Shear Modules Research Articles

Thermal buckling analysis of composite doubly‐curved shells with viscoelastic core

AbstractComposite sandwich double‐curved shells (CSDCS) have been extensively employed in the engineering domain of variable temperature environments; consequently, it becomes very significant and essential to present the thermal buckling characteristics of CSDCS to supply some valuable numerical results. The no‐linear strain–displacement relationship due to temperature variation has been taken into consideration based on the Von‐Karman non‐linear strain theory, and Hamilton's principle is adapted to derive the buckling differential equations of the CSDCS. The Navier method is employed to solve the eigenvalue problem for obtaining the critical buckling temperature. Finally, through studying the variation rule of thermal buckling temperature (CBT), several interesting findings on thermal buckling of the CSDCS are shown, as follows: As the h3/h1 rises, the CBTs of CSDCS first decrease then increase. With the increase of radius value, the CBTs of spherical shells decline, the CBTs of models (1,1) and (2,2) of hyperbolic paraboloidal shells are essentially unchanged, but the ones of models (1,2) and (2,1) decrease. As the h2 increases, the CBT progressively grows after the initial reduction. With the increase in aspect ratio, the CBTs for modes (1,1) and (2,1) of CSDCS gradually increase, and the ones of modes (1,2) and (2,2) shows an increase after an initial decrease. The CBTs of CSDCS gradually increase as the shear module of damping layer increases.Highlights Thermal buckling of composite doubly‐curved sandwich shells was studied. A solution was proposed to derive the buckling differential equations. The change rules of critical buckling temperature were obtained.

Shear Stress-Induced AMP-Activated Protein Kinase Modulation in Endothelial Cells: Its Role in Metabolic Adaptions and Cardiovascular Disease.

Endothelial cells (ECs) line the inner surface of all blood vessels and form a barrier that facilitates the controlled transfer of nutrients and oxygen from the circulatory system to surrounding tissues. Exposed to both laminar and turbulent blood flow, ECs are continuously subject to differential mechanical stimulation. It has been well established that the shear stress associated with laminar flow (LF) is atheroprotective, while shear stress in areas with turbulent flow (TF) correlates with EC dysfunction. Moreover, ECs show metabolic adaptions to physiological changes, such as metabolic shifts from quiescence to a proliferative state during angiogenesis. The AMP-activated protein kinase (AMPK) is at the center of these phenomena. AMPK has a central role as a metabolic sensor in several cell types. Moreover, in ECs, AMPK is mechanosensitive, linking mechanosensation with metabolic adaptions. Finally, recent studies indicate that AMPK dysregulation is at the center of cardiovascular disease (CVD) and that pharmacological targeting of AMPK is a promising and novel strategy to treat CVDs such as atherosclerosis or ischemic injury. In this review, we summarize the current knowledge relevant to this topic, with a focus on shear stress-induced AMPK modulation and its consequences for vascular health and disease.

Abstract 6971: The impact of lecithin retinol acyltransferase in squamous cell carcinoma: Tissue formation, cell mechanics, and gene transcription

