Modulus Of Composites Research Articles

Numerical FE Three-phasic Simulation to Predict the Effect of Air Voids on the Dynamic Modulus of Bituminous Composites

In this study, the mechanical performance of bituminous composites was predicted using an upscaling methodology that integrated both finite element analysis and analytical modeling. The FE approach was employed to incorporate intricate geometries and material characteristics. The dynamic modulus of the matrix and the elastic properties of aggregates served as inputs for the numerical models at various scales. This approach considers the distinctive attributes of the granular framework at each level. Furthermore, the investigation involved the influence of air void proportions on the composite's modulus. The numerical models encompassed the random incorporation of air voids within the matrix at varying levels. Notably, it was observed that at low frequencies air voids reduced the dynamic modulus of asphalt more than at high frequencies due to its effect on viscoelastic nature of the bituminous composite. Moreover, heightened temperatures intensified the impact of air void on the dynamic modulus of the asphalt mixture.

Characterization of different size reinforcement effects on microstructural failure mechanism in carbon nanotube-reinforced aluminum composites

In this study, we investigated the effect of reinforcement sizes on the tensile strength and ductility of carbon nanotube (CNT)-reinforced aluminum matrix composites fabricated through ball milling, followed by hot extrusion of a powder encapsulated in an aluminum container. We analyzed the microstructural properties of the samples, including the aluminum grain size, its spatial variation with the alignment of CNT, and CNT length. Nanoindentation test results revealed the spatial variation of hardness and Young’s modulus of composites with small-diameter CNTs, indicating local Al4C3 formation and interlock structure resulting from dislocation accumulation during the fabrication process. This explains dimples of different sizes observed on the fracture surfaces of the samples and the occurrence of CNT pullout. Furthermore, we proposed the failure mechanism of the composites under tensile strain and calculated the failure strain using the Whitehouse–Clyne model. The calculated failure strain agrees well with the experimental values. The high ductility of the composites is attributed to the large grain fracture and rotation of neighboring grains due to the constraint imposed by CNTs.

Modeling the influence of microstructural variations on the Young’s modulus of carbon nanotube-reinforced cement composites

Modeling the influence of microstructural variations on the Young’s modulus of carbon nanotube-reinforced cement composites

Adjustment of Mechanical Properties of 3D Printed Continuous Carbon Fiber-Reinforced Thermoset Composites by Print Parameter Adjustments.

Reinforcing thermoset polymers with continuous carbon fiber (CF) tow has emerged as a promising avenue to overcome the thermal and mechanical performance limitations of 3D printed polymeric structures for load-bearing applications. Unlike traditional methods, manufacturing continuous fiber-reinforced composites by 3D printing has the unique capability of locally varying the mechanical properties of the composites. In this study, continuous CF thermoset composite specimens were printed with varying line spacing, resin flow rate, and nozzle sizes. The resin flow rates for different line spacings and nozzle sizes were optimized by topographic analysis. Printed composite mechanical properties were evaluated, and their trends were correlated with the trend of print parameter changes. Results showed that tensile strength and modulus could be altered and improved by ~50% by adjusting the printing process parameters. Higher composite strength and modulus were obtained by shortening the line spacing and nozzle diameter.

Effect of kaolin ratio on wear, water absorption, acidic resistance, and mechanical properties of thermoset composites

Natural fiber reinforced composites are easy to decompose in nature compared to synthetic fiber reinforced composites. However, due to environmental effects, natural fibers cannot maintain their properties for a long time. This situation has led researchers to search for natural but non-degradable materials. Kaolin is one of the most abundant minerals in nature and is an easy material to obtain. This study investigated the use of kaolin as a potential natural additive for polymer composites. In this direction, different proportions by weight of kaolin were added to two different polymer matrices (polyester and polyvinylester) materials. Mechanical tests were performed on the samples, and a series of tests were carried out to understand the acid resistance, wear resistance and water absorption properties of the samples. Also, SEM images of the fracture surface, wear surface, and surface exposed to the acidic solutions were taken and examined. According to test results, kaolin improved compression strength while reducing tensile and flexural strength. However, serious improvements have been achieved by nearly 45% and 115% in the tensile modulus and nearly 84% and 218% in the flexural modulus of polyester and polyvinylester composites, respectively. Also, kaolin improved acid resistance and wear properties and reduced the water absorption rate of the composites.

