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Tissue susceptibility to histotripsy disintegration has been reported to depend on its elastic properties. This work was aimed at investigation of histotripsy efficiency for liquefaction of human hematomas, depending on their stiffness and degree of retraction over time (0–10 d). As an in vitro hematoma model, anticoagulated human blood samples (200 mL) were recalcified at different temperatures. In one set of samples, the shear modulus was measured by shear wave elastography during blood clotting at 10℃, 22℃ and 37℃, and then daily during further aging. The ultrastructure of the samples was analyzed daily with scanning electron microscopy (SEM). Another set of blood samples (50–200 mL) were recalcified at 37℃ for density and retraction measurements over aging and exposed to histotripsy at varying time points. Boiling histotripsy (2.5 ms pulses) and hybrid histotripsy (0.2 ms pulses) exposures (2 MHz, 1% dc, P +/ P –/ A s = 182/–27/207 MPa in situ) were used to produce either individual cigar-shaped or volumetric (0.8–3 mL) lesions in samples incubated for 3 h, 5 d and 10 d. The obtained lesions were sized, then the lysate aspirated under B-mode guidance was analyzed ultrastructurally and diluted in distilled water for sizing of residual fragments. It was found that clotting time decreased from 113 to 25 min with the increase in blood temperature from 10℃ to 37℃. The shear modulus increased to 0.53 ± 0.17 kPa during clotting and remained constant within 8 d of incubation at 2℃. Sample volumes decreased by 57% because of retraction within 10 d. SEM revealed significant echinocytosis but unchanged ultrastructure of the fibrin meshwork. Liquefaction rate and lesion dimensions produced with the same histotripsy protocols correlated with the increase in the degree of retraction and were lower in retracted samples versus freshly clotted samples. More than 80% of residual fibrin fragments after histotripsy treatment were shorter than 150 µm; the maximum length was 208 µm, allowing for unobstructed aspiration of the lysate with most clinically used needles. The results indicate that hematoma susceptibility to histotripsy liquefaction is not entirely determined by its stiffness, and correlates with the retraction degree. [ABSTRACT FROM AUTHOR]

This work focuses on the characterization of CuZnAl shape-memory alloy in its 3 states (austenitic, mixed, and martensitic) by a non-destructive technique to determine its elastic properties. This technique is based on the principle of acoustic microultrasound. It allows measuring the propagation velocities of the longitudinal, transverse, and Rayleigh acoustic waves, from which the elastic constants of the material (Young's modulus E, shear modulus G) are calculated. Thus, the obtained results of the measurements allow the modelling of the acoustic signature V(z) and the reflection coefficient R(θ) to compare the resulting Rayleigh velocities, which were modelled and measured experimentally in the different phases. [ABSTRACT FROM AUTHOR]

With the introduction of carbon nanotubes, their fascinating features, including outstanding strength, exceptional stiffness, low density, and structural integrity at the nanoscale, became evident. These qualities generated excitement for a variety of technological applications. Over the last ten years, an evolving understanding of carbon nanotube mechanics has been shaped by a combination of experimental validation, the refutation of theoretical predictions, and the application of various computer simulation techniques. The objective of this research was to explore theoretical predictions concerning the visualization and manipulation of minute structures. The central focus is on examining mechanical characteristics, including Young's modulus, Poisson's ratio, shear modulus, and buckling criteria in diverse configurations of single-walled carbon nanotubes. Beam elements are utilized in this study to model the covalent bonds between Carbon-Carbon (C-C) atoms in Carbon Nanotubes (CNTs). Using a continuum mechanics framework, the paper aims to predict the characteristics of these beam elements. Baseline values for the properties of C-C bonds are established through numerical analysis to conduct simulations. The paper employs a finite element methodology to scrutinize the mechanical behavior of carbon nanotubes and carries out a parametric investigation to evaluate the influence of single-walled carbon nanotube diameter on shear modulus and buckling loads. [ABSTRACT FROM AUTHOR]

