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To investigate the fracture initiation mechanisms and establish the relationship between the ductile fracture mechanism and macro stress–strain for high-strength structural steel, the mechanical response and fracture behavior of Q460C steel and its butt welds were studied via tests, numerical analysis and scanning electron microscopy (SEM) in this paper. The mechanical properties of high-strength steel (HSS) under different stress triaxialities were studied by uniaxial tensile tests on standard specimens and notched round rods. The finite element model is set up according to the characteristic length which is based on SEM observations. By combining experimental results and numerical simulations, the constitutive model and fracture prediction model were established. The relationship between the ductile fracture mechanism and the macro stress strain was obtained. The toughness parameters of the micromechanical model of Q460C steel and its welded joints were compared with those of Q345 steel and seven other types of structural steel from the United States and Japan. The results show that the characteristic length of the crack tip is the key factor affecting the accuracy of predicting fracture toughness under a large stress–strain gradient. The toughness predicted by the model is in good agreement with the traditional fracture toughness test results when taking the average value. The experimental results and finite element analysis verified the effectiveness of the VGM and SMCS micromechanical models in predicting the fracture toughness of Q460C steel and its welded joints, which can provide a theoretical basis and practical guidance for the anti-fracture design and application of HSS structures. [ABSTRACT FROM AUTHOR]

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Auxetic metamaterials have emerged as a class of advanced materials with exceptional physical and mechanical properties that are not typically found in conventional materials. This work mainly focuses on the buckling and free vibration of axially functionally graded (AFG) graphene origami (GOri)-enabled auxetic metallic metamaterial (GOEAM) beams. The beam is comprised of GOEAMs with GOri content varying through the beam length within different patterns to realize axially gradient-changing Young’s modulus, Poisson’s ratio and mass density. The material properties of AFG-GOEAMs are evaluated by using the micromechanical model including volume fraction and folding degree of GOri, geometric characteristics of graphene, material properties of matrix, and local temperature. The first-order shear deformation theory is employed to derive the governing equations via the state-space procedure, and then analytically solved with the discrete equilong segment model along beam length direction. The effects of GOri content, axial distribution pattern, folding degree and temperature on the buckling and free vibration of AFG-GOEAM beams are mainly focused on. The numerical results indicate that the development of auxetic metal metamaterials can be achieved by incorporating GOri into the metal matrix, leading to the tunable bucking and natural frequencies of AFG beams, which provide significant insights into the design of high-performance structures. [ABSTRACT FROM AUTHOR]

Nowadays, it is still a huge challenge to predict the interlaminar shear strength (ILSS) of three‐phase carbon fiber reinforced polymer (CFRP). Herein, the three‐phase micromechanical model is innovatively constructed to predict the ILSS of CFRP, and the conception of new matrix is proposed by establishing a connection between the third phase and the matrix, which effectively solves the problem of uneven distribution of the third phase. To verify the accuracy of the micromechanical model, the Ti3C2Tx MXene/CFf/epoxy composites were fabricated by the co‐blending, layer‐by‐layer assembly and hot‐pressing technology, and the finite element simulation analysis was also performed based on the micromechanical model. The results show that the micromechanical model possesses high accuracy. Specifically, the experimental value of ILSS of the composite with 1 wt% Ti3C2Tx MXene content is 52.12 MPa, and the errors of simulation value (56.64 MPa) and theoretical prediction value (58.69 MPa) are 8.67% and 12.61% MPa, respectively. Besides, the detailed fracture mechanism of the composite is presented based on the fracture morphology and simulation results. It is believed that this work will provide more possibilities for the prediction of the interlaminar shear performance of three‐phase composites. Highlights: A novel micromechanical model is used to predict the ILSS of three‐phase composite.The accuracy of the micromechanical model is verified by simulation and experiment.The main failure form of the Ti3C2Tx MXene/CFf/epoxy composite is matrix broken.The micromechanical model of the three‐phase composites has high accuracy. [ABSTRACT FROM AUTHOR]

