Modulus Of Composites Research Articles

Mechanical Properties of ZTA-Cr2O3 Ceramic Composites Prepared with Nano and Micron Sized of Cr2O3 Powder on Different Ratios

In this study, the effect of Cr2O3 addition in different powder sizes on the densification and mechanical properties (elastic modulus, hardness and flexural strength) of ZTA composites were investigated. Nano and micron sized of Cr2O3 powder were added to the ZTA composite separately in different weight ratios (0.3, 0.6, 1%) and uniaxially dry pressing right after pressureless sintering at 1650°C/2 h in the air used as processing procedure. The relative density values of all the composites were close to each other for the Cr2O3 containing composites. A slight decrease in both densification and elastic modulus was observed with the addition of Cr2O3 due to the evaporation problem. Also, the addition of Cr2O3 did not have a serious effect on the hardness of the ZTA composites. The main effect of Cr2O3 addition on ZTA composites was seen for flexural strength. Compared to the ZTA, a nearly 7% increase in strength was obtained for 0.6%Cr2O3 containing composite prepared with micron sized Cr2O3 powder due to the generated compressive stresses in the grain boundary caused by solid solution formation.

Multiscale characterization and design of cellulose composites based on polymers with movable cross-links

To combine the conflicting properties of impact resistance, stiffness, and toughness, we focused on composite materials reinforced with cellulose nanofibers and polymers with movable cross-links using cyclic macromonomers and analyzed their mechanical properties through experiments and computational simulations. Based on the experimental foundation, the mechanical properties of cellulose nanofibers modified with citric acid and flexible crosslinked polymer composites using cyclodextrin were investigated. On the other hand, multi-scale finite element analysis simulation based on homogenization theory was employed to systematically clarify the effects of aspect ratio and content ratio of cellulose fibers by considering polymer blending and modification of molecular structure in the base material. For modification of the matrix polymers and the fiber morphologies, the elastic modulus of the cellulose composite was comprehensively organized by the fiber contribution based on strain energy. A design method for cellulose composites based on fiber contribution proportion was also developed. The design method was applied to a new cellulose composite with a different polymer of the matrix, and it was demonstrated that the elastic modulus can be predicted with an error of less than 10 %.

The mechanical and heat aging properties of natural rubber latex modified by carbon nanodots

AbstractDue to their unique structure and tuneable physical, optical, and electronic properties, carbon nanodots (CDs) become one of the perfect nano‐materials in many fields such as biomarkers, optical sensing, and catalysis. The application of CDs in modifying polymers has also attracted much interest. In this work, a simple process was employed for introducing CDs to modify natural rubber (NR) latex. Glucose was applied as the precursor to prepare CDs by hydrothermal method, subsequently, the crude CDs were directly added to NR latex at a very lower concentration to prepare NR/CDs films. The results of mechanical properties demonstrate that the 500% modulus, tensile and tear strength of NR composites are significantly improved by the introduction of CDs. When the theoretical loading of CDs is 2 phr, the tensile strength and tear strength of NR/CDs film reach to 33.1 MPa and 56.4 N/mm, and improve 17.8% and 29.4% than NR without CDs respectively. It is particularly noteworthy that when the amount of CDs is higher than 1.5 phr, the heat‐aging resistance of NR has been enhanced. It has been confirmed by crosslink density, dynamic mechanical analysis, and Fourier Transform Infrared Spectrometer analysis that CDs have a certain confinement effect on the mobility of rubber molecular segments through physical adsorption and chemical crosslinking. The Tube model theory was employed to calculate parameters of the network structure of NR/CDs films (based on the stress–strain curves), the results indicate that CDs give NR film more chemical crosslinking points and less entanglement network.Highlights The crude carbon nanodots are used to modify NR latex at a lower concentration The mechanical properties of NR films are obliviously improved The heat‐aging resistance of NR has been enhanced by adding carbon nanodots higher than 1.5 phr The Tube model theory are employed to analysis the crosslink network CDs give NR film more chemical crosslinking points and less entanglement network

Upcycling of HDPE Milk Bottles into High-Stiffness, High-HDT Composites with Pineapple Leaf Waste Materials.

