extensible (i.e. accommodating of new materials and product forms) and modular (i.e. subsections of the method can be easily substituted or refined). Known limitations of the current method are clearly presented and discussed. A companion paper will present validation of the approach for simple uniaxial and biaxial coupon experiments and will discuss how the method can be applied to a range of existing composite characterisation testing standards. [ABSTRACT FROM AUTHOR]

Abstract Modelling the damage of composite materials is not an easy task because different modes of ruins coexist: Fiber matrix decohesion,matrix cracks, delamination, and fiber cracks. In the case of laminated composites, the matrix cracks have the particularity to remain parallel to the fibers. As a consequence of the orientation of this crack network, only shear and transverse moduli in the plane of the ply are degraded in proportion to the increase of the crack density. The main point of this work is to characterize the relation linking transverse and shear damage with respect to the crack density. Following this objective, full field calculations are run using CraFT, a software developed at the LMA. The modeling is done in two steps: first the undamaged composite is homogenized, then, as a second step, the damaged behavior is determined by introducing cracks into the healthy composite. The behavior is calculated from an optimal size of RVE (Representative Volume Element) in order to determine numerically the relation between transverse and shear moduli variables. [ABSTRACT FROM AUTHOR]

Abstract A new three-dimensional (3D) micromechanical model is proposed to simulate the arbitrary multidirectional carbon fiber reinforced polymer (CFRP) composite laminates. Carbon fiber is assumed as transversely isotropic and linear elastic, matrix is assumed as isotropic and elastic–plastic. Maximum strain criterion is used to describe the failure of fiber and matrix. The stresses, strains and damage are described in the fiber and matrix levels, but the debonding between the fiber and matrix and the delamination between two plies are not modeled in the present analysis. Numerical analyses of nonlinear mechanical behavior of angle-ply [±θ] 2s under tension are conducted to verify the validity of the present micromechanical model. Numerical results of nonlinear mechanical behavior, negative Poisson's ratio through the thickness direction, and stress distribution on the free edge show good agreement with previous experimental and analytical results. [ABSTRACT FROM AUTHOR]

Abstract In order to benefit from the expected high luminosity performance provided by the Phase-I upgraded LHC at CERN, the New Small Wheel (NSW) will be installed in the ATLAS detector during the Long Shutdown 2. The ATLAS NSW will be equipped with a new technology for the detection of muons: the MicroMegas (MM) detectors. They consist of different panels made of composite materials and when charged particles traverse the drift space, the gas is ionized and electrons are liberated; the avalanche of electrons takes place in the amplification region after the mesh and they are detected by read-out strips to reconstruct the trajectory of muons produced after the collision. Very tight mechanical tolerances are given in the design phase and they must be preserved from the panel construction to the final operation in the ATLAS cavern. In this paper the construction procedure of these very precise particle detectors is described and the mechanical modelling to predict their mechanical behaviour is presented. Finally, the experimental tests done to validate the numerical models are discussed. [ABSTRACT FROM AUTHOR]

Abstract A multiscale analysis was developed for the evaluation of graphene nanoplatelet (GNP)/carbon fiber/epoxy materials and the laminated composite plate. Computational molecular dynamic and micromechanics were utilized in the modeling and simulation of the material systems to characterize their elastic behavior when subjected to thermo-mechanical loadings. In this investigation, the approach for analyzing the structures of graphene/carbon fiber/epoxy composite at various length scales was documented. The methodology employed for evaluating the thermomechanical loadings was also specified. The predicted results at various length scales showed that the addition of GNP into the material system does not only increase the elastic moduli of the material at evaluated temperatures, but it also improves the mechanical integrity of the laminated composite plates. [ABSTRACT FROM AUTHOR]