Enhancement and Compatibilization of Waste-Sourced Biocomposites Through Elastomer Blending and Matrix Grafting Modification

A novel elastomer-modified multicomponent, multiphase waste-sourced biocomposites, was prepared for converting waste biomass and plastic into value-added products. The effects of blending elastomer–olefin block copolymer (OBC) and maleic anhydride (MAH), and divinylbenzene (DVB) co-grafting of recycled polypropylene (rPP) matrix on the adhesion interface, structure, and properties of high wood flour-filled (60 wt.%) composites were thoroughly investigated. The results indicated that DVB introduced branched structures into the polymer matrix molecular chain and increased the MAH grafting rate. Co-grafting rPP/OBC blends enhanced the interfacial adhesion among rPP, OBC, and wood flour. Additionally, MAH-grafted OBC was prone to encapsulating rigid wood flour, thereby forming an embedded structure. Notably, the tensile modulus and impact strength of the final three-component composites increased by 60% and 125%, respectively, compared with the unmodified composites. Additionally, dynamic mechanical analysis revealed that DVB-induced branching promoted the formation of microvoids in the OBC shell layer surrounding the wood, which in turn induced significant plastic deformation in the polymer matrix. This work offers a facile and efficient method for preparing high-toughness, high-stiffness, and low-cost waste PP-based composites for automotive interiors, and indoor and outdoor decoration.

Surface modification of Cu-coated carbon fiber for improved mechanical performance of Acrylonitrile Butadiene Styrene composites using 3-Aminopropyl triethoxy silane

This study investigates the use of 3-Aminopropyl triethoxy silane as a surface modifier for Cu-coated Carbon Fibers. The modified fibers were subsequently incorporated into Acrylonitrile Butadiene Styrene matrix composites through melt blending and high-temperature compression molding. The research evaluates the effect of 3-Aminopropyl triethoxy silane on the interfacial structure and mechanical performance of these composites. Results demonstrate a substantial enhancement in the wettability and surface energy of Cu-coated Carbon Fibers, with the static contact angle reduced from 111.2° to 84.5° and surface energy increased from 44.67 mN·m−1 to 56.66 mN·m−1. These surface modifications contributed to an 82.7 % increase in tensile strength and a 76.4 % improvement in tensile modulus of the resultant composites.

Bridging the gap: A novel approach for predicting the Young's modulus of nanodiamond polymer composites

Bridging the gap: A novel approach for predicting the Young's modulus of nanodiamond polymer composites

Prediction of Tensile Properties of Natural Fiber Reinforced PP Hybrid Composites by Facca-Kortschot-Yan (FKY) and Palsule Equations

Abstract Natural fiber reinforced polymer hybrid composites are advanced materials for commercial and engineering applications. Rule of hybrid mixtures has been applied to develop Facca-Kortschot-Yan (FKY) Equation and Palsule equation for predicting tensile strength and modulus of these hybrid polymer composites. This study predicts the values of tensile strength and modulus of a few natural fibers reinforced polypropylene hybrid composites by these two equations and compares them with the reported experimental values.

Effect of different silane coupling agent modified SiO2 on the properties of silicone rubber composites: Based on molecular dynamics

Silicone rubber composites doped with nanoparticles are widely used in the field of electrical and aerospace insulation. The silane coupling agent modified on the surface of the particles enhances the compatibility between the nanoparticles and the insulating material, thus further improving the mechanical, dielectric properties and thermal stability of the composites. On this basis, the silicone rubber composite system models of three silane coupling agents (KH550, KH560, KH570) modified SiO2 are established respectively. Through the analysis methods of interaction energy, free fraction volume, radial distribution function and pull-out simulation, the improving mechanism of three silane coupling agents modified SiO2 on material properties can be explored from the perspective of molecular simulation. The results show that the interaction energy between KH570/SiO2 and silicone rubber system is the largest regardless of temperatures (280K ~ 400K). At low temperature (280K), the free fraction volume of KH550 and KH560 modified SiO2 systems is lower than that of KH570 modified system, while at high temperature, the free fraction volume of KH570/SiO2 system is the lowest. The three silane coupling agents modified SiO2 all increase the Young's modulus and bulk modulus of silicone rubber composites, and reduced the relative dielectric constant of the composites. The silicone rubber composite system mixed with KH570/SiO2 has the largest adsorption capacity for water molecules and the most obvious effect to inhibit the diffusion of water molecule. The results of this work can provide reference for the design and performance optimization of modified SiO2/silicone rubber composites in hygrothermal environment.

