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The thermal conductivity of glasses is well-known to be significantly harder to theoretically describe compared to crystalline materials. Because of this fact, the fundamental understanding of thermal conductivity in glasses remain extremely poor when moving beyond the case of simple glasses, e.g., glassy SiO2, and into so-called "modified" oxide glasses, that is, glasses where other oxides (e.g., alkali oxides) have been added to break up the network and alter, e.g., elastic and thermal properties. This lack of knowledge is apparent despite how modified glasses comprise the far majority of known glasses. In the present work, we study an archetypical series of sodium silicate [xNa2O–(100 − x)SiO2] glasses. Analyses of modal contributions reveal how increasing Na2O content induces increasing vibrational localization with a change of vibrations to be less ordered and a related general decrease in modal contributions to thermal conductivity. We find the vibrational phases (acoustic vs optical) of sodium vibrations to be relatively disordered compared to the network-forming silicon and oxygen species, explaining how increasing Na2O content decreases thermal conductivity. Our work sheds new light on the fundamentals of glassy heat transfer as well as the interplay between thermal conduction and modal characteristics in glasses. [ABSTRACT FROM AUTHOR]

The smooth emergence of shear elasticity is a hallmark of the liquid to glass transition. In a liquid, viscous stresses arise from local structural rearrangements. In the solid, Eshelby has shown that stresses around an inclusion decay as a power law r−D, where D is the dimension of the system. We study glass-forming hard sphere fluids by simulation and observe the emergence of the unscreened power-law Eshelby pattern in the stress correlations of the isotropic liquid state. By a detailed tensorial analysis, we show that the fluctuating force field, viz., the divergence of the stress field, relaxes to zero with time in all states, while the shear stress correlations develop spatial power-law structures inside regions that grow with longitudinal and transverse sound propagation. We observe the predicted exponents r−D and r−D−2. In Brownian systems, shear stresses relax diffusively within these regions, with the diffusion coefficient determined by the shear modulus and the friction coefficient. [ABSTRACT FROM AUTHOR]

This study proposes a simple yet effective dynamic method that can nondestructively evaluate the elastic properties of homogeneous isotropic solid materials. Like some dynamic methods, such as resonance ultrasound spectrometry and impulse excitation technique, the proposed method consists of two steps: experimentally acquiring the specimen's natural frequencies and numerically calculating the elastic properties. Compared with the existing methods, the proposed method has much lower requirements on all four aspects of experimental operations: specimen preparation, specimen positioning, vibration excitation, and vibration detection. An inverse method based on finite element modal analysis is proposed to calculate the specimen's elastic properties, and it can deliver optimal estimations with high precision and accuracy. The performance of the proposed method was assessed using the well-established sound speed-based dynamic method, i.e., ultrasound pulse-echo testing. Taking a square aluminum specimen as an example, the differences in the measurements of Young's modulus and Poisson's ratio between these two methods are 2.25% and −2.07%, respectively; the differences in the measurements of shear modulus and bulk modulus are 0.01% and −1.46%, respectively. In summary, the proposed method provides a cheaper and experimentally simpler approach to determining the elastic properties of solid materials while maintaining accuracy and reliability similar to the established methods, which typically require sophisticated, costly equipment. [ABSTRACT FROM AUTHOR]

Multi-principal component transition metal (TM) diborides represent a class of high-entropy ceramics (HECs) that have received considerable interest in recent years owing to their promising properties for extreme environment applications that include thermal/ environmental barriers, hypersonic vehicles, turbine engines, and next-generation nuclear reactors. While the addition of chemical disorder through the random distribution of TM elements on the cation sublattice has offered opportunities to tailor elastic stiffness and hardness, the effects of irradiation-induced structural damage on the physical properties of these complex materials have remained largely unexplored. To this end, changes in the hardness and elastic moduli of a high-entropy TM diboride (Hf0.2Nb0.2Ta0.2Ti0.2Zr0.2)B2 and three of its quaternary subsets following irradiation with 10 MeV gold (Au) ions to fluences of up to 6 × 1015 Au cm−2 are investigated at the micrometer and sub-micrometer length-scales via the dispersion of laser-generated surface acoustic waves (SAW) and nanoindentation, respectively. The nanoindentation measurements show that the TM diborides exhibit an initial increase in hardness following irradiation with energetic Au ions, with a subsequent decrease in hardness following further irradiation. One quaternary composition, (Hf1/3Ta1/3Ti1/3)B2, exhibits a notable exception to the trend and continues to exhibit an increase in hardness with ion irradiation fluence. Although differences in the absolute values of the effective elastic moduli obtained from the measured SAW dispersion and nanoindentation are observed (and attributed to microstructural variations at the measurement length-scale), both techniques yield similar trends in the form of an initial reduction and subsequent saturation in the elastic modulus with increasing ion irradiation fluence. The quaternary TM diboride (Hf1/3Ta1/3Ti1/3)B2 again exhibits a departure from this trend. The high-entropy TM diboride (Hf0.2Nb0.2Ta0.2Ti0.2Zr0.2)B2 exhibits the greatest recovery in hardness and modulus when irradiated to high ion fluences following initial changes at low fluence, indicating superior resistance to radiation-induced damage over its quaternary counterparts. Opportunities for designing HECs with superior hardness and modulus for enhanced radiation resistance (compared to their single constituent counterparts) by tailoring chemical disorder and bond character in the lattice are discussed. [ABSTRACT FROM AUTHOR]

Healing outcomes of periodontal and implant-related regenerative procedures are closely related to wound stability, which is partially determined by biomechanical properties and behaviors of oral mucosal tissues. Studies on soft tissue behavior under biomechanical forces in oral regeneration models are scarce. Thus, this review aims to (1) contrast the microstructural differences between the attached gingiva (AM) and lining (LM) mucosa; (2) evaluate biomechanical behaviors of the two mucosal types; and (3) relate residual flap tension to the prevalence of wound opening after regenerative procedures. Compositional and structural differences between the AM and LM explain their biomechanical property differences. Wound destabilizers, including tissue recoil stemming from its viscoelastic property, muscle pull, and inflammatory edema (created after the flap-releasing procedure for primary wound closure) interfere with wound stability. Residual flap tension < 0.05 N is a prerequisite for sustained wound closure. Tissues under stress can exert negative cellular changes, resulting in necrosis and wound dehiscence. Biomechanical properties and the variations between AM and LM dictate the degree of wound stability. Efforts should be made to reduce the negative impact of the potential destabilizers to optimize wound stability. [ABSTRACT FROM AUTHOR]