Abstract Squamous cell carcinoma, along with several other cancers, has been found to lack expression of lecithin retinol acyltransferase (LRAT), a protein which catalyzes retinol esterification and thereby mediates retinoic acid biosynthesis. When expression of LRAT was reintroduced in squamous cell carcinoma, the protein promoted cell differentiation in addition to retinoid status normalization—whether this effect was dependent on the known enzymatic activity of LRAT in retinol esterification, versus another function, has not yet been established. Cell elasticity differences have also been reported between squamous cell carcinoma and normal keratinocytes. In this study, the role of LRAT expression and activity was evaluated in human squamous cell carcinoma cell line SCC13. LRAT was integrated into the genome of SCC13 via retroviral transduction, both as wild-type LRAT and LRAT with a cysteine-to-serine mutation at the active site for retinol esterification (C161-S). In these transformed cell lines, LRAT promoted formation of a cohesive sheet of tissue which remained intact after its removal from the tissue culture plastic surface, as evaluated at two weeks post-confluence. SCC13 alone produced tissue which easily fragmented during this scraping assay. In an evaluation of cell elasticity with shear modulation force microscopy, relative cell modulus measurements of pre-confluent SCC13 with LRAT expression were found to be significantly greater and consistent with the cell modulus of human keratinocytes (DO33). These effects persisted with mutation of the retinol esterification active site, suggesting that LRAT possesses an additional function which has yet to be described. Variation in transcription levels of multiple genes—urokinase-type plasminogen activator, plasminogen activator inhibitor 1, tissue inhibitor of metalloproteinases 1, and kallikrein 5—was also found based on LRAT expression and level of confluence. These findings suggest that the presence of LRAT influences tissue formation, cell elasticity, and gene transcription in SCC13. Citation Format: Emily Peterson, Kuan-Che Feng, Jay Gao, Miriam Rafailovich, Marcia Simon. The impact of lecithin retinol acyltransferase in squamous cell carcinoma: Tissue formation, cell mechanics, and gene transcription [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6971.

Soft glassy materials with tunable extensibility.

Extensibility is beyond the paradigm of classical soft glassy materials, and more broadly, yield-stress fluids. Recently, model yield-stress fluids with significant extensibility have been designed by adding polymeric phases to classically viscoplastic dispersions [Nelson et al., J. Rheol., 2018, 62, 357; Nelson et al., Curr. Opin. Solid State Mater. Sci., 2019, 23, 100758; Dekker et al., J. Non-Newtonian Fluid Mech., 2022, 310, 104938]. However, fundamental questions remain about the design of and coupling between the shear and extensional rheology of such systems. In this work, we propose a model material, a mixture of soft glassy microgels and solutions of high molecular weight linear polymers. We establish systematic criteria for the design and thorough rheological characterization of such systems, in both shear and extension. Using our material, we show that it is possible to dramatically change the behavior in extension with minimal change in the shear yield stress and elastic modulus, thus enabling applications that exploit orthogonal modulation of shear and extensional material properties.

柔顺障碍环境下收获甜椒末端执行器的设计与试验

Picking sweet peppers by hand is often time-consuming and laborious. To overcome this, in the current study, we developed an end effector for mechanized and non-destructive harvesting of sweet pepper. The design includes grip modules, shear modules and control systems. Based on the establishment of an approximate mathematical model of sweet pepper fruit and the analysis of the biomechanical characteristics of sweet pepper fruit, a pinch finger was proposed. The proposed mechanism is able to successfully achieve non-destructive and stable fixation of sweet pepper and fruit bunches. Key parameters of peduncles cutting were obtained by the cutting test. A cutting mechanism was then designed to achieve efficient separation of the fruit and fruit stem. The designed end effector achieves precise control through a single-chip microcomputer and multi-sensor integrated control system to achieve mature target fruits. The test results showed that the picking success rate, damage rate and picking time of peppers were 93.3%, 1.6% and 5 seconds, respectively. The end effector designed for sweet pepper picking has a simple and reliable structure, which provides a reference for further research on sweet pepper picking robots.

INVESTIGATION DYNAMIC PROPERTIES OF SOIL (THE DAMPING RATIO AND SHEAR MODULUS) FOR RESISTANCE DESIGN AT THE LNG BAC LIEU GAS PIPELINE PROJECT BY CYCLIC TRIAXIAL TEST

