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In this study, a segmented degradation model was established for the first time to predict and evaluate the dynamic degradation characteristics of carbon fibre-reinforced epoxy composite (CFRC) shells accurately by considering temperature variations during heating, maintenance, and cooling. The model is based on the Reddy's high-order shear deformation theory, complex modulus method, and coefficient fitting approach. First, explicit expressions of material parameters and thermal expansion coefficients (TECs) in different thermal degradation stages were proposed, followed by the derivation of the differential equations to solve the structural dynamic degradation characteristics. Moreover, an identification method for the fitting coefficients of the CFRC material was described, which is based on experimental tests and iterative calculations of elastic moduli, loss factors, and TECs at different degradation time points in different thermal degradation stages. Finally, the natural frequencies, damping ratios, and time-domain responses were measured using a novel testing system for the dynamic degradation of specimens subjected to a pulse excitation load to validate the developed model. Theoretical and experimental results indicate that the natural frequencies decreased as the degradation time increases at the heating-up and temperature maintenance stages, whereas they increased at the cooling stage. However, an uptrend in the damping and response behaviours was observed in the first two stages, whereas a downtrend was recognized at the cooling stage.

The coefficient of restitution describes the energy dissipation resulting from particle-particle and particle–surface interactions in solid–fluid flows. The energy loss depends on the mechanical characteristics of the solid phase, therefore, to correctly predict the behavior of these systems it is necessary to use reliable coefficient values based on the properties of the particles. This paper investigated the energy dissipation in particle–surface collisions using 7 types of particles with a wide range of mechanical properties (Young's modulus between 1.38 × 104 and 2.83 × 109 Pa). Three empirical equations have been proposed to calculate the coefficient of restitution based on the impact velocity and the compressional wave velocity. The experimental results presented an inverse relation between the impact velocity and the coefficient of restitution. This effect was more pronounced for less elastic particles. The models presented an accurate fit to the experimental data and statistical analysis showed that the Power model presented the greater capacity to predict the coefficient of restitution from generic data. The experimental results showed the predominant effect of mechanical characteristics on the coefficient of restitution. In addition, the proposed equations are proved to be precise tools for predicting particle coefficients of restitution with a wide range of elasticity modulus at low velocities.

It is well known that no useful analytical models are available for predicting the porosity dependence of effective properties for partially sintered ceramics with an open (interconnected) pore space where concave pore surfaces are dominating. This does not mean, however, that that the problem of determining the effective properties of partially sintered ceramics does not have a unique solution for a given microstructure. It just means that this solution can be obtained only numerically. In this contribution we report the polynomial fits of our numerical results for the effective elastic moduli (Young’s modulus, shear modulus, bulk modulus) and conductivity (thermal or electrical) for model materials based on the random close packing of monosized spheres. These relations are recommended as benchmark relations for the porosity dependence of the effective properties of partially sintered ceramics.

Many models of damage or cracking of isotropic solids consider a single damage/crack density variable. Based on both continuum damage mechanics (CDM) and effective medium theory (EMT), we model the impact of isotropic damage in the form of microcracks on the elastic properties of an isotropic solid. For each approach, we consider the complete tensorial description of the elastic moduli involving two damage/crack density variables $$D_{1}$$ and $$D_{2}$$ , or $$\alpha$$ and $$\beta$$ ; and possible scalar approximations involving a single variable (with either $$D_{2}$$ = 0, or $$\beta$$ = 0). We assess the accuracy of scalar approximations commonly employed for each approach against laboratory measurements of ultrasonic wave velocities and density obtained on a dry and isotropic specimen of thermally cracked Carrara Marble (CM) subjected to an increasing confining pressure up to 50 MPa. Overall, this laboratory dataset and the CDM and EMT modelling and inversion results reported here suggest that: (i) irreversible thermal cracking and microcrack opening occur after heating and sudden cooling of the CM specimen, whereas reversible and progressive microcracks’ closure occurs with increasing confining pressure; (ii) tensorial damage/cracking models involving either two damage variables (CDM) or two crack density variables (EMT) fit equally well and virtually perfectly the laboratory data for any confining pressure tested; (iii) single scalar approximation models commonly used in CDM or the EMT models give comparable results to their complete tensorial counterparts, which is particularly true for the CDM approach; (iv) single scalar approximations derived from the CDM approach, and assuming a constant Poisson’s ratio of the cracked rock, reproduces all the elastic moduli more accurately than the corresponding scalar approximation derived from the EMT approach, where a constant ratio of Young’s modulus to Poisson’s ratio is assumed instead; and (v) it is more reliable to use a tensorial rather than a scalar description of the effect of reversible microcrack closure with pressure on all elastic parameters, including Poisson’s ratio. If the impact of reversible microcrack closure is accounted for, then a single scalar description of irreversible thermal damage with the CDM approach is remarkably accurate.