Ceramic materials are widely used in armor or protective structures, providing weight saving at equivalent performance in comparison to their steel counterparts. Plate-impact experiments are commonly used to investigate the dynamic behavior of ceramics under compressive loading. Using the particle velocity measured at the back of the target, some mechanical properties such as the Hugoniot elastic limit (HEL) as well as the Hugoniot curve of the material can be deduced. Nevertheless, these tests do not provide a direct measurement of the plastic hardening (post-HEL) behavior of the target. In the present work, an experimental shockless plate-impact configuration was developed and implemented to conduct a Lagrangian analysis. This configuration relies on the use of a wavy-machined flyer plate impacting a target made of a buffer, two ceramic plates of different thicknesses, and two window plates as backing. First, the use of wavy flyer plates to generate a loading ramp was validated by considering the impact of the wavy-machined flyer plate against a target, both made of 316L steel. A numerical analysis of this test was developed to confirm the pulse-shaping effect observed experimentally. Next, a ceramic, F99.7 alumina was subjected to the shockless plate impact test in Lagrangian configuration considering the same steel as a buffer and flyer plate material. These tests coupled with Lagrangian analysis enable the curve of axial-stress vs axial-strain beyond the isentropic elastic limit (IEL) to be deduced. The experimental data allow identifying the parameters of an elastoplastic with strain-hardening model to describe the behavior of the tested alumina. [ABSTRACT FROM AUTHOR]

We numerically investigated the aggregation dynamics and resulting network structures of colloidal gels using the slippery diffusion-limited cluster aggregation (DLCA) model. In this model, bonds are irreversibly formed upon the particle contacts, but the angles among them are not fixed, unlike the conventional DLCA. This allows clusters to be deformed in the process of aggregation. By characterizing the aggregation dynamics and using a reduced network scheme, our simulation revealed two distinct branching structure formation routes depending on the particle volume fraction ϕ. In lower volume fraction systems (ϕ ≤ 8%), the deformations of small-size clusters proceed prior to the percolation. When the Maxwell criterion is satisfied and the clusters become mechanically stable, the formation of the branching structure is nearly completed. After forming the branching structures, they aggregate and form a larger percolating network. Then, the aggregation proceeds through the elongation and straightening of the chain parts of the network. In higher volume fraction systems (ϕ > 8%), on the other hand, the clusters percolate, and a fine and homogeneous branching structure is formed at the early stage of the aggregation. In the aging stage, it collapses into a denser and more heterogeneous structure and becomes more stable. Our quantitative analyses of the branching structure will shed light on a new strategy for describing the network formation and elasticity of colloidal gels. [ABSTRACT FROM AUTHOR]

The elasticity of polymer networks, formed by cross-linking high molecular mass polymers in the melt state and then swollen by a solvent, involves contributions from both the presence of cross-link network junctions and the interchain interactions associated with the combined effect of excluded volume interactions and topological constraints that become modified when the network is swollen. We test the capacity of the previously developed localization model of rubber elasticity, a mean field "tube model," to describe changes in elasticity observed in classical experimental studies of the mechanical properties of this type of network. In order to obtain a satisfactory comparison to the experiments, it was found to be necessary to account for the independently observed tendency of the network junctions to become localized in the network with appreciable swelling, as well as the interchain interactions emphasized in previous discussions of the localization model. [ABSTRACT FROM AUTHOR]

At the line of triple contact of an elastic body with two immiscible fluids, the body is subjected to a force concentrated on this line, the fluid–fluid surface tension. In the simple case of a semi-infinite body, limited by a plane, a straight contact line on this plane, and a fluid–fluid surface tension normal to the plane, the classical elastic solution leads to an infinite displacement at the contact line and an infinite elastic energy. By taking into account the body–fluid surface tension (i.e., isotropic surface stress) and applying Kolosov's approach of plane strain elasticity, we present a new and simple expression of the solution concerning the semi-infinite body, which gives a finite displacement and a ridge at the contact line, and finite elastic energy. A detailed description of the displacements, strains, and stresses in the neighborhood of the contact line is given. This solution also shows that Green's formulae, in the volume and on the surfaces, are valid (these formulae play a central role in the theory). [ABSTRACT FROM AUTHOR]

Coarse-grained models have emerged as valuable tools to simulate long DNA molecules while maintaining computational efficiency. These models aim at preserving interactions among coarse-grained variables in a manner that mirrors the underlying atomistic description. We explore here a method for testing coarse-grained vs all-atom models using stiffness matrices in Fourier space (q-stiffnesses), which are particularly suited to probe DNA elasticity at different length scales. We focus on a class of coarse-grained rigid base DNA models known as cgDNA and its most recent version, cgDNA+. Our analysis shows that while cgDNA+ closely follows the q-stiffnesses of the all-atom model, the original cgDNA shows some deviations for twist and bending variables, which are rather strong in the q → 0 (long length scale) limit. The consequence is that while both cgDNA and cgDNA+ give a suitable description of local elastic behavior, the former misses some effects that manifest themselves at longer length scales. In particular, cgDNA performs poorly on twist stiffness, with a value much lower than expected for long DNA molecules. Conversely, the all-atom and cgDNA+ twist are strongly length scale dependent: DNA is torsionally soft at a few base pair distances but becomes more rigid at distances of a few dozen base pairs. Our analysis shows that the bending persistence length in all-atom and cgDNA+ is somewhat overestimated. [ABSTRACT FROM AUTHOR]

The thermal transport and elastic properties of materials are often measured using the laser-induced transient grating spectroscopy (TGS) technique. The analysis of the TGS signal usually involves fitting well-known expressions, derived assuming the limiting cases of opaque or transparent materials, to the measured data. In this paper, the system of thermoelastic equations is analytically solved for an isotropic homogeneous material assuming finite laser penetration depth, which is an important consideration when the penetration depth is on the order of the acoustic wavelength. The need to use such a solution is discussed and compared to the expression for opaque material. The solution is benchmarked against TGS signal measured on single-crystal silicon with {100} surface orientation and is found to significantly improve the accuracy of the calculated thermal diffusivity as compared to using the expression for opaque material. [ABSTRACT FROM AUTHOR]

Constitutive models are essential for describing the mechanical behavior of materials under high temperatures and pressures, among which the Steinberg–Guinan (SG) model is widely adopted. Recent work has discovered a peculiar dual anomaly of compression-induced softening and heating-induced hardening in the elasticity of compressed vanadium [Phys. Rev. B 104, 134102 (2021)], which is beyond the capability of the SG model to describe. In this work, a modified SG elasticity constitutive model is proposed to embody such an anomalous behavior. Elemental vanadium is considered as an example to demonstrate the effectiveness of this improved model in describing the dual anomalies of elasticity. This new SG elasticity model can also be applied to other materials that present an irregular variation in the mechanical elasticity and are important to faithfully model and simulate the mechanical response of materials under extreme conditions. [ABSTRACT FROM AUTHOR]

