Composite Material Model Research Articles

Modeling analysis of elastic properties of graphene‐carbon nanotube (G‐C) reinforced composites

AbstractThis article describes in detail the research on the elastic properties of carbon nanotube reinforced composite materials and graphene‐carbon nanotube (G‐C) reinforced composite materials. Several different composite material models were established using finite element software ABAQUS to study the influence of the inclination angle, quantity and volume fraction of carbon nanotubes and graphene on the elastic modulus of reinforced composites. The results show that as the volume fraction of graphene and carbon nanotubes increases, the Young's modulus and shear modulus of the reinforced composite material increase significantly. In addition, the tilt angle and quantity of graphene and carbon nanotubes will also affect the elastic properties of the composite material. The Young's modulus E and the shear modulus G decrease with the increase of the inclination angle, and increase with the increase of the number of graphene and carbon nanotubes.

Analytical model of mechanical properties of carbon fiber magnetic powder film-level magnetic materials for high-speed motors

The speed of high-speed permanent magnet motor has always been restricted by the strength of the rotor. Therefore, this paper proposes a type of magnetic composite rotor suitable for high-speed permanent magnet motors, which can fundamentally solve the problem that it is easy to cause damage for permanent magnets in high speed. In this paper, a combination of theoretical calculation, numerical simulation and experimental verification are used for the magnetic composite material. Based on the theoretical model of the composite micromechanics rule of mixture method, the mechanical properties of the three-phase magnetic composite material are successively deduced. The calculation model of magnetic composite material was compared by using the finite element method and the analytical method, the experimental result was used to verify the correctness of the calculation results. Finally, the influence of carbon fiber thickness and magnetic powder content on the mechanical properties of the material was studied.

Experimental and Digimat-FE Based Representative Volume Element Analysis of Dye-Mixed Colored Resin and Carbon Fiber.

Recently, the automobile industry has demanded weight reduction, so research on materials is being actively conducted. Among this research, carbon fiber-reinforced composite materials are being studied a lot in the automobile industry due to their excellent mechanical properties, chemical resistance, and heat resistance. However, carbon fiber-reinforced composite materials have disadvantages, in that they are not free from color selection, and have weak interfacial bonding strength. In this study, a colored epoxy resin was prepared by mixing epoxy—which is a thermosetting resin according to the pigment concentration (0.1, 0.3, 0.5, 1.0 wt%)—and curing shrinkage. Thermal expansion characteristics were analyzed and the concentration of 0.5 wt% pigment showed the lowest shrinkage and thermal expansion characteristics. In addition, to measure the interfacial shear strength (IFSS) of the carbon fiber and the colored epoxy resin, the IFSS was obtained by performing a microdroplet debonding test, and the strength of the pigment concentration of 0.5 wt% was reduced to a relatively low level. Through these experiments, it was determined that an epoxy resin in which 0.5 wt% pigment is mixed is the optimal condition. Finally, using the composite material modeling software (Digimat 2020.0), the representative volume element (RVE) of the meso-scale was set, and interfacial properties of carbon fibers and colored epoxy resins were analyzed by interworking with general-purpose finite element analysis software (Abaqus CAE).

Numerical simulation of structure design of magnetoelectric composite ultrasonic levitation device based on multi-physical field coupling

Aiming at the coupling simulation problem that ignores the acoustic structure boundary in the traditional acoustic suspension simulation, based on the magnetostrictive effect, the piezoelectric effect, and the acoustic-structure coupling model, this paper uses a magnetoelectric structure composed of the magnetostrictive material Terfenol-D and the piezoelectric ceramic PZT-5H. The composite material is used as, and the magneto-electric-acoustic fully coupled model of the magneto-electric composite material is established and compared with the one-way coupling model; The particle levitation of magnetoelectric composite materials in the multi-field coupling environment of the magnetic field, electric field, sound field, and displacement field was simulated and calculated; the influence of different widths of magneto-electric composite materials and the size of the resonant cavity on the effect of acoustic levitation was analyzed, and the best results were obtained. The geometric parameters required for optimal suspension are analyzed; the sound pressure output performance of the overall magnetoelectric composite ultrasonic suspension device under the optimal size and the judgment of the suspension position is analyzed, and I displayed the good suspension of the simulated particles in the sound field visually. The research results show that the difference in the amplitude output of the transducer will affect the sound pressure output performance of the transducer, and there is a large error in the one-way coupling; the magnetoelectric composite material can be used as an ultrasonic transducer to achieve acoustic suspension, and suspended particles It shows a good acoustic levitation effect in the simulation. The fully coupled simulation of ultrasonic transducers and the research on such ultrasonic transducers can open new ideas for the research and development of new ultrasonic transducers in the future.