In the pursuit of sustainability and reduced dependence on new plastic materials, this study explores the upcycling potential of high-density polyethylene (HDPE) milk bottles into high-stiffness, high-heat-distortion-temperature (HDT) composites. Recycled high-density polyethylene (rHDPE) sourced from used milk bottles serves as the composite matrix, while reinforcing fillers are derived from dried pineapple leaves, comprising fibers (PALF) and non-fibrous materials (NFM). A two-roll mixer is employed to prepare rHDPE/NFM and rHDPE/PALF mixtures, facilitating filler alignment in the resulting prepreg. The prepreg is subsequently stacked and pressed into composite sheets. The introduction of PALF as a reinforcing filler significantly enhances the flexural strength and modulus of the rHDPE composite. A 20 wt.% PALF content yields a remarkable 162% increase in flexural strength and a 204% increase in modulus compared to neat rHDPE. The rHDPE/NFM composite also shows improved mechanical properties, albeit to a lesser degree than fiber reinforcement. Both composites exhibit a slight reduction in impact resistance. Notably, the addition of NFM or PALF substantially elevates HDT, raising the HDT values of the composites to approximately 84 °C and 108 °C, respectively, in contrast to the 71 °C HDT of neat rHDPE. Furthermore, the overall properties of both the composites are further enhanced by improving their compatibility through maleic anhydride-modified polyethylene (MAPE) use. Impact fracture surfaces of both composites reveal higher compatibility and clear alignment of NFM and PALF fillers, underscoring the enhanced performance and environmental friendliness of composites produced from recycled plastics reinforced with pineapple leaf waste fillers.

Faster Bootstrapping via Modulus Raising and Composite NTT

FHEW-like schemes utilize exact gadget decomposition to reduce error growth and ensure that the bootstrapping incurs only polynomial error growth. However, the exact gadget decomposition method requires higher computation complexity and larger memory storage. In this paper, we improve the efficiency of the FHEWlike schemes by utilizing the composite NTT that performs the Number Theoretic Transform (NTT) with a composite modulus. Specifically, based on the composite NTT, we integrate modulus raising and gadget decomposition in the external product, which reduces the number of NTTs required in the blind rotation from 2(dg + 1)n to 2(⌈dg⌉/2 + 1)n. Furthermore, we develop a modulus packing technique that uses the Chinese Remainder Theorem (CRT) and composite NTT to bootstrap multiple LWE ciphertexts through one blind rotation process.We implement the bootstrapping algorithms and evaluate the performance on various benchmark computations using both binary and ternary secret keys. Our results of the single bootstrapping process indicate that the proposed approach achieves speedups of up to 1.7 x, and reduces the size of the blind rotation key by 50% under specific parameters. Finally, we instantiate two ciphertexts in the packing procedure, and the experimental results show that our technique is around 1.5 x faster than the two bootstrapping processes under the 127-bit security level.

Enhanced toughness and strength of 3D printed carbide-oxide composite for biomedical applications

Natural materials derived/extracted Ceramics is an excellent material for developing ceramic-based orthopedic implants. Recently, we have demonstrated an easily scalable, energy-efficient green method to extract ceramic particles from bio-waste i.e. chicken bone. Though the chicken bone extract (CBE) has good biocompatibility, it lacks good mechanical properties in the 3D printed condition as that of human bones. Here, we have reinforced CBE with different weight proportions of silicon carbide to improve the mechanical characteristics of the composite. The hybrid of CBE (oxide) and carbide (SiC) is sintered at different temperatures to understand the effect of the interface of the two ceramics. It is observed that temperature has minimal effect and composition has a noticeable effect on mechanical strength as well as bio-toxicity. The toughness (∼3.58 MJ/m3) and compressive strength (∼64.64 MPa) of the 90:10 composition sintered at 1250 °C show the maximum optimum values. A mathematical model has also been developed to predict and correlate the toughness with porosity, volumetric loading, and elastic modulus of the 3D-printed ceramic composite.

Assessment of Hydrothermal Treatment Effects on Coir Fibers for Incorporation into Polyurethane Matrix Biocomposites Derived from Castor Oil.