Abstract Micromechanics based models are used for predicting the effective mechanical properties of reinforced polymer matrix composites. This paper reviews micromechanics based models for fiber reinforced polymer composites starting with the bounds established by Voigt and Reuss models, Hashin-Shtrikman model and then on to well-known micromechanics based models like Mori-Tanaka model, Self-consistent model and Differential scheme based models. The main objective is to critically review the areas in which these micromechanics based models hold good and analyse the limitations of these models. One of the limitations of the above mentioned models is the assumption of dilute dispersion and this is overcome in this paper by revising the Mori-Tanaka model by combining the differential scheme with Eshelby's model to take into account the non-dilute dispersion effect. Numerical results are verified by finite element based simulation of the representative volume element (RVE). Experiments were carried out to estimate the effective elastic constants for different fiber volume fractions. Theoretical results are reviewed with reference to experimental measurements. [ABSTRACT FROM AUTHOR]

Abstract An experimentally validated, multi-physics and multi-scale processing model was developed to predict the residual stress buildup in a polymer matrix composite during manufacturing. At the macroscale, the composite was modeled as discrete layers of homogeneous, transversely isotropic laminae, while micromechanics was implemented at the subscale to compute the effective lamina responses based on the fiber and matrix properties through an Extended Concentric Cylinder Assemblage (ECCA) model. The composite temperature and Degree of Cure (DOC) distributions were solved by incorporating resin cure kinetics into heat transfer analysis, which were used in the subsequent stress analysis to determine the cure-dependent composite responses, including cure-dependent modulus, thermal strain, and chemical shrinkage. This integrated processing model was applied to predict the cure-induced warpage of a non-symmetric laminate. The proposed model, which incorporates resin cure kinetics, cure-dependent constitutive law, and tool-part interaction, demonstrates good agreement with the experiment on the prediction of the warpage curvatures. [ABSTRACT FROM AUTHOR]

Abstract This study investigates the failure mechanisms of notched unidirectional (UD) carbon fiber reinforced polymer (CFRP) laminates subjected to longitudinal compressive loading. A sequence of failure initiation and propagation is observed based on optical microscopy images of specimens during failure. The micrographs reveal that the main failure mechanism in UD laminates is fiber kinking failure. The influence of manufacturing defects and voids on fiber kinking mechanisms is also analyzed. The results show that the voids in the resin-rich area lead to kink-band splitting, while in some cases the voids cause the kink-band to deflect in a new direction depending on the location of the voids. The next focus of this study is to propose a computational micromechanics model considering local fiber waviness to study the fiber kinking failure mechanism. The computational results on kink-band formation and stress-strain response show good consistency with our experimental analysis. Finally, the failure envelopes of σ 11 -σ 22 and σ 11 - τ 12 subjected to combined loading conditions are obtained from the computational model, which provide essential inputs for future theoretical failure criteria. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a prediction for the dynamic matrix-dominated failure behavior of a carbon fiber reinforced polymer (CFRP) under impact loading, by using hierarchical multi-scale analysis. In this study, the analysis results were compared to experimental results to verify the validity of the multi-scale model. In the experiment, the split Hopkinson pressure bar (SHPB) test was conducted by using two types of cylindrical CFRP specimens. The commercial finite element analysis (FEA) software Abaqus was used for the analysis. We conducted micro-scale and macro-scale analysis, which corresponded to the experiments. In the micro-scale analysis, a two-dimensional periodic unit-cell (PUC) model, which consisted of 20 fibers, resin, and zero-thickness interface is used. The micromechanical model could simulate the matrix failure and debonding of the fiber/matrix interface by the Christensen failure criterion and cohesive zone modeling, respectively. Additionally, the strain rate dependency failure of matrix was considered. The PUC analysis was conducted under a multi-axial stress state, to obtain the failure envelope. Subsequently, a macro-analysis by FE was conducted with parameters obtained from the micromechanics analysis. The simulation was found to be in good agreement with experimental results. Finally, we investigated the relationship between interfacial strength and the failure load of CFRP. [ABSTRACT FROM AUTHOR]