Consideration of Yarn Anisotropy in the Investigation of the Puncture Resistance of Fibrous Materials.

High-performance yarns are widely used to produce protective fabrics, including stab-resistant materials. The most common approach to studying the mechanism of puncture prevention is to use simulation to assist analysis. However, the anisotropy of the yarn is often overlooked during simulation owing to various factors. In fact, there is a marked difference between the axial and radial properties of a yarn. This may lead to large errors in research. In the present study, a composite material with a grid structure for puncture analysis was designed to investigate the influence of yarn anisotropy on the accuracy of simulation results. The present study combined an actual experiment with a simulation. In the actual experiment, Kevlar yarn/epoxy resin was used to prepare a mesh composite with a spacing of 1 mm. In the simulation, a 1:1 simulation model of composite material was established using finite element software. A simulated puncture experiment was conducted based on the actual experimental conditions and material parameters. After considering yarn anisotropy, the simulation results were closer to the actual experimental results. The simulation revealed that the main failure modes of the mesh material were the fracture of the resin and the bending deformation of the yarns at the junctions, while the surrounding areas were almost unaffected.

Virtual testing for design and certification of (fusion) bonded longitudinal joints in a fibre composite fuselage: A proposal using FEM-based progressive damage analysis

In the design of bonded aircraft structures, the type of failure is crucial. More specifically, the failure in case of overload should be limited to the surrounding fibre composite structure. Due to the interaction of damage phenomena, failure behaviour cannot be easily predicted. To simplify the design process, guidelines should ensure that the desired failure behaviour occurs. This work investigates if suitable progressive damage analysis methods can, at least in parts, replace physical test campaigns to substantiate these design guidelines. Using the design of a longitudinal fuselage joint as an example, a continuum damage model for composite materials previously developed by the author is used to analyse the strength and occurring failure modes in detail. It is shown that physical tests could be reduced to a minimum in the future.

Time-dependent retardation effect of epoxy latexes on cement hydration: Experiments and multi-component hydration model

The kinetics and thermodynamics of the retardation effect of epoxy latexes on cement hydration were investigated using isothermal calorimetry and in-situ x-ray diffraction. The experimental results showed that the retardation effect of epoxy latexes on cement hydration was time-dependent. When the epoxy latexes were added to cement pastes, heat-generation rate was slowed, the hydration induction and acceleration periods were delayed, and the heat-flow maxima were suppressed. The addition of epoxy latexes markedly retarded silicate and aluminate hydrations by retarding both the dissolution of cement clinker minerals and the precipitation of hydration products. Higher epoxy latex content led to even slower cement hydration. Based on these results, a multi-component hydration model for composite cementitious materials, considering the time-dependent retardation effect of epoxy latexes on cement hydration, was established. The numerical results showed that the model showed great potential to predict the kinetics and thermodynamics of cement hydration with different epoxy latex contents, and provided more details about the phase evolution of the clinker minerals during cement hydration.

Energy Harvesting Model and Experiment of Piezoelectric Fiber Composite Material Under the Fishtail Swing Excitation and Dynamic Fluid

Energy Harvesting Model and Experiment of Piezoelectric Fiber Composite Material Under the Fishtail Swing Excitation and Dynamic Fluid

Modeling and simulation of composite materials used for permanent dental fillings

The aim of this paper was to determine the roughness and Vickers hardness of popular composite materials used for direct tooth fillings. The tests were carried out on the surfaces of samples previously polished with traditional silicone polishing rubbers and discs used in dentistry. The testing methodology and software used for statistical analysis is important to the validity of engineering tests. Measurement systems use sophisticated computer algorithms that are part of the equipment. Analysis of measurement data requires very complex algorithms often based on artificial intelligence. A model and procedure were also prepared to simulate the composite itself under near real-world conditions.