Biological lipid membranes are generally asymmetric, not only with respect to the composition of the two membrane leaflets but also with respect to the state of mechanical stress on the two sides. Computer simulations of such asymmetric membranes pose unique challenges with respect to the choice of boundary conditions and ensemble in which such simulations are to be carried out. Here, we demonstrate an alternative to the usual choice of fully periodic boundary conditions: The membrane is only periodic in one direction, with free edges running parallel to the single direction of periodicity. In order to maintain bilayer asymmetry under these conditions, nanoscale "sticky tapes" are adhered to the membrane edges in order to prevent lipid flip-flop across the otherwise open edge. In such semi-periodic simulations, the bilayer is free to choose both its area and mean curvature, allowing for minimization of the bilayer elastic free energy. We implement these principles in a highly coarse-grained model and show how even the simplest examples of such simulations can reveal useful membrane elastic properties, such as the location of the monolayer neutral surface. [ABSTRACT FROM AUTHOR]

We present results of resonant ultrasound spectroscopy (RUS) measurements applied to granular high explosive materials at different bulk pressing densities and degree of thermal conditioning. The material chosen in this study is a ubiquitously used explosive material known as pentaerythritol tetranitrate (PETN), which is used commercially in civil and defense applications both as a binderized plastic bonded explosive material and an unbinderized neat material. However, changes in granular PETN bulk elastic properties due to thermal conditioning, which could have implications for better understanding environmental aging-related effects, have not been well studied even though it is believed that elasticity may play an important role in explosive material initiation mechanisms. Furthermore, monitoring elastic property changes in granular explosive pressings has not yet been demonstrated using RUS, which is an appealing non-destructive characterization tool that requires only dry point contact with the explosive material. To this end, we report the first study using RUS to quantify the elastic properties of binderized and neat PETN pressings as well as to quantify changes in elastic properties as a function of both thermal conditioning and bulk pressing density. Elastic stiffness coefficients, sometimes more commonly referred to as elastic constants, calculated from the RUS measurements on the different PETN-based materials show a significant increase for the post-conditioned samples compared to the pre-conditioned samples. This trend of increasing elastic properties with thermal conditioning was consistent for different density pressings, different thermal exposure conditions, and even different neat PETN pressings of differing average crystal sizes and/or specific surface areas. [ABSTRACT FROM AUTHOR]

Low-crosslinked polymer networks have recently been found to behave auxetically when subjected to small tensions, that is, their Poisson's ratio ν becomes negative. In addition, for specific state points, numerical simulations revealed that diamond-like networks reach the limit of mechanical stability, exhibiting values of ν = −1, a condition that we define as hyper-auxeticity. This behavior is interesting per se for its consequences in materials science but is also appealing for fundamental physics because the mechanical instability is accompanied by evidence of criticality. In this work, we deepen our understanding of this phenomenon by performing a large set of equilibrium and stress–strain simulations in combination with phenomenological elasticity theory. The two approaches are found to be in good agreement, confirming the above results. We also extend our investigations to disordered polymer networks and find that the hyper-auxetic behavior also holds in this case, still manifesting a similar critical-like behavior as in the diamond one. Finally, we highlight the role of the number density, which is found to be a relevant control parameter determining the elastic properties of the system. The validity of the results under disordered conditions paves the way for an experimental investigation of this phenomenon in real systems, such as hydrogels. [ABSTRACT FROM AUTHOR]

Owing to magnetoelastic coupling, surface acoustic waves (SAWs) may be scattered resonantly by magnetic elements, such as nickel stripes. The scattering may be further enhanced via the Borrmann effect when the elements are organized into an array that matches the acoustic wavelength. We use finite-element modeling to consider single- and double-layer stripes patterned on top of a lithium niobate surface that carries Love surface waves. We do observe enhancement in the coupling for single-layer stripes, but only for Gilbert damping below its realistic value. For double-layered stripes, a weak yet clear and distinct signature of Bragg reflection is identified far away from the acoustic band edge, even for a realistic damping value. Double-layered stripes also offer better magnetic tunability when their magnetic period is different from the periodicity of elastic properties of the structure because of staggered magnetization patterns. The results pave the way for the design of magnetoacoustic metamaterials with an enhanced coupling between propagating SAWs and local magnetic resonances and for the development of reconfigurable SAW-based circuitry. [ABSTRACT FROM AUTHOR]

Many microorganisms propel themselves through complex media by deforming their flagella. The beat is thought to emerge from interactions between forces of the surrounding fluid, the passive elastic response from deformations of the flagellum and active forces from internal molecular motors. The beat varies in response to changes in the fluid rheology, including elasticity, but there are limited data on how systematic changes in elasticity alter the beat. This work analyses a related problem with fixed-strength driving force: the emergence of beating of an elastic planar filament driven by a follower force at the tip of a viscoelastic fluid. This analysis examines how the onset of oscillations depends on the strength of the force and viscoelastic parameters. Compared to a Newtonian fluid, it takes more force to induce the instability in viscoelastic fluids, and the frequency of the oscillation is higher. The linear analysis predicts that the frequency increases with the fluid relaxation time. Using numerical simulations, the model predictions are compared with experimental data on frequency changes in the bi-flagellated alga Chlamydomonas reinhardtii. The model shows the same trends in response to changes in both fluid viscosity and Deborah number and thus provides a possible mechanistic understanding of the experimental observations.

A review of the structural, elastic, and thermodynamic properties of cubic and hexagonal ScxAl1−xN crystals over the range of possible random alloys is provided. Based on measured and simulated lattice and internal cell parameters of NaCl (B1), CsCl (B2), and α-ZnS (B3) type cubic ScxAl1−xN lattices as well as of β-ZnS (B4), lh-MgO (Bk), and NiAs (B81) type hexagonal ScxAl1−xN crystals, their atomic positions, distances to nearest neighbor atoms, geometric dimensions of crystal cells, mass density, as well as their average bond length and bond angles are presented in dependence on the alloy composition. The understanding gained about the crystal lattices is used to provide a model for the transitions from the β-ZnS to the lh-MgO or NaCl lattice induced by the alloying of AlN with ScN. Based on published data sets of stiffness coefficients, the compliance coefficients, Young's modulus, shear modulus, Poisson's ratio, compressibility, and the sound velocities are presented in relation to the orientation of representative crystal planes and axes for rock salt, layered hexagonal, and wurtzite ScxAl1−xN crystals. Particular attention is paid to the directional anisotropies of elastic properties of the different crystal lattices if Sc atoms substitute an increasing number of Al atoms. Based on sound velocities determined, an overview of the fundamental thermodynamic properties of cubic and hexagonal ScxAl1−xN alloys is provided, such as the Debye temperature, heat capacity, minimum heat conduction, and melting temperature. [ABSTRACT FROM AUTHOR]