AbstractIn this article, we organize a stretchable-thickness model to present a frequency analysis for a composite plate applicable in badminton court which is reinforced with origami graphene. A higher order kinematic model is extended in this work including three bending, shear, and stretching functions, where the stretching functions is responsible for satisfying the out of plane shear strains and stresses at top/bottom surfaces of the badminton equipment. The sport or composites plate is manufactured from a copper matrix reinforced with graphene origami where the effective material properties are calculated based on micromechanical models as a function of volume fraction and folding degree of graphene origami, material properties of matrix and reinforcement and temperature. The numerical results are presented with changes of volume fraction, folding degree of reinforcement, and thermal loading along the thickness direction. The main novelty of this work is accounting thickness stretching deformation for the analysis of a graphene origami reinforced plate and investigating the responses of graphene origami as a new reinforcement. A verification investigation is presented for approve of the methodology, and solution procedure. An investigation on the order of deformation is presented for various thickness ratio of the badminton sport plate. [ABSTRACT FROM AUTHOR]

AbstractThis paper studies the free vibration and harmonic response of Functionally Graded Graphene/Epoxy composite plates, considering the First Order Shear Deformation Plate Theory. The weight fraction of graphene variation along the thickness direction with graphene homogeneous dispersed in a polymer matrix. The effective Young Modulus of the plate is predicted by a new micro-mechanical model. The model includes the aspect ratio and weight fraction of nanoplatelets embedded into the matrix. The modal and harmonic of Graphene/Epoxy plates are obtained by the Boundary Element Method formulation for composite plates. The Young modulus calculated from the proposed micro-mechanical model highly agrees with those obtained from experimental results reported in the literature. Results demonstrate a high correlation of the micromechanical model with experimental results and other analytical models. Graphene weight fraction and ratio aspect increase the effective Young modulus of the composite. Boundary Element results show high agreement with Finite Element solutions. Numerical results for modal and harmonic analysis show concentrating graphene near the top and bottom surfaces of the plate is the most effective way to reinforce the plate for increased natural frequencies. The results demonstrate the BEM formulation and micromechanical model can be used as reliable engineering tools for the vibrational analysis of functionally grade graphene composite plates. [ABSTRACT FROM AUTHOR]

Glass fiber-reinforced cement-based material incorporating hollow glass beads (GFRC-HGB) is an innovative lightweight building material with exceptional energy-saving properties. Based on the framework of variational asymptotic homogenization theory, a micromechanical model is developed for predicting the effective elastic properties and recovering the local fields of unidirectional GFRC-HGB. This model starts with expressing the displacements of the heterogeneous GFRC-HGB in terms of those of the corresponding homogeneous material and fluctuation function. Then, the principle of minimum potential energy is used along with variation asymptotic method to formulate the governing variational statement for the micromechanics model, the micromechanical model is used to quantitatively investigate the influence of internal structural parameters of HGB on the elastic properties of unidirectional GFRC-HGB. The numerical results demonstrate the effectiveness and accuracy of the micromechanical model in predicting the effective elastic modulus and local fields. The numerical simulation and SEM images of the tensile fracture prove that the local stress distributions are closely related to the loading direction, and the transverse deformation is restrained by glass fibers. [ABSTRACT FROM AUTHOR]