The mechanical features evaluated theoretically using Makishima-Mackenzie's model for glasses xBaO-(50-x) PbO–50P2O5 where x = 0, 5, 10, 15, 20, 30, 40, and 50 mol%. Wherefore, the elastic characteristics; Young's, bulk, shear, and longitudinal modulus calculated. The obtained result showed an increase in the calculated values of elastic moduli with the replacement of the PbO by BaO contents. Moreover, the Poisson ratio, micro-hardness, and the softening temperature calculated for the investigated glasses. Besides, gamma and neutron shielding ability evaluated for the barium doped lead phosphate glasses. Monte Caro code (MCNP-5) and the Phy-X/PSD program applied to estimate the mass attenuation coefficient of the studied glasses. The decrease in the PbO ratio has a negative effect on the MAC. The highest MAC decreased from 65.896 cm2/g to 32.711 cm2/g at 0.015 MeV for BPP0 and BPP7, respectively. The calculated values of EBF and EABF showed that replacement of PbO with BaO contents in the studied BPP glasses helps to reduce the number of photons accumulated inside the studied BPP glasses. © 2021 Korean Nuclear Society. Taif University, Saudi Arabia is kindly acknowledged for Supporting our work through the Project number (TURSP-2020/84).

Non-destructive pulse-echo ultrasonic testing was conducted to measure ultrasonic parameters, i.e. longitudinal velocity (Vl), shear velocity (Vs) and attenuation coefficient (α) in Al–Al2O3 nanocomposites. Elastic constants were also determined using the relationship between Vl and Vs. The aim was to reveal the correlation between ultrasonic parameters and the microstructural features of Al–Al2O3 nanocomposites. The effect of addition of Al2O3 nanoparticles on the Vl and Vs velocities is mainly attributed to variation in the elastic modulus of Al–Al2O3 nanocomposites. Both Vl and Vs velocities and Young's modulus (E) were found to vary approximately in linear fashion with the increase of Al2O3 content. A considerable effect of milling process on Vl and Vs velocities was revealed, where they increase by increasing the milling time. The increment of Vl and Vs is owing to refinement of Al particles, homogenous dispersion of Al2O3 and particularly reducing porosity by proceeding milling time. In addition, increasing of Al2O3 content, better dispersion uniformity of Al2O3 and refinement of Al particles contribute to increase α values. Elastic constants were found to vary in the same manner as ultrasonic velocities. Interestingly, the improvement in E values by increasing Al2O3 content and milling time is attained, while the ductility did not change significantly.

The concrete transition zone plays an important role in bridge expansion joint structure, which provides a good connection between the expansion joint installation and bridge decks. However, the premature deteriorations of concrete transition zone are found to be the major diseases of expansion joint during service life. Therefore, a material with high ductility, superior durability, and low modulus/stiffness is highly desired for transition zone. Engineering cementitious composites (ECC), a kind of high-performance concrete featuring the prominent ductility and durability, are a promising material for transition zone of expansion joint. This paper introduces a specific ECC material for transition zone, which is modified by emulsified asphalt (EA-ECC), and has the high deformation ability and low modulus/stiffness. The flexural mechanical properties including flexural stress-load displacement relation, flexural secant stiffness, and elastic modulus of the EA-ECC’s matrix were investigated experimentally. The microstructures of EA-ECC were observed via scanning electron microscope (SEM) imaging. Additionally, the influence of test temperature on flexural mechanical properties of EA-ECC was also investigated. It is found that the ultimate flexural stress of EA-ECC reduces gradually with increasing EA content. Conversely, the flexural deformation capacity shows an increasing trend with EA content. Additionally, incorporating EA significantly reduces the flexural secant stiffness and elastic modulus of EA-ECCs. The research results concluded that incorporating EA in ECC can significantly improve the flexural deformation ability accompanied by relatively lower modulus, which is likely to reduce the impact load on transition zone caused by vehicle bumping and prolong the service life of the whole bridge expansion joint structure.