Face-layer density is widely known to be important for bending properties such as modulus of rupture (MOR), static bending Young's modulus (Es), and dynamic bending Young's modulus (Ed), whereas outer core-layer density is not. According to this study, the outer core-layer density is more important than face-layer density in commercial particleboard. Core and face layers were manufactured with coarse and fine particles, respectively. The coarse particles increased bending properties due to the presence of long wood fibers. However, fine particles did not increase the bending properties due to the absence of long wood fibers. Long wood fibers in the outer core layers, as opposed to the face layers, increase the bending properties. MOR can be predicted using Es (or Ed) and outer core-layer density. Furthermore, shear modulus (G) was determined, and the effects of layer density on G were investigated. However, they were not indicated. [ABSTRACT FROM AUTHOR]

3D geomechanical characterization of "Fuja" field reservoirs, Niger Delta, was carried out to evaluate the mechanical properties of the reservoir rock which will assist in reducing drilling and exploitation challenges faced by operators. Bulk density, sonic, and gamma-ray logs from four wells were integrated with 3D seismic data and core data from the area to estimate the elastic and inelastic rock properties, pore pressure, total vertical stress, as well as maximum and minimum horizontal stresses within the reservoirs from empirical equations, using Petrel and Microsoft Excel software. 3D geomechanical models of these rock properties and cross-plots showing the relationship between the elastic and inelastic properties were also generated. From the results, Young's modulus, bulk modulus, bulk compressibility, shear modulus, Poisson's ratio, and unconfined compressive strength recorded average values of 5.11 GPa, 5.10 GPa, 0.023 GPa−1 , 2.39 GPa, 0.39, and 39.0 GPa, respectively, in the sand, and 6.08 GPa, 6.09 Gpa, 0.016 GPa−1 2.84 GPa, 0.42, and 42.3 GPa, respectively, in shale, implying that the sand is less elastic and ductile and will deform before the shale under similar stress conditions. Results also revealed mean pore pressures of 13,248 psi and 15,220 psi in sand and shale units, respectively, mean total vertical stress of 28,193 psi, mean maximum horizontal stress of 26,237 psi, and mean minimum horizontal stress of 21,532 psi. From the geomechanical models, the rock elastic and inelastic parameters revealed higher values around the northeastern and parts of the eastern and western portions of the reservoir implying that mechanical rock deformation will be minimal in these sections of the field compared to other sections during drilling and post-drilling activities. The generated cross-plots indicate that a relationship exists between the elastic rock properties and unconfined compressive strength. Stress estimations within the reservoirs in relation to the obtained elastic and rock strength parameters show that the reservoirs are stable. These results will be invaluable in mitigating exploration and exploitation challenges. [ABSTRACT FROM AUTHOR]

A methodology for achieving the maximum bulk or shear modulus in an elastic composite composed of two isotropic phases with distinct Poisson's ratios is proposed. A topology optimization algorithm is developed which is capable of finding microstructures with extreme properties very close to theoretical upper bounds. The effective mechanical properties of the designed composite are determined by a numerical homogenization technique. The sensitivities with respect to design variables are derived by simultaneously interpolating Young's modulus and Poisson's ratio using different parameters. The so-called solid isotropic material with penalization method is developed to establish the optimization formulation. Maximum bulk or shear modulus is considered as the objective function, and the volume fraction of constituent phases is taken as constraints. The method of moving asymptotes is applied to update the design variables. Several 3D numerical examples are presented to demonstrate the effectiveness of the proposed structural optimization method. The effects of key parameters such as Poisson's ratios and volume fractions of constituent phase on the final designs are investigated. A series of novel microstructures are obtained from the proposed approach. It is found that the optimized bulk and shear moduli of all the studied composites are very close to the Hashin-Shtrikman-Walpole bounds. [ABSTRACT FROM AUTHOR]

The resonant column test includes torsional and flexural modes that can be used to obtain reduction curves for the shear modulus and Young's modulus of the soil, respectively. When the resonant column test is performed under flexural mode, Young's modulus is calculated mainly using the measured resonant frequency following the formula proposed by Cascante et al. However, this formula does not consider the rotational inertia effect of the electromagnetic drive disk of the resonant column apparatus and thus may inaccurately calculate Young's modulus. In this study, the formula was modified by considering the rotational inertia effect of the electromagnetic drive disk, and its accuracy was verified by using three aluminum calibration rods with different diameters as a dummy specimen for the resonant tests in flexural and torsional modes. [ABSTRACT FROM AUTHOR]

