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Structural coloring of dental resin-based composites (RBC) is used to create universal chromatic materials designed to meet any aesthetic need, replacing the mixing and matching of multiple shades. The microstructural adjustments to create this desideratum involve nanoscale organic–inorganic core–shell structures with a particular arrangement. The generally higher polymer content associated with these structures compared to universal chromatic RBCs colored by pigments, which in their microstructure come close to regularly shaded RBCs, can influence the way the material ages. Accelerated and slow aging up to 1.2 years of immersion in artificial saliva at 37 °C were therefore compared in relation to their effects on the materials described above and in relation to the immersion conditions prescribed by standards. Quasi-static and viscoelastic parameters were assessed to quantify these effects by a depth-sensing indentation test equipped with a DMA module. The microstructure of the materials was characterized by scanning electron microscopy. The results convincingly show a differentiated influence of the aging protocol on the measured properties, which was more sensitively reflected in the viscoelastic behavior. Accelerated aging, previously associated with the clinical behavior of RBCs, shows a 2- to 10-fold greater effect compared to slow aging in artificial saliva of up to 1.2 years, highly dependent on the microstructure of the material.

This study aims to characterise the interface creep behaviour between geomembrane and geotextile (i.e. GM-GT) in the liner system. Two types of GM (i.e. smooth SGM and textured TGM) and two types of GT (i.e. nonwoven NWGT and woven WGT) were investigated using the conventional direct shear apparatus for four combinations of GM-GT. The interface friction angles ( φ i n ) between GM-GT were firstly determined at the normal stresses ( σ n ) of 25, 50, 100 and 200 kPa. The results show that TGM-NWGT has a much larger φ i n (23.9°) than the other three combinations which ranged from 9.5° to 11.1°. Subsequently, creep tests were conducted at three shear stress ( τ ) levels (i.e., 30, 50 and 70% of the peak stress ( τ p ) under each normal stress). The creep test results of the four combinations were analysed and a power equation of time was used to estimate creep displacement ( δ c p ) . The coefficients A and B in the power equation were found to be functions of Young's modulus of the composite material ( E c ), time, σ n , τ , τ p , and φ i n . The tertiary creep stage was not observed in the test and it is recommended that longer duration GM-GT interface creep tests should be conducted for in-depth understanding of the interface creep mechanism.

Flexible thermal conducting materials with the combination of excellent thermal conductivity and mechanical strength are highly desired for many practical applications, but meeting this strict requirement remains as a big challenge. Herein, facile preparation of highly aligned carbon nanotube (CNT) films is demonstrated, which involves the continuous production of a hollow cylindrical CNT assembly, followed by in-situ alignment of CNTs through optimizing the winding rate and a further stretching-pressing process. Benefiting from the resultant excellent CNT alignment and high density (1.59 ± 0.05 g cm−3), the CNT film simultaneously has a high thermal conductivity of 558.06–700.15 W m−1 K−1, electrical conductivity of 4870 ± 150 S cm−1, mechanical strength of 2.74–2.95 GPa, and Young's modulus of 55.2–58.9 GPa. The combination of such high thermal and mechanical properties is outstanding for carbon-based thermal conducting materials. Furthermore, the CNT material exhibits negligible structural and mechanical decay even after 500 cycles of bending test. Our study provides an effective strategy toward developing new thermal conducting materials for applications under harsh conditions.

Surface initiated electro-polymerization of acrylamide on carbon fiber with methodically varied amounts of acrylamide monomer and N,N′-methylene bis-acrylamide crosslinker is explored in this study. The effect of the polymer coating on tensile strength, Young's modulus, and interfacial properties of carbon fibre in an epoxy resin was determined. A significant improvement in tensile strength, tensile modulus, and interfacial shear strength (IFSS) across all modified samples was observed, with the most notable improvements to tensile strength, tensile modulus and IFSS being 38%, 15% and 192.5%, respectively. This covalently bound polymer coating provides the best kind of solution for the two most crucial limitations of carbon fibre, with the minimum amount of effort, time, and cost.

The processing scale and mechanical properties of graphene (Gr) reinforced metal matrix composites are highly desired for a wide range of critical applications. However, a long-standing problem is that Gr possesses poor dispersibility and weak interfacial strength with the metal matrix. In this work, we offer an in-situ liquid metallurgy strategy for fabricating Mg matrix composites with excellent modulus, strength and plasticity by a chemical reaction between carbon dioxide (CO2) and Mg melt. This processing route enables the in-situ synthesis and modification of Gr in the metal melt simultaneously, which yields an optimal microstructure including uniform dispersion of Gr and strong interfacial bonding between Gr and Mg matrix. This novel approach can be readily adapted to large-scale industrial production of Mg matrix composites and even offers a general design pathway for manufacturing metal matrix composites.

The physical, thermal, structural, and mechanical properties of poly(methyl methacrylate) PMMA foils cast from solutions of toluene were investigated by differential scanning calorimetry, optical microscope, Fourier infrared spectroscopy, and dynamical mechanical analysis. The PMMA foils were prepared from a different ratio of PMMA powder with toluene solvent by the solution cast method. The surface features, glass transition temperature, and C-H bonds of foils were investigated and compared with commercial PMMA foil. The mechanical characterization of foils was examined by using static and dynamic loads in axial and transverse modes. The tensile behaviors of the commercial and as-prepared foils were investigated by using a strain rate of 0.01/s. The dynamical behavior of the foils was tested in tensile mode using 0.1 N of stress with a frequency of 1 Hz for the determination of storage, loss modulus, and damping values of the tan delta. A significant shape memory was observed in all of the prepared PMMA foils. The solution cast method allows for tuning the glass transition temperature of polymer foil that could easily integrate with the NiTi alloy phase transition temperature to fabricate a suitable composite structure. Integrating both structures will open the flexibility in bistable actuators in composite structures as a function of thermal cycles.