Reproduction 162(4), 259-266 (2021). doi:10.1530/REP-21-0122, Published by BioScientific, Bristol

This work presents an investigation on the morphology, mechanical, viscoelastic and transport properties of acrylonitrile–butadiene–styrene (ABS) nanocomposites reinforced with nanosilica (NS) and multiwalled carbon nanotubes (MWCNTs). The nanofillers content was varied from 1 to 5 wt%. Morphological and mechanical investigations revealed a better dispersion and effective stress transfer in carboxyl-treated MWCNT composites with respect to silane-treated NS. The highest values of tensile strength and Young’s modulus were reached for 5 wt% of MWCNT. Theoretical modelling of elastic modulus of the composites with carbon nanotubes (CNT) was in good agreement with experimental data. On the other hand, in the case of composites with NS an interfacial modulus of 2.5 GPa was assumed in the model to approach the experimental data. The highest value of storage modulus was reported at a MWCNT content of 5 wt% followed by 3 wt% which discloses the stiffening effect of long curly CNTs in comparison with NS. The damping behaviour indicated a lowering and broadening of tan δ peak induced by CNT. The storage modulus and damping behaviour of the nanocomposites were analysed using theoretical models in which aspect ratio, stiffening effect, adhesion and entanglement phenomena were included. The lowest solvent diffusivity and permeability was exhibited by composite with MWCNT at 5 wt% owing to the tortuosity, higher adhesion and aspect ratio of the filler and revealed a decrement in permeability by 62% with regard to neat ABS.

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

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

Halide double perovskite Cs2AgBiBr6 shows promising potential applications in next-generation photovoltaic devices. The strain engineering strategy has been proven as a reliable method to improve its performance. The fundamental physical tensor of elastic constants Cij has not been accurately measured yet, due to the limited size of samples. The aim of this work is to measure its full elastic tensor Cij using various techniques. We utilized nanoindentation and contact resonance atomic force microscopy (CR-AFM) techniques to measure the elastic modulus on an as-grown facet, which is along the [111] direction. Then, the inelastic X-ray scattering (IXS) approach and density functional theory were introduced to obtain the accurate full elastic constant Cij of single crystal Cs2AgBiBr6. The full elastic constants were measured as C11 = 44.52 GPa, C12 = 17.63 GPa and C44 = 8.56 GPa. The results for the modulus along the [111] direction reveal that nanoindentation and CR-AFM are sufficiently reliable for quantitative measurements of small single crystals Cs2AgBiBr6. The results provide guidelines for strain engineering in the photovoltaic applications using Cs2AgBiBr6 and for elastic property measurements in nanomaterials.

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

High temperature thermal-mechanical stability of tribological thin coatings is extremely important to a large number of applications in modern industries. DC magnetron sputtering of single metallic element (Cr, Si) and alloy (Ni:Cr) targets formed transition metal nitrides film coatings, CrSiN and CrNiN onto M2 steel. High temperature in-situ synchrotron X-ray diffraction, in the range 25 °C–700 °C, obtained experimental data for a range of structural and mechanical properties. Furthermore, experimental room temperature Nanoindentation measurements, made before and after the in-situ heating cycle, provided corresponding hardness and shear modulus results. The structural results identified microstructure and phase transformation changes, while the mechanical results identified microstrain, hardness, elastic modulus and deformation resistance properties of the coatings. Density functional theory (DFT) and quasi-harmonic approximation (QHA) modelled the high temperature thermal and mechanical properties such as: Young's modulus, shear modulus and thermal expansion coefficients (populated up to 1200 °C). Estimates of hardness are made by correlating the bulk phase hardness and shear modulus, of the CrN and Ni phases, as a function of temperature. Results indicate that Si doping enhances the hardness of the CrN framework, increasing from 29 to 36 GPa and improves the coatings elastic modulus, and resistance to deformation. However the addition of Ni reduced these properties. Furthermore, formation of (Cr,Si)N and Ni(Cr) solid solutions is inferred from DFT, Rietveld and lattice constant analysis.

