Behavior Of Polymer Matrix Composites Research Articles

Fully-reversed tension-compression fatigue of 2D and 3D woven polymer matrix composites at elevated temperature

High-temperature tension-compression fatigue behavior of polymer matrix composites with a 2D and a 3D fiber architecture was examined. The two composites studied in this work have the same NRPE polyimide matrix and carbon fiber reinforcement, but different fiber architectures. The 3D composite is a single-ply non-crimp 3D orthogonal weave material whereas the 2D laminated composite contains fifteen 0/90 woven plies. The study aims to evaluate the fitness of the two materials for service in aerospace thermal-protection systems. Thus mechanical testing was conducted under environmental conditions mimicking the realistic service environment: one side of the test specimen was held at 329 °C whilst the other side remained open to ambient laboratory air. The tension and compression stress-strain responses of the two composites were investigated and the basic tensile and compressive properties measured. The high-temperature properties were similar to those obtained at room temperature. Fully-reversed tension-compression cyclic tests were carried out at elevated temperature. The frequency was 1.0 Hz, the ratio of minimum to maximum stress was −1.0, and the runout condition was defined as survival of 200,000 cycles. The evolution of maximum and minimum strains with cycles as well as the progressive change in modulus were examined for each test. The 3D composite produced a higher fatigue limit, while the 2D laminated composite displayed a slightly better fatigue performance at higher stress levels. All specimens that survived 200,000 cycles without failure were tested in tension to failure to assess the retained tensile strength and stiffness. Examination of tested specimens with an optical microscope showed extensive delamination of the 2D composite. The 3D composite proffered enhanced delamination resistance.

The mechanisms behind the tribological behaviour of polymer matrix composites reinforced with TiO2 nanoparticles

In this present work, the sliding wear behaviour of hybrid polymer nanocomposites was investigated under different loading conditions and against different counterface roughness. Two different polymers matrices, epoxy and polyamide 66, with classic micro-sized short carbon fiber and graphite flakes as tribo-fillers were investigated with and without TiO2 reinforcing nanoparticles. It was found that the synergistic effect between nanoparticles and micro-sized fillers on friction and wear performance depended on the tribological system involved. In particular, for epoxy-based composites, the incorporation of TiO2 nanoparticles was only beneficial against a sufficiently rough disc but detrimental otherwise. Whilst for polyamide nanocomposites, the combination of nanoparticles and other fillers resulted in low friction and wear against both rough and smooth disks, particularly at higher applied contact pressures. When the cross-sections of the transfer films were analysed using a high-resolution SEM, it was found that TiO2 nanoparticles are only beneficial if they can blend with other wear debris to form a TiO2-enriched transfer film. The strengthened film provides the support required for other dislodged TiO2 nanoparticles to achieve the rolling effect, thus reducing friction and wear. In contrast, if TiO2 cannot effectively blend into the transfer film, TiO2 nanoparticles act as an abrasive that readily abrades away the comparatively softer film, thus exposing the polymer to fresh asperities on the steel counterface, a detrimental outcome to both friction and wear. Hence, to design high wear resistant composite materials, it is important to understanding the interactions between different tribo-fillers for particular circumstances or contact conditions.

Particulate Reinforced Polymer Matrix Composites: Tribological Behavior and 3D Printing by Fused Filament Fabrication

Abstract A brief literature review and case study explore the effect of particulate reinforcements and processing parameters on the tribological behavior of polymer matrix composites made by 3D printing via fused filament fabrication.

Artificial Neural Network and Response Surface Methodology Based Analysis on Solid Particle Erosion Behavior of Polymer Matrix Composites.

Polymer-based fibrous composites are gaining popularity in marine and sports industries because of their prominent features like easy to process, better strength to weight ratio, durability and cost-effectiveness. Still, erosive behavior of composites under cyclic abrasive impact is a significant concern for the research fraternity. In this paper, the S type woven glass fibers reinforced polymer matrix composites (PMCs) are used to analyze the bonding behavior of reinforcement and matrix against the natural abrasive slurry. The response surface methodology is adopted to analyze the effect of various erosion parameters on the erosion resistance. The slurry pressure, impingement angle and nozzle diameter, were used as erosion parameters whereas erosion loss, i.e., weight loss during an erosion phenomenon was considered as a response parameter. The artificial neural network model was used to validate the attained outcomes for an optimum solution. The comparative analysis of response surface methodology (RSM) and artificial neural network (ANN) models shows good agreement with the erosion behavior of glass fiber reinforced polymer matrix composites.