The object of study is the vertical wave propagation in a sand deposit. This paper is aimed at analyzing the vertical wave propagation in a sand deposit through micromechanical modeling that inherently takes account of intergranular slips during deformation. Such a problem, which is part of the general framework of wave propagation in the soil, has long been analyzed using continuum models based on approximate behavior laws. For this purpose, a 2D Discrete Element Method (DEM) model is developed. The DEM model is based on molecular dynamics with the use of circular shaped elements. The intergranular normal forces at contacts are calculated through a linear viscoelastic law while the tangential forces are calculated through a perfectly plastic viscoelastic model. A model of rolling friction is incorporated in order to account for the damping of the grains rolling motion. Different boundary conditions of the profile have been implemented; a bedrock at the base, a free surface at the top and periodic boundaries in the horizontal direction. The sand deposit is subjected to a harmonic excitation at the base. Using this model, the fundamental and resonance frequencies of the deposit are first determined. The former is determined from the low-amplitude free vibration and the latter by performing a variable-frequency excitation test. It is noted that there is a significant gap between the two frequencies, this gap could be attributed to the degradation of the soil shear modulus in the vicinity of the resonance. Such degradation is well proven in classical soil dynamics. The effects of deposit height and confinement on resonance frequency and free-surface dynamic amplification factor are then investigated. The obtained results highlighted that the resonance frequency is inversely proportional to the deposit’s thickness whereas the dynamic amplification factor Rd increases with the deposit’s thickness. In the other hand, when the confinement increases the deposit becomes stiffer, which results in reducing the amplification. Such result is in accordance with theoretical knowledge which states that the most rigid profiles such as rocks do not amplify seismic movement. [ABSTRACT FROM AUTHOR]

The existing micromechanical damage plasticity models assume that penny-shaped microcracks are present in the rocks, but it is seldom a reality. These models result in the abstract values of the damage variable. It is fundamentally due to the assumption of penny-shaped microcracks. To overcome this limitation, we have modified the micromechanical damage plasticity model such that the damage variable obtained from the proposed constitutive model relates to the measured damage from the recorded Acoustic Emission (AE) signals. This research presents a micromechanical coupled damage plasticity model by utilising AE data to predict the nonlinear mechanical response of intact rocks under Conventional Triaxial Compression (CTC) loading. The novelty of the proposed model is that it overcomes the limitation of penny-shaped microcracks and accounts for arbitrarily shaped microcracks by using a phenomenological approach. The applicability of the proposed model is shown by different rocks originating from varying geology. We have modelled the nonlinear mechanical behaviour of rock salt and coal (sedimentary rocks), tuff (soft igneous rock), and marble (hard metamorphic rock). The model performance is verified by comparing the results with the test data using the coefficient of determination (R2) statistical parameter. The proposed model predicts well the experimental data of damage variables with strain. It also successfully presents both strain hardening and softening behaviour of the rocks. Highlights: The article contributes to the modification of the micromechanical coupled damage plasticity model such that the damage variable of the model relates to the experimentally obtained damage by Acoustic Emissions. The proposed model uses a phenomenological approach to account for arbitrarily shaped microcracks in the micromechanical coupled damage plasticity constitutive model. The proposed model is verified on different rocks with diverse geological genesis, such as rock salt, coal (sedimentary rocks), tuff (soft igneous rock), and marble (hard metamorphic rock) under uniaxial and triaxial compression loading conditions. [ABSTRACT FROM AUTHOR]

In this study, the simulation of a vacuum forming process employing a micromechanical inspired viscoelastic–viscoplastic model is investigated. In the vacuum forming process, a plastic sheet is heated above the glass transition temperature and subsequently forced into a mold by applying a vacuum. The model consists of a generalized Maxwell model combined with an dissipative element in series. Each Maxwell element incorporates a hyperelastic element in series with a viscous element based on a hyperbolical law. While the generalized Maxwell model considers the relaxation due to molecular alignment, the additional viscous element is a modification based on the approach of Bergström and thus considers molecular chain reptation. The model is designed with the aim to converge to the generalized linear Maxwell model in the limit of small deformation. Furthermore, the viscous modeling is temperature activated and follows the Williams–Landel–Ferry approach in the limit of linear viscoelasticity. To simulate rheological standard experiments, a physical‐network‐based implementation into Simscape is presented. To validate the performance of the model in thermoforming, it is implemented into Fortran programming language for finite element simulation with Abaqus/Explicit. It can be shown that the simulation is able to predict the thickness in high correlation with experimental results. [ABSTRACT FROM AUTHOR]

