Mechanical Properties Of Composite Materials Research Articles

Study on Mechanical Properties of the Compound Soil of Feldspathic Sandstone and Sand Based on Micro – level

It is of great practical significance to study the mechanical properties of composite materials of arsenic and sandstone to control the ecological environment in soft sandstone area. In order to understand the material and structural characteristics of composite materials under different compound proportions, the microstructure and the composition of the material elements were analyzed by the microscopic test and the test of mercury injection from the microscopic level. The dynamic three axis instrument was used to carry out the mechanical test under the different mixing ratio. The results showed that the main mineral components of feldspathic sandstone are quartz, albite, montmorillonite and calcite. The structure has the strength in the anhydrous state. When the water is saturated, the structure collapses, the cohesive force decreases rapidly, and it has the collapsibility; Due to the complexity of the structure and the optimization of the gradation, the permeability is greatly reduced; the macroscopic mechanics exhibits strain hardening and nonlinear characteristics.

Расчетно-экспериментальная оценка применимости экструдированного пенополистирола бытового назначения в трехслойных конструкциях корпуса маломерного судна

Object and purpose of research. This paper is an integrated study of extruded polystyrene foam (XPS) practicability for three-layered composite hull structures of small craft. Subject matter and methods. Mechanical properties of composite materials and their components are determined experimentally (three-point bending, longitudinal tension/compression). Elastic properties and limit-state characteristics are obtained from beam theory, mixed model of composite beam, finite-element method, as well as solution of geometrically non-linear contact problems as per Newton-Raphson iterative technique. Main results. The study illustrates final diagrams for structural responses of investigated composite beam, filler and binder as functions of pre-defined displacement of test rigging. It also gives the estimates for equivalent Young’s moduli, as well as preliminary positive opinion about the practicability of XPS as a substitute for the conventional wood veneer in composite structures of small ships. The paper also presents a structurally similar FE model suitable for prediction calculations of large complex structures that can be tested only when the whole full-scale hull is available. Conclusion. This study formulates and solves the elastic problem for the investigated XPS-based sandwich panels. The results give an idea about the practicability of this material for shipbuilding applications.

Analysis of the oscillations induced by a supersonic jet applied to produce nanofibers

High-performance fibers are key components for enhancing the mechanical properties of composite materials. The development of high strength nanofibers augurs the production of new nano-composites with outstanding features. However, the robust production of continuous glass nanofibers that can be feasible processed for efficiently manufacturing nanocomposites is still challenging. Recently, Cofiblas (Continuous Fiberizing by Laser melting and Supersonic dragging) was demonstrated as a technique capable of producing continuous glass nanofibers with unlimited length. Cofiblas process has some similarities with the widely known melt blowing technique for the production of polymeric fibers. In both techniques, the design of the gas nozzle is key to ensure the feasibility of the process since the turbulences of the gas jet may induce strong whipping of the filament.This paper gives novel experimental evidences on the correlation of the supersonic gas jet instabilities with the oscillation of the filament in the melt-blowing and Cofiblas processes, relating these oscillations with the presence of shock waves and unsteadiness in the flow, and gives valuable insight into the use of supersonic jets in the melt blowing process as an effective approach for the formation of nanofibers. A thin 3D-axisymmetric model in OpenFOAM® was put to test by comparing the performance of different solvers which were validated by flow visualization of the exit jet using digital holography (DH). In order to perform a realistic and thorough validation, we simulated the optical measurements of the flow from the CFD simulations of the mass density by Abel transform and numerical differentiation. The application of digital holography as the flow visualization technique makes possible both a precise validation of the density maps obtained from the Abel transformation of the 2D-alike results, and the analysis of the shockwave pattern in the air jet. Conversely, the numerical reconstruction of time-averaged holograms is employed to detect unsteadiness in the flow and to analyze the fiber oscillation, which is essential to assess the stability of the process. Lastly, the analysis and comparison of the vibration of the filament using the basic design and the optimized nozzle demonstrates a clear influence of the shock waves and flow unsteadiness in the stability of the filament.