The mechanical response of individual titanate nanowires (H 2 Ti 3 O 7), synthesized in an upscaled production (kg/month) was investigated by means of an Atomic Force Microscope (AFM) in nanomechanical spectroscopic mode. Because of their layered structure, besides the Young's modulus (E) of 66.7 ± 25 GPa, an important contribution to the mechanical response was identified as coming from the low shear modulus (G) of 1.5 ± 0.8 GPa between the layers. The mechanical energy loss due to shear is at the origin of the material's fatigue, during which the individual titanate layers crack gradually, until the final failure of the structure. The high-temperature treatment at 800 °C transforms the material into anatase (TiO 2) nanowires, which have a considerably higher elastic modulus. [ABSTRACT FROM AUTHOR]

The idealized inverse-opal lattice is a network of slender struts that has cubic symmetry. We analytically investigate the elastoplastic properties of the idealized inverse-opal lattice. The analysis reveals that the inverse-opal lattice is bending-dominated under all loadings, except under pure hydrostatic compression or tension. Under hydrostatic loading, the lattice exhibits a stretching dominated behavior. Interestingly, for this lattice, Young's modulus and shear modulus are equal in magnitude. The analytical estimates for the elastic constants and yield behavior are validated by performing unit-cell finite element (FE) simulations. The hydrostatic buckling response of the idealized inverse-opal lattice is also investigated using the Floquet-Bloch wave method. [ABSTRACT FROM AUTHOR]

It is well-known that laboratory testing of pervious concrete's freeze-thaw performance is too harsh and does not agree well with field observations. The most commonly used laboratory freeze-thaw test method for pervious concrete is similar to that used for conventional concrete even though the void structure of the two materials is completely different. In the present study, a new freeze-thaw test method for pervious concrete is suggested and tested on one baseline mix, with three different contents of entrained air. The evaluation of freeze-thaw damage on pervious concrete beams was evaluated from the decrease in mass and from operational modal analysis which provides an accurate determination of the change in natural frequencies with freeze-thaw exposure. Operational modal analysis was also used to determine the Young's modulus, shear modulus, and Poisson's ratio of the pervious concrete mix. [ABSTRACT FROM AUTHOR]

The Young’s modulus and shear modulus of extruded polystyrene foam were obtained by measurements using the longitudinal and flexural vibration methods on specimens with various lengths and performing a subsequent numerical analysis on the test data. In addition to the vibration tests, ISO 844 compression and ASTM C273/C273M-11 shear tests were conducted, and the results were compared with those obtained from the vibration tests. The Young’s modulus values could be measured accurately by the longitudinal and flexural vibration tests while reducing the effects of the specimen configuration. In contrast, the shear modulus value was often dependent on the specimen configuration. The Young’s modulus and shear modulus values obtained from the vibration tests were often higher than those obtained from the standardised tests because the bending of cell wall is not induced in the vibration test. Although a provisional method for reducing the influence of the specimen configuration was proposed based on the numerical results, further research is required to measure the elastic modulus of extruded polystyrene foam accurately. [ABSTRACT FROM AUTHOR]

The objectives of this study are, 1) to simulate asphalt binder modified with exfoliated multi-layered graphite nanoplatelets (xGNP) using the Molecular Dynamics (MD) method, and 2) to analyze different modulus properties of these asphalt binder models compared with those of the control asphalt binder model. The multi-layered graphene model was used to represent the xGNP particles, which were used to modify the control asphalt in the laboratory. The three-component control asphalt binder model was used as in the authors’ previous study. The xGNP modified asphalt binder model was built by incorporating the xGNP model and control asphalt binder model and controlling mass ratios to represent the laboratory prepared samples. After the xGNP modified asphalt binder model was generated, the densities of the control and xGNP modified asphalt binder models were computed and verified. Mechanical properties of these models were simulated and calculated in MD simulations using procedures similar to those in the experiments, which include the bulk modulus, Young’s modulus, shear modulus and Poisson’s ratio. The simulation results indicate that the temperature-modulus trends of these asphalt binder models were comparable to those of the laboratory data. The MD simulation data were larger than the laboratory results due to limitations of the current MD simulation, which are discussed in this study. In addition, Poisson’s ratios calculated from the MD simulations coincided with the laboratory results. [ABSTRACT FROM AUTHOR]