This study proposed an analytical model to investigate strain transfer mechanism between FBG sensor and measured geogrid. Both geometric and mechanical parameters (bonding length, bonding thickness, bonding width, and Young's modulus) of interaction interface can be taken into account in this model. Both laboratory tensile tests of geogrid and experimental data in published literatures were used to verify the developed model. Validation study shows that the maximum relative error between experimental values and theoretical values is 8.2%, indicating that this theoretical model can be used to reflect geogrid deformation. Parametric study indicates that bonding length, bonding thickness, bonding width, Young's modulus of adhesive layer, and substrate layer have significant influence on strain transfer coefficient. Grey Relational Analysis (GRA) method was used to analyze influencing sensitivity of different parameters. GRA parameter values of bonding width and length are higher than 0.72, indicating that bonding width and bonding length are relatively dominant factors affecting average strain transfer coefficient in comparison with bonding thickness, Young's moduli of substrate and adhesive layers (their related GRA values are all lower than 0.692).

To obtain the optimum balance between performance and cost, white mud (lime mud) was incorporated into the shell layer of core–shell structured wood-plastic composites (Co-WPCs). The purpose of this study was to observe the effect of the white mud loading in the shell on the water absorption, surface wettability, and mechanical and dynamic thermomechanical properties of Co-WPCs. The results showed that the shell layer improved the water resistance. The flexural strength and modulus increased by filling the shell layer with white mud, but the impact strength decreased. For Co-WPCs with 20% white mud in the shell, the surface free energies of the core layer and shell layer material were similar, which indicated good interfacial adhesion between them. Dynamic thermomechanical analysis indicated that the storage modulus of the Co-WPCs was higher when the white mud content was 15%, and the interfacial interaction parameter B of the composites increased significantly. The storage modulus had the strongest frequency dependence in the glassy state, while the composites displayed no dependence in the rubbery state. The glass transition activation energy of the composites decreased upon increasing the white mud content in the shell layer, indicating that a high white mud content affected the interface of the Co-WPCs. These findings demonstrate that filling the shell with white mud reinforced the Co-WPCs, and 15–20% white mud exhibited the best properties.

A simple method for measuring the Young's modulus of thermoplastic polymers at the nanoscale is proposed. Nanoindentation tests have been carried out on three polymers (ABS, PET and PP) using the Berkovich indenter tip. The elasticity moduli obtained from the reduced moduli thanks to the slope of the initial part of the discharge curve were greater than the real moduli of these polymers. For this, a simple method is proposed to minimize the error made on the determination of the modulus which is based on the calculation of several stiffnesses between 10 and 98% of the maximum load on the experimental unloading curve. The results show that the calculated moduli at a load less than 50% of the maximum load were close to the macroscopic moduli and the effect of viscosity was minimized. In the end, the elastic Young's modulus obtained by our approach is in very good agreement with the result of the tensile tests.

The behavior of the concentrated compressive load applied to the narrow face of cross-laminated timber (CLT) panels is an essential parameter in the design of multi-story timber buildings. Therefore, this paper presents a methodology to evaluate the strength and stiffness of the concentrated compressive load on the narrow face of the CLT. The methodology accounts for the effects of side margins, CLT directions, and CLT composition. In this methodology, a dented shape at the surface of CLT resulting from loading, which has an important role in the behavior of the concentrated compressive load applied to the narrow face, is examined via finite element (FE) analysis. The reproducibility of the FE models is verified experimentally. The proposed methodology is then used to predict the yield stress and Young’s modulus of the concentrated compressive load on the narrow face of the CLT panels using equations, which were proposed based on the exponential function curves. The calculated values of the yield stress and Young’s modulus obtained by the equations based on the exponential function curves considering the effects of the out-of-plane deformations in the outermost laminae were similar to the experimental results of previous studies.

Acid rain is often formed in southwestern China. Red-bed landslides often occur and cause major social and economic losses. The shear-slip process of red-bed landslides is affected by the creep characteristics of the weak interlayers in the rock mass. Samples of red-bed soft rock with weak interlayers of mudstone in Lufeng County of the Central Yunnan Water Diversion Project were tested in shear-creep tests in an acid environment. Combining with the functional relationship between the viscoelastic modulus and the acidic environment change, a stress-acidity-strain–time model is established based on the Burgers model. The results show that the long-term strength of the red-bed soft-rock weak interlayer in a mudstone gradually decreases with the increase of acidity. The viscoelastic modulus is linearly related to acidity. Compared with the traditional Burgers model, the improved Burgers model taking into account the effect of the acidic environment provides improved accuracy in describing the shear-creep behavior of the red-bed soft-rock weak interlayers.

Pigments are often used in water borne barrier coatings but tend to make the coatings prone to failure. The pigment properties effects on this issue is lacking in literature. In this work, coatings that used pigments with different moduli but with similar size and aspect ratio were characterized in terms of water vapor resistance before and after folding. Coatings with talc had better water vapor resistance than coatings with similar sized kaolin. Talc also limited the degradation of barrier properties when folded. Coatings with metalized poly(ethylene terephthalate) (PET) flakes had better failure resistance than coatings with similarly sized rigid mica. Both results are likely caused by the ability of the low modulus pigment to deform and allow for strain to occur in the pigment as well as the latex phase. Styrene-butadiene (SB) and natural rubber (NR) latex coatings had a better failure resistance than styrene-acrylate (SA) latex, which is likely due to their low glass transition temperatures and high strain-to-failure values. However, coatings with high amounts of SB or NR latex may lead to blocking issues in production. Adding kaolin into SA and SB latex mixtures resulted in improved water vapor barrier property and failure resistance.