An Investigation on the Effect of Humidity on the Mechanical Properties of Composite Materials Based on Polymethyl Methacrylate Polymer Optical Fibers (POFs)

An Investigation on the Effect of Humidity on the Mechanical Properties of Composite Materials Based on Polymethyl Methacrylate Polymer Optical Fibers (POFs)

Multiscale embedded models to determine effective mechanical properties of composite materials: Asymptotic Homogenization Method combined to Finite Element Method

A reliable way to determine the effective properties of heterogeneous media plays an important role in engineering design. As an experimental test to obtain effective properties may be tedious and expensive to perform, and as computational approaches, when all heterogeneities of the media are considered during the simulations, might become impractical due to computational effort, homogenization procedures are a good alternative to estimate the effective properties of the media, mainly considering damage and manufacturing defects in the material. Among several homogenization methods, the Asymptotic Homogenization Method (AHM), a well-established mathematically based method, is considered for deriving the relations for the effective properties of the media, and the Finite Element Method (FEM) is used to solve the equilibrium relations. In this work, a fiber-reinforced composite is considered, with three different regions depicted: intact, damaged fibers, and regions with resin/void pockets. The proposed AHM-FEM approach is used to simulate a tensile test in all scenarios with standard and multiscale embedded Unit Cells used to obtain the effective elastic modulus on the fiber direction. Discussions regarding computational efficiency are carried out, as well as numerical comparisons among the types of Unit Cells used to model the media. In a second scenario, the complete fourth-order elasticity tensor of the media is investigated, considering the fibers as both isotropic and transversely isotropic. The results for the transversely isotropic fibers approach literature data, while when isotropic fibers are considered, poor results are achieved. Finally, the approach is extrapolated to obtain the mechanical properties of metamaterials, defined here as a composite reinforced by two different kinds of fibers.

Some Mechanical Properties of Composite Materials with Chopped Wheat Straw Reinforcer and Hybrid Matrix.

Modern agriculture produces a very large amount of agricultural waste that remains unused. The use as a reinforcer of these renewable resources for the realization of composite materials, and the finding of useful industrial applications, constitutes or provokes the groups of researchers in this field. The study conducted in this article falls in this direction. Composites were fabricated with the chopped wheat straw reinforcement and epoxy resin matrix or hybrid resins with 50% and 70% Dammar volume proportions. Some mechanical properties of this type of composite materials were studied based on tensile strength, SEM analysis, water absorption/loss, vibration behavior and compression strength. The strength–strain and strain–strain diagrams, the modulus of elasticity, the breaking strength and the elongation at break were obtained. Compared to the epoxy resin composition, those with 50 and 70% Dammar, respectively, have a 47 and 55% lower breaking strength and a 30 and 84% higher damping factor, respectively. Because the values of these mechanical properties were limited, and in practice superior properties are needed, sandwich composites were manufactured, with the core of previously studied compositions, to which the outer faces of linen fabric were applied. These composites were applied to the bend (in three points), obtaining the force–deformation diagrams. The obtained properties show that they can be used in construction (paneling, shells, etc.), or in the furniture industry.

High Pressure Resistant Aramid Fiber Reinforced Polymer Matrix Composite Pipe Design

In this study, a total of 6 different composites were obtained by adding 5%, 10% and 15% chopped aramid fiber reinforcement in 6 mm dimensions to each of the polypropylene and polyethylene matrix elements under the same production method and same conditions. The reinforcement and matrix materials were mixed using the extrusion method and then formed into plates by the press molding technique. Tensile and charpy tests of these composites were performed and their mechanical properties were examined. S/N ratios were calculated for the mechanical properties of the composites and the effect of matrix, fiber and additive ratios on mechanical properties was determined using analysis of variance (ANOVA). According to the Signal/Noise (S/N) ratios and ANOVA results, it was observed that the composites had different effects on the mechanical properties. Pipes are designed considering the mechanical properties of composite materials with 15% aramid fiber added to each matrix element. The composite pipe design to be pressure tested was designed in Solidworks program with a length of 500 mm according to ISO 1167 standards. Pipe dimensions with an outer diameter of 125mm, which are used as a standard in natural gas infrastructure works, are taken as reference.