Cyclic compressive deformation behavior of polymer matrix composites: Experiments and constitutive modeling

AbstractThis article presents integrated experiments and constitutive modeling of cyclic compressive deformation and Poisson behavior of unidirectional (UD) fiber‐reinforced polymer matrix composites (PMCs). Consecutive loading‐unloading tests with a gradually increasing peak stress are performed for five cycles and on UD laminates with different fiber orientations. Nonlinear accumulation of plastic strain with the peak stress is observed both in the axial and lateral directions for all fiber orientations and described by a nonassociative plasticity model. This model enables the collapsing of axial and lateral stress‐plastic strain curves from different fiber orientations into a single master curve in the effective stress‐effective plastic strain plane and allows accurate predictions of compressive plastic Poisson's ratio. Nonlinear unloading behavior appears in the cycles and is attributed to the recovery of nonlinear elastic strain. A linear relationship between plastic strain and nonlinear elastic strain is assumed regardless of the axial and lateral directions. By incorporating this linear dependence into the nonassociative plasticity model, the cyclic evolution of nonlinear elastic strain is simulated. Experimental results of UD laminates with different fiber orientations are used to validate the accuracy of the model in the cyclic compressive nonlinear response and Poisson effect of PMCs.

Influence of the remnant magnetization, size distribution and content of soft magnetic reinforcement in micro-mechanical behavior of polymer matrix composites

Abstract In this work, the influence of the remnant magnetization, size distribution and content of soft magnetic reinforcement in micro-mechanical behavior of polymer matrix composites (Fe81Ga19/silicone) are evaluated. Melt spinning ribbons were pulverized in a planetary milling machine to act as composite particle reinforcement. The instrumented microindentation behavior (Young's modulus and Vickers micro-hardness), the pseudo-creep and relaxation phenomena as a function of the microstructure have been studied. In general, the micro-hardness, stiffness and elastic recovery of the studied composite materials increased with the filler content. Magnetic saturation did not change with the milling technique, and composite remnant magnetization increased with either contend or particle size. Additionally, the magnetization process improved the Vickers micro-hardness and Young's modulus of composites. Finally, pseudo-creep and stress relaxation behavior was also dependent on Fe81Ga19 content and size distribution.

Experimental Analysis on Wear Behavior of PMCs Reinforced with Electroless Coated Silicon Carbide Particulates

Glass fibres reinforced composite materials are widely used in shipping industries, water treatment plants, and aerospace. In those industries, these materials are subjected to surface abrasion due to constant abrasive particle slurries interactions. To improve the performance of these composites, the surface treatment of reinforced particles can be the possible approach. Keeping in mind these obligations, the present research work focuses on analyzing the influence of reinforcing electroless coated silicon carbide particulates (SiCp) on wear behaviour of polymer matrix composites (PMCs). The experimentation was performed using L18 orthogonal array based on Taguchi’s methodology. Workpiece reinforcement, sliding velocity, abrasive surface and applied load were used as process parameters whereas wear loss was observed as a response parameter. The bonding behaviour between reinforcement and matrix was analyzed using field emission scanning electron microscope, and surface analysis of abraded workpiece was performed using a scanning electron microscope. The identification of composite ingredients was accomplished by energy dispersive spectroscopy using mapping analysis. The wear test results indicate that surface treatment and curing of reinforcing particles improves interfacial bond strength which in result improved wear resistance property of PMCs.

Microhardness of poly(methyl methacrylate)-multiwalled carbon nanotubes composites: Effect of ultraviolet irradiation

Understanding the mechanical behavior of polymer matrix composites under the service conditions is of practical importance to improve structural durability and reliability. In this work, we study the microhardness of poly(methyl methacrylate)-multiwalled carbon nanotubes (PMMA-MWCNTs) composite as a function of the fraction of MWCNTs and the irradiation of ultraviolet (UV) light in a temperature range of 50–80 °C. Increasing temperature, heating time, and the weight fraction of MWCNTs causes the increase of the microhardness of the PMMA-MWCNT composite, while increasing the UV-irradiation dose causes the decrease of the microhardness of the PMMA-MWCNT composite. A first-order kinetic process is proposed to analyze the variation of the microhardness of the PMMA-MWCNT composite with time. The activation energy for the first-order kinetic process increases with increasing the weight fraction of MWCNTs, and decreases with increasing the UV-irradiation dose. The temperature dependence of the microhardness of the PMMA-MWCNT composite at equilibrium state follows the van't Hoff relation.