EXPERIMENTAL AND NUMERICAL RESEARCH OF JOINTED ROCK MASS ANISOTROPY IN A THREE-DIMENSIONAL STRESS FIELD

Joints often have a significant influence on material characteristics. The discontinuities’ coalescence mechanism and complex jointed rock mass structure as a composite need to be further explored. In this study, compression and shear tests were carried out on a jointed rock mass. The purpose of the jointed rock mass behaviour study was to determine the deformation-strength dependencies and to determine the parameters for a quantitative assessment of the joints’ influence on mechanical characteristics. The results show that compression strength depends on the materials’ structure, and there is a detailed description of the joints’ orientation influence on stress-strain dependencies during compression experiments. The numerical method used in this study could be used for the modelling of composite materials and their properties.

Fitness analysis of experimental results and finite element simulation results about bullet velocity based on ABAQUS simulation for impact of three dimensional woven reinforced composite

Four layers of glass fiber filaments with the fineness of 2400 tex were used as warp yarns, five layers of glass filaments with the fineness of 600 tex were used as weft yarns 110 tex and aramid fibers were used as Z yarns to process a three-dimensional woven reinforcement. Then, 307-3 unsaturated polyester resin was used as the matrix, and the three-dimensional woven reinforced composite was prepared by the VARTM method (resin transfer molding method). The bullet impact composite was modeled by ABAQUS (Finite element software). The starting conditions of the bullet incidence and the actual conditions were set consistently to analyze the change of the remaining velocity and acceleration of the bullet and the worth energy loss after the bullet impact. The results showed that the theoretical and experimental values of bullet incidence velocity and residual bullet velocity were linearly related. When the impact velocity of bullet incidence was higher, the slope of the straight line of the initial phase of bullet velocity decrease was larger, and the peak of the absolute value of acceleration after bullet impact was larger. The calculated value of energy loss after bullet impact simulation is basically consistent with the experimental value, This also fully proved that the bullet impact composite material model established was correct and effective.

A viscoelastic in-plane damage model for fibrous composite materials

This work presents a viscoelastic in-plane damage model for fibrous composites. The material behavior is modeled as linear viscoelastic, with brittle failure in the fiber-dominated direction, and progressive degradation of the matrix-dominated properties, when the composite is loaded perpendicularly to the fibers or in in-plane shear. An evaluation procedure has been performed by comparing computational stress-strain curves against tensile tests curves under three different displacement rates. In addition, a calibration of the viscoelastic properties, by means of the response surface methodology, is also presented. The proposed material model has shown reasonable performance up to the material reaching an experimentally-verified modulus transition zone. Besides, the viscoelastic calibration procedure has produced a good agreement with the experimental results, concerning maximum stresses. It was observed that the computational stress-strain curve has deviated from the experimental one for higher stress values, indicating that it is necessary to improve the assessment of the nonlinear phenomena, which occur within the material.

Methodology for composite materials shrinkage definition for use in shipbuilding and marine technology

Deformations of steel material in shipbuilding and marine technology applications as a result of mechanical or temperature influences are a well-known problem. However, in the modern shipbuilding industry, the application of alternative materials, especially composite materials, in the structure and for the equipment of the ship is increasingly represented. Consequently, there is a need to determine the deformation and change of characteristics of such composite materials as a result of various mechanical, and especially temperature influences that cause the so-called shrinkage. The basic composite production process involves connecting the matrix with a catalyst and accelerators that create temperature, then the material shrinks by cooling when it can change its dimensions and characteristics. Also, in order to achieve the best possible mechanical properties, composite materials are specially heated and then cooled according to strictly defined processes and curves. The ability to predict the characteristics and parameters of such deformations is important in the context of the application of composite materials. To define such deformations, different methods are used within individual numerical solvers, whose results can differ significantly from each other. Therefore, the authors in this paper present an established methodology for predicting mechanical and temperature deformations, and modelling of composite materials, based on the analysis of analytical methods and numerical solvers with the aim of defining the most accurate numerical solver. By applying the presented methodology, it is expected to raise the level of accuracy and quality of composite materials production as well as to raise the quality of design solutions and efficiency of production procedures during shipbuilding in particular, but also within different marine technology applications and during the product’s life cycle.