• An experimental and analytical study on the flexural creep of concrete reinforced with resin-impregnated woven fabrics is performed. • An analytical viscoelastic model is developed based on multi-scale micromechanics, classical lamination theory, and Alfrey's correspondence principle to predict the upper and lower limits of creep deformation of TRC. • Short-term and long-term creep tests are conducted to evaluate the proposed model. • The results showed that a probabilistic model is more appropriate to predict the creep behavior of TRC rather than a deterministic model. Textile-reinforced concrete (TRC) is a promising composite material that has growing demands in the construction industry. The time-dependent behavior of TRC is a less-studied characteristic of these materials. Since the wide use of TRC in constructing thin-walled concrete structures, the present study performed an experimental and analytical study on the flexural creep of concrete reinforced with resin-impregnated woven fabrics. An analytical viscoelastic model is developed based on multi-scale micromechanics, classical lamination theory, and Alfrey's correspondence principle to predict the upper and lower limits of creep deformation of TRC. Due to uncertainty observed in the cracking force of TRC, this parameter is considered a random variable with normal distribution. Probabilistic intervals are calculated for TRC midspan creep deflections. Short-term and long-term creep tests are conducted to evaluate the proposed model. The results showed that a probabilistic model is more appropriate to predict the creep behavior of TRC rather than a deterministic model. [ABSTRACT FROM AUTHOR]

A new coupled micromechanical-damage formulation is presented by directly integrating the phase-field (PF) modeling approach for fracture and damage with the Parametric High-Fidelity-Generalized-Method-of-Cells (PHFGMC) micromechanical model. The combined PHFGMC-PF approach is proposed for progressive damage analysis of multi-phase heterogeneous composites with evolving microstructure subject to general multi-axial remote loading. New variational equations are introduced to couple the macro/micro deformation and PF variables of the discrete finite volumes (subcells). An iterative computational formulation is also presented for the numerical solution of the overall nonlinear equations. The proposed approach can accommodate various phase-field damage models and fracture energy approximations. Two PF damage laws, available in the literature, are implemented. The proposed PHFGMC-PF model verification is first accomplished by solving the single-edge crack problem under tension and shear and comparing the results to a finite element PF (FE-PF) analysis. Results of the presented case studies demonstrate a comparable ability of the PHFGMC-PF to solve similar FE-PF non-periodic problems. Applications are presented for progressive damage of carbon-fiber-reinforced (CRP) composites. The PHFGMC-PF in-situ elastic and fracture properties are calibrated for the carbon-reinforced polymer IM7/977-3 composite material system at the fiber–interface–matrix constituents. The micromechanics-PF model can capture the composite overall nonlinear mechanical and damage responses compared to experimental data. [ABSTRACT FROM AUTHOR]

The theory of finite-volume direct averaging micromechanics (FVDAM) has recently been used to analyze composite materials to obtain their effective properties. This technique has been continuously improved and applied to different problems and is promising in the heterogeneous materials research area with excellent results compared to other numerical approaches. As it is a relatively new technique, many applications have not been performed yet. This work applies the FVDAM for the first time to the numerical study of reinforced masonry, which presents complex behavior, often requiring structural reinforcement despite being an old material. Thus, the FVDAM theory is compared with results obtained by mechanics of structure genome (MSG), which has already been applied to the homogenization of unreinforced and FRP-reinforced masonry and by the finite element method (FEM). Lastly, FVDAM is applied to the solution of some examples involving different types of masonry unit cells, including the investigation of the effects of structural reinforcement, volume fraction, unit cell geometry, and the influence of block properties on effective mechanical properties. The results of such examples are compared with numerical methods such as MSG and FEM, demonstrating the good performance of FVDAM against the methods used in the comparison. • Novel application of the FVDAM technique to the numerical study of reinforced masonry. • FVDAM is compared with mechanics of structure genome and finite element method. • The examples showed the good performance of FVDAM against the other methods. • FVDAM is used to assess the effective elastic properties of reinforced masonry. [ABSTRACT FROM AUTHOR]