This study presents the material characterization of pultruded fiber-reinforced polymer beams of different sizes using experimental and analytical methods. Various tests were performed to determine the material properties such as Young's and shear moduli using tensile and bending tests of coupons and beams. The stiffness measured from the four-point bending test of both beams is in close agreement with analytical methods. It is shown that the numerically obtained flexural response of the beam using ABAQUS software with material properties obtained from the four-point beam bending test is close to the experimental response. [ABSTRACT FROM PUBLISHER]

A Lateral Force Unit (LFU) as a second measuring head for nanoindenters is now available as a commercial tool with the necessary accuracy to investigate the elastic contact between a sphere and a flat surface with sub-nanometer resolution. The combination of normal and lateral load-displacement measurements at one and the same sample position gives two independent measurement results and can therefore be used to extract beside Young's modulus a second elastic constant. This can be shear modulus or Poisson's ratio for elastically isotropic materials. To realize that, it is necessary to determine all necessary corrections with high precision. This comprises normal and lateral instrument compliance, indenter area function, spring constant of the holding springs of the LFU and the surface slope. Two algorithms were developed and tested for the determination of the Poisson's ratio from fully elastic measurements with a spherical indenter. One is using the ratio of normal and lateral contact stiffness and the other the curvature of the lateral load-displacement curve at the turning points and the transition from sticking to sliding friction. By measuring six different materials it was shown that the ratio of normal and lateral contact stiffness results in relatively large errors for the Poisson's ratio of up to 50% against literature data while the other method had only an error (1σ) between 6% and 20%. The last method is restricted to hard and smooth materials to enable measurements in fully elastic regime but it can also be applied to coatings if they are about 2.5–4 times ticker than the contact radius during the measurement. This is nevertheless a progress against the current situation where the Poisson's ratio of coatings is mostly unknown. [ABSTRACT FROM AUTHOR]

Successful synthesis of the stable metal-free two-dimensional polymer graphitic carbon-nitride with remarkable properties has made it as one of the most promising nanostructures in many novel nanodevices, especially photocatalytic ones. Understanding the mechanical properties of nanostructures is of crucial importance. Thus, this study employs density functional theory (DFT) to obtain the mechanical properties of graphene-like graphitic carbon-nitride (g-C3N4) nanosheets such as Young's, bulk and shear moduli and Poisson's ratio. Based on the results, Young's, bulk and shear moduli of this nanosheet are lower than those of graphene and hexagonal boron-nitride sheet. Besides, it is observed that the values of the aforementioned properties for graphene-like g-C3N4 nanosheets are higher than those of porous graphene and SiC. It is further observed that the Poisson's ratio of graphene-like g-C3N4 nanosheets is lower than those of any similar two-dimensional graphitic structures. [ABSTRACT FROM AUTHOR]

The elastic constants and elastic modulus of un-doped and Cd-doped (4–6, 0) zigzag SWCNTs with different diameters are studied by density functional theory. This research has three crystal structures: hexagonal, orthorhombic, and triclinic. Besides, all cases have anisotropy features. This work showed that the elastic constants (ECs) had positive and negative values. Negative signs of ECs mean that the material has soft's features. The elastic modulus results indicated that the curve value of Young's modulus (Y), shear modulus (G), and bulk modulus (B) fluctuated up-down depending on the un-doped and Cd-doped (n, 0). The correlation between these elastic moduli as a function diameter of un-doped and Cd-doped zigzag SWCNTs is studied. The results show that Voigt's Y increases with increased tube diameter for both un-doped and Cd-doped. Simultaneously, Reuss and Hill's Y fluctuated for both un-doped and Cd-doped. The explanations of G are similar to Y for the curve value of G and the relation between G and tube diameter. The B values of un-doped (4–6, 0) increased with the increased diameter. Besides, the situation of Cd-doped (4–6, 0) is contrary. These results are strongly related to the diameter, n index, un-doped, and Cd-doped. [Display omitted] [ABSTRACT FROM AUTHOR]