The present research focuses on proposing a novel theoretical micromechanical model (TMM) designed to derive the frequency-dependent storage and loss moduli of woven fabric (WF)-matrix composites, as well as WF-particulate matrix (Hybrid) composites, based on their constituent properties. The TMM serves as a higher-order modulus operator, accounting for the composite woven fabric unit cell geometry and the effective modulus of both the fabric and matrix using equivalent modulus theory. This model also incorporates viscoelastic parameters obtained from literature and experiments for each constituent, namely woven glass fabric and SiC particles embedded in an epoxy matrix. The proposed TMM is validated by comparing its predictions of the frequency-dependent storage modulus and loss factor with experimental data acquired through dynamic mechanical analyzer tests on samples with varying fiber and particulate volume fractions. To address the inherent complexities of the higher-order modulus operator, the model is streamlined into a lower-order form expressed as a function of two separate variables: volume fraction and a differential time operator. This advancement enhances the applicability and usability of the model for predicting the mechanical behaviour of these complex composite materials. This novel mathematical model eliminates the cost and time for conducting the explicit experiments as well as can be applied to different range of similar hybrid composites considering the fact that the constituent properties are known. [ABSTRACT FROM AUTHOR]

• A novel time-dependent micromechanical model is proposed to consider the glass fiber dissolution phenomenon. • The dissolution phenomenon is linked to the mechanical properties of the glass-reinforced composite. • The governing equations of conveying fluid composite pipe systems with fiber dissolution defects are presented. • Natural frequencies, divergence and flutter critical flow velocities of the composite pipe are investigated. The motivation for the present study comes from the appearance of fiber dissolution in industrial applications of composite pipes under different flowing fluids and operating conditions. To mitigate the consequences of glass fiber dissolution in glass fiber reinforced plastics (GRP) pipes, it is essential to investigate the dynamic characteristics of the pipes under internal fluid flow. This paper presents a novel time-dependent micromechanical model and examines the effects of glass fiber dissolution on the instability and vibrational behavior of a composite pipe conveying fluid. The Hamiltonian principle obtains the governing equations of the conveying fluid composite pipe system with fiber dissolution defects. The Finite Element Method (FEM) is then used to solve the eigenvalue problem for the natural frequencies, divergence, and flutter critical velocities of the composite pipe conveying fluid. The effects of different parameters, such as span and amount of dissolution, as well as the quality of the dissolved portion of the fibers, are highlighted on the instability and vibration characteristics of composite pipes. The results show that fiber dissolution significantly affects the behavior of composite pipes conveying fluid. This work also provides a better understanding of the above-mentioned "environmental aging" type in fiber-reinforced composites. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced polymer composites (CFRPC) are being used as primary structures in many applications. However, unlike metallic materials, they are susceptible to damage by lightning strikes. When lightning strikes, due to its poor electrical conductivity, the composite material generates localized resistive heating near the strike area. This resistive heat causes elevated temperatures near the strike area, which leads to material property changes and the structural material's stiffness and strength reduction. As part of this study, a finite element (FE)-based coupled electro-thermo-mechanical modeling approach was adopted to simulate the effect of lightning strikes on a unidirectional (UD) carbon fiber reinforced polymer composite model to predict the residual compressive strength of the material. In the current study, a two-dimensional (2D), micromechanical finite element model of CFRPC was used to quantify its residual compressive response when subjected to simulated lightning strikes with different peak currents using the software ABAQUS. The normalized residual compressive strengths for various peak currents obtained from the proposed electro-thermo-mechanical model were compared with the available experimental data from the literature. The effectiveness of an electrically conductive protective coating in minimizing the compressive strength reduction was also evaluated. Further, the optimum electrical conductivity of the coating in terms of the matrix conductivity, for maintaining the desired compressive strength was also estimated. Furthermore, the effect of change in thickness of the conductive coating in compressive strength change was evaluated by considering two different coating thicknesses. The results show that for a given peak current, the thinner coating will not compromise the compressive strength as long as the conductance of the thin and thick coating is the same. [ABSTRACT FROM AUTHOR]