Investigating Features and Output Correlation Coefficient of Natural Fiber-Reinforced Poly(lactic acid) Biocomposites

Polylactic acid (PLA) material has the potential to be applied in various industrial fields, but this material has shortcomings in terms of mechanical properties, especially mechanical strength, due to brittleness nature of PLA. The manufacture of PLA composite material with the addition of natural fibers as a reinforcing phase is one of the methods to increase the impact strength and maintain the biodegradable properties of the material. However, in theory, there are many factors that affect the mechanical properties of composite materials, thus making the mechanical properties of composites more complex than monolithic materials. The mechanical properties of these composite materials can be predicted using deep learning by paying attention to the relationship between factors, and between factors and their mechanical properties. This relationship has an important role in creating a predictive model with good accuracy. Therefore, correlation analysis is an important thing to do. Correlation analysis was applied using Python programming language to determine the relationship between the impact strength of natural fiber-reinforced PLA biocomposites with its feature information: chemical composition, density, dimensions, surface chemical treatment of natural fibers, matrix-reinforcement volume fraction, and the type of processing used to manufacture the material.

Study on wood chips modification and its application in wood-cement composites

Wood-cement composites have the advantages of high flexural strength, toughness, and impact resistance. However, the components such as hemicellulose and lignin in the wood chips can inhibit cement hydration, and thus the interface bonding between wood chips and cement matrix is poor. In order to address these issues, alkali cooking (mass concentration is 2–8%) and silane coupling agent (mass concentration is 1–5%) were used in this study to modify wood chips, and the resulting compressive and flexural strengths of wood-cement composites prepared from different kinds of modified wood chips were evaluated. Further, the XRD, SEM, and FT -IR tests were carried out to characterize the modified wood chips and explore the mechanism of modified wood chips incorporated composites. The results showed that the alkali cooking agent could effectively remove amorphous components, such as hemicellulose and lignin, from wood chips, improve crystallinity and relative cellulose content, and increase the surface roughness of wood chips. The silane coupling agent could chemically bond with wood chips to improve the interfacial properties between wood chips and cement matrix. The flexural strength of the composites prepared with wood chips treated with 3% silane coupling agent and 4% alkali cooking agent was increased, which was 11.9% higher than that of the composites prepared from wood chips treated only with 4% alkali cooking agent, while it was 27.1% and 31.6% higher than the composites prepared with untreated wood chips and mortar without wood chips, respectively. Alkali cooking modification and silane coupling agent treatment of wood chips can effectively improve the mechanical properties of composite materials.

Grain size, coefficient of thermal expansion and corrosion behavior of eggshell and rice husk ash reinforced composite material

PurposeThe purpose of this study to find an alternate method to minimize waste i.e., eggshell and rice husk ash. In this paper, eggshell (ES) and rice husk ash (RHA) particles are used as reinforcements for examining their effect on the coefficient of thermal expansion (CTE), grain size (GS) and corrosion behavior for developed composite material.Design/methodology/approachIn this investigation, 5 Wt.% each of ES and RHA reinforcement particles have been introduced. To investigate the microstructures of the developed composite material, scanning electron microscope was used. Physical and mechanical properties of composite material are tensile strength and hardness that have been examined.FindingsThe result of this paper shows that number of grains per square inch for composition Al/5% ES/5% RHA composite was found to be 1,243. Minimum value of the volume CTE was found to be 6.67 × 10–6/°C for Al/5% ES/5% RHA composite. The distribution of hard phases of ES particles in metal matrix is responsible for improvements in tensile strength and hardness. These findings demonstrated that using carbonized ES as reinforcement provides superior mechanical and physical properties than using uncarbonized ES particles.Originality/valueThere are several articles examining the impact of varying Wt.% of carbonized ES and rice husk reinforcement on the microstructures and mechanical characteristics of metal composites. CTE, GS and corrosion behavior are among of the features that are examined in this paper.