The incorporation of natural lignocellulosic fibers as reinforcements in polymer composites has witnessed significant growth due to their biodegradability, cost-effectiveness, and mechanical properties. This study aims to evaluate castor-oil-based polyurethane (COPU), incorporating different contents of coconut coir fibers, 5, 10, and 15 wt%. The investigation includes analysis of the physical, mechanical, and microstructural properties of these composites. Additionally, this study evaluates the influence of hydrothermal treatment on the fibers, conducted at 120 °C and 98 kPa for 30 min, on the biocomposites' properties. Both coir fibers (CFs) and hydrothermal-treated coir fibers (HTCFs) were subjected to comprehensive characterization, including lignocellulosic composition analysis, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The biocomposites were subjected to water absorption analysis, bending tests, XRD, SEM, FTIR, and TGA. The results indicate that the 30 min hydrothermal treatment reduces the extractive content, enhancing the interfacial adhesion between the fiber and the matrix, as evidenced by SEM. Notably, the composite containing 5 wt% CF exhibits a reduced water absorption, approaching the level observed in pure COPU. The inclusion of 15 wt% HTCF results in a remarkable improvement in the composite's flexural strength (100%), elastic modulus (98%), and toughness (280%) compared to neat COPU. TGA highlights that incorporating CFs into the COPU matrix enhances the material's thermal stability, allowing it to withstand temperatures of up to 500 °C. These findings underscore the potential of CFs as a ductile, lightweight, and cost-effective reinforcement in COPU matrix biocomposites, particularly for engineering applications.

Possibility of decryption speed-up by parallel processing in CCA secure hashed ElGamal.

In order to prove the ElGamal CCA(Chosen Ciphertext Attack) security in the random oracle model, it is necessary to use the group where ICDH(Interactive Computational Diffie Hellman) assumption holds. Until now, only bilinear group with complex algebraic structure has been known as the ICDH group. In this paper, we introduce the ICDH group with simple algebraic structure. In other words, we prove that ICDH assumption holds in the integer group with composite modulus. On the basis of this, we propose the CCA secure hashed ElGamal and its fast variant to speed up decryption by parallel processing. Our parallel scheme has the fastest decryption among all CCA secure PKE(Public Key Encryption) schemes implemented in integer group and gives the possibility that ElGamal protocol could be practical when the big modulus numbers are used to resist the quantum attack.

Nonlinear static bending and dynamic behaviors of graphene platelets reinforced dielectric porous arches

This paper comprehensively investigates the electro-induced nonlinear static bending and vibration behaviors of the graphene platelets reinforced dielectric porous (GPLRDP) arches. The effective dielectric permittivity and Young's modulus of GPLRDP composites are determined based on the effective medium theory (EMT). The nonlinear governing equations for the GPLRDP arch under the electrical voltage are derived by using the Hamilton principle and are numerically solved by utilizing the differential quadrature method (DQM) together with an iterative scheme to obtain its electro-induced nonlinear static bending and dynamic responses. The influences of the porosity, GPL concentration, boundary condition, central angle, and DC and AC voltage on the nonlinear behaviors of the GPLRDP arch are discussed in detail. It is found that the addition of GPLs has significant effects on the electro-induced mechanical behaviors of the GPLRDC arch when the GPLs weight fraction exceeds the percolation threshold. Numerical analysis proves that the electro-induced static and dynamic behaviors of the GPLRDC arch can be designed and actively tuned through adjusting material and structural parameters, providing valuable insights for the development of smart GPLRDP arches.

Biocompatible organic coating fabrication via polymer/clay nanocomposites: Evaluation of mechanical improvements

AbstractThis study focuses on achieving mechanical enhancements in biocompatible organic coatings. A solvent‐based method is employed to produce biocompatible nanocomposites using polyvinylpyrrolidone (PVP) and bentonite nanoclays (BNT) as constituents to achieve this objective. Subsequently, the nanocomposites are spin‐coated onto a glass substrate, resulting in smooth and defect‐free films with a thickness of 5 μm. Through instrumented‐indentation testing, it is observed that BNT reinforcement leads to significant improvements in mechanical properties. Specifically, the addition of 0.5, 1, and 5 wt% of BNT in PVP results in enhancements of 105%, 77%, and 430% in elastic modulus, respectively, while hardness is improved by 166%, 211%, and 448%, respectively. The considerable improvements in the composite modulus cannot be adequately explained by assuming perfect adhesion between the constituents of the composite (as suggested by the Halpin–Tsai model) or by considering the contributions from the interface/network of silicate layers (as proposed by the Modified Halpin–Tsai model). Instead, the significant enhancements in hardness and modulus values are primarily attributed to a notable increase in the BNT volume fraction, ranging from 4 to 9 times, occurring under the Berkovich tip due to the aggregated silicate layers. The findings highlight the role of aggregated silicate layers in enhancing both hardness and modulus and contribute to the development of advanced biocompatible coatings with improved mechanical properties.Highlights Enhanced mechanical properties in biocompatible coatings. Biocompatible nanocomposites of polyvinylpyrrolidone (PVP) and bentonite nanoclays (BNT). Spin‐coated nanocomposite films on glass: smooth, defect‐free, 5 μm thick. BNT reinforcement boosts elastic modulus and hardness of PVP. Aggregated silicate layers under compression drive substantial mechanical improvements.