Critical analysis of generalized Maxwell homogenization schemes and related prospective problems

A linear composite medium consisting of a homogeneous matrix containing either the periodic or random set of heterogeneities is considered. Both the original and generalized Maxwell schemes are analyzed by reducing the problem to calculation of elastic fields in a finite volume of the composite embedded in the infinite homogeneous matrix medium and subjected to a constant external stress or strain field at infinity. We investigate (qualitatively and quantitatively) a correspondence between the Maxwell schemes (the original and generalized versions) and other different basic assumptions, conceptions, and methods of analytical micromechanics such as effective field method (EFM) and Mori–Tanaka method (MTM). Some deficiencies and inconsistencies of generalized Maxwell schemes in particular examples are detected and explained how the mentioned difficulties can be easily overcome by the classical micromechanical methods EFM and MTM. For the modeling of both periodic and random structure composites, the generalized Maxwell schemes taking into account the inclusion interactions inside the cluster are analyzed. The incorrectness of using of some generalized Maxwell schemes for the modeling of random structure composite materials (CMs) is shown and the directions for its improvements in the framework of the second background of analytical micromechanics are proposed.

Variety of fiber orientation tensors

Fiber orientation tensors are established descriptors of fiber orientation states in (thermo-)mechanical material models for fiber-reinforced composites. In this paper, the variety of fourth-order orientation tensors is analyzed and specified by parameterizations and admissible parameter ranges. The combination of parameterizations and admissible parameter ranges allows for studies on the mechanical response of different fiber architectures. Linear invariant decomposition with focus on index symmetry leads to a novel compact hierarchical parameterization, which highlights the central role of the isotropic state. Deviation from the isotropic state is given by a triclinic harmonic tensor with simplified structure in the orientation coordinate system, which is spanned by the second-order orientation tensor. Material symmetries reduce the number of independent parameters. The requirement of positive-semi-definiteness defines admissible ranges of independent parameters. Admissible parameter ranges for transversely isotropic and planar cases are given in a compact closed form and the orthotropic variety is visualized and discussed in detail. Sets of discrete unit vectors, leading to selected orientation states, are given.

Compressive mechanical behavior and model of composite elastic-porous metal materials

This work presents the experimental characterization and theoretical modeling of composite elastic-porous metal materials (C-EPMM). C-EPMM is a novel porous metallic damping material made of wire mesh and wire helix. A series of quasi-static compressive experiments were carried out to investigate the stiffness and energy absorption ability of the C-EPMM with different mass ratios. The experimental results show that the mass ratios can significantly affect the stiffness and loss factor of C-EPMM. To efficiently predict the nonlinear mechanical properties of the C-EPMM a theoretical model of C-EPMM was proposed for the first time, the model was based on the manufacturing process. A comparison between the predicted data and the experimental data was conducted. The results show that the theoretical model can accurately predict the mechanical performance of C-EPMM. The conclusions derived from this work can provide a new method for adjusting the mechanical performance of EPMM in applications.

Interpretation of Specific Strength-Over-Resistivity Ratio in Cu Alloys.

Reaching simultaneously high mechanical strength and low electrical resistivity is difficult as both properties are based on similar microstructural mechanisms. In our previous work, a new parameter, the tensile strength-over-electrical resistivity ratio, is proposed to evaluate the matching of the two properties in Cu alloys. A specific ratio of 310 × 108 MPa·Ω−1·m−1, independent of the alloy system and thermal history, is obtained from Cu-Ni-Mo alloys, which actually points to the lower limit of prevailing Cu alloys possessing high strength and low resistivity. The present paper explores the origin of this specific ratio by introducing the dual-phase mechanical model of composite materials, assuming that the precipitate particles are mechanically mixed in the Cu solid solution matrix. The strength and resistivity of an alloy are respectively in series and parallel connections to those of the matrix and the precipitate. After ideally matching the contributions from the matrix and the precipitate, the alloy should at least reach half of the resistivity of pure Cu, i.e., 50%IACS, which is the lower limit for industrially accepted highly conductive Cu alloys. Under this condition, the specific 310 ratio is related to the precipitate-over-matrix ratios for strength and resistivity, which are both two times those of pure Cu.