Monte Carlo simulation for exploring the mechanical properties of particle-reinforced composites based on the scale boundary finite element method

Particle-reinforced composites are a widely favored high-performance material. Mechanical properties are important indicators for evaluating composite materials. This paper presents a method for analyzing the mechanical properties of particle-reinforced composites. The way is based on the Scaled Boundary Finite Element Method (SBFEM) and Monte Carlo method to study the mechanical properties of composite materials. This study will explore the mechanical properties of particle reinforced composites from three aspects: equivalent modulus, equivalent Poisson's ratio, and the major principal stress. First, the number of models is determined by the Monte Carlo method. Secondly, the factors affecting the mechanical properties of composites and their influencing laws are analyzed from inclusion distribution (inclusion volume ratio, inclusion number, inclusion distribution density) and inclusion shape factor (elliptical Shape features, 6inclusion distribution angle). Finally, the fitting equation for evaluating the mechanical properties of composites is given. Compare the calculated results with the statistical results to verify the validity of the fitting function. A total of 160,000 computational models are analyzed in this work. The conclusion includes the variation law and fitting function of particle-reinforced composites' mechanical properties.

Modeling of Polymer Composite Materials Chaotically Reinforced with Spherical and Cylindrical Inclusions.

The technical and economic efficiency of new PCMs depends on the ability to predict their performance. The problem of predicting the properties of PCMs can be solved by computer simulation by the finite element method. In this work, an experimental determination of the physical and mechanical properties of PTFE PCMs depending on the concentration of fibrous and dispersed filler was carried out. A finite element model in ANSYS APDL was built to simulate the strength and load-bearing capacity of the material with the analysis of damage accumulation. Verification of the developed computer model to predict the mechanical properties of composite materials was performed by comparing the results obtained during field and model experiments. It was found that the finite element model predicts the strength of chaotically reinforced spherical inclusions of composite materials. This is due to the smoothness of the filler surfaces and the lack of filler dissection in the model. Instead, the prediction of the strength of a finite element model of chaotically reinforced cylindrical inclusions of composite materials requires additional analysis. The matrix and the fibrous filler obviously have stress concentrators and are both subject to the difficulties of creating a reliable structural model.

Sparse Polynomial Chaos Expansion for Uncertainty Quantification of Composite Cylindrical Shell with Geometrical and Material Uncertainty

The geometrical dimensions and mechanical properties of composite materials exhibit inherent variation and uncertainty in practical engineering. Uncertainties in geometrical dimensions and mechanical properties propagate to the structural performance of composite cylindrical shells under hydrostatic pressure. However, traditional methods for quantification of uncertainty, such as Monte Carlo simulation and the response surface method, are either time consuming with low convergence rates or unable to deal with high-dimensional problems. In this study, the quantification of the high-dimensional uncertainty of the critical buckling pressure of a composite cylindrical shell with geometrical and material uncertainties was investigated by means of sparse polynomial chaos expansion (PCE). With limited design samples, sparse PCE was built and validated for predictive accuracy. Statistical moments (mean and standard deviation) and global sensitivity analysis results were obtained based on the sparse PCE. The mean and standard deviation of critical buckling pressure were 3.5777 MPa and 0.3149 MPa, with a coefficient of variation of 8.801%. Global sensitivity analysis results from Sobol’ indices and the Morris method showed that the uncertainty of longitudinal modulus has a massive influence on the critical buckling pressure of composite cylindrical shell, whereas the uncertainties of transverse modulus, shear modulus, and Poisson’s ratio have a weak influence. When the coefficient of variation of ply thickness and orientation angle does not surpass 2%, the uncertainties of ply thickness and orientation angle have a weak influence on the critical buckling pressure. The study shows that the sparse PCE is effective at resolving the problem of high-dimensional uncertainty quantification of composite cylindrical shell with geometrical and material uncertainty.