This paper focuses on the disposal of iron tailings sand (ITS) and reclaimed inorganic binder stabilized aggregate (RAI), and a new “ITS plus RAI” solid waste treatment method is innovatively proposed, which uses ITS and RAI as a new base course material to replace of new aggregates by 100%. It is found that the new ITS and RAI mixture has excellent compressive performance by designing the material composition of the mixture, which can meet the design strength of different levels of pavement under various load conditions. A series of laboratory tests are used to study the effect of the content of special cementitious material and iron tailings on the uniaxial compressive strength, flexural-tensile strength, compressive resilience modulus, and flexural-tensile resilience modulus of recycled mixture. And, the scanning electron microscope test (SEM) and X-ray diffraction test (XRD) are used to compare the surface morphology characteristics and hydration products of the recycled mixture under different ratios and to discuss the formation mechanism of the strength of the mixture. The test results show that the macroscopic change pattern in laboratory tests is basically consistent with the results in microanalysis. The relationship between compressive strength and compressive resilience modulus and flexural resilience modulus is also established by linear regression. This solid waste treatment method is applied to the pavement renovation project of national and provincial roads in Shanxi Province (within Linfen), to replace the existing base material by using recycled mixture, and the results show that it can save not only the carbon emission from stone mining and processing but also the construction cost, while producing good social and economic benefits and promoting the process of carbon neutralization in the world.

3D printing technology has the potential to allow for the development of customized lightweight porous materials with superior mechanical performances that are difficult to produce by conventional methods. In this study, Ti–Zr gyroid scaffolds with high compressive strength were produced via a selective laser melting (SLM) process using a pre-mixed Ti–ZrH2 powder. The effect of lattice geometries and the addition of ZrH2 on compressive performance were investigated. The results indicated that there was a homogeneous distribution of Zr in α-Ti. By increasing the concentration of ZrH2 to 7 wt.%, the yield strength and ultimate compressive strength increased by 35–55% compared to those of the Zr-free alloy. Young’s modulus was found to be in the range of 1–5 GPa. The high compressive strength and low Young’s modulus of the Ti–Zr gyroid scaffolds obtained in this study showcase the strong potential of this material for implant applications.

Abstract Open-cell Al foams were produced by the replication casting technique in three different pore sizes. All produced foams were physically characterized, determining their relative density, porosity, and pores per inch, as well as their mean pore surface area and diameter. Permeability tests were carried out by means of the injection of a highly pressurized gasoline additive at room temperature and 200 °C, at pressures of up to 25,000 psi. The structural capacity of the studied specimens to conduct fluids at these critical experimental conditions was assessed by means of compression tests in order to determine their mechanical properties after the permeability tests, e.g., energy absorption capacity, Young’s modulus, and plateau stress. It was found that the produced open-cell Al foams were able of conducting the gasoline additive at critical flow conditions of pressure and temperature, without suffering important physical nor structural damage. Graphic abstract

Several studies have confirmed the geocell reinforcement system as potential road material. However, there is a wide gap between the number of research studies evaluating the geocell in the laboratory and those dealing with road design methods using the geocell. Due to this gap, the geocell system has not reached its full potential in highways. The present study proposes fragility modeling to design low volume roads by considering the geocell reinforced layer's modulus. A predictive model was developed to estimate the geocell layer's modulus using laboratory and finite element analysis results. The results indicate that geocell reinforcement reduces the stresses on the underlying road layers. The developed fragility approach is then used to examine three road designs for Texas's low volume road involving different geocell reinforced layers. The obtained fragility curves indicate the reliability of each of the three road designs against the traffic load and can thereby assist decision-makers in selecting the optimum design. By designing geocell reinforced roads via fragility modeling, highway officials will be able to integrate any uncertainties in the design inputs and check designs against road performance criteria such as rutting and fatigue cracking, and against decision criteria such as cost, emissions, etc.

The microstructure, mechanical and magnetic properties of Zr–x (8, 9, 10, wt.%)Nb–4Sn alloys were investigated to obtain novel Zr-based alloy with low Young’s modulus and magnetic susceptibility for biomedical implants. After homogenization annealing, hot forging and solution annealing, Zr–8Nb–4Sn, Zr–9Nb–4Sn and Zr–10Nb–4Sn alloys were composed of β+α″ phase, β+α″ phase, β+ω phase, respectively. The temperature at which the α" and ω phase were transformed into β phase during the heating process was about 200 ​°C, and the phase transformation temperature decreased with the increase of Nb element. Among all the Zr–x (x ​= ​8,9,10)Nb–4Sn(wt.%) alloys, Zr–9Nb–4Sn alloy had the lowest Young's modulus of 46.6 ​GPa and the low magnetic susceptibility of 1.294 ​× ​10−6 cm3g−1, which has a good application prospect for biomedical applications.

Composite materials designed by nature, such as nacre, can display unique mechanical properties and have therefore been often mimicked by scientists. In this work, we prepared composite materials mimicking the nacre structure in two steps. First, we synthesized a silica gel skeleton with a layered structure using a bottom-up approach by modifying a sol-gel synthesis. Magnetic colloids were added to the sol solution, and a rotating magnetic field was applied during the sol-gel transition. When exposed to a rotating magnetic field, magnetic colloids organize in layers parallel to the plane of rotation of the field and template the growing silica phase, resulting in a layered anisotropic silica network mimicking the nacre's inorganic phase. Heat treatment has been applied to further harden the silica monoliths. The final nacre-inspired composite is created by filling the porous structure with a monomer, leading to a soft elastomer upon polymerization. Compression tests of the platelet-structured composite show that the mechanical properties of the nacre-like composite material far exceed those of nonstructured composite materials with an identical chemical composition. Increased toughness and a nearly 10-fold increase in Young's modulus were achieved. The natural brittleness and low elastic deformation of silica monoliths could be overcome by mimicking the natural architecture of nacre. Pattern recognition obtained with a classification of machine learning algorithms was applied to achieve a better understanding of the physical and chemical parameters that have the highest impact on the mechanical properties of the monoliths. Multivariate statistical analysis was performed to show that the structural control and the heat treatment have a very strong influence on the mechanical properties of the monoliths.