This paper presents a constitutive model for the behavior of steel fiber reinforced concrete (SFRC) under mixed mode cracking taking into account the fiber orientation effect by using a micromechanical approach. Firstly, the resistant mechanisms of an inclined fiber are modeled by a closed-form analytical function. The bridging force is calculated by integrating on the cracked surface, the product of the fiber extraction force by its orientation probability. A modified model of the aggregate interlock mechanism is combined with the fiber bridging stresses to obtain the cohesive stresses. This mesoscale model is then extended using an elastic damage model and a fixed smeared cracking concept to assess the structural behavior. The model is finally implemented in a Finite Element Analysis (FEA) software, its performance is tested with some experimental results collected in the literature. The model successfully integrates the fiber orientation effect and shows a good prediction of stress transmission. [ABSTRACT FROM AUTHOR]

This work applies a higher order thickness-stretched model for the electro-elastic analysis of the composite graphene origami reinforced square plate sandwiched by the piezoelectric/piezomagnetic layers subjected to the thermal, electric, magnetic and mechanical loads. The plate is manufactured of a copper matrix reinforced with graphene origami where the effective material properties are calculated based on the micromechanical models as a function of volume fraction and folding degree of graphene origami, material properties of matrix, reinforcement, and local temperature. The governing equations are derived using the virtual work principle in terms of the bending, shear and stretching functions, in-plane displacements, electric, and magnetic potentials. The numerical results including various displacement components, maximum electric, and magnetic potentials are presented with changes of volume fraction, folding degree of reinforcement, electrical, magnetic, and thermal loading. A verification investigation is presented for approve of the methodology, and the solution procedure. The main novelty of this work is simultaneous effect of the thickness stretching and the multi-field loading on the electromagnetic bending results of the sandwich plate. Another novelty of this work is usage of graphene origami nano-reinforcement as a controllable material in a sandwich structure subjected to multi-field loadings. The results show an increase in bending, shear, and stretching deflections with an increase in electromagnetic loads, and folding degree as well as a decrease in volume fraction of reinforcement.

The mechanical properties of BaTiO 3 filled HDPE nanocomposites are studied by experimental and numerical approaches. First, the viscoelastic behavior of neat HDPE is highlighted experimentally in tensile and relaxation tests. A method is then proposed to define a constitutive viscoelastic law representative of this behavior at different tensile crosshead speeds at room temperature. Afterward, this law is implemented in a finite-element-based micromechanical model representing the BaTiO 3 filled HDPE nanocomposites with different filler amounts. The experimental and numerical results are further compared. Both the experiments and numerical simulations confirm the viscoelastic behavior of the polymer nanocomposite. For nanocomposites with filler concentrations up to 20 %, the error between the experimental and numerical findings remains less than 8 %, confirming that the model represents well the composite behavior for low and moderate filler amounts. The proposed strategy can be applied to other polymer composites in order to predict the complete mechanical behavior of viscoelastic composite materials. [Display omitted] • The viscoelasticity of polymer nanocomposites is highlighted. • The master curve of HDPE relaxation modulus is experimentally obtained. • A constitutive law based on the generalized Maxwell model is established for HDPE. • Mechanical properties of nanocomposites are predicted using a micromechanical model. [ABSTRACT FROM AUTHOR]

The longitudinal extensional viscosity of a highly aligned discontinuous fiber (ADF) thermoplastic matrix composite is investigated to develop a model and validate microstructural evolutionary mechanisms. Samples stretched at constant temperature and strain rate are shown to exhibit a strain softening behavior. X-ray CT analysis and optical micrographs show that the composite microstructure deconsolidates before forming and evolves with deformation. The conventional unit cell micromechanical model includes the effects of matrix viscosity, fiber aspect ratio and fiber volume fraction. This model is modified to include the stiffening effect of fiber spacing variability, and the softening effects of porosity and decreasing fiber overlap length with elongation. Calibration of the model reveals that matrix shear strain rate is an order of magnitude higher than previously predicted due to local fiber spacing. This effect is captured by a fiber spacing variability parameter which scales average spacing down by an order of magnitude. The observed strain softening behavior is described and a combinations of fiber overlap length reduction and local fiber spacing increase. [Display omitted] [ABSTRACT FROM AUTHOR]