Моделирование характеристик композиционного материала с "жидкой" матрицей

A theoretical model of composite material consisting of a fibrous reinforcing filler, epoxy and elastomer matrices is proposed. The main purpose of the elastomer matrix is relaxation of all stresses occurring under loading and blocking the crack growth. Such elastomer matrices were named as «liquid». The calculation of the stress-strain state of the developed composite material with «liquid» matrix was carried out by using the finite-element software Ansys. It was found out that when elastic characteristics of used elestomers were less, the level of maximal stresses was less and the load factor values were higher. Decreasing stresses results in the blocking of crack growth that leads to increasing durability of such materials.

Proposing a three-phase model for predicting the mechanical properties of mortar and concrete

The interfacial transition zone (ITZ) around aggregates is known as the weakest zone in mortar and concrete, which highly influences the mechanical properties. In this study, the influence of ITZ on mechanical properties such as Young’s modulus and Poisson’s ratio of cementitious materials is evaluated using a multi-scale model (developed in five hierarchical levels: nano-scale cement hydrates∼ scale of concrete). In the proposed model, the microstructure of mortar/ concrete is considered as a three-phase material: fine/ coarse aggregates, ITZ of aggregates and bulk paste/ mortar. The primary input is the microstructure of cement paste and ITZ, which are predicted as the function of curing time using coupled cement hydration-thermodynamic model. The ITZ volume fraction is analytically computed based on aggregate particle size distribution. Multi-level homogenization methods (based on three-phase sphere model for two-phase composite material) are finally implemented to predict the effective properties of mortar and concrete. Here, the equivalent matrix consisted of fine/ coarse aggregate, bulk paste/ mortar and ITZ are obtained with the first and second levels homogenization procedures for mortar/ concrete. To validate the predictability of the models for mortar and concrete, predicted values are compared with independent experimental data sets. The results show a reasonable agreement with experimental results of Poisson’s ratio and Youngs modulus (in the error range of 5 GPa). The influences of ITZ on properties of mortar and concrete are also discussed based on the outcomes.

Molecular modeling of methacrylic composite materials doped with nonlinear optical azochromophores with various acceptor fragments

The methacrylate-based composite polymer materials with various weight content of azochromophores-guests – aminoazobenzenes with various acceptor moieties: AAB-NO2, AAB-DCV, AAB-TCV, and AAB-TCP, – are studied by atomistic modeling. Polymer matrices are PMMA, copolymer of methyl methacrylate and methacrylic acid, MMA-MAA, and copolymer MMA-MAZ, MAZ unit containing azochromophore, covalently attached to the side chain via spacer. The realization of various non-covalent interactions (hydrogen and π-π interactions) is considered, special emphasis is given to the role of chromophore structure and polymer matrix nature.It is shown that rather uniform distribution of chromophores in composite materials is retained even at 30 wt% content. In all composites with chromophore content growth both the number of non-covalently bound chromophores and the proportion of chromophores bound inter se increase, while the proportion of chromophores, bound with polymer matrix, decreases.The number of hydrogen bonds (HBs) between chromophores-guests is determined mostly by the nature of the acceptor group of the chromophore, maximum number of HBs being formed by AAB-TCP. The MMA-MAA matrix allows realization of greater number of inter-chain HBs compared to MMA-MAZ matrix, while such bonds are absent in PMMA.Azochromophores in MAZ units of MMA-MAZ matrix form π-π-stacking structures with mostly codirected chromophore dipole moments, besides AAB-TCV guests form such stacking structures with host matrix chromophores. Chromophores in MAZ units more easily interact with guests than with each other via π-π stacking. The studied matrices could be considered promising to be used as hosts at developing composite materials with quadratic nonlinear optical response.