The LNG Bac Lieu gas pipeline project is part of the 3.200MW LNG power plant complex in Bac Lieu province. The entire pipeline will be designed underground at the sea floor to be directly subjected to dynamic loads (earthquakes, waves ...). Soil response to dynamic loads is measured by the soil's dynamic properties such as dynamic strength, shear modulus and damping ratio. These soil parameters are very significant to study the movement of the ground as well as the local reaction of soil sediments under the effect of loads and cyclic soil structure. Therefore, it is very important to investigate the earth's dynamic properties (dynamic strength, damping ratio and shear modulus) to design seismic resistance for this project. From the relevant literature, it is known that the dynamic properties of the soil are influenced by the soil type and the position of the soil structure. 6 soil samples were examined randomly at different depths to determine soil properties. When studying dynamic strength, people often use direct test methods such as torsion cutting, cyclic flat cutting and cyclic triaxial test to determine the dynamic strength (dynamic resistance) of the soil. In which, the cyclic triaxial test method allows the simulation of real-world conditions to be easily simulated. The results of applying this method to soft clay and clay phases show that the damping ratio is 0.117-0.162D, the average is 0.136D, the shear module is 1650-2632kPa, the average is 2141kPa.

Comparative Study of the Seismic Response Characteristics of Three Special Soils

Because of its special material composition, formation environment and special structure, special soil usually shows different seismic response characteristics from general soil, and sometimes causes serious seismic disasters. Therefore, the study of seismic response characteristics of special soil has important practical significance for engineering construction and disaster prevention in special land areas, and a site seismic response analysis is an important way to study the impact of site conditions on ground motions. Based on the existing research work, the uniform and single ideal soil layer profiles of three special soils are established, and the seismic response analysis program of the soilquake soil layer is used to study the effects of the dynamic shear module ratio, damping ratio and shear-wave velocity of soft soil, loess and laterite on the characteristic period and platform value of the design response spectrum under different input ground motion intensities. At the same time, three typical actual drilling data values are selected to establish the calculation model of the site soil layer. On the basis of the seismic response analysis and calculation of the soil layer, three special soil dynamic characteristics are compared from the aspects of peak acceleration and characteristic parameters. Based on the research results of this paper, the recommended values of the dynamic shear module ratio and damping ratio of three special soils are given. This work has important reference value for seismic design in soft soil, loess and laterite areas, and also enriches the research results of soil dynamic parameters.

Comparative evaluation on decay process of asphalt-aggregate interfaces under solution erosion

In order to analyze the decay process of fractions of asphalt mixture caused by solution erosion, molecular dynamics (MD) simulations and dynamic shear rheometer (DSR) tests were conducted to study the solution-induced response. The settled environments are salt, pure water, and alkali solutions, respectively. The cohesive failure of asphalt-solution-asphalt (A system), adhesive failure of asphalt-solution-quartz/calcite aggregate (B-1 and B-2 systems), and “water-aging” of bitumen and mastic were thereby concluded. Results show that the asphalt-base system has less susceptibility towards solution as compared to aggregate-base system, where the calcite-base one possesses the lowest energy ratio (ER) value, namely the least moisture resistance. Thus, adhesion failure of alkaline aggregate usually occurs first, while cohesive bonding in asphalt is considerably stable. Besides, the diffusion coefficient (D) value of SARA in asphalt-aggregate keeps higher than that in asphalt-base system, where water molecules have a stronger intervention effect. By constructing the master curves of complex shear modules (G*) via laboratory DSR results, it is verified that with the increase of erosion days, solution has “water aging” effect on virgin and SBS asphalt/mastic, and alkali solution performs the most deterioration. Here, mastic with 1.2 filler/bitumen ratio (FBR) maintains the most stable solution erosion resistance.