This work addresses the role of rigid inclusions in determining the elastic modulus of particle-filled colloidal networks by modifying an established fractal scaling model. The approach acknowledges the heterogeneous nature of stress distribution at length scales beyond the colloidal aggregates, while maintaining structural information at the level of individual clusters. This was achieved by introducing a scaling factor to account for system heterogeneity which contains intrinsic information about the network’s capacity to form load-bearing links. Rigid fillers bound to the network induce stress concentration, but additionally serve as junction zones which introduce additional load-bearing pathways. This gives rise to the observed increase in the modulus with filler volume fraction. The proposed relationship between the load-bearing network connectivity and scaling behavior may have additional implications on the fractal dimension determined by rheological methods. Further, this model accommodates an experimentally observed correlation between the scaling behavior of the modulus associated with the addition of fillers and that arising from increasing structurant concentration. The modified fractal model thus provides an alternative view of how fillers contribute to the small- and large-deformation mechanical behavior of filled colloidal gels in a manner consistent with experimental observations.

Rock mechanical properties play a crucial role in fracturing design, wellbore stability and in situ stresses estimation. Conventionally, there are two ways to estimate Young’s modulus, either by conducting compressional tests on core plug samples or by calculating it from well log parameters. The first method is costly, time-consuming and does not provide a continuous profile. In contrast, the second method provides a continuous profile, however, it requires the availability of acoustic velocities and usually gives estimations that differ from the experimental ones. In this paper, a different approach is proposed based on the drilling operational data such as weight on bit and penetration rate. To investigate this approach, two machine learning techniques were used, artificial neural network (ANN) and support vector machine (SVM). A total of 2288 data points were employed to develop the model, while another 1667 hidden data points were used later to validate the built models. These data cover different types of formations carbonate, sandstone and shale. The two methods used yielded a good match between the measured and predicted Young’s modulus with correlation coefficients above 0.90, and average absolute percentage errors were less than 15%. For instance, the correlation coefficients for ANN ranged between 0.92 and 0.97 for the training and testing data, respectively. A new empirical correlation was developed based on the optimized ANN model that can be used with different datasets. According to these results, the estimation of elastic moduli from drilling parameters is promising and this approach could be investigated for other rock mechanical parameters.

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

In the current study, a series of laboratory triaxial loading and unloading experiments were conducted for the purpose of comprehensively understanding the effects on sandstone of loading processes under axial stress conditions and unloading processes under confining pressure conditions. The mechanical properties and crack propagation behaviors of sandstone specimens were analyzed. In addition, a new damage variable based on crack evolution was proposed. The experimental results showed that the strain-softening modulus of the sandstone specimens under triaxial loading and unloading compression conditions decreased with the increases in the loading rate. Meanwhile, the elastic modulus was only observed to undergo small changes. This study found that with the increases in the loading rates of axial stress, the deformation and strength levels of the sandstone specimens also increased. In addition, the crack initiation stress showed a linear increasing trend with the increases in the loading rates of axial stress. The peak crack volumetric strain displayed a slight increase with the loading rate of axial stress, which indicated that the larger the loading rate of axial stress on the sandstone specimens was, the smaller crack propagation strain levels at the peak stress levels would be. The crack propagation velocities were observed to be larger when the loading rates of axial stress were higher. Also, at the same loading rate of axial stress, the crack propagation velocity corresponding to the peak stress of the volumetric cracks was the largest, followed by radial cracks. The crack propagation velocity of the axial cracks was determined to be the smallest. In this study, a new crack damage variable based on crack volumetric strain was proposed. According to the evolution of the crack damage variables of the sandstone specimens, the following four stages of the failure process were obtained: original damage stage; elastic stage; linear damage stage; and accelerated damage stage. The results obtained in this research study provided an important scientific basis for the support of future designs and safety protection measures in underground mining operations.

Seasonal and diurnal variations can significantly impact Falling Weight Deflectometer (FWD) measurements and, thus, any deflection-based parameter such as slab elastic modulus (Epcc), modulus of su...

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

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

Accurate measurement of cancellous bone's apparent elastic modulus, E, is confounded by the experimental artefacts created when trabeculae are severed during specimen preparation. Although standardized axial testing protocols have been developed to deal with the so-called "end effects" caused by severed trabeculae at the loading surfaces, much less attention has been given to the "side effects" around the periphery and the specimen size dependence they create. Two models (one theoretical, one empirical) have been proposed in the literature to predict the reduction in E with decreasing specimen diameter. The current study used finite element method (FEM) modelling to analyze bovine cancellous bone from five different anatomic sites and quantify the changes in E that occurred with specimen diameter. The two models were adapted so that they could predict E based on diameter and architectural parameters (BV/TV, DA, Tb.Sp) alone, without requiring that a "true" modulus be known a priori. Both models fit the data equally well; however, the empirical model gives simpler estimations as a function of trabecular separation (Tb.Sp). A minimum diameter of 5-8 Tb.Sp is recommended.