In the present work the influence of nc-TiN nanocrystals on the elastic properties of nc-TiN/a-Si 3 N 4 nanocomposite is discussed. The elastic moduli (shear modulus, compression modulus, Young’s modulus) for both amorphous matrix a-Si 3 N 4 and nc-TiN nanocrystals of different size were calculated by first-principles method and molecular static method correspondingly. The Volkov-Stavrov approach was applied for modeling elastic properties of nanocomposite taking into account size and volume fraction of the TiN inclusions. The results of modeling showed the increase the effective elastic moduli of the nc-TiN/a-Si 3 N 4 nanocomposite with nc-TiN inclusions size and volume fraction growth. The obtained results are compared to the experimental data. [ABSTRACT FROM AUTHOR]

Functional adaptation of the femur has been investigated in several studies by embedding bone remodelling algorithms in finite element (FE) models, with simplifications often made to the representation of bone's material symmetry and mechanical environment. An orthotropic strain-driven adaptation algorithm is proposed in order to predict the femur's volumetric material property distribution and directionality of its internal structures within a continuum. The algorithm was applied to a FE model of the femur, with muscles, ligaments and joints included explicitly. Multiple load cases representing distinct frames of two activities of daily living (walking and stair climbing) were considered. It is hypothesised that low shear moduli occur in areas of bone that are simply loaded and high shear moduli in areas subjected to complex loading conditions. In addition, it is investigated whether material properties of different femoral regions are stimulated by different activities. The loading and boundary conditions were considered to provide a physiological mechanical environment. The resulting volumetric material property distribution and directionalities agreed with ex vivo imaging data for the whole femur. Regions where non-orthogonal trabecular crossing has been documented coincided with higher values of predicted shear moduli. The topological influence of the different activities modelled was analysed. The influence of stair climbing on the properties of the femoral neck region is highlighted. It is recommended that multiple load cases should be considered when modelling bone adaptation. The orthotropic model of the complete femur is released with this study. [ABSTRACT FROM AUTHOR]

The mechanical properties of the glass-epoxy composite material known as “G-10,” which is primarily used for electrical insulation purposes in electromechanical systems, have long been a topic of uncertainty and controversy. In the present paper, we demonstrate the application of an experimental methodology that exploits the Direct Strain Imaging (DSI) full field method to fully assess the elastic anisotropic mechanical properties of G-10. Tension and compression experiments were conducted for three distinct inclinations of the specimen orthotropic axes relative to the loading directions, while strain and displacement were monitored at relevant locations on the specimens via digital image capturing and subsequent application of DSI. Based on these experiments, we present the stress-strain experimental data, the associated data post processing, the engineering properties, the anisotropic compliance matrix and the ultimate strength properties of the G-10 composite material. Confidence bounds on the material properties based on the results from repeated tests on identical specimens are also reported. [ABSTRACT FROM AUTHOR]

Young modulus of magnetostrictive materials such as Permendur are changed by altering the external magnetic field. This phenomenon is called Δ E effect. In this paper, it has been experimentally shown that the shear modulus in Permendur is also changed in such a way that the ratio between Young modulus and shear modulus is not constant in different magnetic fields. Thus, Poisson ratio of it is also changed in different magnetic fields. Acoustic pulse–echo method is exploited to measure dependency of these properties to magnetic fields. In this method, longitudinal and shear sound wave velocities in Permendur are measured in different magnetic fields. Using these data, dependency of Young modulus, shear modulus and Poisson ratio on magnetic bias field in Permendur are calculated. Measurements are repeated 30 times in order to study test uncertainty. Changing in Poisson ratio can be interpreted as a result of changing in volume of magnetostrictive materials in different magnetic field (Nagaoka–Honda effect). The amount of this effect in ferromagnetic material is small. Hence, change in Poisson ratio in this material is predicted to be remarkably slight. For instance, based on presented results in Permendur, maximum changing in Poisson ratio is less than 0.014. [ABSTRACT FROM AUTHOR]

For the first time, we determine the modulus of elasticity (Young's modulus), the shear modulus, and the coefficient of transverse deformation (Poisson's ratio) for hot-pressed dodecaborides by using the basic thermal characteristics of the dodecaborides of rare-earth metals and zirconium YB, TbB, DyB, HoB, ErB, TmB, YbB, LuB, and ZrB and the experimental methods of static and dynamic investigations. The numerical and experimental values of the mechanical parameters coincide. The modulus of elasticity of dodecaborides is approximately twice smaller than for pure boron and does not increase, as theoretically predicted, in the sequence MeB → MeB → MeB. This fact can be explained by the structural features of the crystal lattice of dodecaboride phases, the lengths of the B-B, Me-B, and Me-Me bonds, and the forces of interaction between the atoms in these phases. [ABSTRACT FROM AUTHOR]

