Modulus Of Material Research Articles

Advancing mechanical performance in sustainable engineering: Synergistic effects of graphene oxide/nano‐silica hybrid nanofiller via latex coagulation in natural rubber composites

AbstractThis research investigates the utilization of a hybrid nanofiller comprising graphene oxide (GO) and amine‐modified nano silica in natural rubber matrix via the latex stage coagulation method. The resulting novel composite materials were characterized comprehensively for their static and dynamic mechanical properties. The hybrid nanofiller exhibited excellent dispersion within the rubber latex, facilitating the formation of a well‐interconnected network structure. The formed network resulted in remarkable improvements in tensile strength, elongation at break, and modulus of the composites. Dynamic mechanical analysis revealed that the hybrid filler (GO/nano‐silica hybrid (GO/NS)) could effectively reinforce the rubber matrix by constraining the mobility of rubber chains, leading to increased stiffness and mechanical strength. In fact, the confinement effect of the nanofillers has been carefully evaluated from dynamic mechanical spectroscopy. The increased glass transition temperature of the rubber nanocomposites specifies the restricted segmental mobility of the rubber chains. Moreover, the hybrid composites displayed significantly low rolling resistance, particularly GO/NS 2 (31% reduction), indicating their potential application as tire treads for fuel‐efficient and green tire manufacturing. The mechanical and rolling resistance properties achieved in these composites can be attributed to the efficient dispersion of the GO/nano‐silica hybrid(GO/NS) nanofiller and the resulting network formation within the rubber matrix. Findings emphasized the composites' viability as sustainable and eco‐friendly tire materials, potential for enhanced fuel efficiency, and reduced environmental footprint in tire manufacturing technology.Highlights The hybrid nanofiller (GO/nano silica hybrid) exhibited excellent dispersion within the rubber latex, leading to the formation of a well‐interconnected network structure. The resulting network structure significantly improved the tensile strength, elongation at break, and modulus of the composite materials. Dynamic mechanical analysis demonstrated that the hybrid filler effectively reinforced the rubber matrix, increasing stiffness and mechanical strength by constraining the mobility of rubber chains. Our hybrid composites displayed a remarkable reduction in rolling resistance, particularly GO/NS2, with a 31% reduction, indicating their potential application as tire treads for fuel‐efficient and green tire manufacturing. The study emphasized the composites viability as sustainable and eco‐friendly tire materials, offering potential benefits for enhanced fuel efficiency and reduced environmental footprint in tire manufacturing technology.

Emerging technologies and advanced analyses for non-invasive near-surface site characterization

The in-situ small-strain shear modulus of soil and rock materials is a parameter of paramount importance in geotechnical modeling. It can be derived from non-invasive geophysical surveys, which provide the possibility of testing the subsurface in its natural and undisturbed condition by inferring the velocity of propagation of shear waves. In addition, for soil dynamics and earthquake engineering applications, the small-strain damping ratio plays a relevant role, yet its estimation is still challenging, lacking consolidated approaches for its in-situ evaluation. Recent advancements in instrumentation, such as distributed acoustic sensing (DAS), combined with advanced analysis methodologies for the interpretation of seismic wave propagation (e.g., machine learning and full waveform inversion), open new frontiers in site characterization. This paper presents and compares some advanced applications of measuring 1D and 2D variations in shear wave velocity and attenuation in-situ with reference to a specific case history.

Profiling Elastoplastic and Chemical Parameters to Assess Polymerization Quality in Flowable Bulk-Fill Composites.

In the chronology of polymer-based composite materials, flowable bulk-fill composites represent the most recent development. They enable a significant reduction in treatment time by being applied in larger increments of 4 to 5 mm. The aim of the investigation was to assess the polymerization quality and mechanical performance of a new formulation that has just entered the market and was still in experimental formulation at the time of the investigation, and to compare these results in the context of clinically established materials of the same category. Adequate curing in increments of up to 4 mm could be confirmed both by profiling the elastoplastic material behavior of large increments in 100 µm steps and by real-time assessment of the degree of conversion and the associated polymerization kinetic. A slightly lower amount of filler in the experimental material was associated with slightly lower hardness and elastic modulus parameters, but the creep was similar and the elastic and total indentation work was higher. The kinetic parameters were assigned to the specific characteristics of each tested material. The mechanical macroscopic strength, evaluated in a three-point bending test and supplemented by a reliability analysis, met or exceeded the standards and values measured in clinically established materials, which for all materials is related to the higher flexibility of the beams during testing, while the modulus of elasticity was low. The low elastic modulus of all flowable bulk-fill materials must be taken into account when deciding the clinical indication of this material category.