Modelling the effect of temperature on the probabilistic stress–life fatigue diagram of glass fibre–polymer composites loaded in tension along the fibre direction

Predicting the fatigue performance of composites has proven to be a challenge both conceptually, due to the inherent complexity of the phenomenon, and practically, because of the resource-intensive process of fatigue testing. Moreover, mechanical behaviour of polymer matrix composites exhibits a complicated temperature dependence, making the prediction of fatigue performance under different temperatures even more complex and resource intensive. The objective of this paper is to provide a method for the prediction of fatigue life of glass–polymer composites loaded in the fibre direction at various temperatures with minimal experimental efforts. This is achieved by using a static strength degradation approach to fatigue modelling, where only two parameters (including static strength) are temperature dependent, in conjunction with relationships for these two fatigue model parameters temperature dependence. The method relies on fatigue data at a single temperature and simple static tests at different temperatures to predict the effects of temperature on the material’s fatigue behaviour. The model is validated on experimental data for two unidirectional and one woven glass–epoxy composites and is found to accurately predict the effect of temperature on fatigue life of composites. A method to obtain probabilistic stress-life [Formula: see text] fatigue diagrams including temperature effects is also presented.

Strain Rate Effects in Polymer Matrix Composites Under Shear Loading: A Critical Review

A critical review of behavior of polymer matrix composites under high strain rate shear loading is presented. A brief review of experimental methods used to investigate the dynamic shear properties of composites are included. Experimental results obtained by various researchers for high strain rate shear properties of polymer matrix composites are discussed and compared for both unidirectional and woven fabric composites. The effect of strain rate on the in-plane and interlaminar shear properties is summarized by giving a property change factor, the ratio of the value at high strain rate compared with the value at quasi-static loading. Possible damage mechanisms and modes are also discussed. For unidirectional composites the property change factor for in-plane shear strength and shear modulus ranges between 1.26 and 1.82 and 0.39–1.25 respectively and for interlaminar shear strength and modulus ranges between 0.71 and 1.47 and 0.87–0.98 respectively. On the other hand, for woven fabric composites the property change factor for in-plane shear strength and shear modulus ranges between 0.79 and 1.75 and 0.12–1.75 respectively and for interlaminar shear strength and modulus ranges between 1.55 and 1.70 and 1.24–1.33 respectively.

Influences of graphene nanoplatelet aspect ratio and thermal treatment on dielectric performances of poly(methyl methacrylate) composites

The dielectric property and percolated behaviour of polymer matrix composites largely depend on the morphology of conductive fillers and external stimulations especially when the composites are processed by melting blending and extrusion-injection way. In this study, the poly(methyl methacrylate) (PMMA) matrix composites incorporated by two kinds of graphene nanoplatelets (GNP), G5 and G150 with different aspect ratios (the ratio of diameter and thickness) are prepared to study the influence of GNP morphology on the dielectric performances close to percolation threshold (fc). After annealing at glass transition temperature (Tg) for 1 h, the dielectric permittivities of PMMA/G5 and PMMA/G150 near fc increase 43 and 38%, respectively, while the dielectric loss change little. This improvement on the dielectric property is possibly attributed to the slight change of the distance between adjacent GNPs after annealing at Tg which enables to arouse stronger polarisation by tunnelling effect.