Mechanical properties of seaweed/banana fiber/hBN filled epoxy composites using Box–Behnken method

Natural particulate reinforced polymer (NPRP) composites are developed to replace synthetic fibers, aiming to reduce costs and environmental impact. Industries such as automotive, electronics, construction and aerospace are turning to filler-reinforced polymer composites and natural bio-fibers to enhance structural properties and develop eco-friendly products. This article presents research on epoxy-based composites fortified with natural and ceramic micro-sized fillers, including seaweed filler (SF), banana fiber (BF) and hexagonal boron nitride (hBN), fabricated using the hand layup technique. Through experiments, the effect of filler loading on the enhancement of mechanical properties such as tensile strength (TS), toughness (T), Young's modulus (YM), resilience (R) and yield strength (YS) of multiphase hybrid composites is investigated. Incorporating mixtures of ceramic filler and natural fillers into the epoxy matrix improves mechanical properties. The results demonstrated that the interlaced composites achieved optimum mechanical properties for S6 sample, including a TS of 24.85 MPa, T of 25.47 MJ/m3, YM of 7.15 GPa, R of 0.698 MJ/m3 and YS of 3.34 MPa. In comparison with S11 samples, the mechanical properties such as TS, T, YM, R and YS of the S6 composite sample are increased by 110.95%, 57.8%, 450%, 501.7% and 292.9%, respectively. The tensile fracture's scanning electron images reveal a homogenous surface with the formation of a fractured surface and defects. Statistical analysis at a 96% confidence level revealed the significance of the interaction between natural and ceramic micro particulate on the TS of the developed interlaced composite material, with a p-value of 0.007.

Damage investigation of hybrid flax-glass/epoxy composites subjected to impact fatigue under water ageing

The aim of this study is to investigate the fatigue behaviour of hybrid flax-glass/epoxy composites under repeated impact loading subsequent to water ageing. Different plates of these composite materials were fabricated using the vacuum infusion technique. Five stacking sequences were considered: [F8], [G/F3]S, [G2/F2]S, [G3/F]S, and [G8], where F and G stand for flax/epoxy and glass/epoxy plies, respectively. Water ageing was conducted by immersing the composite specimens in tap water at room temperature for various durations, and until saturation was reached. Fatigue impact tests were carried out using three impact energies: 3, 4, and 5 J. An advanced high-resolution camera was used to monitor the evolution of damage mechanisms occurring on the non-impacted surfaces, while a laser thermometer was considered to track the temperature variations within each composite specimen. The obtained results show that flax-glass hybridization reduces the mass of absorbed water in flax/epoxy composite by up to 70%. Furthermore, there is a more pronounced decrease in longitudinal modulus and maximum stress in aged composites, with reductions of up to 70% compared to unaged ones. Additionally, visible damage occurs even at low energy levels, manifesting from the initial impacts in both aged and unaged composite laminates. Moreover, a correlation between the number of impacts to failure and the cumulative energy is revealed. Ultimately, water aging reduces the strength of the studied composite laminates and their resistance to impact fatigue. Furthermore, the hybrid laminates with high proportion of flax layers are particularly susceptible to water ageing effects.

Periodic free vibrations of composite laminates with curvilinear fibres and CNTs

This article addresses the combined effect of using curvilinear fibres and carbon nanotubes (CNTs) reinforcements in the non-linear modes of vibration of laminated composite plates. To arrive at the material properties of the three-phase composite material, a two-step hierarchic procedure is followed. A modified version of the Halpin–Tsai model is employed to predict the Young’s modulus of the CNT enriched resin and expressions, deduced from equilibria of a unit cell where a fibre is embedded in resin, are applied to obtain the diverse elasticity moduli of the three-phase composite. Moderately large displacements are considered, with von Kármán strain–displacement relations. Although the presented model is an equivalent single layer one, it applies to thick plates, because a Third-order Shear Deformation Theory (TSDT) is followed. The set of autonomous non-linear equations of motion is reduced using static condensation and a modal basis with selected modes, chosen after a convergence analysis. The reduced set of equations of motion is solved by the shooting method. Numerical tests considering plates with diverse curvilinear fibre paths, CNT contents and thicknesses are carried out. The results obtained are thoroughly analysed.