Surface Modification of Micro-Silicon Anode for High-performance Lithium-Ion Batteries

Advanced lithium-ion batteries are urgently needed in consumer electronic products, electric vehicles, and energy storage, while the traditional carbonaceous anode materials with relatively low specific capacity gradually become difficult to meet the practical requirements in the market. Silicon-based anodes are considered one of the most promising alternatives in LIBs with high specific energy due to their considerable theoretical specific capacities. However, the large volume variation and severe surface parasitic reactions still limit the practical application of silicon anode. In this work, to suppress the surface side reactions and great volume changes, the electrochemical inert Li3PO4 is proposed to be coated as the physical barrier between the silicon and electrolyte. The as-coated micro-silicon has been successfully prepared via a facile spray drying method with a low-temperature thermal treatment. Li3PO4 coating layer with high shear modules can not only passivate the surface but also enable to suppression of the severe volumetric expansion and shrinkage of the silicon particle, thus enhancing the initial columbic efficiency and structural integrity of the silicon materials during long-term cycling. The optimized silicon anode with the proper amount of Li3PO4 displays a superior initial columbic efficiency higher than 90% and a highly reversible capacity of 1394 mAh g-1 after charging and discharging 200 times. It is hoped this work should shed light on the modification of high-capacity anode materials.

Selection of Wood Based on Acoustic Properties for the Solid Body of Electric Guitar

For the purpose of making of a solid body of an electric guitar the acoustic- and mechanical properties of walnut- (Juglans regia L.) and ash wood (Fraxinus excelsior L.) were researched. The acoustic properties were determined in a flexural vibration response of laboratory conditioned wood elements of 430 × 186 × 42.8 mm used for making of a solid body of an electric guitar. The velocity of shear- and compression ultrasonic waves was additionally determined in parallel small oriented samples of 80 × 40 × 40 mm. The research confirmed better mechanical properties of ash wood, that is, the larger modulus of elasticity and shear modules in all anatomical directions and planes. The acoustic quality of ash wood was better only in the basic vibration mode. Walnut was, on the other hand, lighter and more homogenous and had lower acoustic- and mechanic anisotropy. Additionally, reduced damping of walnut at higher vibration modes is assumed to have a positive impact on the vibration response of future modelled and built solid bodies of electric guitars. When choosing walnut wood, better energy transfer is expected at a similar string playing frequency and a structure resonance of the electric guitar.

Predicting the electronic and mechanical properties of 2D diamond-like carbon and cubic boron nitride intercalated structures

Two-dimensional (2D) diamond-like (Diam) carbon (C) and cubic boron nitride (cBN) with different interface atoms named as BCB, BCN and NCN are investigated by first principal studies. The calculations reveal that the CB bond may be the most energetically favored bonding configuration in the Diam/cBN epitaxy. The electronic properties can be tuned not only by different interfacial atoms, but also by varying the number of intermediate C-layers. The application of negative stress transforms the 2D Diam/cBN intercalated structures from a semiconductor to a metal. The Young's and shear module indicate prominent mechanical properties for these intercalated structures, in particular for BCN that can be compared to bulk. The predicted 2D Diam/cBN intercalated structures presented here show that the stacking order, the number of intermediate C-layers, and the use of strain-induced structures can open new avenues for the application of novel ultra-thin and ultra-tough electronic reserve material devices.

ЭЛЕКТРОУПРУГИЕ СВОЙСТВА НАЧАЛЬНО-НАПРЯЖЕННОЙ ПЬЕЗОКЕРАМИКИ PZT-4 С ОДНОНАПРАВЛЕННЫМИ ТУННЕЛЬНЫМИ ПОРАМИ

Prediction results and numerical analysis of effect on effective transversal-isotropic electroelastic properties of porous piezoceramics of PZT-4 with unidirectional cylindrical (tunnel) pores of values of its initial axisymmetric stress state are presented. Effective constants have been identified: Young's and shear modules, Poisson's ratio in the transversal plane of isotropy and the "longitudinally/transverse" piezomodule of porous ceramics, which are most significantly influenced by the nature and values of its initial deformation in comparison with other practically "invariant" constants. It has been found that the "transversal" hydrostatic initial deformation of the porous ceramic has a greater effect on the effective constants of the porous ceramic than the same values of the "longitudinal" axial initial deformation.