Performance of delaminated CFRP composite under pure bending using two-dimensional digital image correlation

ABSTRACT Delamination is an interlaminar damage which may be pre-existing in multilayered fibre reinforced polymer composite parts due to manufacturing imperfections or generated by out of plane loading during service life. Its existence leads to significant reduction of structural integrity, strength and stiffness of the material. Hence, to study the effect of induced delamination on the performance of a composite under pure bending, a circular polytetrafluoroethylene (PTFE) film was introduced between the second and third plies of a sixteen layered carbon/epoxy laminate during fabrication. The bending tests were conducted in displacement control mode. The displacements and strains were measured through the thickness of the composite using two-dimensional digital image correlation. The damage modes were captured using CCD camera and the causes were explained. The flexural strength and modulus of composite were 329.74 MPa and 104.58 GPa respectively. The delaminated composite behaved as a single member without any crack within the elastic range. The existence of PTFE drastically reduced flexural stiffness of composite beyond the stress at 75.81% of its ultimate strength. The ± 45º plies offered low mechanical performance against the induced off axis loading. Hence, in these plies fibre breakage was higher. In the portion of PTFE, the strains were higher due to larger outward displacements produced by local buckling.

A developed Takayanagi model to estimate the tensile modulus and interphase characteristics of polymer nanocellulose composites

This study analyzes the tensile modulus of nanocellulose-reinforced composites by developing the Takayanagi model considering the interphase section and filler size. The model accuracy is assessed by reported experimental moduli of composites and by parametric studies. The estimates of advanced model fit to the measured moduli of numerous examples. Also, it is revealed that the treatment of nanocellulose increases the modulus and thickness of interphase in nanocomposites. The relative modulus (Er) as the ratio of nanocomposite modulus to the modulus of matrix significantly changes when nanocellulose modulus (Ef) is raised from 50 to 100 GPa; however, Er unimportantly rises at Ef > 100 GPa. Additionally, nanocellulose radius (R) of 2 nm maximizes the Er to 1.636, though Er decreases to 1.09 at R = 58 nm and the variation of Er is insignificant at R > 20 nm. Furthermore, the interphase moduli (Ei) below 10 GPa meaningfully affect the nanocomposite modulus, but Ei > 10 GPa cannot cause the considerable change in Er. Therefore, Er does not change at the high levels of Ef, R and Ei.

A Study on Lacunary Strong Convergence according to Modulus Functions

In this article, we study a new generalization of the lacunary strongly convergent sequences and introduce the concept of lacunary strong convergence according to $$g^k$$ for sequences of complex (or real) numbers, where $$g^k=g\circ g\circ\dots\circ g$$ ($$k$$ times) represents a composite modulus function. After that, we determine the connections of lacunary strong convergence and lacunary statistical convergence to lacunary strong convergence according to $$g^k$$. Furthermore, we investigate several properties of this generalization.

To the magnetorheological properties of magnetic gels with non-spherical particles. Viscoelastic modulus relaxation after the field alternation

We present a theoretical model of magnetorheological effects in a soft magnetic gel with non spherical (disc-shaped) magnetizable particles. This model is based on micro-mechanic consideration of the particles reorientation in a soft elastic-viscous medium after step-wise alternation of an applied magnetic field. Analysis of dynamics of the composite macroscopic shear modulus change after the field alternation is in focus of our consideration. The presented results explain recently experimentally observed magnetorheological and relaxation effects in ferrogels with the discotic particles: increase of the composite modulus under the field action; relaxation of its storage and loss components as well as overshoot of the loss modulus after the field stepwise activation and deactivation.