In this study, the performance of the stone column encased with conductive jute geotextile in improving the characteristics of soft clay under k0 stress condition was evaluated using a custom-designed large-scale consolidation test setup. The electrokinetic-encased stone column (e-ESC) was designed as a cathode, while mild steel rods were chosen as anodes, and by applying a voltage gradient of 0.1 V/mm between the electrodes, electrokinetic processes were initiated. The efficacy of using the e-ESC in improving the performance of soft clay was assessed by comparing the results with an ordinary stone column (OSC) and encased stone column (ESC) reinforced soft clay. The results from the study reveal that the inclusion of stiffer material like OSC and ESC in soft clay has significantly increased undrained shear strength and modulus of subgrade reaction of the composite ground with a reduction in settlement and compression index. Due to the application of the voltage gradient between the electrodes, the rate of consolidation settlement of composite ground has significantly increased when compared to the OSC/ESC case. Further, it was confirmed from the chemical and mineralogical analysis that the pH, chemical composition, mineral phases, and microfabric of soft clay were altered with the voltage gradient.

Two-dimensional (2D) trigonal selenium (t-Se) has become a new member in 2D semiconducting nanomaterial families. It is composed of well-aligned one-dimensional Se atomic chains bonded via van der Waals (vdW) interaction. The contribution of this unique anisotropic nanostructure to its mechanical properties has not been explored. Here, for the first time, we combine experimental and theoretical analyses to study the anisotropic mechanical properties of individual 2D t-Se nanosheets. It was found that its fracture strength and Young's modulus parallel to the atomic chain direction are much higher than along the transverse direction, which was attributed to the weak vdW interaction between Se atomic chains as compared to the covalent bonding within individual chains. Additionally, two distinctive fracture modes along two orthogonal loading directions were identified. This work provides important insights into the understanding of anisotropic mechanical behaviors of 2D semiconducting t-Se and opens new possibilities for future applications.

Zirconium based alloys, as refractory metallic materials, can be fabricated into brittle zirconium hydride by hydrogen charging and can then be used as neutron moderators in the nuclear industry. In this study, the fracture toughness of bulk e zirconium hydride was attempted to be estimated by means of Vickers microhardness indentation. Several representative semi-empirical formulas based on Palmqvist and half-penny crack models were adopted, and relevant parameters including Young’s modulus, Vickers hardness, indentation dimension, and crack length were respectively determined. It was observed that cracks began to nucleate at impression corners and peripheries when the load was higher than 500 gf. Crack length at 1000 gf was measured and used to estimate the fracture toughness. The results showed similar values to previous reports obtained from conventional experimental means, indicating that Vickers microhardness indentation is an available method for estimating the fracture toughness of e zirconium hydride.

In this study, Ti-(0-30 wt.%)Nb alloys developed from elemental powders were fabricated by the Selective Laser Melting (SLM) process. Compositional homogeneity, microstructure and mechanical performance were investigated as a function of energy density. The proportion of un-melted Nb particles and isolated pore count reduced with increasing energy density, while Ti allotropic content (i.e. α’, α” and β) varied with energy density due to in-situ alloying. Increasing the Nb content led to the stabilisation of the α” and β phases. The mechanical properties were similar to those compositions manufactured using casting methods, without further post processing. The addition of 20Nb (wt.%) and using an energy density of 230 J/mm3 resulted in a Young’s Modulus of 65.2 ± 1.8 GPa, a yield strength of 769 ± 36 MPa and a microstructure of predominantly α” martensite. This strength to stiffness ratio (33% higher than Ti-10Nb and 22% higher than Ti-30Nb), is attributed to in-situ alloying that promotes solid solution strengthening and homogenisation. These alloys are strong contenders as materials suitable for implantable load-bearing orthopaedic applications.

The cubic-phase antimony trioxide (α-Sb2O3) is a room-temperature stable molecular crystal, composed of cage-like tetraantimony hexoxide (Sb4O6) molecules. Despite its versatile functionality, the van der Waals (vdW) bond-dominated nanomechanics is still unclear. Here, the bending plate-like linear behaviors of high-quality α-Sb2O3 nanoflakes were observed using the nanoindentation method. It is found that the cage-molecular crystal owns a very low in-plane Young's modulus of 14.9 ± 0.8 GPa and a remarkable maximum tensile strain of 6.0-8.8%, corresponding to a rupture strength of 0.89-1.31 GPa. Elucidated by the atomistic simulations, the compliant elastic modulus and the unexpectedly strong rupture strain are associated with the high-symmetry vdW bonding structure. The vdW nanomechanics is of fundamental and technological relevance to nanoelectronics.

This study explores the benefits of utilizing recently developed protocols for microstructure quantification and the multiresolution mechanical characterization of Ti-based bulk metallic glass matrix composites. Four alloys with different compositions and amorphous (glass) fractions were studied. Microstructure quantification of the amorphous and crystalline phase in these alloys was performed using rotationally invariant 2-point spatial statistics and principal component analysis on approximately 1300 micrographs. Mechanical properties of the constituent phases as well as the bulk mechanical properties of the composites were measured using recently established high-throughput multiresolution spherical indentation stress–strain protocols. The results showed that decreasing amorphous volume fraction results in a decrease in both bulk Young’s modulus and the bulk yield strength of the samples, without significant changes in the mechanical properties of the constituent phases.

We have developed cross-linked polyrotaxane (cPR) that is composed of moveable cross-links and slide-ring components, in its backbone. The cPR is blended with oil well cement to improve elastic properties, and it has demonstrated improvement in elastic modulus with minimum effect on compressive strength. The optimization of curing time, fluid flow behavior, and dynamic strength development in the presence of cPR in cement are also evaluated. The Young’s modulus and compressive strength are measured at 20 MPa and 150°C to simulate downhole conditions. Remarkably, cement—cPR has, revealed a 33% increase in strain compared to neat cement.

In this paper, an Artificial Intelligence (AI) model is constructed for the behavior prediction, i.e. Young’s modulus, of polymer/carbon-nanotube (CNTs) composites. The AI is proposed to overcome t...