This study focused on an innovative practical method using computer vision for particle size measurement, which serves as a key precursor for predicting the elastic modulus of polymer nanocomposites. This approach involved the morphological segmentation of the nanodispersed phase. It aimed, for the first time, to address the impractical conditions resulting from the assumption of idealized single-particle sizes in a monodispersed system during modeling. Subsequently, a micromechanical finite element framework was employed to determine the interphase thickness and modulus in ultrahigh molecular weight polyethylene/nanozeolite composites, following the quantification of nanoparticle sizes. The size measurement approach relied on morphological images extracted from scanning electron microscopy micrographs of impact-fractured surfaces. To compute the interphase thickness, experimental data was fitted to an interphase-inclusive upper-bound Hashin-Shtrikman model, with the measured average particle size per composition serving as a crucial input. Subsequently, the interphase elastic modulus was computed based on its thickness, employing a hybrid modified-Hashin-Hansen and Maxwell model. These estimated interfacial variables were then utilized as inputs for the finite element model to determine the tensile modulus. A comparison between the model results and measured data revealed a maximum discrepancy of 3.29%, indicating the effectiveness of the methodology employed in quantifying interfacial properties.

Phenomenological models are commonly used to model void nucleation from second phase particles in ductile fracture simulations. Parameters in these continuum models are typically estimated using indirect methods, by comparison with experimental fracture data. In this paper, a novel approach based on acoustic emission (AE) measurements in smooth and notched bar tension tests is proposed to estimate void nucleation model parameters such as the mean and standard deviation of the nucleation strains. Tensile tests on AA 7075-T651 specimens combined with AE data establish a robust correlation between AE amplitude and the average void nucleation rate. The nucleation parameters are calibrated using a dog-bone tensile specimen. Simulations using these calibrated parameters accurately reproduces AE amplitude trends in other specimen geometries. This approach provides a promising alternative to traditional calibration methods, enhancing the reliability and adaptability of void growth based ductile fracture models. [Display omitted] • A correlation exists between void nucleation and acoustic emission (AE) amplitude for AA 7075-T651. • The Chu and Needleman void nucleation parameters can be calibrated using acoustic emission. • With calibrated parameters, the model reproduces AE amplitude characteristics in various geometries. [ABSTRACT FROM AUTHOR]

• A novel multiscale analysis is developed to assess the buckling behavior of MWCNT-reinforced laminated composites. • Integration of microstructural factors like MWCNT clustering, alignment, and curvature in evaluating composite material performance. • Comprehensive assessment of the influence of moisture and temperature on the buckling performance of MWCNT composites. • Results successfully compared and validated with existing experimental and theoretical data. • Offers significant insights for the design and optimization of MWCNT-reinforced composites. This study introduces a detailed method for analyzing the buckling behavior of laminated composite structures strengthened with multi-walled carbon nanotubes (MWCNTs). We propose a multi-scale analysis that combines analytical and computational techniques to assess the mechanical performance of MWCNT-reinforced composites under combined moisture, temperature, and mechanical stress conditions. The Halpin-Tsai equations are used to calculate the overall stiffness properties of the nano-enhanced matrix, considering factors like MWCNT clustering, alignment, and curvature. Additionally, we incorporate the nanoscopic, size-dependent features of MWCNTs into our model. The Chamis micromechanical formulas are applied to determine the individual elastic properties of the nanocomposite layers, considering the impacts of temperature and moisture. We then explore how variables such as MWCNT content and size, along with temperature and moisture levels, influence the critical buckling load of MWCNT-based laminated composite beams and plates using our multi-scale model. Our results are successfully compared with existing experimental and theoretical data to validate our approach. The developed method offers significant insights for the design and optimization of MWCNT-reinforced composites, potentially benefiting various engineering fields, including aerospace and automotive industries. [ABSTRACT FROM AUTHOR]