It is valuable to build an empirical model to estimate rock mass deformation modulus which is difficult to be determined by in situ tests. Based on 84 data sets from Yalong River Jinping-I hydropower station, the correlation between some easily measured geotechnical parameters and rock mass deformation modulus is analyzed. A two-parameter estimation model with higher estimation capacity than previous models is established based on a nonlinear regression algorithm. The P-wave acoustic velocity (Vp) and Q-value of rock mass are included in this two-parameter estimation model. Besides, according to the obtained data, it is not suitable to use an empirical model including elastic modulus of intact rock (Ei) to estimate rock mass modulus under high crustal stress condition.

In this study, Ni electroplating is applied to the surface of the lightweight Mg alloy specimen to form a sandwich structure, and strengths improvement is quantitatively compared with the bare Mg alloy. Specifically, the mechanical properties of three specimens were compared one with another using mechanical tensile testing. Accordingly, two Ni electroplated specimens (Ni electroplated only and Ni electroplated with hydroxypropyl cellulose additive) were prepared and compared with the bare Mg alloy. As a result, both Ni electroplated specimens exhibit drastic improvement of the mechanical strength, which is attributed to the interaction between the sandwich structure covered with stiffer Ni material and grain refinement. Consequently, the rule of mixture was used to calculate the intrinsic elastic modulus of the Ni layer from the effective modulus. Finally, the calculated moduli were implemented using FEA (finite element analysis) and compared with the experimental results to examine their accuracy and validity.

Elastic moduli parameters and photon attenuation competence of phosphate (P2O5)/sodium (Na2O)/calcium (CaO) glasses with form 45P2O5–(55-x)Na2O–xCaO: x = 0–55 mol% (PNC-0:PNC-55) have been estimated and clarified. The development in Poisson’s ratio and elastic moduli parameters (bulk, Young’s, shear, and longitudinal) of the heavier CaO content of the PNC-glasses were proved through Makishima-Mackenzie (M-M) and bond compression (B-C) models. The B-C bulk elastic (KB-C) modulus was found to raise from 71.4 to 95.16 GPa, while the M-M bulk (KM-M) modulus was increased from 22.48 to 40.75 GPa for PNC-0 (glass sample free with CaO) and PNC-55 (glass sample rich with CaO), respectively. The highest mass attenuation coefficient (MAC) values were reported for PNC-55 sample, whereas the lowest were reported for PNC-0 sample. Half value layer (HVL) values were reported as 1.6526 cm, 1.6181 cm, 1.5734 cm, 1.5275 cm, 1.4847 cm, 1.441 cm, and 1.4172 cm for PNC-0, PNC-10, PNC-20, PNC-30, PNC-40, PNC-50, and PNC-55 samples at 0.1 MeV, respectively. The effective atomic numbers (Zeff) were reported as 10.2658, 10.4393, 10.6149, 10.7924, 10.9719, 11.1536, and 11.2451 for PNC-0, PNC-10, PNC-20, PNC-30, PNC-40, PNC-50, and PNC-55 samples at 0.1 MeV, respectively. The PNC-55 sample was reported with a maximum value of effective atomic weight for absorption (Aeff). The lowest exposure and energy absorption buildup factors (EBF and EABF) values were discovered for the PNC-55 sample, while the highest EBF values were found for the pure PNC-0 sample. Finally, one can conclude that the PNC-55 is a superior for gamma-ray attenuation competencies.

The equivalent in-plane elastic modulus [Formula: see text] of a honeycomb sandwich in the direction of cell vertical wall can be assessed by the law of mixture from the modulus of face sheet [Formula: see text] and the equivalent modulus of honeycomb core [Formula: see text]. However, significant errors as large as 40% can be made depending on material and geometry parameters, when the used [Formula: see text] is obtained from a cellular model of core alone without considering the skin effect of face sheet. The main reason of the error is that the rigidity to deformation of y-direction is different greatly between the vertical cell wall of core and inclined cell wall of core. In the present paper, an analytical model is proposed to assess [Formula: see text] of honeycomb sandwich with considering the interference effect of the core with the face sheet. In the proposed model, the influence of the face sheet rigidity on [Formula: see text] is taken into account. The results demonstrate that the contribution of the core to [Formula: see text] is also dependent on the face sheet rigidity significantly. The validity of presented model is verified by comparing the results with numerical results of FEA.