Coatings used in tribological applications often exhibit high hardness and stiffness to achieve high wear resistance. One coating characterization method frequently used is nanoindentation which allows the determination of indentation hardness and indentation modulus among other material properties. The indentation modulus describes the elastic surface behavior during indentation and is, among hardness, a direct indicator for wear resistance. To obtain the true indentation modulus of a coating, it must be measured with varying loads and then extrapolated to zero load. Current recommendation of the standard ISO 14577-4:2016 is a linear extrapolation which fits poorly for nonlinear curves. Such nonlinear curves are commonly found for high hardness mismatches between coating and substrate, for example, superhard tetrahedral amorphous carbon coatings (ta-C) on a steel substrate. In this study, we present a new empirical fit model, henceforth named sigmoid. This fit model is compared to several existing fit models described in the literature using a large number of nanoindentation measurements on ta-C coatings with wide ranges of indentation modulus and coating thickness. This is done by employing a user-independent and model agnostic fitting methodology. It is shown that the sigmoid model outperforms all other models in the combination of goodness of fit and stability of fit. Furthermore, we demonstrate that the sigmoid model’s fit parameter directly correlates with coating thickness and thus allows for a new approach of determining ta-C coating thickness from nanoindentation.

Li-ion solid-state electrolytes (SSEs) have great potential, but their commercialization is limited due to interfacial contact stability issues and the formation and growth of dendrites. In this study, a machine learning regression algorithm was implemented to screen for mechanically superior SSEs among 17,619 candidates. Elasticity information (14,238 structures) was imported from an available database, and their machine learning descriptors were constructed using physiochemical and structural properties. A surrogate model for predicting the shear and bulk moduli exhibited R2 values of 0.819 and 0.863, respectively. The constructed model was applied to predict the elastic properties of potential SSEs, and first-principles calculations were conducted for validation. Furthermore, the application of an active learning process, which reduced the prediction uncertainty, was clearly demonstrated to improve the R2 score from approximately 0.6-0.8 by adding only 32-63% of new data sets depending on the type of modulus. We believe that the current model and additional data sets can accelerate the process of finding optimal SSEs to satisfy the mechanical conditions being sought.

Pyrolytic carbon (PyC) plays a critical role in many applications for its unique properties. In ceramic composite systems, the elastic properties of PyC at the fiber/matrix interface drive toughening mechanisms, enabling structural performance at increased operating temperatures. PyC expresses a wide range of crystallographic texture depending on fabrication parameters. As a result, modelling and optimization requires direct understanding of the texture-property relationships at the relevant length scales. This research leverages high-resolution transmission electron microscopy (HRTEM) to link the PyC microstructure to the elastic response observed via digital image correlation (DIC) during micropillar compression. The HRTEM and DIC results quantitatively resolve a gradient for microstructural texture and Young's modulus respectively, showing that disordered texture increases compressive stiffness normal to the average orientation of the PyC basal planes. The values for modulus ranged from 55 to 150 GPa, which are large compared to most experimental methods, but may be more realistic considering the uniaxial stress state and length scale. The behavior supports findings from numerical homogenization models, suggesting that this advanced technique may provide a path forward for optimization and validation of these nanoscale elasticity models.

We report on the fabrication of oriented collagen films by drying a dilute collagen solution on a polydimethylsiloxane (PDMS) substrate with a micrometer grooved surface. The resultant films show optical and mechanical anisotropy along the groove direction, and have a high mechanical strength with Young's modulus of 2.3 GPa. This process might enable collagen materials to be applied to anisotropic biocompatible substrates, large-area functional scaffolds, and soft robotic materials.

Rubber nanocomposites experiencing dynamic shears at large strain amplitudes (γ) exhibit the nonlinear Payne effect featured by decays of storage and loss moduli (G′ and G″) or by G′ decay accompanied with G″ overshoot near a critical strain amplitude. The occurrence of the Payne effect has been assigned to damages of “filler network” and rubber-filler interfacial interactions for a long time and to Rouse dynamics of rubber chains recently. To solve the dispute, influences of extraction, crosslinking, and paraffin swelling on the Payne effect of carbon black filled natural rubber nanocomposites are investigated systematically. Master curves of G′ as a function of γ could be always created, and overshoot of G″ in the filled vulcanizates weakens with increasing filler content and intensifies by dilution via paraffin swelling, suggesting that the Payne effect is not mainly rooted in the “filler network” and rubber-filler interfacial interactions. The filler reduces the onset strain amplitude of the Payne effect by amplifying microscopic strain amplitude of the rubber phase, irrespective of whether the matrix is crosslinked or not and whether the crosslinked matrix is swollen or not. Partial removal of bound rubber by compounding the paraffin swollen compounds could lower modulus and eliminate G″ overshoot of the deswollen vulcanizates without influence on the mechanism of G′ decay accompanying Payne effect. The overshoot is found to be closely related to the overall viscous characteristic of the vulcanizates in the linear viscoelastic regime. Provided herein are new insights for recognizing the important roles of the viscoelastic rubber phase on the Payne effect of the nanocomposites.

Brittle thin film photovoltaics (PV) that are integrated with load-bearing structures can be subjected to large strains that lead to fragmentation and performance degradation. Such adverse effects can be mitigated, or altogether eliminated, by mechanically isolating a thin PV module from the underlying load-bearing structure. We developed an effective and efficient strain attenuation strategy to eliminate strain transfer from a stiff unidirectional Carbon Fiber Reinforced Polymer (CFRP) laminate to an integrated thin amorphous Si PV module. An analytical model of the three-layer material system (CFRP laminate, interface layer and PV module) was employed to create strain attenuation maps that depend on the length of the PV module and capture the coupled effects of the shear modulus and the thickness of the interface layer (G2, t2), and the Young’s modulus and the thickness of the PV module (E3, t3) through the terms G2/t2 and E3t3, respectively. Based on these strain attenuation maps, polydimethylsiloxane (PDMS) was identified as an effective and versatile interface material, which provided up to 100% strain attenuation between the CFRP laminate and the PV module. After accounting for confinement effects on the effective modulus of the PDMS interface layer, a very good agreement was achieved between the measured and the predicted strain attenuation. Importantly, the PDMS interfacial layer preserved the initial fill factor of the PV module until CFRP laminate failure at 1.7% strain, while in the absence of the PDMS interface the fill factor decreased when the CFRP laminate strain exceeded 0.80%.