Effective elastic moduli of composites with a strongly disordered host material

Effective elastic moduli of composites with a strongly disordered host material

On algebraic twists with composite moduli

On algebraic twists with composite moduli

Maintaining modulus of polypropylene composites with ultra-high low temperature toughness by synergistic branched polyethylene and nucleating agents

In this work, the synergistic effect of highly branched polyethylene (HBPEs, s = 1, 2) elastomers featuring dendritic structure and α-type nucleating agents (NA1, NA2) on the toughness and stiffness of block polypropylene (PP–B) was investigated. Blends of PP-B/HBPE/nucleating agent ternary systems were prepared, yielding materials with exceptionally high low-temperature toughness and minimal stiffness loss. The results indicate that HBPE enhances the low-temperature impact strength of the system but leads to a reduction in modulus. After the addition of the nucleating agent, both the low-temperature toughness and stiffness of the blend are improved simultaneously. The PP-B/HBPE2/NA2 (90/10/0.2) blend achieves the optimal balance between low-temperature toughness and stiffness, with its low-temperature impact strength increasing by a factor of 7 compared to PP-B, reaching 56.9 kJ/m2, and a bending modulus of 1110 MPa, nearly identical to PP-B. Dynamic mechanical properties and phase morphology results indicate that HBPE reduces the glass transition temperature of the rubber phase in the blended system and exhibits good compatibility with PP-B. Analysis of the crystallization behavior reveals that the significant increase in the crystallization temperature of PP-B and the substantial reduction in the size of spherical particles observed in PP-B/HBPE/NA blends are facilitated by NA1 and NA2. Additionally, NA1 and NA2 promote the transformation of the PP-B matrix into α-type crystals and enhance the crystallinity of PP-B.

Correlation between Infill Percentages, Layer Width, and Mechanical Properties in Fused Deposition Modelling of Poly-Lactic Acid 3D Printing

The field of additive manufacturing (AM) has seen a transformation in the production of intricate and complex parts for various applications. Fused Deposition Modelling (FDM), among AM techniques, has garnered significant attention, particularly in fields like fibre-reinforced composites (FRC). In this study, the world of FDM-printed Polylactic Acid (PLA) components is explored, with a focus on how mechanical properties are influenced by infill percentages and layer widths. Through the utilisation of Response Surface Methodology (RSM), the optimisation of FDM-PLA 3D printing for a wide range of biomaterial applications is achieved, along with the unveiling of the potential for remarkable improvements in mechanical performance. Notably, a remarkable 91% reduction in surface roughness for PLA composites was achieved, accompanied by an impressive 25.6% and 34.1% enhancement in the tensile strength and Young’s modulus of fibre-reinforced PLA composites, respectively. This work, positioned at the crossroads of FDM, lays the groundwork for substantial advancements in the realm of additive manufacturing.

A fast Fourier transform-based solver for elastic micropolar composites

This work presents a spectral micromechanical formulation for obtaining the full-field and homogenized response of elastic micropolar composites. The algorithm relies on a coupled set of convolution integral equations for the micropolar strains, where periodic Green’s operators associated with a linear homogeneous reference medium are convolved with functions of the Cauchy and couple stress fields that encode the material’s heterogeneity, as well as any potential material nonlinearity. Such convolution integral equations take an algebraic form in the reciprocal Fourier space that can be solved iteratively. In this vein, the fast Fourier transform (FFT) algorithm is leveraged to accelerate the numerical solution, resulting in a mesh-free formulation in which the periodic unit cell representing the heterogeneous material can be discretized by a regular grid of pixels in two dimensions (or voxels in three dimensions). For verification, the numerical solutions obtained with the micropolar FFT solver are compared with analytical solutions for a matrix with a dilute circular inclusion subjected to plane strain loading. The developed computational framework is then used to study length-scale effects and effective (micropolar) moduli of composites with various topological configurations.

Parametric theoretical prediction of elastic properties and strength of fine weave pierced C/C composites

This paper developed a parametric model of fine weave pierced carbon/carbon (FWPCC) composites based on the structural relationship of actual sample information. The elastic constants and compressive strengths of FWPCC composites with various Z-directional yarn contents were parametrically investigated. The developed theoretical prediction model agreed well with the experimental data. The parametric prediction results found Z-directional modulus of FWPCC composites with 6 K Z-directional yarns increased by 88.21 % compared to FWPCC composites with 1 K Z-directional yarns; X/Y-directional modulus decreased by 17.32 %; Z-directional compressive strength increased by 337.33 %; X/Y-directional compressive strength only decreased by 6.12 %. The accuracy of the two failure criteria (Hoffmann, Hashin failure criterion) used for the model was compared. The accuracy of the model prediction using Hashin failure criterion was better than that of the Hoffmann criterion. The predicted results using Hashin criterion also showed that under Z-directional compressive loading, the composite failure was mainly the compressive failure of the Z-directional yarns; under X/Y-directional compressive loading, the composite failure was mainly the compressive failure of the fibers in the bending section in the X/Y-directional yarns. The developed theoretical model was of great significance for the engineering application of C/C composite.