Abstract In this work, a coated ellipsoid assemblage model for the prediction of the effective thermal conductivity of composites with imperfect interfaces is developed. Based on the Green’s function technique, the study proposes a new formulation of the composite ellipsoid assemblage model with an imperfect interface between the inclusion and the surrounding matrix. The solution of the integral equation is obtained thanks to the concept of interior- and exterior-point Eshelby’s conduction tensors. Thereafter, the analytical expressions of the heat intensity and the effective thermal conductivity are proposed for ellipsoidal inclusion and anisotropic thermal conductivity per local phase. In order to test the relevance of the model, its predictions have been compared with the exact solutions of spherical and cylindrical inclusion. Moreover, the capability of the model to well describe the thermal behaviour of composites with high volume fractions of inclusions has been tested through some comparisons with numerical results proposed in the literature. A parametric study is then conducted to analyse the effects of the morphology and the volume fraction of the inclusion, the interface thermal resistance and contrast of thermal conductivity of local phases, on the predictions of the developed model. [ABSTRACT FROM AUTHOR]

Micromechanical simulation of composite material failure requires a pressure-dependent failure model for the polymeric matrix. Available pressure-dependent damage formulations assume a certain shape of the stress-strain law under uniaxial loading. However, upon close inspection none of the available formulations is able to reproduce the assumed shape. This implies that input values for the fracture energy cannot be recovered exactly. In this paper, a new methodology for developing consistent pressure-dependent damage models for polymeric materials is presented. Using this method the predefined shape of the stress-strain relation of an element with localized deformation under uniaxial tension can be exactly reproduced which enables further to recover the exact amount of energy dissipation consistent with the input toughness. The methodology is demonstrated for two different softening laws, namely linear and exponential softening. These models are applied to the damage analysis of unidirectional continuous fiber-reinforced composites. The formulation is validated by simulation of a test for Mode-I fracture energy characterization and comparing the load-displacement response with that obtained with cohesive elements. [ABSTRACT FROM AUTHOR]

In this paper, a two-step incremental micromechanics formulation in conjunction with FEM and weakened interface model is utilized to characterize elasto-plastic behavior of CNT/polymer nanocomposites. For the validation purpose, results corresponding to the perfect bonding assumption are compared with the experimental data. The micromechanics approach considering the weakened interface is extended to represent the nanotube, its surrounding polymer and the interfacial interactions via an equivalent fiber. The most important factor in the developed method is the sliding parameter determined through comparing the results of the model with that of a molecular structural mechanics-finite element multiscale approach at various loading conditions. Subsequently, employing several case studies, various aspects of the effects of interfacial strength on the elastoplastic behavior of these nanocomposites are systematically examined. The results show that the interfacial bonding characteristics plays a crucial role in enhancing the mechanical behavior of the host polymer and thus, should be thoroughly studied. [ABSTRACT FROM AUTHOR]

This paper focuses on strengthening carbon fiber hierarchical composite square honeycomb structures (HCSH) by selecting high-modulus hierarchical phase and optimizing its thickness. HCSH have been manufactured from carbon fiber composite foam sandwich structures by a simple snap-fit and bonding method. The measured compressive and shear strengths are shown to be well predicted by micromechanics failure models of HCSH. Compared to the monolithic composite square honeycomb structures (CSH), the measured specific out-of-plane compressive strength of HCSH improves to approximately 330% and the specific shear strength improves to about 180%. Furthermore, the relationships between hierarchical phase modulus and its optimum thickness are developed to design the optimum HCSH. Carbon fiber HCSH are found to exhibit better mechanical properties than other cellular structures, and thus provide new opportunities for light-weight multifunctional sandwich structures. [ABSTRACT FROM AUTHOR]