The structural, mechanical, optical and dielectric properties of aminated PMMA-Ag-GO nanocomposite for coatings

The present study reports the synthesis and characteristics of an aminated PMMA-Ag-GO polymer nanocomposite (PNGAg) for coatings. The XRD diffractogram data indicated the presence of crystallinity in samples. The lattice strain of (002) planes and crystallite size were computed to estimate the number of graphene oxide (GO) layers. The homogenous dispersion of GO with silver (Ag) nanoparticles over the surface of the samples was verified by the SEM and EDAX tests. The thermal stability and interaction of fillers with aminated PMMA is confirmed by of TGA–DTA and FTIR analysis. Moreover, the substantial shift of FTIR bands supports the bonding of functional groups with Ag decorated GO and the stability of nanocomposite. The estimated mechanical properties like flexural strength and composite modulus (> 90 MPa) supported the applicability of PNGAg as coatings. The UV–Vis spectroscopy evidenced the characteristic absorption peaks of GO in line with range of UVC radiation in aminated PMMA. Along with high values of relative permittivity, the shift of loss tangent maxima to higher end with increase in GO concentration is attributed to greater number of interfaces. Owing to the functionalisation by naproxen along with dispersion of GO, contributed to MWS polarisation and hence strengthen the dielectric properties. As the concentration of GO rises from 0.1 mol% to 0.7 mol%, substantial shift of AC conductivity (i.e. 2.49 × 10−6 Scm−1 to 37.9 × 10−6 Scm−1) is observed. The high conductivity of PNGAg5 at 0.9 mol% GO suggests the presence of numerous layers, leading to increased interfacial polarization and a higher dielectric constant. In addition to that, the semi-circle in impedance plot and bulk resistance also supported the optimal dielectric properties of samples. As a whole, the results have shown that PNGAg nanocomposites are good coating materials for wide variety of devices.

DEVELOPMENT OF A CORRELATION MODEL FOR TORSIONAL SHEAR MODULUS PROPERTIES BETWEEN STRUCTURAL SIZE SPECIMENS BASED ON EN 384:2016 AND SMALL CLEAR SPECIMENS (MS544: PART 2)

In timber design, the shear modulus of beams is crucial for ensuring torsional stability and minimizing vibrational issues. Traditionally, the ratio of modulus of elasticity (E) to shear modulus (G) is assumed to be 16:1. However, bending tests often combine flexural and shear stresses, making it difficult to assess pure shear properties. The British Standard BS EN 408:2012 now recommends the torsion test as the preferred method for determining the shear modulus of structural-size timber and timber composites. This method has received limited attention in Malaysia. This study investigates the torsional shear modulus of Malaysian tropical timber species across different strength groups (SG), including Balau (SG1), Kempas (SG2), Kelat (SG3), Kapur (SG4), Resak (SG4), Keruing (SG5), Mengkulang (SG5), Light Red Meranti (SG6), and Geronggang (SG7). Torsion tests were conducted in line with BS EN 408, and the results were compared with modulus of elasticity values from MS554: Part 2. The findings showed that the E to G ratio for these species ranged from 17:1 to 29:1, with an average of 21:1—exceeding the conventional 16:1 ratio. This indicates that torsional shear modulus must be experimentally tested rather than inferred from the traditional ratio.

Synthesis of bio-polyol-functionalized nanocrystalline celluloses as reactive/reinforcing components in bio-based polyurethane foams by homogeneous environment modification

Nanocrystalline Cellulose (NCC or CNC) is widely used as a filler in polymer composites due to its high specific strength, tensile modulus, aspect ratio, and sustainability.However, CNC hydrophilicity complicates its dispersion in hydrophobic polymeric matrices giving rise to aggregate structures and thus compromising its reinforcing action. CNC functionalization in a homogeneous environment, through silanization with trichloro(butyl)silane as a coupling agent and subsequent grafting with bio-based polyols, is herein investigated aiming to enhance CNC dispersibility improving the filler-matrix interaction between the hydrophobic PU and hydrophilic CNC. The modified CNCs (m_Ci) have been studied by XRD, SEM, and TGA analyses. The TGA results show that the amount of grafted polyol is strongly influenced by both its molar mass and OH number and the maximum amount of grafted polyol reaches up to 0.32 mmol per grams of functionalized CNC, within the explored conditions. The effect of different concentrations (1–3 wt%) of m_Ci on the physical, morphological, and mechanical properties of the resulting bio-based composite polyurethane foams is evaluated. Composite PU foams present compressive modulus up to 4.81 MPa and strength up to 255 kPa more than five times higher than those reinforced with unmodified CNC or with modified CNC in heterogeneous chemical environment. The improvement of mechanical properties of the examined PU foams, as a consequence of the incorporation of bio-polyols modified CNCs where polyol's OH groups interact with polyurethane precursors, could further broaden the use of these materials in building applications.