This study provides an insight into the structure-property relationship of graphene network (GN) reinforced metal matrix composites (MMCs). Molecular dynamics results show that the interlocking structure improves the deformation compatibility between the GN and matrix, as well as increases the load-sharing of GN. And the mechanical interlocking can be further enhanced by the dislocation-GN interactions as the GN being straightened. The straightening of GN also enables itself to release its stress concentrations through overall deformation, which helps the GN perform better in dislocation-blocking than graphene sheets. Besides, curved portions of GN contribute more to dislocation-GN interactions while the straight portions do better in load-sharing. With the hole-like defects on whether straight or curved portions of GN, both the strength and Young's modulus of the imperfect GN reinforced composites are reduced. However, these defects enable the matrix to be connected into a continuous body, by which the ductility of imperfect GN reinforced Ni matrix composites is improved since their failures are mainly dictated by the fracture of Ni matrix, while the rupture of GN determines the failure of composites reinforced by the GN without hole-like defects.

The melt-quenching technique was used to synthesize tellurite glasses of the chemical composition 80TeO2-(20-x) ZnO-xV2O5. X-ray diffraction (XRD) patterns indicate the amorphous nature of the prepared glasses. Raman and FTIR measurements demonstrate a progressive substitution of the Te-O-Te linkages by the Te-O-V bridges and the formation of VO4 and VO5 units by a change of the vanadium coordination due to the higher number of oxygens incorporated by further addition of V2O5. The AC conductivity was investigated in the frequency range of 40 Hz to 107 Hz between 473 K to 573 K. A good coherence of the AC conductivity was found using a model correlating the barrier hopping (CPH) and the dominant conduction process changes from ionic to polaronic with the addition of V2O5. The dielectric constant exhibits high values in the range of lower and medium frequencies. Both variations of the electric modulus and the dielectric loss parameters with frequency and temperature showed a relaxation character mainly assigned to the vanadate phases. The electric modulus displays a non-Debye dielectric dispersion and a relaxation process. The present results open the door to future zinc-tellurite glasses-doped vanadium exploitation as a potential electrolyte-based material for solid-state batteries.

An ecofriendly fiber reinforced polymer (FRP) had been used in the last decade to enhance the short concrete column’s strength and deformation capacity. This study involves the wrapping of FRP sheets with a thickness of 3 mm and 5 mm on a short column, and then the compressive strength is determined. The rectangular columns of size 150 mm × 300 mm are used for this study, and cast under the grades of M20 and M40 are wrapped with GFRP sheets at the thickness of 3 mm and 5 mm. These results are clarified at a specific thickness of the FRP-wrapped columns. It provides a maximum axial compressive strength, and Young’s modulus gets enhanced rigorously when it is to be compared to the normal concrete. This thesis deals with experimental studies of different parameters associated with wrapped glass fiber reinforced polymer (GFRP). In M20 grade, when the 3 mm wrapped specimen and the 5 mm wrapped specimen are compared, the specimen wrapped with 5 mm increases 5.182% more than the specimen wrapped with 3 mm. In M40 grade, when the 0 mm, 3 mm, and 5 mm wrapped specimens are compared, the specimen wrapped with 5 mm increases 2.47% more than the specimen wrapped with 0 mm. The 5 mm wrapping attains the maximum strength.

Nanoporous metals have received significant attention as a new class of structural and functional materials. However, the macroscopic brittle fracture under the tensile test is an impediment to their practical applications. Thus, it is of central importance to develop nanoporous materials with low cost and high tensile ductility. Herein, a nanoporous Cu film supported on a pure Cu substrate (NPC@Cu) was fabricated by utilizing a liquid Ga assisted alloying-dealloying strategy, and the thickness of NPC film can be precisely regulated by changing the mass loading of liquid Ga. In-situ X-ray diffraction was performed to further explore the alloying/dealloying mechanisms. The NPC@Cu films show good tensile mechanical properties with a minimum elongation of 13.5 %, which can be attributed to the good interface bonding and certain modulus matching between the nanoporous Cu layer and the Cu substrate. Our findings demonstrate that the design of film-substrate structure provides a feasible strategy for enhancing the mechanical properties of nanoporous metals.

Mastering mechanical properties of polymers at nanometer scale is highly demanded yet remains challenging. Pioneering advances determined Young's modulus in ultrathin polymer films and attained unprecedented results including rubbery stiffening. However, many viscoelastic properties such as dynamic mechanical behavior of freestanding nanoconfined polymer films are still unknown. Here we demonstrate striking changes of stiffness and the ratio between elastic and viscous responses in thin PDMS films, using a microvibrational system which enables direct measurements of dynamic stress-strain relation of freestanding films. The results show that elastic modulus is enhanced by a factor of 135 in 50 nm films than the bulk, while the viscous response substantially increases at strains >0.05 in 125 nm films. These observations exhibit significant alterations of viscoelasticity under nanoconfinement. With insights on the underlying mechanism of these results, this study is expected to provide new evidence toward gaining a comprehensive understanding of nanoconfinement effect of soft matter.

Delamination and fiber pull-out remain significant problems with carbon fiber-reinforced epoxy composites due to the brittle nature of epoxy and weak fiber–matrix interface. The present study approaches overcome these problems by fabricating a multiscale carbon fiber-epoxy composites laminated composite with graphene nanoplatelets reinforced matrix, using a vacuum-assisted resin infusion method. Incorporation of 0.2 wt.% graphene nanoplatelets in carbon fiber-reinforced epoxy composites enhances fracture toughness by ~ 35% and ultimate tensile strength by ~ 22%, owing to significant adhesion between fiber and matrix. Thorough fiber–matrix interfacial characterization revealed improved modulus gradient across the interface, ~ 38% more energy absorption during delamination, and ~ 42% higher fiber pull-out strength from the matrix.