The present paper discusses the results obtained by using a micro-mechanical FE numerical model for the study the bond behavior of some curved specimens strengthened by Fiber Reinforced Polymer (FRP) composite materials. The numerical model, implemented into the FE code Abaqus, is a sophisticated micro-modelling (heterogeneous) approach, where bricks and mortar are meshed separately by means of 4-noded plane strain elements exhibiting distinct damage in tension and compression, FRP is assumed elastic and an elastic uncoupled cohesive layer is interposed between FRP reinforcement and masonry pillar. The experimental investigation considered to benchmark the numerical approach is aimed at characterizing the influence of normal stresses induced by curved supports on the stress-transfer mechanism of FRP materials. To this scope some single lap shear tests performed at the University of Florence on FRP reinforced curved pillars with two different curvature radii (1500 and 3000 mm) are here considered. The obtained numerical results show a promising match with experimental evidences, in terms of elastic stiffness, peak loads and post-peak behavior. Indeed, the proposed approach allows to correctly account for important local effects, such as the effect of FRP-masonry interfacial normal stresses on the global delamination strength and the distribution of damage in the pillar volume. By using the proposed modelling approach, comprehensive numerical sensitivity analyses to investigate the role played by the curvature on the ultimate delamination strength, are also presented in the paper. [ABSTRACT FROM AUTHOR]

Although composite materials are now used throughout the marine industry their susceptibility to impact events is still an unresolved problem. The complex nature of the problem in terms of the distinct material and impact event parameters specific to marine applications, damage tolerance and durability has been discussed in parts I, II and III of this review. Here, work addressing marine composite impact scaling and strain-rate effects, and impact studies not explicitly concerning marine applications yet considering laminates typical of the marine industry have been reviewed. Together with parts I, II and III, this paper gives a comprehensive review of ‘marine impact on marine composites’, providing a valuable resource for the marine industry and research fields. [ABSTRACT FROM AUTHOR]

The mechanics of structure genome has been extended to heat conduction problem of composite materials with a general linear thermal imperfect interface model. This full field micromechanics approach is applied to predict the effective thermal conductivity of composite materials containing thermal imperfect contact between the matrix and the reinforcements. Examples of spheroidal particles reinforced composites are used to demonstrate the robustness and accuracy of this micromechanics theory. The size-dependency of the overall thermal conductivity shows the importance of imperfect interfaces in modeling the thermal behavior of composite materials. The proposed micromechanics method is versatile and can be applied for estimating the effective thermal conductivity of nanocomposite materials. [ABSTRACT FROM AUTHOR]

Based on the recently discovered mechanics of structure genome, a micromechanics theory is developed for computing the effective properties and local fields of aperiodic heterogeneous materials. This theory starts with expressing the displacements of the heterogeneous material in terms of those of the corresponding homogeneous material and fluctuating functions. Integral constraints are introduced so that the kinematics including both displacements and strains of the homogeneous material can be defined as the average of those of the heterogeneous material. The principle of minimum information loss is used along with the variational asymptotic method to formulate the governing variational statement for the micromechanics theory. As this theory does not require conditions applied on the boundaries, it can handle microstructures of arbitrary shapes. This theory can also straightforwardly model periodic materials by enforcing the equality of the fluctuating functions on periodic edges. This theory provides a rational approach for avoiding the difficulty of creating periodic meshes and automatically captures finite dimension effects. Furthermore, this theory can model heterogeneous materials with partial periodicity. We have used several examples to verify and demonstrate the capability of this theory. [ABSTRACT FROM AUTHOR]

This paper presents a probabilistic multiscale approach to model the random spatial distribution of local elastic properties arising from the heterogeneous waviness and orientation of CNT fillers within a 3D microscale continuum representative volume element (RVE) of a CNT-reinforced polymer matrix. The proposed direction-sensitive 3D Karhunen-Loève expansion (KLE) provides the basis to simulate stochastic variations in the CNT orientations rather than assuming a perfect alignment. Computational homogenization analyses are carried out to investigate the effects of the statistical parameters of random CNT waviness on the microscale continuum RVE size. The proposed probabilistic multiscale modelling framework allows to consider the uncertainty associated with the use of CNT nanocomposites for various applications. [ABSTRACT FROM AUTHOR]