Acoustic properties of underwater acoustic metamaterials based on multi-physical field coupling model

In this paper, according to the internal structure of underwater acoustic metamaterial, a multi-physical field coupling model of underwater acoustic metamaterial is established by using finite element analysis. Based on the model, the influence of typical underwater acoustic metamaterial structure and material parameters on sound absorption performance is studied. The results show that increasing the height or radius of the local resonance mass unit in the metamaterial is beneficial to improve the low frequency sound absorption performance. With the increase of the distance between mass elements and the thickness of elastic material, the acoustic absorption performance increases first and then decreases. Increasing the elastic modulus of elastic material of the local resonance unit or matrix will lead to the decrease of low frequency sound absorption performance of the material and the improvement of high frequency sound absorption performance. Increasing the loss factor of elastic material of the local resonance unit or matrix material can broaden the sound absorption band. These rules can provide guidance for the design of underwater acoustic metamaterials.

Numerical Investigation of Stress-Strain State Effects on Strain Measurements with Fiber Bragg Grating Sensors

This study investigates the behaviour of resonant wavelengths of Fiber Bragg Gratings (FBG) inscribed within optically isotropic fibers under transverse loading, both in free and embedded conditions. A numerical-analytical approach is employed, utilizing the finite element method to calculate strain tensor components in the optical fiber core, followed by an analytical determination of resonant wavelengths and reflected FBG spectrum shape. The research demonstrates the influence of the ratio of host material and optical fiber elastic moduli on the birefringence level in FBG area under transversal loading. Based on analytical model of FBG spectrum simulation the discrepancy between analytically calculated and experimentally recorded resonant wavelength shifts in FBG embedded within isotropic material under varying transverse load levels is demonstrated.

Finite element solution of crack-tip fields for an elastic porous solid with density-dependent material moduli and preferential stiffness

In this paper, the finite element solutions of crack-tip fields for an elastic porous solid with density-dependent material moduli are presented. Unlike the classical linearized case in which material parameters are globally constant under a small strain regime, the stiffness of the model presented in this paper can depend upon the density with a modeling parameter. The proposed constitutive relationship appears linear in the Cauchy stress and linearized strain independently. From a subclass of the implicit constitutive relation, the governing equation is bestowed via the balance of linear momentum, resulting in a quasi-linear partial differential equation (PDE) system. Using the classical damped Newton’s method, the sequence of linear problems is then obtained, and the linear PDEs are discretized through a bilinear continuous Galerkin-type finite element method. We perform a series of numerical simulations for material bodies with a single edge-crack subject to a variety of loading types (i.e. the pure mode-I, II, and mixed-mode). Numerical solutions demonstrate that the modeling parameter in our proposed model can control preferential mechanical stiffness with its sign and magnitude along with the change of volumetric strain. This study can provide a mathematical and computational foundation to further model the quasi-static and dynamic evolution of cracks, utilizing the density-dependent moduli model and its modeling framework.

Into a rapid polymer characterization employing optical measurement systems and high-power ultrasonic excitation

This study presents a novel methodology for estimating the master curve of the complex modulus of viscoelastic materials using a combination of optical measurement systems and ultrasonic excitation. Traditional techniques for characterizing properties of viscoelastic materials are often time-consuming and encounter limitations that hinder their accuracy at high strain rates. To address this, a method was proposed that leverages two optical measurement systems to quickly assess material properties at multiple points on a sample. A high-power ultrasonic transducer was employed to excite the material at its first longitudinal natural frequency, creating non-uniform temperature variations and strain rates. A scanning laser Doppler vibrometer measured vibrations across the material, enabling computation of the complex modulus magnitude under varying conditions. These results were correlated with temperature readings obtained from an infrared camera. The constructed master curve using the proposed methodology closely resembled those established through quasi-static and dynamic uniaxial compression tests in the literature. Additionally, this method revealed a more substantial increase in complex modulus at high strain rates compared to traditional experiments, where this characteristic is less pronounced.

Cement-Stabilized Granular Volcanic Ash Materials for Construction of Low-Traffic Roads in Yemen

Granular volcanic ash (GVA) is a volcanic activity material with low density, high porosity, and other undesirable properties that must be improved prior to use in any construction. This material can be considered an alternative for use in road building, given its availability in many locations and in large quantities in Yemen. This article aims to investigate the potential use of GVA for the construction of roads in Yemen when treated with cement stabilizer. Two types of GVA materials with different colors were selected and referred to as red and black GVA materials. Tests performed included the unconfined compressive strength (UCS), compaction, indirect tensile strength (ITS), wetting–drying durability test, and ultrasonic pulse velocity (UPV) test for samples curried for 7 and 28 days. For each GVA–cement mixture, the cement content varied as 2%, 5%, and 8% by dry weight of GVA. Test results revealed that the compaction energy applied during sample preparation led to a significant reduction in the finesse modulus for red and black coarse GVA materials, with reductions of 10% and 23%, respectively. In addition, the cement content and curing period had a significant effect on UCS, ITS, and UPV for cement-treated GVA. The applicable quantity of cement required stabilizing GVA and achieving the base course specification for strength and durability criteria in flexible pavement with low traffic is 8% cement.