It is still debated whether arterial elasticity provides prognostic information for cardiovascular risk beyond blood pressure measurements in a healthy population. To investigate the association between arterial elasticity obtained by radial artery pulse wave analysis and risk for cardiovascular diseases (CVD) in men and women. In 2002-2005, 2362 individuals (men=1186, 50.2%) not taking antihypertensive medication were included. C2 (small artery elasticity) was measured using the HDI/Pulse Wave CR2000. Data on acute myocardial infarction or stroke, fatal or non-fatal, was obtained between 2002-2019. Cox- regression was used to investigate associations between C2 and future CVD, adjusting for confounding factors such as age, sex, systolic blood pressure, heart rate, HOMA-IR (Homeostatic Model Assessment for Insulin Resistance), LDL- cholesterol, CRP (C-Reactive Protein), alcohol consumption, smoking and physical activity. At baseline, the mean age of 46 ± 10.6 years and over the follow-up period, we observed 108 events 70 events in men [event rate: 5.9%], 38 in women [event rate: 3.2%]. In the fully adjusted model, and for each quartile decrease in C2, there was a significant increase in the risk for incident CVD by 36%. (HR = 1.36, 95% CI: 1.01-1.82, p = 0.041). The results were accentuated for all men (HR = 1.74, 95% CI: 1.21-2.50, p = 0.003) and women over the age of 50 years (HR = 1.70, 95% CI: 0.69-4.20). We showed a strong and independent association between C2 and CVD in men. In women after menopause, similar tendencies and effect sizes were observed.

Interactions between fluid flow and elastic structures are important in many naturally occurring and engineered systems. This review collects and organizes recent theoretical and experimental developments in understanding fluid-structure interactions at low Reynolds numbers. Particular attention is given to the motion of objects moving in close proximity to deformable soft materials and the ensuing interplay between fluid flow and elastic deformation. We discuss how this interplay can be understood in terms of forces and torques, and harnessed in applications such as microrheometry, tribology, and soft robotics. We then discuss the interaction of soft and wet objects close to contact, where intermolecular forces and surface roughness effects become important and are sources of complexity and opportunity.

The nonlinear forced vibration behavior of truncated open conical nanoshells is investigated in this paper. Nonlocal elasticity theory has been employed to modify the size-dependent effect of micro/nanostructure. Von Karman nonlinear strains are used to consider the geometric nonlinearity of the nanoshells. Using Hamilton's principle, the equations of motion and boundary conditions of truncated open conical nanoshells are derived. Galerkin method is used to solve the governing equations. Then, to determine the nonlinear forced vibration behavior of truncated open conical nanoshells, complex averaging and arc-length continuation methods are employed. Finally, the effect of nonlocal parameters, cone apex angle, the amplitude of harmonic excitation, structural damping coefficient, and geometrical parameters on the nonlinear frequency response of the truncated open conical nanoshells are discussed. [ABSTRACT FROM AUTHOR]

An improved naturally stabilized nodal integration (NSNI) is presented for resolving displacement locking concerned with highly orthotropic and nearly incompressible materials in the linear setting. It is recognized that the original NSNI is susceptible to the locking when dealing with these types of materials. The proposed method utilizes spectral decomposition to split the elasticity matrix into stiff and nonstiff parts. The terms associated with the stiff modes in the bilinear form are sampled by nodal integration (NI) without stabilization, whereas the other terms are integrated with NSNI. This approach leads to a unified implementation to handle locking in both types of materials. The performance and convergence of the proposed formulation are verified through several two‐ and three‐dimensional numerical examples, illustrating the advantages of the presented method over its standard counterpart. [ABSTRACT FROM AUTHOR]

This work explores the investigation of tin monochalcogenides i.e. SnX (X: S, Se, Te) at room temperature (300 K). The mechanical, thermophysical and ultrasonic properties of SnX (X: S, Se, Te) have been evaluated using the computed values of second- and third-order elastic constants (SOECs and TOECs). The SOECs and TOECs have been obtained using Born–Mayer potential model at 0 K and 300 K. The brittleness behavior of tin monochalcogenides is detected by Pugh's ratio. It is observed that phonon–phonon interaction mechanism is dominant in tin monochalcogenides leading to high ultrasonic attenuation. The obtained temperature dependence behavior of tin monochalcogenides is validated via comparison with available works of literature data in previous works done experimentally as well as theoretically by others. [ABSTRACT FROM AUTHOR]

First-principles study is used to comparatively study the hydrogen embrittlement resistance, elastic properties, and electronic structures of VWH and VMoH phases with various W and Mo concentration. Calculations reveal that the VMo phases have lower hydrogen solubility compared to VW phases, leading to higher hydrogen embrittlement resistance in VMo. In addition, the concentrations of W and Mo above 0.1875 would enhance the hydrogen embrittlement resistance of V membrane. Conversely, the W or Mo concentrations below 0.1875 would reduce the hydrogen embrittlement resistance. It is also demonstrated that adding W and Mo at concentrations below 0.25 would reduce the solid-solution strengthening of VH phase, thereby reducing its brittleness. This study will enhance comprehension of the underlying physics of VWH and VMoH phases and align with existing experimental literature. • Adding Mo is more effective than adding W in improving the hydrogen embrittlement resistance of V membrane. • The concentrations of W or Mo above 0.1875 would enhance the hydrogen embrittlement resistance of V membrane. • The W or Mo concentrations below 0.1875 would reduce the hydrogen embrittlement resistance. • Adding W and Mo at concentrations below 0.25 would reduce its brittleness. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to investigate the thermoelastic interactions in a homogeneous, transversely isotropic infinite medium with a spherical cavity in the context of two temperature Lord-Shulman (2TLS) generalized theory of thermoelasticity considering Eringen's nonlocal theory and memory dependent derivative (MDD). Memory-dependent derivative is found to be better than fractional calculus for reflecting the memory effect which leads us to the current investigation. Design/methodology/approach: The governing field equations of the problem are solved analytically using the eigenvalue approach in the transformed domain of Laplace when the cavity's boundary is being loaded thermomechanically. Using MATLAB software the numerical solution in real space-time domain is obtained by Stehfest method. Findings: Numerical results for the different thermophysical quantities are presented in graphs and the effects of delay time parameter, non-local parameter and two temperature parameters are studied thereafter. The outcomes of this study convince that the displacement u, conductive temperature ϕ, thermodynamic temperature θ are concave upward whereas radial stress τrr is concave downward for every choice of delay time parameter ω, two temperature parameter η and non-local parameter "ζ". As a specific instance of our findings, the conclusions of an equivalent problem involving integer order thermoelasticity theory can be obtained, and the corresponding results of this article can be readily inferred for isotropic materials. Originality/value: The novelty of this research lies in the adoption of generalized thermoelastic theory with memory dependent derivative and Eringen's nonlocality for analyzing the thermoelastic interactions in an infinite body with spherical cavity by employing eigenvalue approach. It has applications to many thermo-dynamical systems. [ABSTRACT FROM AUTHOR]