A multiscale experimental approach is introduced that facilitates correlating globally applied stress to the local material response at yarn scale. Using a high-resolution optical digital image correlation, low and high strain zones in off-axis woven composite samples loaded in uniaxial tension are identified and the corresponding full-field strains are quantified. The local strain response quantified over low and high strain domains are used along with the continuum scale deformation to establish a correlation between global and local deformation behavior as a function of fiber orientation. In addition, global stress-local strain curves are extracted for low and high strain domains at different fiber orientation angles. A simple plasticity model in conjunction with the obtained stress-strain curves is implemented and utilized to develop a phenomenological model that enables correlating global stress with the locally developed strain at different locations in a composite specimen subjected to off-axis tensile load. [ABSTRACT FROM AUTHOR]

For fiber reinforced polymer composites, it is important to obtain a good interfacial bonding between the fibers and the polymer matrix to enhance the physical properties of the composites. In particular, the mechanical and thermal properties of the composites differ depending on the interfacial bonding strength, lengths, and orientations of the fibers. We investigate the microstructural anisotropy of the basalt fiber reinforced polypropylene composites and evaluate their mechanical properties, such as elastic modulus and ultimate tensile strength in order to understand the relationship between the local anisotropy and the mechanical strength of the composites. Dynamic mechanical and thermal analyses are performed to characterize the grafting effect of maleic anhydride polypropylene on the basalt fibers. The grafting effect enhances the bonding strength between the basalt fibers and matrix and the thermomechanical properties of the composites. The elastic modulus and ultimate tensile strength of the composites with the grafting effect show enhancement compared to the composites without the grafting effect. The predictions of the elastic modulus by the Mori–Tanaka model and the ultimate tensile strength by the rule of mixture model are in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Damping properties of polymer matrix nanocomposites (NC) reinforced by vapor grown carbon fiber (VGCF) are investigated by presenting a multi-stage analytical micromechanical model. A third phase as interphase is considered due to the complex chemical and physical state in the region near to matrix/fiber interface. Both uniform and graded properties of the interphase through the thickness are considered. Acceptable agreements in comparison with experiments and appropriate mesh sensitivity analysis prove the efficiency and accuracy of the proposed model. The effects of various meaningful parameters, including the interphase bonding strength, thickness and types and also the VGCF volume fraction, aspect ratio, orientation, diameter, waviness and cone angle are investigated. Stored and dissipated energy in the NC constituents are obtained as well. It is concluded that the NCs reinforced by long nanofiber possess greater storage and loss modulus than the NCs owing short fiber. However, the specific damping capacity picks lower values. Higher bonding strength and lower thickness of the interphase enhance the NC effective damping properties. Increasing VGCF diameter, waviness and cone angle result declining in the damping properties. The interphase portion in the stored and dissipated energy increases by decreasing the interphase bonding strength and increasing the interphase thickness. [ABSTRACT FROM AUTHOR]

Traditional ASTM D6641 standard is not suitable for ultrahigh modulus carbon fiber reinforced polymer (CFRP) composites under longitudinal compression due to the unacceptable failure mode of end crushing. Experiments and micro-mechanical finite element simulations are conducted for [90/0] ns laminates under compression to check if it is acceptable using results of [90/0] ns laminates to calculate longitudinal compressive strength. Experimental results show that failure modes in [90/0] ns laminates are acceptable. Fiber splitting, fiber breakage and kink band are found clearly in 0-degree lamina under SEM. Failure index distributions before peak load in simulation show that it is fiber failure in 0-degree lamina that causes the final failure which indicates that [90/0] ns laminates can be used to calculate compressive strength. Four different types of fibers with different modulus and [0/90] ns micro-mechanical model for ultrahigh modulus CFRP are also built for comparison. Results show that this method is also applicable for T800H CFRP composites, but not for T300 and T700 CFRP composites. [ABSTRACT FROM AUTHOR]