Synergistic enhancement of modulus and ductility in Mg matrix composites: A new strategy for GNPs&MgOnp and SiCp hybrid reinforcement

SiC particles (SiCp) reinforced magnesium matrix composites (MMCs) exhibit elevated specific stiffness. However, the non-uniform distribution of SiCp and the interfacial cracking between the SiCp and Mg matrix compromise the ductility. This paper presents a novel approach to enhance the modulus and ductility of the MMCs by utilizing in-situ synthesized graphene nanoplatelets (GNPs) and MgO nanoparticles (MgOnp). The in-situ reaction of GNPs and MgOnp (GNPs&MgOnp) conducted at a high temperature (720 °C) demonstrates an improvement in the local agglomeration of SiCp compared to the conventional semi-solid temperature (590 °C). Moreover, the GNPs&MgOnp optimized interfacial structure and transferred the load during plastic deformation, inhibiting stress concentration and crack propagation at the interface of SiCp. The ductility and modulus are enhanced by approximately 70 % and 10 % compared to SiCp/Mg-6Zn composites, demonstrating the effectiveness of the strategy employing micro-nano hybrid reinforcement and synergistic enhancement of ductility and modulus.

Study on the nuclear shield behaviors of basalt/carbon fibers reinforced PbO blended epoxy matrix composite – A novel material for thermal insulation applications

This study introduces a novel composite material engineered for thermal insulation, specifically in environments requiring radiation shielding. The composite is composed of basalt and carbon fibers reinforced varying with lead oxide (PbO) nanoparticles for five different composite laminates, all integrated into an epoxy matrix. The research primarily focuses on evaluating the composite's thermal insulation capabilities, gamma-ray attenuation effectiveness, and microstructural characteristics. Mechanical testing reveals that the incorporation of basalt and carbon fibers significantly enhances the composite's tensile strength and modulus. Thermal analysis demonstrates the composite's excellent insulation properties, attributed to the synergistic effects of the fibrous reinforcement and the epoxy matrix, which effectively reduce thermal conductivity. Gamma attenuation tests indicate a substantial improvement in radiation shielding effectiveness with the addition of lead oxide nanoparticles. The composite exhibits improved gamma-ray attenuation compared to conventional materials, due to the high atomic number of lead, which enhances photon absorption and scattering mechanisms.Microstructural analysis provides detailed insights into the composite's structure. Morphological images show a uniform dispersion of PbO nanoparticles and strong adhesion between the fibers and the matrix. Elemental analysis confirms the elemental composition, highlighting the successful integration of PbO nanoparticles, which significantly enhances radiation shielding.

Comparison of the effects of different ageing tests on flexural properties of flax fibre composites

This study investigates the changes in the flexural properties and microstructure of flax fibre thermoset composites induced by accelerated and natural ageing methods. The reductions in flexural strength and modulus of composites, ranging from 14 %–48 % and 6 %–57 %, respectively or even an increase in flexural properties after the cyclic ageing test, show the diverse effects of the tests on the flax composites. Only small differences in the composites' performance were found between the natural ageing under the shade and natural ageing exposed to sunlight. The long-term moisture cycling did not cause progressive damage; instead, the composite's flexural properties increased, likely due to an improvement in both the fibre's and matrix's mechanical properties. The water immersion test seems to be predictive of the long-term durability of uncoated flax composites in natural conditions. Microstructure analysis supports composites' flexural test results, with flax/epoxy showing superior properties compared to flax/polyester. The results suggest that uncoated flax composites can withstand extreme humidity changes, but perhaps not in applications wherein composites come in contact with liquid water for long periods, likely due to the effects of leaching. The varied impacts of the different ageing tests on flax fibre composites underscore the need to thoroughly select testing protocols that simulate service conditions relevant to the composites' intended application.

Estimation of Effective Bulk Modulus of Metamaterial Composites with Coated Spheres Using a Reduced Micromorphic Model

Estimation of Effective Bulk Modulus of Metamaterial Composites with Coated Spheres Using a Reduced Micromorphic Model