Synthesis and research of basalt microfiber‐reinforced polyurethane elastomer composites

AbstractBasalt microfiber‐reinforced polyurethane elastomer composites (BMF/PUE) were prepared by semi‐prepolymer method in this study. The degree of microphase separation and quantitative analysis of H‐bonding formation in polyurethane were determined by infrared spectroscopy. The fiber surface and the morphology at the tensile fracture interface of the composite materials were observed by scanning electron microscopy. The mechanical properties of composite materials were further measured on an electronic universal testing machine. Dynamic thermomechanical analysis and acoustic impedance tube were used to study the damping and acoustic properties of composite materials, respectively. The results indicated that the composite material prepared by adding 6 g of basalt microfibers treated with 3 min' crushing had the best overall performance. Compared with the matrix, BMF/PUE showed good sound insulation performance with a much wider effective damping temperature range. On the basis of ensuring its excellent overall performance, the mechanical properties were increased by 50.4% in tensile strength, 28.1% in elongation at break, and 14.2% in tear strength.

The Effect of Alkali Treatment to Mechanical Properties of Resin Composite Reinforced with Coir Coconut Fiber

Previous research related to the effect of alkali treatment on mechanical properties of composite materials which generate the regression model is still rare. From the previous research, alkali treatment does not always improve the mechanical properties of composite materials. Therefore, it is necessary to research to make sure the effect of alkali treatment on coconut fiber composite. This study aims to examine the effect of alkali treatment of fiber combined with fiber weight content on the mechanical and physical properties of epoxy resin matrix composite. Mechanical properties testing is done by impact test and torsion test. The fracture surface was observed using optical microscopy. Data from the test results were analyzed to see the effect of alkali treatment on the mechanical properties of the resulting composite material by generating the regression model of impact strength and shear strength for treated and untreated fiber composites. The coefficient of determination (R2) of all models was 1. This study obtained that the untreated fibers have better impact strength and shear strength than the treated ones. The highest impact strength, 7.07 kJ.m2, and the highest shear strength, 1.81 MPa were obtained from the samples containing 4% untreated fibers.

Quantitative description of filler dispersion in composite materials by fractal analysis and fluorescent labeling‐LSCM visualization technology

AbstractFiller dispersion is one of the key factors that significantly affect the performance of composite materials. Quantitative description of the dispersion state of fillers in composites and the internal relationship between the dispersion state and the macro‐mechanical properties of composites are very important for the performance design, prediction and processing process control of composites. In order to quantitatively and visually describe the dispersion state of inorganic fillers in matrix, research the relationship between fillers dispersion and composites properties. Here, by the fluorescent labeling technology of inorganic fillers and the surface organic modification technology, a modified fluorescently labeled calcium carbonate (MF‐CaCO3) with red fluorescence effect and good dispersibility was obtained, and polypropylene (PP)/MF‐CaCO3 composites with different loadings were prepared (the weight concentrations of MF‐CaCO3 in filler is 2, 5, 10, 15, and 20 wt%, respectively). The fractal dimension D value for evaluating the uniformity of filler dispersion has been successfully received, based on fractal analysis and fluorescent labeling‐laser scanning confocal microscope three‐dimensional (3D) visualization technology. Through the statistical results of experimental data, it was found that the value of fractal dimension D was obviously negatively correlated with the macroscopic mechanical properties of composite materials. When the dispersion of the filler was the best, that is, the fractal dimension D value took on a minimum and the composites had the best impact resistance. At the same time, this method based on fractal analysis and 3D visualization technology provides a new idea for quantitatively describing the dispersion state of fillers and its relationship with the mechanical properties of composites.