DEFORMATION PROPERTIES OF HIGHLY FILLED METAL-POLYMER COMPOSITIONS

The deformation behavior of model highly filled metal polymer aluminum powder compositions in polyethylene glycol under simultaneous action of compression and shear studied. The compression module increases with the increase of the compression, wherein the shear module significantly reduces. The discovered effect is related to the redistribution of the elastic layer between the rigid particles of the filler in the normal direction and in the shear area. The model of behavior of highly filled polymer compositions in these conditions proposed.

Vibration response of machine foundations protected by use of adjacent multi-layer geocells

The response of soil beds reinforced with multi-layer geocell systems that support machine foundations is investigated by laboratory testing that incorporates vertical machine vibrations of a square concrete foundation (400 × 400 mm) resting on soil that is unreinforced or reinforced with single-, double- or triple geocell layers. The tests are performed under three different vibration moment levels and three static force levels using a mechanical oscillator and concrete blocks, respectively. The vibration responses are studied in terms of resonant amplitude, resonant frequency, shear modules and damping coefficient. The results reveal that the resonant amplitude significantly reduced in the presence of geocell reinforcement whereas the resonant frequency, shear modulus and damping coefficient increased. In the range of applied vibration load and frequency, and hence the induced amplitude, maximum improvement (i.e., the greatest reduction in vibration amplitude) was observed in the presence of the triple-layer geocell reinforcement. Since the rate of improvement decreases steadily with an increase in the number of geocell layers, thus, further geocell layers would deliver little further benefit. The optimum placement depth of the first geocell layer and vertical spacing of the geocell layers were found to be 0.1 and 0.05 of the foundation's width respectively.

Experimental Study of Awash Soil under Static and Cyclic Shear Loading

The dynamic soil properties (shear modulus and damping ratio) are of great importance for the analysis and design of geotechnical structures subjected to dynamic loads such as earthquake. Cyclic simple shear tests were conducted to study the variation of shear modulus and damping ratio with a different number of factors for strain amplitudes of 0.01%, 0.1%, 1%, 2.5%, and 5% and for a frequency of 1 Hz at an axial stress of 150 kPa, 275 kPa, and 400 kPa. The result shows that the damping ratio decreases with an increase in confining pressure at different cyclic shear strains. The shear modulus increases with an increase in the void ratio at different cyclic shear strains. The damping ratio increases with a decrease in soil plasticity. The obtained values of shear modules were in the ranges of 0.292 MPa to 15.998 MPa and the damping ratio values from 0.146% to 30.851%. In concluding the major influencing factors that affect the dynamic properties of soils are confining pressure, void ratio, shear strain amplitude, and soil plasticity.

Estimation of contact lengths using deep learning neural network

One of the most common problems in engineering is contact problems. In recent years, researchers have turned to alternative methods that can offer effective solutions in a shorter time, instead of solutions containing complex and long mathematical expressions. This study focuses on the estimation of the contact lengths in a homogeneous elastic layer suppressed by two elastic punches with two solution methods. Firstly, a new model was designed for estimation using Deep Learning Neural Network (DNN), one of the deep learning structures. Estimation of contact lengths was provided with the output of the DNN model, which was fed with the homogeneous elastic layer, the ratio of shear modules of the punches and the input parameters of punch radii. The finite element method was used as the second solution method. The problem was modeled in the ANSYS programme and the solution was made with the same parameters used in DNN modeled. The results obtained from both solutions were compared with the solutions obtained by the theory of elasticity and classical NN in the literature. It had been seen that the results obtained with DNN and ANSYS were compatible with the results obtained with analytical and classical NN and the margin of error was smaller.