Field stiffening: A way to break the bounds on the properties of composites

It is common practice for humans to enhance the stiffness of a material by adding stiffer ingredients into it, which leads to the development of various composites of wide applications. However, irrespective of the configuration of the constituents of a multiphase composite, its compression elastic moduli are always between some bounds which are determined by the volume fractions and elastic moduli of the constituents inherently. Here, we report a magnetic composite material that is composed of a soft matrix material and two magnetic thin plates with small volume fraction. The compressive elastic modulus of the composite material is 25 times higher than the Halpin-Tsai upper bound due to the effect of the internal magnetic field. The measured maximum initial tangent modulus of the magnetic composite is ca. 40 times and 54 times higher than that of the nonmagnetic composite and PDMS matrix, respectively. This work provides a new direction for improving the performance of materials by fields.

An equation of state based on the scaling properties of vibrational spectra at high pressure

Inter-atomic forces control vibrational properties and elastic moduli of a solid material. Based on first-principle calculations, it has been reported that, for elemental solids, the Debye frequency scales linearly with density to high accuracy. Combining this with other scaling properties of vibrational frequencies at high pressure, a new equation of state is presented. The proposed equation of state is tested against available experimental data for various kinds of solids at high pressure and room temperature. The quality of description of the compressional behavior of solids by our proposed equation of state is, for many cases, comparable to or better than that with the Vinet EOS.

Discrete element investigation into Cosserat effects of granular materials: The measurement of couple stress and Cosserat modulus

Granular materials can be modeled as Cosserat continua at the macroscale. However, whether the Cosserat effect of granular materials exists has been controversial. In this paper, by using discrete element method (DEM), the macroscopic stresses like couple stress and the normalized modulus like Cosserat modulus in representative volume element (RVE) of granular materials are compared under two boundary conditions. The results shows that the couple stress and Cosserat modulus are not found in the RVEs under the displacement and rotation boundary, but are found under strain and moment boundary. The Cosserat modulus is significantly affected by size effect, as well as particle arrangement and aspect ratio. In addition, the presence of strain gradients can lead to an increase in the Young's modulus of granular materials, indicating that granular materials are affected by both strain and strain gradients. At the same time, two shear moduli are also measured and discussed.

Nonlinear dynamics of graphene-reinforced aluminum matrix composite aero-engine blade in thermal environment

This paper analyzes the nonlinear dynamic behaviors of the graphene-reinforced aluminum-based aero-engine blade under the primary resonance using the amplitude-frequency response curves, bifurcation diagram, Lyapunov exponent and Poincaré map. The lateral aerodynamic load, longitudinal aerodynamic load, centrifugal force and temperature are investigated for the graphene-reinforced aluminum-based aero-engine blade. Three kinds of configurations for the functionally graphene-reinforced gradient are considered. The effective Young's modulus of the composite material is given by Halpin-Tsai mode. The rule of the mixture gives other material properties. The results demonstrate that the bifurcation diagrams of the modal amplitude for the blade with the lateral aerodynamic load, longitudinal aerodynamic load and temperature have the periodic-chaos dynamic evolution process under the disturbance of the engine rotation speed. When the disturbance amplitude reaches a specific value, a new round of the periodic-chaos dynamic evolution will be continued. The results also clearly indicate that the aero-engine blade has the rich and complex nonlinear dynamic behaviors which include the hyperchaos, chaos, almost periodic, typical period-doubling bifurcation and anti-period-doubling bifurcation vibrations. This research is more helpful for the engineers to understand the nonlinear dynamic behavior of the blade.