Molecular characterization of polymer resin systems is significantly important in prediction and advancing understanding of properties and phenomena of resin-based composites. In this work, molecular dynamics simulations of a resin composite model, i.e., silica nanoparticle reinforced Bis-GMA/TEGDMA resin composite, were performed to investigate the effects of organic and inorganic components on the structure and properties of the resulting composites. It was revealed that even a small amount of silica nanoparticles (up to 10 wt%) could improve the mechanical properties considerably due to increased intermolecular hydrogen bonds and polymer chain contraction. The reinforcement effect induced by silica nanoparticles is much more intensive than that caused by the stiff resin monomer of Bis-GMA. The composite modulus, increasing with the silica nanoparticle content, was further compared with micromechanics methods and exhibited good agreement with the Counto model, indicating strong matrix-particle interactions. Moreover, it was found that the diffusion dynamics of the resin matrix is significantly suppressed at higher contents of Bis-GMA or silica nanoparticles, which signifies a strong dependence on the hydrogen bonds and chain conformational changes. The findings in this work are believed to provide the atomic/molecular scale understanding of the structures and performances of Bis-GMA/TEGDMA resin blend and composite systems. [ABSTRACT FROM AUTHOR]

This paper presents an analytical micromechanics model for predicting the three-dimensional effective elastic properties of multidirectional composite laminates with ply wrinkle defects. A representative volume element (RVE) was chosen for analysis and the geometry of wavy plies in the wrinkled laminates was described by sinusoidal functions. The derivation of the effective elastic moduli was based on the mixed boundary conditions, and a two-step homogenization technique was proposed. The analytical predictions were compared with the published numerical and experimental results for unidirectional and cross-ply carbon/epoxy laminates. The model was also applied to quasi-isotropic laminates, and the effect of wrinkles on their effective properties was examined. The developed analytical micromechanics model was found to accurately predict the in-plane and out-of-plane effective properties of the wrinkled laminates, making it a useful tool for providing information on the relationships between wrinkle defects and the macroscale response of composite laminates and for designing composite structures. [ABSTRACT FROM AUTHOR]

A nonlinear multiscale damage analysis is proposed based on the parametric High Fidelity Generalized Method of Cells (HFGMC) micromodel. Two repeating unit-cells (RUCs), square and hexagonal, for the composite microstructure are discretized into subcells which represents the fiber and matrix phases. Average traction and displacement continuities, periodicity conditions, and volumetric equilibrium are applied. The proposed modeling approach is implemented as a user material subroutine within displacement-based layered-shell FE models, where each layer can be represented with at least one RUC. The RUC through-thickness stress and stiffness contributions are eliminated in case of a failure. Two failure criteria, in conjunction with compressive strength equation, are applied to determine RUC failure. In the first, the Tsai-Wu failure criterion is used at the RUC level. The second employs the strain invariant failure theory (SIFT) within each subcell, leading to its extinction. The in-situ properties and damage parameters of the RUC are determined by calibration using axial, transverse, and shear data of unnoteched laminates. The accuracy of the proposed framework is demonstrated by a comparison with experimental results of open-hole laminates. [ABSTRACT FROM AUTHOR]

The homogenized properties and localized field distributions of coated magneto-strictive porous heterogeneous materials are extensively investigated using the extended Finite Volume Direct Averaging Micromechanics (FVDAM) with coupled mechanical-magnetic capabilities. Both square and hexagonal microstructures are employed to mimic different hollow coating arrangements. In order to validate the present technique, the corresponding finite element model is constructed in Abaqus to provide rigorous comparisons, and no visible difference is observed between two different models’ predictions. The effects of the thickness of coatings are tested on the effective and local responses, where the hollow coatings play significant roles in the variations of homogenized properties and transmissions of stress concentrations. Finally, a two-step multiscale framework is established on periodic wavy structures, wherein the layers are composed of CoFe 2 O 4 material reinforced by BaTiO 3 hollow coatings with two different volume fractions. The amplitude-to-wavelength ratio is varied to effectively study its impact on the field distributions of homogenized layers and local microstructures. [ABSTRACT FROM AUTHOR]