Hardwood is increasingly trying to get established in the building industry in order to realise a larger material output and to take advantage of the superior mechanical properties of hardwood in comparison to softwood for structural applications. For calculations of stress and strain in boards and glued-laminated timbers it is essential to know the specific values of wood in the main directions: longitudinal, radial and tangential. Therefore, the specific values of Young's modulus, shear modulus, Poisson's ratio, the specific values of strength and also these of mass and heat flux (diffusion coefficient, thermal conductivity) were determined on European beech. [ABSTRACT FROM AUTHOR]

The on-going need to improve design or scale-up of particulate solids processes, may it be handling, storage, transport or prediction of nature's phenomena, led to the use of the Discrete Element Method (DEM) which can help to develop a fundamental understanding of the particulates' behaviour. The interest is often focused on the particle trajectories, bulk structure, forces and velocities. Research and reviews were carried out on theoretical treatments and applications of DEM, DEM coupled with CFD or in comparison to continuum modelling. Whatever DEM code or contact model is chosen, an elasticity parameter such as the Young's modulus, the shear modulus or yet the loading/unloading stiffness is implemented. The elasticity parameter not only accounts for the deformation behaviour but also for the time step. Concerning the latter one the elasticity is often reduced to lower the running time of a simulation. Our review on the influence of these elasticity parameters on numerical results revealed that in pure numerical studies the elasticity is often reduced, neglecting any probable change of numerical response. However, we also found that awareness of the importance of the elasticity has increased lately. This study is part of the PARDEM research network: www.pardem.eu . [ABSTRACT FROM AUTHOR]

• Physics- and chemistry-informed machine learning models were developed for predicting glass properties. • Young's modulus, shear modulus and electrical resistivity were predicted by artificial neural network (ANN), support vector machine (SVM), and random forest (RF) models. • Relationships between glass properties and their first and second important features were revealed. Physics- and chemistry-informed machine learning (ML) models were trained by using descriptors in the element physical and chemical properties domain, which include stoichiometric, elemental-property-based, valance orbital occupation, and ionicity features. Young's modulus, shear modulus and electrical resistivity (ρ) data for a group of oxide glasses were used to train artificial neural network (ANN), support vector machine (SVM), and random forest (RF) models. In comparison with experimental values, the ANN performs the best in predicting elastic moduli, whereas the RF is the best in predicting the temperature dependence of ρ in terms of the coefficient of determination (R2) value. The benefits of the ML models using descriptors in the element physical and chemical properties domain were demonstrated by revealing the relationships between the predicted glass properties and their first and second important features through a grid search. [ABSTRACT FROM AUTHOR]

Elastic moduli (Young's modulus and shear modulus) are material properties that describe a material's elastic stress-strain relation, and are therefore two of the most important properties in geotechnical engineering design and analysis. For soils, in addition to their well-known dependence on stress, these moduli depend on volumetric water content and/or matric suction, particularly for silty and clayey soils. This study proposes a simple power law to describe the dependence of these two moduli on volumetric water content for all types of soils. A series of uniaxial compression tests are conducted on various compacted soils under varying volumetric water content. Young's moduli are measured and used to test the validity of the proposed power-law relationship. Additional validation and comparative analyses are conducted using other compacted soils studied by previous investigators and empirical models for shear modulus from the literature. It is shown that the proposed power law agrees well with the other models, but is much simpler because the other models use both matric suction and volumetric water content as independent variables and involve more fitting parameters. A practical three-point testing procedure is provided to determine the single fitting parameter that defines the power law for any type of soil. The procedure involves measuring elastic moduli at three states of water content: dry, wet (nearly saturated), and the middle points. Test results for 16 soils demonstrate that the proposed three-point testing procedure can accurately capture the dependence of Young's moduli for all types of soils from sandy to silty to clayey soils ( R2>95% for most soils). The proposed power law provides a simple and practical way to describe changes in elastic moduli of soils under variably saturated conditions. [ABSTRACT FROM AUTHOR]