Macro-indentation testing of soft biological materials and assessment of hyper-elastic material models from inverse finite element analysis

Mechanical characterization of hydrogels and ultra-soft tissues is a challenging task both from an experimental and material parameter estimation perspective because they are much softer than many biological materials, ceramics, or polymers. The elastic modulus of such materials is within the 1 - 100 kPa range, behaving as a hyperelastic solid with strain hardening capability at large strains. In the current study, indentation experiments have been performed on agarose hydrogels, bovine liver, and bovine lymph node specimens. This work reports on the reliable determination of the elastic modulus by indentation experiments carried out at the macro-scale (mm) using a spherical indenter. However, parameter identification of the hyperelastic material properties usually requires an inverse finite element analysis due to the lack of an analytical contact model of the indentation test. Hence a comprehensive study on the spherical indentation of hyperelastic soft materials is carried out through robust computational analysis. Neo-Hookean and first-order Ogden hyperelastic material models were found to be most suitable. A case study on known anisotropic hyperelastic material showed the inability of the inverse finite element method to uniquely identify the whole material parameter set.

Theoretical solution for bond-slip behavior of composite structures consisting of H-shape beam and concrete based on experiment, numerical simulation, and theoretical derivation

This paper presents a theoretical solution for bond-slip behavior of SRC interface based on experiment, numerical simulation, and theoretical derivation. Push-out tests of five specimens were firstly carried out, based on which, the simplified bond-slip model was proposed. The specimen was fabricated using the Q345H-shape steel (400 mm × 200 mm×13 mm × 8 mm) and C50 concrete (350 mm × 600 mm) with a bonding length of 500 mm. A FE model was established based on the bond-slip model to analyze the nonlinear bonding stress that are difficult to obtain from the experiment. The research shows that although the bonding stress in the elastic stage is not uniformly distributed, it is basically uniformly distributed when the ultimate bearing capacity is reached. It proves that assuming the average interfacial bonding stress under ultimate load to replace the maximum bonding stress is reasonable, which is crucial for designer to estimate interface bearing capacity and maximum bonding stress. Moreover, five different stages were obtained by the FE model analysis and the theoretical equations of bonding stress nonlinear distribution were obtained based on the boundary condition of each stage. The theoretical solution clearly showed the relationship between interface nonlinear stress distribution and influencing parameters including the bond area, elasticity modulus of material, section area of specimen, bond-slip constitutive model, and the external load. Based on the theoretical model, the influences of different parameters can be directly obtained without conducting further experiments and establishing different FE models.

Effect of lattice type on biomechanical and osseointegration properties of 3D-printed porous Ti6Al4V scaffolds

Porous structure is an efficient tool for optimizing the elastic modulus and osseointegration properties of titanium alloy materials. However, the investigations on pore shape remain scarce. In this study, we created porous Ti6Al4V scaffolds with a pore size of 600 μm but different lattices (cubic pentagon, diamond, cuboctahedron). The mechanical and biological properties of the scaffolds were investigated in static simulation analysis, in vitro mechanical compression test, computational fluid dynamics, as well as cell and animal experiments. The results demonstrated that the calculated yield strength difference between the three Ti6Al4V porous scaffolds was negligible, at approximately 140 MPa, allowing them to match the strength requirements of human bones. The diamond scaffold has the lowest calculated elastic modulus (11.6 GPa), which is conducive for preventing stress shielding. The shear stress was largely concentrated in the diamond scaffold, and the stress range of 120–140 MPa accounted for the greatest share. The mouse MC3T3-E1 cells were found to attach to all three scaffolds, with the diamond scaffold displaying a higher degree of cell adherence. There was more proliferating cells on the diamond and cubic pentagon scaffolds than on the cuboctahedron scaffolds (P < 0.05). The diamond scaffold exhibited the highest alkaline phosphatase activity and calcium salt accumulation in cell differentiation tests. Besides, the expression of osteogenic genes on the diamond scaffold was higher than that on the cuboctahedron scaffold, the cubic pentagon scaffold displaying the lowest expression. The in vivo studies revealed that all three scaffolds fused well with the surrounding bone and that there was no loosening or movement of the prosthesis. Micro-computed tomography, corroborated by the staining results of hard tissues, revealed that the level of new bone formation was the highest in the diamond scaffold, followed by the cuboctahedron scaffold (P < 0.05). Taken together, the diamond scaffold is comparatively better at optimizing the elastic modulus and osseointegration properties of titanium alloy materials, and thus is a preferred choice for porous design.