We discuss how Dirichlet boundary conditions can be directly imposed for the Moulinec–Suquet discretization on the boundary of rectangular domains in iterative schemes based on the fast Fourier transform (FFT) and computational homogenization problems in mechanics. Classically, computational homogenization methods based on the fast Fourier transform work with periodic boundary conditions. There are applications, however, when Dirichlet (or Neumann) boundary conditions are required. For thermal homogenization problems, it is straightforward to impose such boundary conditions by using discrete sine (and cosine) transforms instead of the FFT. This approach, however, is not readily extended to mechanical problems due to the appearance of mixed derivatives in the Lamé operator of elasticity. Thus, Dirichlet boundary conditions are typically imposed either by using Lagrange multipliers or a "buffer zone" with a high stiffness. Both strategies lead to formulations which do not share the computational advantages of the original FFT-based schemes. The work at hand introduces a technique for imposing Dirichlet boundary conditions directly without the need for indefinite systems. We use a formulation on the deformation gradient—also at small strains—and employ the Green's operator associated to the vector Laplacian. Then, we develop the Moulinec–Suquet discretization for Dirichlet boundary conditions—requiring carefully selected weights at boundary points—and discuss the seamless integration into existing FFT-based computational homogenization codes based on dedicated discrete sine/cosine transforms. The article culminates with a series of well-chosen numerical examples demonstrating the capabilities of the introduced technology. [ABSTRACT FROM AUTHOR]

The doctrine of adverse possession presents a risk to forestland ownership because timber management is infrequent. In this study, the extent of adverse possession claims on forestland in the United States is examined through a set of 243 published legal cases, and the determinants of the case outcomes are analyzed by a multinomial logit model. Those cases are from 32 states and distributed over 200 years, with an average of 12 cases per decade. Adverse possession claimants win 44% of the cases. The regression analysis reveals that whether an adverse possessor has a defective title is the leading factor in determining the case outcomes, and the periods required by statutes tend to negatively impact the winning probability of adverse possessors. The empirical findings have implications for landowners to defend their titles or remove a cloud on titles and for legislators to revise relevant laws in the future. [ABSTRACT FROM AUTHOR]

Wave propagation in slender beams is addressed in the framework of nonlocal continuum mechanics. The elastodynamic problem is formulated exploiting consistent methodologies of pure integral, mixture and nonlocal strain gradient elasticity. Relevant wave solutions are analytically provided, with peculiar attention to reflection and near field phenomena occurring in presence of boundaries. Notably, the solution field is got as superimposition of incident, reflected, primary near field and secondary near field waves. The latter contribution represents a further effect due to the size dependent mechanical behaviour. Limit responses for vanishing nonlocal parameter are analytically evaluated, consistently showing a zero amplitude of the secondary near field wave. Parametric analyses are carried out to show how length scale parameter, amplitude of incident wave and geometric and elastic properties of the beam affect the amplitudes of reflected, primary near field and secondary near field waves. The results obtained exploiting different nonlocal integral elasticity approaches are compared and discussed. [ABSTRACT FROM AUTHOR]

Effect of the external surface layer on the phase transition (PT) between the low pressure phase and high pressure phase (HPP) in a NiAl bicrystal is investigated. Using a phase field model, the external surface layer is included, within which the elastic properties and surface energy are properly distributed. After resolving a stationary layer, the coupled phase field and elasticity equations are solved to capture the HPP evolution. Residual stress concentrator is included as a shear band representing an inelastic shear strain. Due to the small grain size, the surface layer can influence the stress distribution and consequently, the critical inelastic shear strain γ cr for the HPP growth. Above a certain applied pressure, the surface layer width Δ ξ shows no effect on γ cr , e.g., P = 10 GPa for the grain size of L = 20 nm. For lower pressures, γ cr increases as pressure reduces. Due to the interplay of size addition by the surface layer and size reduction by the transformation strain, γ cr reduces versus Δ ξ and then increases for larger Δ ξ . For smaller grain sizes, the surface layer effect is promoted as it is imposed to a larger transformation work. The lowest γ cr is obtained for P = 19 GPa, in good agreement with the theoretical pressure of 20 GPa. Combining the external shear on pressure adds an extra shear term to the transformation work, which allows for the relaxation of the shear band and results in a nonlinear reduction of the PT pressure versus applied shear. [ABSTRACT FROM AUTHOR]

In this study it is approached a linear model for the mixture of two Cosserat bodies having pores. It is formulated the mixed problem with initial and boundary data in this context. The main goal is to show that the coefficients that realize the coupling of the elastic effect with the one due to voids can vary, without the mixture being essentially affected. In a more precise formulation, this means that a small variation of the coefficients in the constitutive equations of the two continua causes only a small variation of the solutions of the corresponding mixed problems, that is, the continuous dependence of the solutions in relation to these coefficients is ensured. The considered mixture model is consistent because all estimates, specific to continuous dependence, are made based on rigorous mathematical relationships. [ABSTRACT FROM AUTHOR]

Cracks are a common rock microstructure and have a large effect on elastic properties during wave propagation. The fluid flow between a crack and its adjacent pore space can cause wave attenuation and dispersion. In this work, we introduce a crack connectivity parameter which is meant to improve the expression of local flow by weighting the contributions of fully connected and isolated cracks. We then update the analytical expression for frequency-dependent moduli by modifying the boundary conditions of the linearized Navier–Stokes equation and mass conservation equation. The proposed model contains the effect of cracks and stiff pores, in which the attenuation and dispersion are determined by squirt-flow and stiff-pore relaxations. The resulting model shows the squirt-flow relaxation frequency depends on not only the crack aspect ratio but also the crack connectivity. However, their contributions are different. The crack connectivity has little effect on the attenuation amplitude of shear modulus, but affects the attenuation amplitude of bulk modulus when multiple sets of cracks exist in the rock. The attenuation frequency band is also affected by the crack connectivity. As the crack connectivity deteriorates, the attenuation peak moves to low frequencies. In addition, by comparing the crack connectivity with the fluid viscosity coefficient, it is observed that the crack connectivity only affects the attenuation frequency band of cracks, whereas the fluid viscosity coefficient affects the attenuation frequency bands of cracks and stiff pores simultaneously. Thus, the introduction of crack connectivity is a supplement to the theoretical model of cracked fluid-saturated rocks. It helps understand the local fluid flow induced by seismic waves and provides a reasonable variation analysis of moduli and attenuation, especially for tight reservoirs. [ABSTRACT FROM AUTHOR]

Summary: Bighead carp has the largest production amount among freshwater fish in China, but its physicochemical properties change rapidly with the denaturation of their myofibril protein (MP). The protein–polysaccharide complexes have shown interesting physicochemical properties as stabilisers and emulsifiers. In this study, arabinoxylans (AXs) were prepared and mixed with bighead carp MP to form a composite gel. The effect of AXs on the thermal stability, emulsification and emulsion stability of the composite gel was investigated. The results showed that fraction precipitated by 60% ethanol (F60) and by 90% (F90) improved the denaturation temperature of bighead carp MP from 65.99 °C to 67.39 °C and 68.22 °C, respectively. The emulsifying capacity of F60 (0.54 m2 g−1) was similar to that of sucrose (0.52 m2 g−1). The effect of F90 on the emulsion stability of bighead carp MP was better than that of F60. The elasticity of bighead carp MP was improved by F60 and F90. The hydroxyl group interactions, hydrophobic interactions and electrostatic forces exist between the macromolecules. AXs of fresh maize bran could prevent protein denaturation and improve the emulsion capacity and gel properties of bighead carp MP. [ABSTRACT FROM AUTHOR]