Reliability analysis of composite sandwich structure for fuselage skin based on surrogate model

Composite structures are characterized by multiple source uncertainties in mechanical properties, geometric dimension, etc., and multiple failure modes, which bring challenges to their design and application. In order to explore the reliability analysis method of composite sandwich structures with multi-source uncertainties and multi-failure modes, a parametric finite element model and an acoustic boundary element model were established for deterministic analysis of a fuselage skin sandwich structure. Considering the randomness of the mechanical properties of composite materials and the laminate thickness, the structural reliability models were established for three typical failure modes of sandwich structures: static strength failure, global buckling and vibration noise. In order to reduce the computational effort, the Kriging surrogate models of failure modes were constructed, and the subset simulation method was used to predict the system failure probability of the sandwich structure of fuselage skin. The proposed computational framework provides support and tool for the fine design of composite sandwich structure.

Effect of particles on tensile and bending properties of jute epoxy composites

Abstract In this investigation, mechanical properties of composite materials produced from woven jute type were investigated. These composites were produced in the form of epoxy adhesive layers by using hand lay-up method in which aluminum, mica and ceramic particles were added into epoxy as a structural adhesive by 2, 4 and 6 wt%. Samples produced according to ASTM D procedures were subjected to tensile and three point bending loads to examine the effect of the particles. Experimental results were presented in tables and graphs. As a result, it was observed that the tensile and bending failure loads of the composite materials obtained by using the particle reinforced adhesive increased. Also, the biggest rise in tensile strength was achieved with 4 wt% aluminum and the biggest increase in bending strength was observed for 2 wt% aluminum particles.

Effect of Fiber-matrix Interface Decohesion on the Behavior of Thermoset and Thermoplastic Composites Reinforced with Natural Fibers: A Comparative Study

In this article, a comparative study was carried out on two types of thermosetting and thermoplastic matrices to study the effect of the fiber-matrix interface damage on the behavior of thermosetting and thermoplastic composites reinforced by the same natural alfa and wood fibers. The genetic modeling was based on the probabilistic formalism of Weibull. The results have been compared with those obtained by the nonlinear acoustic technique, the two results found to coincide perfectly. The numerical simulation also shows a good concordance with the real behavior of the materials studied, and shows that thermosetting composites are the most resistant to applied thermal stress by 21% compared to thermoplastic composites. Statistical analysis demonstrates that the correlation coefficient values found are very close to 1 (0.964 and 0.973), these values are very satisfactory, and confirm that the results obtained by the genetic model and the nonlinear acoustic technique are in very good agreement with the statistical analysis data. The experimental work presented by Antoine Le Duigou et al. and the work of Bodros et al. have shown that the use of natural fibers greatly improves the mechanical properties of composite materials.

Flame retardancy of silicone rubber foam containing modified hydrotalcite

AbstractSilicone rubber material (silicone rubber foam [SRF]) composites is a new type of polymer foam material, which has the characteristics of high elasticity and high‐temperature resistance, but this material is flammable. In order to improve the flame retardant properties of SRF composites. The co‐precipitation method is used to prepare modified hydrotalcites (LDHs) with different Ce/Al molar ratios for application to SRF composites. X‐ray diffraction, scanning electron microscopy (SEM), and FT‐IR are used to characterize modified LDHs with different Ce/Al molar ratios. The combustion performance, thermal decomposition, and mechanical properties of composite materials are studied through the limiting oxygen index (LOI), vertical combustion test, thermal gravimetric analysis, cone calorimeter test, and SEM. Results show that the LOI value of SRF composite with addition of 3% LDHs at a Ce/Al molar ratio of 0.3:0.7 is 31.2%, and the heat release rate, the smoke production rate, and total smoke production of the SRF composite are reduced by 53.64%, 34.92%, and 66.19%, respectively. Besides, the addition of modified LDHs leads to increase in the thermal stability of the SRF composite. The results obtained from this study can provide guidance for the development of environmentally friendly SRF.