Despite the significant progresses in discrete-based numerical studies of granular materials, most efforts have been placed in the study of large deformation problems and there are many unresearched areas in the multi-scale analysis and the influence of grain-scale parameters on the bulk behavior of granular systems in the regime of small strains. In this work, we present a numerical investigation into the small and small-to-medium strain shear modulus of sands performing DEM analyses, exploring the influence of grain-scale parameters, and attempting to link micromechanical-based quantities with the macroscopic behavior of granular materials. For the calibration, we used real experimental grain-scale data for the contact stiffness and interparticle friction, and resonant column macroscopic test results on a quartz sand were used as the benchmark model sample. Subsequently, a parametric DEM study was carried out investigating the influence of Young's modulus (and contact stiffness) as well as the interparticle friction on macroscopic stiffness and stiffness reduction curves, and additional insights were obtained based on the inferred contact forces and force networks, coordination number and fabric anisotropy. The numerical results contribute to understand the differences between different sand types as reported in the literature in the regime of small-to-medium strains. [ABSTRACT FROM AUTHOR]

Experimental procedures have been developed to obtain the mechanical stiffness and strength properties of an orthotropic polyurethane-coated nylon fabric for use in a finite element analysis of an inflatable, deployable structure. A method that utilizes a specialized material test fixture and photogrammetry to collect the linear and angular displacement data has been employed. Different material holding methods were compared with the objective of producing strength values not influenced by gripping and that allow for use of machine displacement to estimate longitudinal strains during cyclic testing. A series of tension and bias tension tests provided material properties such as Young’s modulus in both warp and fill directions, Poisson’s ratios in plane and through the thickness, and shear modulus. Results obtained from the photogrammetry method show good correlation to machine readings using a pinched gripping method. Additionally, cyclic tests gave the continuous load–unload response and the hysteresis characteristics of the stress–strain in plane and indicated the degree of material degradation. The shear stress–shear strain behavior and shear modulus values are acquired using bias tension tests on 45° skewed specimens. [ABSTRACT FROM PUBLISHER]

DEM (discrete element method) simulations are carried out to evaluate the small strain stiffness (i.e. Young's modulus and shear modulus) of a granular random packing with focus on the effect of stress ratio ( SR). The results show that the Young's modulus in a given direction generally depends on the stress component in that direction. The Young's modulus normalized by the related stress component remains nearly constant when SR is less than a threshold value $$SR_\mathrm{th}$$. When SR is larger than $$SR_\mathrm{th}$$, the normalized Young's modulus decreases, particularly in the minor principle stress direction. Moreover, the Young's modulus during unloading is always smaller than the one during loading at the same stress state, which indicates that the microstructure of the specimen has been modified by the historical shearing process. The shear modulus mainly depends on the mean effective stress and shows similar evolution trend as the Young's modulus. This study finds that the macroscopic stiffness of the specimen is closely related to the evolutions of particle contact number and contact force during shearing. When SR is less than $$SR_\mathrm{th}$$, the specimen only adjusts the distribution of contact forces to resist the external load, without any apparent change of contact number. When SR is larger than $$SR_\mathrm{th}$$, however, the specimen has to adjust both contact number and contact forces to resist the external load. The study also illustrates that there is a good relationship between the macroscopic stiffness anisotropy and fabric anisotropy, and therefore the stiffness anisotropy may be used as an indicator of fabric anisotropy. [ABSTRACT FROM AUTHOR]