Effect of post-curing conditions on surface characteristics, physico–mechanical properties, and cytotoxicity of a 3D-printed denture base polymer

ObjectiveThis study aims to investigate the influence of post-polymerization (post-curing) conditions on surface characteristics, flexural properties, water sorption and solubility, and cytotoxicity of additively manufactured denture base materials. MethodsThe tested specimens were additively manufactured using digital light processing and classified into different post-curing condition groups: submerged in water (WAT), submerged in glycerin (GLY), and air exposure (AIR). An uncured specimen (UNC) was used as a control. The surface topography and roughness were observed. The flexural strength and modulus were determined via a three-point bending test. The water sorption and solubility were subsequently tested. Finally, an extract test was performed to assess cytotoxicity. ResultsDifferent post-curing conditions had no significant effects on the surface topography and roughness (Sa value). Various post-curing conditions also had no significant effects on the flexural strength. Notably, the flexural modulus of the WAT group (2671.80 ± 139.42 MPa) was significantly higher than the AIR group (2197.47 ± 197.93 MPa, p = 0.0103). After different post-curing conditions, the water sorption and solubility of the specimens met the ISO standards. Finally, all post-curing conditions effectively reduced cytotoxic effects. SignificancesPost-curing with different oxygen levels improved flexural properties, and flexural modulus significantly increased after the specimens were submerged in water. In addition, water sorption and solubility, and cytocompatibility were optimized by post-curing, irrespective of the post-curing conditions. Therefore, the water-submerged conditions optimized the flexural modulus of the 3D-printed denture base materials.

Study of antibacterial and mechanical properties of poly(methyl methacrylate‐co‐acrylic acid)/hydroxyapatite biocomposite by using artificial neural network approach

AbstractA novel, promising biocomposite was synthesized through the free radical polymerization method using methyl methacrylate (MMA), acrylic acid (AA), and hydroxyapatite derived from oyster shells (Os‐HA). Fourier transform infrared spectroscopy (FTIR) peaks indicate the conjugation of Os‐HA in the biocomposite. From the TGA analysis, it was observed that a weight loss of nearly 2% is achieved at 210°C, up to 15% at 210 to 420°C, and up to 95% at 420 to 580°C. The SEM image shows the uniform dispersion of the Os‐HA particles and strong interaction with the copolymer matrix. The broad spectrum at 2θ = 14.6° in XRD analysis indicates the amorphous nature of poly(MMA‐co‐AA)/Os‐HA. The higher inhibition zone of the biocomposite is observed at 125 μL against E. coli bacteria. The maximum water absorption is observed at 15 wt% of Os‐HA. The young's modulus gradually increases, while the impact strength decreases up to 20 wt% of Os‐HA. The artificial neural network (ANN) model has been used to assess the optimum values of impact strength, tensile strength, and Young's modulus of the biocomposite material. The correlation factor (R = 0.998) of the ANN model data indicates greater accuracy of the experimental result.

In silico optimization of actuation performance in dielectric elastomer composites via integrated finite element modeling and deep learning

Dielectric elastomers (DEs) require balanced electric actuation performance and mechanical integrity under applied voltages. Incorporating high dielectric particles as fillers provides extensive design space to optimize concentration, morphology, and distribution for improved actuation performance and material modulus. This study presents an integrated framework combining finite element modeling (FEM) and deep learning to optimize the microstructure of DE composites. FEM first calculates actuation performance and the effective modulus across varied filler combinations, with these data used to train a convolutional neural network (CNN). Integrating the CNN into a multi-objective genetic algorithm generates designs with enhanced actuation performance and material modulus compared to the conventional optimization approach based on FEM approach within the same time. This framework harnesses artificial intelligence to navigate vast design possibilities, enabling optimized microstructures for high-performance DE composites.

Comparison of the Flexural Strength and Elastic Modulus of Conventional, Milled and 3D-Printed Interim Restorative Materials Subjected to Different Intervals of Accelerated Aging

Comparison of the Flexural Strength and Elastic Modulus of Conventional, Milled and 3D-Printed Interim Restorative Materials Subjected to Different Intervals of Accelerated Aging

Regulating interface interaction in alumina/graphene composites with nano alumina coating transition layers.

The structure and properties of graphene/alumina composites are affected by the interface interaction. To demonstrate the influence of interface interaction on the structure of composite materials, a composite without graphene/matrix alumina interface was designed and prepared. We introduced a nano transition layer into the composite by pre-fabricating nano alumina coating on the surface of graphene, thus regulating the influence of interface interaction on the structure of the composite. According to the analysis of laser micro Raman spectroscopy, the structure of graphene was not seriously damaged during the modification process, and graphene was subjected to tensile or compressive stress along the 2D plane. The fracture behavior of the modified graphene/alumina composites is similar to that of pure alumina, but significantly different from that of pure graphene/alumina composites. The elastic modulus and hardness of composite material G/A/A are higher, while its microstructure has better density and uniformity. In situ HRSEM observation showed that there was a transition layer of alumina in the modified graphene/alumina composite. The transition layer blocks or buffers the interfacial stress interaction, therefore, the composite material exhibits a fracture behavior similar to that of pure alumina at this time. This work demonstrates that interface interactions have a significant impact on the structure and fracture behavior of graphene/alumina composites.