In the fused filament fabrication (FFF) additive manufacturing process, a part is manufactured by layer-by-layer deposition of thermoplastic filaments extruded from a nozzle. This process results in microscopic voids that are stochastic in size and randomly distributed in space. Also, the elastic properties of the extruded filaments show variation. These uncertainties in the FFF process and the resulting microstructure cause a variation in the structural response (load–displacement curve) of the final printed part. A multiscale uncertainty propagation framework was developed in this study to examine the effect of microscopic inhomogeneity on the variations in the macroscopic structural behavior. Experimental data was used to quantify uncertainty at the micro-scale, while Monte Carlo simulation was used to quantify uncertainty at the meso- and macroscales. A hook model was considered as a case study for uncertainty propagation in the FFF process. [ABSTRACT FROM AUTHOR]

This study focuses on the use of bio-based materials for structural purposes in the packaging field, which requires the identification of their mechanical properties at a representative scale. The mechanical properties of bio-based materials are more variable than those of traditional composite materials. In a standard characterization approach using elemental coupons under uniaxial loading, the variability depends on the chosen representative elementary volume (REV), free edges, boundary conditions, etc. for elastic properties that are not identified for representative working conditions; this could lead to the ineligibility of these bio-based materials as structural materials. This paper contributes to the debate on how to study the response of bio-based materials within a structure, here a packaging structure as a logistic unit (LU) subjected to a compressive load simulating storage and stacking conditions. In the set of tools and methods for the design of packaging materials made of bio-based materials, an elastic nonlinear geometric finite element model (FEM) and an experimental approach are presented. The FEM allows the numerical identification of zones of interest within the LU. Inevitably, the FEM classically requires input data which are elastic properties of the equivalent homogeneous material. The design of the FEM is based on a calculation-test approach using an existing reference LU and it can be summarized in two main steps. The first step concerns the development of a FEM able to restore the experimental conditions of vertical compression imposed by transport standards for packaging. The second step is based on updating the input properties of the FEM by reverse identification, to achieve the representative working condition properties, using experimental results obtained on the existing reference LU. For the reverse identification a multi-scale investigation is mandatory. For this purpose, the linear elastic part of the load/vertical displacement curves (at the LU stiffness scale) and the displacement and strain fields measured (at the local LU scale) by 3D digital image correlation (3D DIC) are evaluated. Then, FEM property updating is carried out by reducing the deviation of displacement/strain fields between FEM and experimentally measured results (3D DIC). Finally, we explain how FEM and 3D DIC help in decision-making by allowing the recognition of zones of interest in a phase of design of new LUs with the concept of Multi-Instrumented Technological Evaluator (MITE). [ABSTRACT FROM AUTHOR]

Deformation fields near the tip of a crack in a material with properties depending on the type of stress state are presented for conditions of longitudinal shear. These properties are revealed in rocks, concretes, refractory ceramics, cast iron, structural graphite, some composites, and many other microheterogeneous materials. The behavior of heterogeneity depends on the loading conditions, and as a result, the deformation properties of these materials are stress state-dependent. Moreover, shear and volume deformation processes are interrelated in these materials. Therefore, it is impossible to distinguish between the fields corresponding to shear strain and bulk strain in solids. For the study of stress, strain, and displacement fields at a crack tip, corresponding constitutive equations are used to simulate the dependence of equivalent elastic properties on the type of stress state and to describe the relationship between shear strains and volumetric deformations. The traditional approach based on anti-plane strain hypothesis cannot be used for solving problems under longitudinal shear conditions because shear strains are not independent of bulk strains. Therefore, the corresponding representations for displacements have been proposed. Nonlinear constitutive relations are used, and conditions for a unique solution to the boundary value problem have been shown. The obtained solutions are compared with the known solutions for a linear elastic solid. The opening of crack faces is observed under conditions of out-of-plane shear, and the dependence of the crack opening on the sensitivity of material properties to the stress state is studied. [ABSTRACT FROM AUTHOR]

Wheel-rail high-frequency interaction is closely related to the formation of railway short-wave defects. Finite element (FE) method has been widely used to simulate wheel-rail dynamic systems, but its validity in modelling high-frequency interaction has not been fully demonstrated in three dimensions (3D). This work aims at comprehensively validating the 3D FE modelling of wheel-rail high-frequency interaction using a downscale V-Track test rig. First, the FE model of the V-Track is developed that comprehensively includes the 3D track elasticity. The simulated track dynamic behaviours are validated against hammer tests, and the major vibration modes are analyzed employing modal analysis. Afterwards, the simulate wheel-rail dynamic responses are comprehensively compared with measurement results up to 10 kHz. Their characteristic frequencies are identified and correlated to the eigenmodes of the vehicle-track system. The results indicate that the proposed 3D FE model is capable of comprehensively and accurately simulating the 3D track dynamics and wheel-rail dynamic interaction of the V-Track up to 10 kHz. Rail vibrations dominate the wheel-rail dynamic contact within 10 kHz, while the wheel vibrations play an increasingly important role at higher frequencies and become decisive near the wheel eigenmode frequencies. The V-Track overall achieves dynamic similarity to the real vehicle-track system. [ABSTRACT FROM AUTHOR]

Phase field models have been employed extensively in the study of microstructure evolution in materials. Elasticity plays an important role in solid‐state phase transformation processes, and it is usually introduced into phase field models in terms of the elastic strain energy by applying Khachaturyan–Shatalov microelasticity theory. Conventionally, this energy is derived in the reciprocal space and results in full‐space Fourier transformation in practice, which becomes bottle‐neck in large‐scale and massively‐parallel applications. In this article, we propose an error‐controlled approximation algorithm for scalable and efficient calculation of the elastic strain energy in phase field models. We first derive a real‐space convolutional representation of the elastic strain energy by representing the equilibrium displacements in the Khachaturyan–Shatalov microelasticity theory using Green's function. Then we propose an error‐controlled truncation criterion to approximate the corresponding terms in the phase field model. Finally, a carefully designed parallel algorithm is presented to carry out large‐scale simulations. The accuracy and efficiency of the proposed algorithm are demonstrated by real‐world large‐scale phase field simulations. [ABSTRACT FROM AUTHOR]

In this paper, a residual-type a posteriori error estimator is proposed and analyzed for a weak Galerkin finite element method for solving linear elasticity problems. The error estimator is proven to be both reliable and efficient, and be used for adaptive refinement. Numerical experiments are presented to illustrate the effectiveness of this error estimator. [ABSTRACT FROM AUTHOR]