Polyacrylamide acrylonitrile magnesium silicate {P(Am-AN)-MgSi} & polyacrylamide acrylic acid magnesium silicate {P(Am-AA)-MgSi} hybrid composites were fabricated utilizing gamma-radiation polymerization initiated about 30 kGy. Different types of dosimetric radiation-induced polymeric composites were irradiated by cesium-137 gamma-ray dose to show its possibility for use as a thermoluminescence dosimeter. The prepared polymeric composites showed useful properties such as good dosimetric and thermal stability behaviors. The mechanical behavior of the samples was measured non-destructively by the ultrasonic pulse-echo technique. It was found that the addition of P(Am-AA) with higher elastic moduli to MgSi with lower ones are produced in the {P(Am-AA)-MgSi} composite sample with a midway value for Young’s modulus of 7.13 GPa and shear modulus of 2.71 GPa. Dissimilar in the {P(Am-AN)-MgSi} composite sample, it shows a significantly improved behavior as Young’s modulus recorded 9.32 GPa and shear modulus 3.61 GPa. Similarly, the microhardness recorded 0.328 GPa and 0.518 GPa a the composites {P(Am-AN)-MgSi} & {P(Am-AA)-MgSi}. As a thermoluminescence dosimeter, various characteristics were studied for these types of polymers. Specific ultrasonic properties were also tested for TL dosimetric properties in different polymers. An insertion of MgSi into P(Am-AN) & P(Am-AA) has indeed been found to increase TL response and lead to good properties being acquired.

Elastomeric nanostructures are normally expected to fulfill an explicit mechanical role and therefore their mechanical properties are pivotal to affect material performance. Their versatile applications demand a thorough understanding of the mechanical properties. In particular, the time dependent mechanical response of low-density polyolefin (LDPE) has not been fully elucidated. Here, utilizing state-of-the-art PeakForce quantitative nanomechanical mapping jointly with force volume and fast force volume, the elastic moduli of LDPE samples were assessed in a time-dependent fashion. Specifically, the acquisition frequency was discretely changed four orders of magnitude from 0.1 up to 2 k Hz. Force data were fitted with a linearized DMT contact mechanics model considering surface adhesion force. Increased Young’s modulus was discovered with increasing acquisition frequency. It was measured 11.7 ± 5.2 MPa at 0.1 Hz and increased to 89.6 ± 17.3 MPa at 2 kHz. Moreover, creep compliance experiment showed that instantaneous elastic modulus E1, delayed elastic modulus E2, viscosity η, retardation time τ were 22.3 ± 3.5 MPa, 43.3 ± 4.8 MPa, 38.7 ± 5.6 MPa s and 0.89 ± 0.22 s, respectively. The multiparametric, multifunctional local probing of mechanical measurement along with exceptional high spatial resolution imaging open new opportunities for quantitative nanomechanical mapping of soft polymers, and can potentially be extended to biological systems.

The anisotropic hardness, elastic modulus, and dislocation behavior of AlN grains were investigated by Berkovich nanoindentation. Grain orientation had a strong correlation with hardness and elastic modulus. The hardness of the basal plane (0001) was higher than those on the two prismatic planes ( 10 1 ‾ 0 ) and ( 1 ‾ 2 1 ‾ 0 ), while the modulus was showing the opposite trend. Further investigation on the deformation behavior of AlN revealed that pop-in, pile-up and slip lines only occurred on the two prismatic planes ( 10 1 ‾ 0 ) and ( 1 ‾ 2 1 ‾ 0 ). Through molecular dynamics (MD) simulation, the mechanisms of anisotropic pop-in events and dislocations were disclosed. The activation of the slip system for different grain orientations was presented by Schmid factor. The method of using Schmid factor to determine the activated slip system was verified by the observation of pile-up and slip lines around the indent, and proven to be accurate in identifying the grain orientation of AlN ceramic. Lower hardness and higher modulus were found to be related to more plastic events like pop-in, pile-up and slip lines, and the crystalline orientation could be roughly determined by the observation of plastic activities from nanoindentation.