This work applies a higher order thickness-stretched model for the electro-elastic analysis of the composite graphene origami reinforced square plate sandwiched by the piezoelectric/piezomagnetic layers subjected to the thermal, electric, magnetic and mechanical loads. The plate is manufactured of a copper matrix reinforced with graphene origami where the effective material properties are calculated based on the micromechanical models as a function of volume fraction and folding degree of graphene origami, material properties of matrix, reinforcement, and local temperature. The governing equations are derived using the virtual work principle in terms of the bending, shear and stretching functions, in-plane displacements, electric, and magnetic potentials. The numerical results including various displacement components, maximum electric, and magnetic potentials are presented with changes of volume fraction, folding degree of reinforcement, electrical, magnetic, and thermal loading. A verification investigation is presented for approve of the methodology, and the solution procedure. The main novelty of this work is simultaneous effect of the thickness stretching and the multi-field loading on the electromagnetic bending results of the sandwich plate. Another novelty of this work is usage of graphene origami nano-reinforcement as a controllable material in a sandwich structure subjected to multi-field loadings. The results show an increase in bending, shear, and stretching deflections with an increase in electromagnetic loads, and folding degree as well as a decrease in volume fraction of reinforcement., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Author(s).)

Most of the concrete structures in service are unsaturated, estimating the ionic diffusion coefficient of unsaturated cement-based material is of paramount significance to assessment of corrosion of reinforced concrete. Taking account of the contributions from different water configurations at multi-scale (water films, interlayer water, large gel pore (LGP) water and capillary pore water) and the corresponding diffusion mechanisms of each type of water, a micromechanical model for estimating the ionic diffusion coefficient of unsaturated hardened cement paste (UHCP), is developed in this study. Model results show that the interconnectivity of the spheroidal capillary pore water is closely related to the aspect ratio of spheroidal capillary pore, the slender the prolate pore, the higher the interconnectivity of the capillary pore water; when the capillary pore water is totally drained, water films and interlayer water within C-S-H governs the ionic diffusion, the higher the water to cement ratio (w/c), the less the contribution of interlayer water, and the greater the contribution of water film, to ionic diffusion within UHCP. Application on saturated hardened cement paste and UHCP shows the capability of the model to accurately reproduce the experimental results. [ABSTRACT FROM AUTHOR]

In this paper, micromechanical models are used to predict the 3D viscoelastic behaviour of asphalt mixtures (with volume fraction of aggregate particles up to 87%) from the mechanical properties of their constituents. To fulfil the objective of study, complex modulus tests are conducted on bituminous materials at three different scales: bitumen, asphalt mastics and asphalt mixtures. The volume fraction of particles varies from 0% (bitumen) to 15%, 25%, 35% (asphalt mastic) and up to 87% (asphalt mixture). In the experimental program, complex modulus of bitumen, asphalt mastic and asphalt mixtures at different temperatures, frequencies are measured. For asphalt mixtures, measurements of complex Poisson's ratio are also performed. The rheological model 2S2P1D is used to simulate the 3D viscoelastic behaviour of tested bituminous materials. From the experimental results and simulations, two micromechanical models (self-consistent and generalized self-consistent model) are used to predict the complex modulus and complex Poisson's ratio of asphalt mixtures. The obtained results show that both micromechanical models give the good prediction of complex modulus for asphalt mastic where the volume fraction of aggregate particles is lower than 35%. At asphalt mixture scale where the volume fraction of particles is up to 87%, only simulation using the generalized self-consistent model can show good results. The prediction using the generalized self-consistent model at the mixture scale can be applied for both complex modulus and complex Poisson's ratio. In addition, the prediction of complex modulus and complex Poisson's ratio of asphalt mixtures becomes better when the asphalt mastic instead of bitumen is considered as viscous matrix. ● Relationships between 3D LVE properties of asphaltic materials are built. ● Large volume fraction of filler/aggregate is considered (from 0 up to 87%). ● Rheological model parameters are linked with volume fraction of filler/aggregates. ● Complex modulus/complex Poisson's ratio is predicted using micromechanical models. ● Asphalt mastic instead of bitumen is considered as the matrix phase of mixture. [ABSTRACT FROM AUTHOR]