[Display omitted] Ultralight graphene aerogels have gained extensive recognition in the impact protection field. However, attaining both elasticity and durability at low material density is challenging due to their intrinsic conflicts. Inspired by the mantis ootheca, we present a simultaneous improvement in the elasticity, durability, and density restrictions of ultralight graphene aerogels via constructing a multiscale honeycomb microstructure (MHM) within the graphene skeleton. This approach enables resulting graphene aerogel to achieve a strength per unit volume of 284.6 cm3 mg−1, the ability to recover its shape within 10 ms after an impact at 3.569 m/s, and maintain 97.2 % of its sample height after 20,000 cycles at 90 % strain. The operand analyses and calculation results reveal that the MHM structure facilitates this aerogel's dual-stage stress transfer pathway. Initially, the macroscale honeycomb structure (millimeter-scale) of the graphene aerogels bear and transmit stress to the surrounding regions, followed by the microscale honeycomb structure (micron-scale) deformation to convert stress kinetic energy into elastic potential energy. This two-stage stress transition mechanism of the MHM structure can effectively mitigate excessive local stress and suppress strain localization, thus providing remarkable elasticity and durability. Ultimately, the obtained graphene aerogel demonstrates promising applications as a fall height detection device and impact protective material. [ABSTRACT FROM AUTHOR]

In this work, the elastic properties of two tellurite glass series 80TeO2-(20−x)WO3-xBi2O3 (80TeWBi) and 70TeO2-(30−x)WO3-xBi2O3 (70TeWBi) (where x = 0 mol.%, 5 mol.%, and 10 mol.%) were quantitatively analyzed and predicted. Many structural and compositional parameters, including the density of network bonds, mean cross-link density, average bond-stretching force constant, total packing density, and dissociation energy per unit volume, were calculated using bond compression (BC), ring deformation (RD), and Makishima–Mackenzie (M–M) models. These parameters were correlated with experimental elastic properties to explore the structural role of WO3 and Bi2O3 in the tellurite network. It was found that WO3 enters the tellurite network of Bi2O3-free 80TeO2-20WO3 and 70TeO2-30WO3 glasses as a network former. This stiffened the structure through the formation of WO4 tetrahedral units, WO6 octahedral units, and Te–O–W linkages. As a result, the theoretical bulk modules (Kbc) increased from 73.23 GPa to 83.90 GPa whereas the theoretical Poisson's ratio decreased from 0.235 to 0.225 with increasing WO3 mol.%. Meanwhile, Bi2O3 enters the network of TeO2-WO3-Bi2O3 glasses as a network modifier. This weakens the glass structure and results in the transformation of some TeO4 trigonal bipyramids into TeO3 trigonal pyramids by breaking the Te–O–W linkages and creating non-bridging oxygen atoms. Excellent agreement was achieved between the theoretical and experimental values of elastic moduli and Poisson's ratio. [ABSTRACT FROM AUTHOR]

The paper presents research results on the influence of a regular perforation pattern on the modulus of elasticity (Young’s modulus) and on the strength properties of EN AW-5754 aluminium alloy sheet. Square and hexagonal array of cylindrical (in the plane of the sheet metal – round) holes was considered, maintaining a constant hole diameter and pitch value. The reference material was solid sheet metal (without perforation) of the same grade and thickness. It was found that hexagonal perforation pattern reduces the Young’s modulus and strength of the material to a greater extent compared to square array of holes, while maintaining a higher uniformity of the distribution of these parameters in the plane of the sheet metal. The comparative analysis of the elastic and strength properties of sheet metal with straight and hexagonal perforation was also carried out accounting for mass loss ratio. [ABSTRACT FROM AUTHOR]

A comprehensive theoretical investigation employing density functional theory explores the electronic structure, temperature‐dependent elasticity, thermodynamic properties, and chemical bonding of trigonal MBO3 (M=Al, Ga) with isolated [BO3] groups. The results uncover MBO3 (M=Al, Ga) as indirect semiconductors with superior mechanical stability, characterized by greater resistance to volume compression over shear deformation. Their elasticity exhibits relatively weak temperature dependence, suggesting excellent thermal stability. Thermodynamic analysis predicts that GaBO3 has a higher thermal expansion coefficient than AlBO3, approximately 2.1×10−5 K−1 and 1.8×10−5 K−1 at 300 K, respectively. Significantly, the overall thermal expansion coefficients of GaBO3 and AlBO3 are lower compared to other borate materials containing isolated [BO3] groups. Chemical bonding insights reveal that GaBO3′s larger thermal expansion is attributed to its larger atomic displacement parameters and weaker Ga−O bond strength. This research positions MBO3 (M=Al, Ga) as prime candidates for optical device applications due to their well‐characterized elasticity and controlled thermal expansion. [ABSTRACT FROM AUTHOR]

Highlights Three dimensional (3D) tubular braided composites are widely used in various industries due to their excellent mechanical properties and lightweight characteristics. However, traditional numerical and experimental methods face challenges in predicting mechanical properties quickly and accurately due to factors such as ambient temperature, component materials, and geometric parameters. To address this issue, this paper combines deep neural networks (DNN) and two‐scale finite element analysis to accelerate the solution speed. The dataset is first obtained through a two‐scale finite element model with temperature based on micro‐CT. Then, the mapping model of macroscopic compression elastic properties and the influencing factors of material properties is established by DNN and Bayesian Optimization with Hyperband (BOHB) hyperparameter optimization algorithm. The rapid prediction of axial compression elastic properties of 3D tubular braided composites under different ambient temperatures, component materials, porosities, braiding angles and fiber volume contents is achieved. Finally, the accuracy of the predicted results of the constructed model is verified by experiments. A BOHB optimized deep learning model coupled with a finite element framework is proposed Fast prediction of elastic properties of 3D tubular braided composites at different temperatures The accuracy of the prediction results of the constructed model is verified by experiments [ABSTRACT FROM AUTHOR]

Using the recently developed traction‐associated peridynamic motion equation (TPME), we investigate the plane axisymmetric problems of elastic deformation. The polar coordinate form of TPME is derived for a plane axisymmetric problem. The transfer function matching with prototype microelastic (PM) model is determined by the inverse method in a one‐dimensional case, and then it is directly extended to plane axisymmetric elasticity problems and plane problems. We promote a strategy to deal with the horizon in the non‐uniform discretization scheme. Based on this strategy, the non‐uniform discretization scheme is used to solve the elastic deformation of a hollow circular plate subjected to uniform inner and outer pressures. Total process from elastic deformation to failure of the hollow circular plate under tension is simulated completely. The results show that TPME does not only need volume and surface corrections, but also can deal with the complex traction boundary conditions conveniently. [ABSTRACT FROM AUTHOR]