Carbon-based nanomaterials have drawn the attention of a large section of the scientific community in recent years. Most research has focused on carbon nanotubes after some experimental studies reported outstanding enhancements of the mechanical properties of polymeric matrices doped with small filler concentrations. Nevertheless, some limiting factors such as high manufacturing cost and difficulty in obtaining adequate uniform dispersions still remain an obstacle to the extensive manufacturing of these composites. Conversely, recent investigations demonstrate the superior properties of graphene, as well as better dispersion and relatively low manufacturing cost. Although these recent findings have begun to turn the attention towards graphene, the number of publications dealing with the theoretical analysis of graphene-reinforced structural elements is rather scant. In this context, the present work reports the bending and vibrational behavior of functionally graded graphene- and carbon nanotube-reinforced composite flat plates. The macroscopic elastic moduli of the composites are computed by means of the Mori–Tanaka model. The results demonstrate superior load bearing capacity of graphene-reinforced composite plates for both fully aligned and randomly oriented filler configurations. In addition, defects in the microstructure stemming from agglomeration and restacking of graphene sheets into graphite platelets are also analyzed. [ABSTRACT FROM AUTHOR]

A micromechanics framework for modelling the mode II interlaminar crack onset and propagation in fibre-reinforced composites is presented with the aim of i) modelling the micro-scale failure mechanisms that underlie interlaminar crack propagation, and ii) determining the effect of the through-thickness pressure on mode II fracture toughness. An algorithm for the generation of the fibre distribution is proposed for the generation of three-dimensional Representative Volume Elements (RVEs). Appropriate constitutive models are used to model the different dissipative effects that occur at crack propagation. Numerical predictions are compared with experiments obtained in previous investigations: it is concluded that the proposed micromechanical model is able to simulate conveniently the interlaminar crack propagation and to take into account the effect of the through-thickness pressure on mode II interlaminar fracture toughness. [ABSTRACT FROM AUTHOR]

In this paper, a new damage modelling approach is presented to describe the mechanical response of unidirectional composites under the small strain assumption. The proposed constitutive equations inherits from the phenomenological theories of Continuum Damage Mechanics (CDM) but brings out a micromechanical description of the damaged Representative Volume Element (RVE) while being formulated in a proper thermodynamical framework. The model is provided with an implicit numerical scheme based on the so-called “return mapping algorithm” as well as the formulation of the tangent operator. The identification and the prediction capabilities of the model are validated using experimental data including off-axis tensile tests. Finally, to provide a better understanding of the model, a multi-axial non-proportional simulation is performed and analysed. [ABSTRACT FROM AUTHOR]

In this contribution, the three-dimensional (3D) finite-volume direct averaging micromechanics (FVDAM) is reconstructed by incorporating parametric mapping capability into the theory’s analytical framework, which allows using arbitrarily shaped and oriented hexahedral subvolumes in the material microstructure discretization. The technique is then further extended to include linear viscoelastic capability to investigate the creep and relaxation behavior of polymeric matrix composites and stress field evolution with either continuous or discontinuous reinforcements. Elastic-viscoelastic correspondence principle is employed in the unit cell solution to relate the governing relations between time domain and Laplace-Carson domain. After establishing the homogenized constitutive equations and solving the boundary value problems in Laplace-Carson domain, Zakian inversion scheme is used to invert the inexplicit homogenization functions to obtain both relaxation moduli and stress distributions during a relaxation history in real space. The FVDAM theory via correspondence principle is validated extensively by comparing with Mori-Tanaka, finite-element, locally exact solutions and experimental data. Good agreement between the present theory and other methods, along with a few numerical investigations, explains not only the accuracy of the 3D parametric FVDAM but also the validity and efficiency of the correspondence principle and Zakian inversion technique. [ABSTRACT FROM AUTHOR]