Revolutionary advances have been observed in lattice structure fabrication, which is a unique capability of additive manufacturing. In particular, lattice structures have been employed to regulate the mechanical properties of metals and polymers. In this work, the true impact of lattice structures on superelastic behavior was experimentally investigated. Finite element analysis was also used to evaluate the stress and displacement of lattice structures. Nylon-12 is an elastic polymer that does not typically demonstrate superelastic behavior. The HP Multi Jet Fusion method was used to fabricate three different lattice structures: a soft box (BSL), X shape, and rhombic dodecahedron (RDL). Mechanical tests showed that BSL was able to recover 30.697% of the strain in the first compression cycle and 66.233% in the fifth compression cycle, which is impressive for a non-superelastic material. The reduced possibility of yield failure, lower Young’s modulus, and low stiffness of SBL increased its strength. SBL displayed better superelastic behavior with the lowest Young’s modulus among the three lattice structures. This study not only designed and tested lattice structures but also compared the superelastic performances of selected lattice structures.

Composite materials of polyethylene terephthalate with silanized halloysite nanoclay were prepared and characterized. Halloysite was first functionalized with benzoyloxypropyltrimethoxysilane and then incorporated it into the polymer matrix via melt extrusion at 0.5, 1, and 2 wt% clay load ratios. The modified clay was characterized by means of elemental carbon quantification, thermogravimetric analysis, X-ray diffraction, and nitrogen adsorption–desorption. The silanization was confirmed to have taken place with an approximate reaction yield of 5%. While the silanization did not significantly affect the crystal structure or the morphological properties of the clay, a mass loss starting from 190 °C attributed to the organosilane compound used to modify the clay was observed in the reacted samples, along with increased thermal stability. The composite materials exhibited an increase in Young’s modulus and a decrease in the ultimate strain, but not a significant change in the oxygen permeability of the composites with respect to the neat PET. Graphical abstract

Abstract Size effects decisively influence the properties of materials at small length scales. In the context of mechanical properties, the trend of ‘smaller is stronger’ has been well established. This statement refers to an almost universal trend of increased strength with decreasing size. A strong influence of size on the elastic properties has also been widely reported, albeit without a clear trend. However, the influence of nanostructure shape on the mechanical properties has been critically neglected. Here, we demonstrate a profound influence of shape and size on the elastic properties of materials on the example of gold nanowires. The elastic properties are determined using in-situ mechanical testing in scanning and transmission electron microscopy by means of resonance excitation and uniaxial tension. The combination of bending and tensile load types allows for an independent and correlative calculation of the Young's modulus. We find both cases of softening as well as stiffening, depending critically on the interplay between size and shape of the wires. Graphic abstract

The stiffness of the perovskite active layer plays a critical role in influencing the flexibility of a solar cell. This is one of the important parameters which must be considered while deciding the architecture of the flexible device. Till now, there have been limited studies on the mechanical properties of 2D and 3D perovskite thin films. In this study, we report the very first time, the elastic modulus of the most commonly used 3D perovskite i.e. methylammonium lead iodide (MaPbI3), the pure 2D perovskite (5-AVA)2PbI4 which is based on 5-aminovaleric acid (5-AVA) cation as well as the 2D-3D mixed perovskites thin films through nanoindentation technique. The elastic modulus for the 3D perovskite has been found to be around 16.5 GPa, while it decreases to 6.3 GPa for pure 2D perovskite. The experimental results have also been corroborated by density functional theory calculations done for the 2D and 3D perovskite. The 2D perovskite shows a much lower modulus than the 3D perovskite and can be used within a 2D-3D mixture for improving the mechanical flexibility of the active layer. Also, it is well established that 2D perovskites are much more stable against moisture as compared to their 3D counterparts due to the presence of hydrophobic organic alkyl ammonium cation. Thus, the device containing an active layer comprising of a mixture of 3D and 2D perovskite can be used to improve the environmental stability of the overall device in addition to achieving mechanical durability.

The strength properties of green sinter beds, including the Young’s modulus and maximum bed strain, were evaluated using uniaxial compression tests. The green-sinter-bed samples were scanned using X-ray computed tomography (XCT), and the geometry characteristics of the granules were quantified by XCT image analysis. The orthogonal array method was applied to determine the concomitant effects of the moisture, hydrated lime, and concentrate contents on the bed strength characteristics. Less bed strain was observed when the granules had a thin adhering layer and increased interlock contacts, which had a great capacity to resist the applied load collectively. The optimal combination for decreasing the bed maximum strain was 5.8% moisture, 2% hydrated lime, and 0% concentrate. The moisture and concentrate contents were the most significant factors determining the green bed strength. Increasing the moisture and concentrate contents produced granules with a thicker and more deformable adhering layer, resulting in a more compact bed. The addition of hydrated lime inhibited rearrangement, deformation, and fracture of the granules in green sinter bed during compression.

Graphene-based coatings (GCs) have emerged as attractive candidates for engineering applications. Despite recent progresses, efforts to achieve high-performance and durable GCs through conventional blending have been frustrated due to the uncontrolled distribution and orientation of graphene nanosheets, which degrades anticorrosion properties. By mimicking the nacre's microstructure, here we successfully fabricated a bioinspired GC, in which graphene nanosheets self-assembly in smectic can order in the epoxy matrix. As the bioinspired coating (∼98 wt% of epoxy polymer) shows an inverse composition to nacre (∼96 wt% of aragonite nanoplatelets), thus which is called an ‘‘inverse nacre-like’’ coating. The resultant bioinspired coating has high compactness and alignment degree, resulting in greatly enhanced physical barrier property and anticorrosion performance. Electrochemical tests reveal that the impedance modulus is 3 orders of magnitude much higher than that of blank coating. More importantly, the bioinspired coating shows a highly anisotropic conductivity due to the anisotropic graphene layers, preventing local galvanic corrosion through eliminating the current leakage in the out-of-plane direction.