A quantitative investigation on vibration durability of viscoelastic relaxation in bolted composite joints

Time-dependent behavior and factors affecting preload relaxation in a carbon/epoxy composite bolted joint under resonance were studied. The effect of viscoelasticity of composite material on bolt relaxation was studied quantitatively through modal analysis from the perspective of energy dissipation and stiffness degradation. Damping ratio and resonance frequency were utilized to characterize the effects of preload relaxation on structural dynamic response. The loss of preload was found to decrease with increasing initial preloads over a 10 h vibration fatigue. However, an increase in preload loss occurred as exciting frequency increases. Vibration fatigue damage was found to result in decaying stiffness and amplitude responses of the bolted joints, along with an increase in damping ratio. As a proof-of-concept study, a beam-like specimens with and without bolted joints were comparatively excited to ascertain their respective dynamic responses; results revealed that relaxation in bolted joints could be attributed to the conjunct mechanisms between viscoelastic behavior of polymer matrix composites and interface friction for different contact surfaces, where such relaxation behavior was mainly due to viscoelasticity of the joint materials.

Prediction of viscoelastic behavior of unidirectional polymer matrix composites

To develop a novel method predicting the viscoelastic behavior of polymer matrix composites according to the viscoelasticity of the matrix, we used the viscoelastic model of the matrix to build new models for unidirectional composites in both 0° and 90° directions. Viscoelastic parameters for both new models were derived, and the obtained equations shared the same form as the viscoelastic constitutive equation of matrix material. The viscoelastic behaviors of matrix material and unidirectional composites were also tested. Results showed that fitting parameters of creep compliance equation were close to the theoretical values of viscoelastic constitutive parameters of the unidirectional composites, proving the validity of the models. A new method was obtained to predict the viscoelastic property of the unidirectional composites based on the viscoelastic property of composite matrix and elastic property of the unidirectional composites. This method provides a theoretical basis for future studies on the viscoelasticity of composite laminates.

Micromechanical Modeling of Viscoplastic Behavior of Laminated Polymer Composites With Thermal Residual Stress Effect

In this paper, a multiscale approach has been developed for investigating the rate-dependent viscoplastic behavior of polymer matrix composites (PMCs) with thermal residual stress effect. The finite-volume direct averaging micromechanics (FVDAM), which effectively predicts nonlinear response of unidirectional fiber reinforced composites, is incorporated with improved Bodner–Partom model to describe the viscoplastic behavior of PMCs. The new micromechanical model is then implemented into the classical laminate theory, enabling efficient and accurate analysis of multidirectional PMCs. The proposed multiscale theory not only predicts effective thermomechanical viscoplastic response of PMCs but also provides local fluctuations of fields within composite microstructures. The deformation behaviors of several unidirectional and multidirectional PMCs with various fiber configurations are extensively simulated at different strain rates, which show a good agreement with the experimental data found from the literature. Influence of thermal residual stress on the viscoplastic behavior of PMCs is closely related to fiber orientation. In addition, the thermal residual stress effect cannot be neglected in order to accurately describe the rate-dependent viscoplastic behavior of PMCs.

High-fidelity micro-scale modeling of the thermo-visco-plastic behavior of carbon fiber polymer matrix composites

An experimentally validated micro-scale analysis of the visco-thermo-mechanical behavior of polymer matrix composites under different loads is proposed. A new constitutive law for the matrix material is developed taking into account the pressure dependence of the material as well as strain-rate and temperature dependence. Capturing the matrix behavior under multi-axial stress states is concluded to be essential to accurately predict the composite material behavior, even when considering simple load cases such as transverse compression and/or shear. Without any calibration procedure at the composite level, good agreement with the experimental data is observed for different loading conditions, including strain-rate dependency.Using this validated micro-scale model, a three-dimensional simulation of the formation of a kink band under longitudinal compression of the composite is conducted. A new evidence at micro-scale is found supporting the hypothesis that shear stresses transferred between fibers and matrix are particularly important in the formation of the kink band.

Prediction of viscoelastic behaviour of polymer matrix composites based on polymer matrix

An effective micromechanics method of predicting the viscoelastic behaviour of polymer matrix composites based on a polymer matrix is presented. First, the Mori–Tanaka method is used to predict the elasticity properties of a unidirectional composite material from the matrix and reinforcement material. Then, the viscoelasticity of a layer in Laplace domain is obtained by the correspondence principle and the Laplace transform. The power law is used to model the polymer matrix's viscoelastic behaviour. Therefore, the inverse Laplace transformation can be used to obtain the viscoelasticity of a layer in the time domain. In the end, classic layer theories are adopted to predict the long-term viscoelastic properties of polymer matrix composites from a unidirectional composite material that is based on the viscoelastic properties of the polymer matrix. The mean relative deviation of the predicted results and experimental results for point 1 is 3·40% and for point 2 is 4·35% in 250 hours.