Herein, an improved mechanical metamaterial is proposed, which is derived from the decomposition, rotation, and reassembly of reentrant structures. The structure is parametric, allowing for rapid redesign. The study focuses on the variations in equivalent stiffness and Poisson's ratio of the structure within the linear elastic range when internal rib angle θ changes. First, based on homogenization simulation analyses, it has been verified that this design achieves the tailorable equivalent elastic modulus and Poisson's ratio over a wide range, meanwhile, maintaining equal elastic properties in the orthogonal direction at all times. Second, to reduce future repetitive experiments, an interpolation model is established to expand the design domain. The fitting formula indicates that by modifying θ and relative wall thickness t/L0, the elastic performance of the structures can be tailored. Additionally, the impact of boundary conditions is discussed to minimize experimental costs. Finally, the accuracy of the simulations is validated through uniaxial compression tests. [ABSTRACT FROM AUTHOR]

Bitumen shows visco-elastic behavior, exhibiting both elastic and viscous properties as predicted by dynamic response and phase angle. Modern asphalt bituminous pavements face issues such as early-stage fatigue cracks, rutting, and permanent deformations due to low-temperature cracking, high-temperature deformation, moisture susceptibility, and overloading. These pavement distresses result in the formation of potholes, alligator cracks, and various deformations, which accelerate the need for rehabilitation and maintenance. To address these concerns, this study focused on utilizing Nitrile Butadiene Rubber derived from surgical gloves as an additive in conventional asphalt pavements to assess its effect on stiffness. Nitrile Butadiene Rubber was added in intervals of 2%, 4%, 6%, and 8% to conventional bituminous pavement. The rheological properties, marshall properties, dynamic modulus, and phase angle were evaluated for varying percentages of Nitrile Butadiene Rubber at different temperature, and frequency. The dynamic response was determined using a simple performance tester at four different temperatures (4.4 °C, 21.1 °C, 37.8 °C, and 54.4 °C) and six different frequencies (0.1, 0.5, 1, 5, 10, and 25 Hz). Response surface methodology was employed to establish a relationship between input and output variables and to optimize the amount of Nitrile Butadiene Rubber in the mix based on dynamic modulus and phase angle. The study concluded that adding up to 6% of Nitrile Butadiene Rubber improved Marshall stability, while higher percentages led to reduced stability. A similar trend was observed in the dynamic modulus, which peaked with the addition of 6% Nitrile Butadiene Rubber, regardless of frequency and temperature. The response surface methodology model indicated that coupling the percentage of Nitrile Butadiene Rubber with frequency increased the dynamic modulus at a constant temperature, with the highest value occurring at 4.4 °C. However, the dynamic modulus decreased as the temperature rose for the same combinations of Nitrile Butadiene Rubber percentages and frequencies. Numerical optimization suggested that a maximum of 5.9% Nitrile Butadiene Rubber should be added to achieve the highest dynamic modulus and lowest phase angle. [ABSTRACT FROM AUTHOR]

Fracture interactions are an important factor that affects rock effective elastic properties. We study the fracture interaction effects by combinations of theoretical modelling, numerical simulations and experiments in this work. First, we propose a simplified differential effective medium scheme and self‐consistent approximation for effective elastic properties of rocks with aligned fractures, and we compare their results to those of non‐interaction approximation. The results show that the predictions by differential effective medium scheme and self‐consistent approximation are lower than those by non‐interaction approximation. This indicates that the differential effective medium scheme and self‐consistent approximation quantify the stress amplification effects but not stress shielding effects. To validate this, we carry out numerical simulations for cases with coplanar cracks and stacked cracks, respectively. We find that the stress shielding effect (stacked cracks) causes a significant increment of effective elastic stiffnesses of fractured rocks. However, the stress amplification (coplanar cracks) has the opposite effect, which induces a slight reduction in rock effective elastic stiffnesses. The differential effective medium scheme quantifies the lower bound for this effect well. Besides numerical simulations, applying theoretical models in experimental measurements also shows a pronounced effect of stress shielding but a small influence of stress amplification on fractured rock elastic properties. This work indicates that the stress shielding is an important effect that affects fractured rock elastic properties. Without considering this effect, the fracture density may be largely underestimated by the seismic or sonic logging inversion. Hence, the models accounting for stress shielding effects need to be developed in the future, which can combine with the above models for the seismic or sonic logging inversion of fracture properties. [ABSTRACT FROM AUTHOR]

Intermetallic titanium aluminides, leveraging the ordered γ-TiAl phase, attract increasing attention in aerospace and automotive engineering due to their favorable mechanical properties at high temperatures. Of particular interest are γ-TiAl-based alloys with a Niobium (Nb) concentration of 5-10 at.%. It is a key question how to model such ternary alloys at the atomic scale with molecular dynamics (MD) simulations to better understand (and subsequently optimize) the alloys. Here, we present a comparative analysis of ternary TiAlNb interatomic potentials developed by the moment tensor potential (MTP) and deep potential molecular dynamics (DeePMD) methods specifically for the above mentioned critical Nb concentration range. We introduce a novel dataset (TiAlNb dataset) for potential training that establishes a benchmark for the assessment of TiAlNb potentials. The potentials were evaluated through rigorous error analysis and performance metrics, alongside calculations of material properties such as elastic constants, equilibrium volume, and lattice constant. Additionally, we explore finite temperature properties including specific heat and thermal expansion with both potentials. Mechanical behaviors, such as uniaxial tension and the calculation of generalized stacking fault energy, are analyzed to determine the impact of Nb alloying in TiAl-based alloys. Our results indicate that Nb alloying generally enhances the ductility of TiAl-based alloys at the expense of reduced strength, with the notable exception of simulations using DeePMD for the γ-TiAl phase, where this trend does not apply. [ABSTRACT FROM AUTHOR]

Intrinsically stretchable conductors are vital components in next‐generation flexible electronics. However, solid conductive networks are generally vulnerable to external deformations due to their incompatible mechanical properties with the highly elastic substrates or matrixes. It is still challenging to achieve precisely controlled conductive structure with stable electromechanical performances. Herein, a nanocomposite conductor with 3D engineered bicontinuous phase system is developed, which is constructed by alternately arranged robust solid‐phase and conductive liquid‐phase via additive liquid/solid assembly. The proper rheological properties and extraordinary structural compatibility of the liquid‐phase prompt the formation of bridged structure within the 3D periodic solid‐phase main skeleton, giving rise to stable and even strain‐enhanced electrical and electromagnetic interference (EMI) shielding properties under external deformation. A negative resistance change of −37% along with unabated EMI shielding effectiveness and mechanical properties are obtained at 100% strain, showing negligible performance degradation even after 10,000 cycles of rigorous stretching and releasing. A strain‐tolerant pressure‐sensing device is further demonstrated using the liquid/solid nanocomposite structure, delivering a unique function of precisely recognizing the local pressure at large tensile loading interference. This work provides a new paradigm for the manufacturing of nanocomposites with desired functionalities using the adequate nanofiller reserve toward practical strain‐tolerant applications. [ABSTRACT FROM AUTHOR]