The influence of alloying elements and heat treatment on the microstructure and mechanical behaviors of extruded Mg–Gd–Nd ternary alloys was investigated in this study. The grain sizes dramatically decreased after extrusion, and the particles which distributed in Mg matrix had great effect on the grain size. The grain sizes of extruded alloys decreased from 26 to 5 ​μm with the alloying content increasing. The mechanical test results show that both Gd and Nd had positive effect on the hardness, yield strength and Young's modulus. The ultimate tensile strength (UTS) was enhanced by Gd content, decreased with Nd content. The elongation of alloys was lower with higher alloying elements. Those extruded alloys were aged for 200 ​h in 200 ​°C. The Young's moduli were decreased by ageing treatment. Combined with microstructure study, the part of the reinforcement which identified as Mg5(Gd/Nd) was dissolved in Mg matrix. Nd element obviously has influence on the solubility of Gd in Mg alloys.

In this experimental research, the effect of waste ground rubber tire powder (WGRT) on vibrational damping behavior and static mechanical properties of polypropylene was investigated. Hammer tests along with modal analysis were performed to evaluate the forced vibration behavior of composite plates under one edge clamped support condition while tensile tests were performed to assess the static mechanical properties. A comparison of test results showed that all the natural damped frequencies of the compounds in the first three modes have a decreasing trend upon increasing the content of tire powder in the polypropylene matrix due to the decrease in Young's modulus and the stiffness. Also, all the damping ratios of the compounds in the first three modes showed an increasing trend with raising the weight percentage of tire powder in the polypropylene matrix due to energy dissipation. Composites with 60 wt.% WGRT powder showed the highest Young's modulus reduction (80.38%), frequency reduction (35.42%) and damping ratio increase (84.45%) compared to pure polypropylene in the first mode. Generally, incorporation of tire powder to polypropylene matrix reduced the static mechanical properties of all the specimens.

In-situ synthesized TiB2/6061 composites were prepared from Al-K2TiF6-KBF4 by high energy ball milling and stir casting. Phase analysis and microstructure observation of the samples were characterized by XRD, SEM and EDS, respectively. The effect of TiB2 particle content on the microstructure, tensile properties and wear resistance of the composites was studied. The results show that the average size of TiB2 particles is 1 μm, which is polygonal shape. The average grain size of the composites can be refined significantly as the TiB2 particle mass content increased from 1 to 3%; however, the grain coarsening occurs in the 5 wt.% TiB2/6061composites. The 3 wt.% TiB2/6061 composites have best tensile strength, yield strength and Young’s modulus among the composites in ranges of the TiB2 mass fraction from 1 to 5%. Strengthening mechanisms of the TiB2/6061 composites were fine grain strengthening, Orwan strengthening and CTE strengthening, in which the CTE strengthening plays an important role as increasing the TiB2 content. The pin-on-disk wear test results indicated that the average friction coefficient and wear rate of the TiB2/6061 composites increased firstly and then decreased with increasing the TiB2 content from 1 to 5 wt.%. The wear mechanism of the TiB2/6061 composites was discussed.

Overdischarge is a severe safety issue that can induce severe mechanical failure of electrode materials in lithium-ion batteries. A considerable volume change of silicon-based composite anodes undoubtedly further aggravates the mechanical failure. However, the mechanical failure mechanism of silicon-based composite anodes under overdischarging conditions still lacks in-depth understanding despite many efforts paid under normal charging conditions. Herein, we have modeled and tracked the mechanical failure evolution of silicon/carbon nanofibers, a typical silicon-based anode, under overdischarging conditions based on the finite element simulation, with derived optimization strategies of optimal Young's modulus and stable microstructure. The severe contact damage between silicon nanoparticles and carbon nanofibers, which causes larger shedding and breakage risks, has been found to contribute to mechanical failure. To improve the electrode stability, an optimal Young's modulus interval ranging from ∼75 to ∼150 GPa is found. Furthermore, increasing the embedding depth of silicon nanoparticles in carbon nanofibers has proven to be an effective strategy for improving electrochemical stability due to the faster lithium salt diffusion and more uniform current density distribution, which was further verified by the experimental capacity retention ratio of carbon-coated silicon and silicon/carbon nanofibers (84 vs 75% after 100 cycles). Our results provide meaningful insights into the mechanical failure of silicon-based composite anodes during overdischarging, giving reasonable guidance for electrode safety designs and performance optimization.

β-type Titanium (Ti) alloy possesses less Young’s Modulus (E), which is significant for manufacturing of medical implants, since it reduces stress shielding effect. In this work, surface quality an...

In the current era of high-strength, lightweight, and durable aircraft components, the need for carbon fiber-reinforced epoxy (CFRP) laminates is highly desired owing to their high specific strength and modulus, low coefficient of thermal expansion, and tunable properties that are unmatched by other materials. However, such components’ catastrophic failure occurs due to the interfacial defects and debonding, thereby reducing service life and economic viability. Therefore, there is a pressing need to enhance the mechanical properties of CFRPs through matrix and fiber modifications and introduce the components’ self-healing ability under a natural trigger. This study assessed the crucial role of “thermoreversible bonds” and graphene oxide (GO) “interconnects”, which worked in tandem toward significantly improving the mechanical properties and imparting self-healing properties in CFRP laminates. The laminates were fabricated with varying percentages of GO-modified epoxy matrix via vacuum-assisted resin transfer molding (VARTM) method. The carbon fibers were covalently modified with bis-maleimide (BMI) to establish a thermoreversible bond with GO at the fiber matrix interface to make interconnects. Flexural strength and interlaminar shear strength (ILSS) values for the optimized GO-modified epoxy laminates with BMI-deposited carbon fibers exhibited a significant increase of 30 and 47%, respectively. After a self-healing cycle triggered at 60 °C, they exhibited a recovery in their ILSS values up to 70%. These improvements are particularly useful for aircraft wings made up of CFRP laminates.