This work analyses shear moduli of conventional and auxetic open-cell polymer foams. Shear moduli are i) measured directly and ii) calculated by applying elasticity theory for isotropic solid materials, using Young's moduli and Poisson's ratios from compression tests. Zero and negative Poisson's ratio foams are fabricated from conventional foams using a thermo-mechanical process. Fabricated and conventional foams are compression tested in three orthogonal directions, up to densification at ~60% compression, with full-field strain measurements obtained using Digital Image Correlation. Compression testing is followed by shear testing. The measured shear moduli vary from 16±7 kPa for negative Poisson's ratio foams to 38±2 kPa for zero Poisson's ratio foams, with conventional foams in between with a mean value of 32±8 kPa. The calculated shear moduli are typically lower than the measured values. The results suggest that the application of elasticity theory to calculate the low strain shear modulus of open-cell foam from Young's modulus and Poisson's ratio measured in compression tests is appropriate if the foam is isotropic. • The open-cell foams with negative, zero and positive Poisson's ratio were tested under compression loading in three orthogonal directions, up to densification; • Full-field strain measurements were done using Digital Image Correlation to determine the Poisson's ratio; • Compression tests were followed by shear testing in three orthogonal directions, up to failure; • Shear moduli was measured directly and calculated by applying the elasticity theory for isotropic solid materials, using Young's moduli and Poisson's ratios from compression tests; • The results suggest that the application of elasticity theory to calculate the low strain shear modulus of open-cell foam from Young's modulus and Poisson's ratio measured in compression tests is appropriate if the foam is isotropic. [ABSTRACT FROM AUTHOR]

The elastic constants play a central role in the regulation of the thermo-mechanical and anisotropic response of materials. Nevertheless, there is still a lack of theoretical and experimental data on these constants which limits the possibility of developing new materials with targeted mechanical responses. The elastic constants of diamond and silicon as second and third-order are obtained using density functional theory (LDA, GGA, and HSE) and for the first time with the adiabatic-connection fluctuation–dissipation theorem in the random phase approximation. Our SOECs calculations show an excellent agreement with experimental data. In this framework, we study the mechanical properties such as Young's modulus, Poisson's ratio, bulk modulus, and shear modulus of diamond and silicon structures. Also, we visualize the 3D plot, as well as 2D for Young's modulus, Poisson's ratio, and others. For the TOECs, we show that can be taken our RPA results as a reference, since there is still a lack of reliable previous theoretical and experimental data of these materials. • We study the SOEC and TOEC of Si and C. • We show that can be taken our RPA results as a reference. • Young's modulus and Poisson's ratio are fully described. • We visualize the 3D plot, as well as 2D for Young's modulus and Poisson's ratio. [ABSTRACT FROM AUTHOR]

Ageing is associated with alterations in the structure and function of the contractile and elastic tissues that enable movement, posture, and balance. Alterations in structure and mechanical properties of the ankle plantarflexors and Achilles tendon are of particular interest due to their important 'catapult-like' function during efficient and healthy human locomotion. In this study, we examined age-related differences in the in vivo mechanical properties of both muscle and tendon in the human ankle plantarflexors in healthy younger (21 ± 3.25 years) and older (69 ± 2.86 years) adults. All participants were physically active, to represent healthy ageing. B-mode ultrasound coupled with force measurements was used to determine in vivo Achilles tendon stiffness and shear-wave elastography was used to measure shear modulus, an index of muscle stiffness, in the medial and lateral gastrocnemii. We found that older adults displayed 43% lower (p = 0.004) Achilles tendon stiffness, 59% lower (p < 0.001) Achilles tendon Young's modulus, and 34% greater (p = 0.002) Achilles tendon cross-sectional area compared to younger participants. We found no difference in the shear modulus of the medial or lateral gastrocnemii between the younger and older individuals. The reduction in Achilles tendon stiffness coupled with similar gastrocnemii muscle shear modulus likely influences the integrated neuromechanical function of the ankle plantarflexor muscle–tendon units during locomotor tasks. Further investigations into the relationship between altered mechanical properties and in vivo muscle–tendon dynamics will provide greater insights into the age-related declines in mobility and locomotor function. [ABSTRACT FROM AUTHOR]

This research article examines the application of various methods to determine the effective elastic properties of beech veneer-wood composites. Using laminate theory, the theoretically calculated effective values of the in-plane and out-of-plane modulus of elasticity as well as shear modulus are compared with the values determined from the natural frequencies of flexural, torsional and longitudinal vibrations of samples having different orientations and numbers of composite layers. The samples are also modelled using the finite element method, and their natural frequencies are calculated by the modal analysis. Research has shown that the laminate theory, which is well established and applied in the world of synthetic composites, can also be applied to beech plywood composites, where the theoretically calculated effective values can be up to 15% higher. Similarly, due to the higher calculated effective elastic properties, higher natural frequencies of flexural, torsional and longitudinal vibrations are also calculated by the finite element method. [ABSTRACT FROM AUTHOR]