A three-dimensional finite element (FE) model for single-walled carbon nanotubes with armchair and zigzag shapes is proposed in this paper (SWCNTs). Nodes are positioned at the locations of carbon atoms to design the FE models. And three-dimensional elastic beam components are used to model the bonds between them. The effect of the diameter length/diameter ratio on the diameter length/diameter ratio, cross sectional aspect ratio and number of elements on the Young’s modulus of SWCNTs has been considered herein. From the conducted experiments it can be observed that, the larger tube diameter can lead to higher Young’s modulus for carbon nanotubes. Such that, maximum elastic modulus for the armchair and the zigzag models has been obtained to be 1.0285TPa and 1.0396TPa when the diameters for the armchair and the zigzag models were 2.034nm and 1.957nm respectively. Increasing the length/diameter ratio has led the Young’s modulus to be increased for armchair and zigzag models such that its values can reach 1.0451TPa and 1.0191TPa respectively. The cross sectional aspect ratio of SWCNTs showed an inversely proportional effect on the elastic modulus in this work. As a result of rising the cross sectional aspect ratio to be2, the Young's modulus for armchair and zigzag models has decreased to 0.7991TPa and 0.8873TPa, accordingly. The change in geometry has been observed to be a defect and it is in general can decrease the modulus of elasticity. The number of elements in the armchair model considered as prominent factor that increases the young’s modulus to be 1.0280TPa when the number of element is 10836. In zigzag model, the number of element has no effect on the elastic modulus since the number of nodes that exposed to the applied load is fixed in this case. The findings showed that the proposed FE model may be useful for studying carbon nanotube mechanical action in the future.

The aim of the presented study was to estimate the material properties of human patellar ligaments from the elderly population by means of tensile tests. The experimental part was conducted on a custom tensile-testing device, with a built-in enclosure to simulate in-vivo conditions, using 25 (15 female, 10 male) bone-ligament-bone samples from elderly (age 83 (8)) human donors. During the tensile tests, the resultant force and displacement of the sample attachments were recorded. With this data and the values of the initial length and the initial cross-sectional area of the samples, the engineering stress and strain, the Young's modulus and the toughness at rupture were calculated for each sample. The results were then averaged and presented for all the samples together and for the female and male populations separately. The measured Young's modulus and the failure stress values were found to be significantly higher for the female samples compared to the male (p < 0.05). All the other measured properties did not show a significant difference. The toe region's material properties for the patellar ligament were also presented as valuable information for the anterior cruciate ligament reconstruction. The tensile-test results were compared to other research carried on human patellar ligaments using samples from younger donors. The comparison showed that the samples from the elderly population exhibit lower values of strain at the end of the toe region and have a lower failure strain for the patellar ligament. The Young's modulus and the failure stress of the samples in this study were in the range of other research conducted on patellar ligaments.

To analyze the effects of freeze-thaw cycles and confining pressure on the mechanical properties of red sandstone, through freeze-thaw cycles and triaxial compression tests, full stress-strain curves of different freeze-thaw cycles and different confining pressures were obtained. The degradation degree of red sandstone was quantitatively considered from different mechanical parameters of ultimate stress, elastic modulus, and Poisson’s ratio. Based on summarizing the characteristics of rock under freeze-thaw and load, the total damage variable of rock was determined by the reasonable measurement of freeze-thaw damage variable and load damage variable, and a damage constitutive model under freeze-thaw and load was established. The research showed that the freeze-thaw cycles aggravate the degree of rock damage deterioration, the rock stiffness and strength were reduced, and the characteristics of plastic deformation and ductile failure were more obvious. The confining pressure inhibited red sandstone internal damage, and with the increase of confining pressure, the stiffness and strength and the plastic characteristics were increased. In the overall trend, the mechanical parameters had different sensitivity to the degradation effect of freeze-thaw cycles and confining pressure. Regardless of the increase in the number of freeze-thaw cycles or confining pressure, the strain softening modulus tended to decrease gradually, and red sandstone plastic damage became more obvious after the stress peak. The total damage evolution path of red sandstone reflected the nonlinear influence of freeze-thaw and load on the total damage propagation. The research results provide theoretical support for the improvement of the technology of the effluent coal rock in Balasu Coal Mine.