Wear resistance and friction behavior of thermoset matrix reinforced with Musaceae fiber bundles

Fiber bundles from agricultural residues are promising sources of reinforcement for composite materials due to their technical and economic advantages. This work aims to compare the effect of variation of the fiber size, resin type and curing agent on friction and wear behavior of polymer matrix composites reinforced with fiber bundles obtained from Musaceae rachis. A pin on disc test equipment was used to study sliding of composites and steel as counter body with fixed test parameters. SEM images were used to identify the wear mechanisms. Results show that the wear resistance of composites is better than neat resin and increases when fiber size is reduced. The main wear mechanisms evidenced in all samples were adhesion, surface fatigue and crazing.

The Role of Viscoelasticity on the Fatigue of Angle-ply Polymer Matrix Composites at High and Room Temperatures- A Micromechanical Approach

A micromechanical approach is adopted to study the role of viscoelasticity on the fatigue behavior of polymer matrix composites. In particular, the study examines the interaction of fatigue and creep in angle ply carbon/epoxy at 25 and 114 °C. The matrix phase is modeled as a vicoelastic material using Schapery’s single integral constitutive equation. Taking viscoelsticity into account allows the study of creep strain evolution during the fatigue loading. The fatigue failure criterion is expressed in terms of the fatigue failure functions of the constituent materials. The micromechanical model is also used to calculate these fatigue failure functions from the knowledge of the S-N diagrams of the composite material in longitudinal, transverse and shear loadings thus eliminating the need for any further experimentation. Unlike the previous works, the present study can distinguish between the strain evolution due to fatigue and creep. The results can clearly show the contribution made by the effect of viscoelasticity to the total strain evolution during the fatigue life of the specimen. Although the effect of viscoelsticity is found to increase with temperature, its contribution to strain development during fatigue is compromised by the shorter life of the specimen when compared to lower temperatures.

Micromechanical modeling on the rate-dependent viscoplastic behavior of polymer composites with thermal residual stress effect

The research focuses on the effect of thermal residual stress on the rate-sensitive viscoplastic behavior of polymer matrix composites with various fiber cross-sectional shapes. Micromechanical analysis was then conducted to incorporate the inelastic deformation and thermal residual stress into the micromechanical properties of a repeating cell and obtained the macromechanical response of polymer matrix composites by using homogenization theory. The responses of AS4/Polyetheretherketone (PEEK) with circular, square, and elliptical fibers are predicted by the method above at 10−5, 10−1, and 100/s with respect to 15°, 30°, 45°, 60°, 75°, and 90° off-axis angles. The results show that the viscoplastic difference of the response for various fiber shapes becomes more evident with the increase of strain rate. The effect of thermal residual stress varying with off-axis angle is similar to the sinusoidal curve. Besides, the thermal residual stress provides the largest effect on the response with square fiber and the smallest effect on the response with elliptical fiber, which of the effect decreases with the strain rate increasing.

Investigation of the behaviour of a chopped strand mat/woven roving/foam-Klegecell composite lamination structure during Charpy testing

This paper presents the investigation of the characteristic behaviour of polymer matrix composites under Charpy impact conditions with different design configurations of the laminate structure. The aim of this study was to evaluate the capability of different lamination designs for composite materials, in term of contact load, energy absorption, deflection and damage behaviour. In this study, laminated panels were fabricated using chopped strand mat (CSM), woven roving fabric (WR) and foam-PVC Klegecell as reinforcement with a combination of epoxy or polyester resin, respectively. Structural panels of composite laminates were produced using a hand lay-up technique. Each configuration design was impact tested to failure. Finite element analyses (FEA) were employed in this study to correlate the experimental value of energy absorption with simulation results. The characteristics of different reinforcement types, matrix type, hybrid type, architecture and orientation type were studied. These characteristics need to be considered, due to their affecting the characteristic behaviour of the composite lamination structures. Based on the results, it was found that differences in configuration design of the lamination structure of the polymer matrix composites do influence the strength and weakness of the materials.