The structural, mechanical, thermal, electronic and optical properties of halide perovskites [formula omitted]: First-principles investigations

The structural, mechanical, thermal, electronic and optical properties of inorganic Pb-free double perovskites Cs2TiX6(X=Cl,Br,I) compounds are investigated. Using the first-principles with full-potential linearized augmented plane wave (FP-LAPW) method, supported the density functional theory, and therefore the generalized gradient approximation (GGA-PBE) and Hybrid exchange-correlation functionals with and without spin-orbit coupling. The computation of the lattice constants showed an honest agreement between our results and the experimental results and the theoretical data available. Using the three independent elastic constants C11, C12 and C44, various mechanical and thermal properties are obtained such as: bulk modules B, shear modules G, Young's modules Y, Pough's ratio B/G, Frantesvich ratio G/B, Poisson's ratio υ, Shear anisotropy character A and Debye temperature ΘD for Cs2TiI6, Cs2TiBr6 and Cs2TiCl6 respectively. Our calculated elastic constant results show that Cs2TiI6, Cs2TiBr6 and Cs2TiCl6 are mechanically stable, anisotropic and ductile in nature. Furthermore, the Cs2TiCl6 compound has the highest Debye temperature, which indicates the highest melting temperature. The electronic band structures reveal the semiconductor conductivity of the three compounds, with a band gap suitable for photovoltaic applications, within the range of 1.5–2.96 eV. Finally, Cs2TiCl6(X=Cl,Br,I) HPs compounds exhibit excellent optical properties like optical absorption, conductivity and refraction index.

The Effect of Doping with Al on the Stability of D03 and L12 Phases in Fe73.44(Ga,Al)26.56 Alloys: Ab Initio Calculation and Monte Carlo Modeling

The effect of doping with Al on the stability of D03 and L12 phases was studied in the magnetostric-tion Fe–Ga and Fe–Ga–Al alloys with a high content of nonmagnetic atoms of ≈27 at %. For the studied D03 and L12 structures, the tetragonal shear modules C' = (C11 – C12)/2 and the Debye temperatures ΘD were found by the methods of density functional theory. The replacement of 4.58 at % of Ga by Al atoms was shown to lead to an increase in ΘD and a decrease in C′. Using the combined approach ab initio and Monte Carlo modeling, the calculations of free energies were performed, and the D03–L12 phase transition temperatures were determined. The Al addition to the Fe–Ga system was shown to decrease the difference between the energies of the D03 and L12 structures.

Pressure effects on structural, electronic and anisotopic elastic properties of Si doped RuGe compound with different concentrations by first-principles calculations

In this study, we have performed first-principles density functional theory (DFT) calculations to investigate pressure and composition effects on the structural, elastic, and electronic properties of silicon doped RuGe ternary compounds (RuSixGe1-x) for an increasing molar fraction of Si atom from 0.0 to 1.0 by 0.1. For each x composition, we have investigated formation energies of different compositions under three different pressure to study the alloying effects on the stability of RuGe in the B2 structure. It was determined that our calculated lattice parameters were in good agreement with the experimental results and decreased with Si content. The band structures and partial density of states (PDOS) have been investigated as electronic property. Using calculated second-order elastic constants, mechanical properties have been obtained for all x compositions. Among the different compositions for RuSixGe1-x under pressure it has been found that the most stable alloys have been obtained for x = 0.9, 0.7, and 0.6 under 0 GPa, 30 GPa, and 60 GPa, respectively. Elastic and dynamical stabilities were confirmed by Born Stability Criteria and positive phonon dispersion curves. Also, the elastic anisotropy has been visualized in detail by plotting the directional dependence of compressibility, Poisson ratio, Young's, and Shear module.

Vibration analysis and energy capability of sandwich axisymmetric curved panel rested on the novel viscoelastic substrate

Due to various applications of electro-rheological materials, in the current work, the vibration analysis and energy capability of a sandwich axisymmetric curved panel made of two graphene nanoplatelets reinforced composite (GPLRC) face sheets, and electro-rheological core is presented for the first time. For GPLRC face sheets, the material properties are acquired according to the micromechanics model along with the Halpin–Tsai. For modeling the accurate viscoelastic foundation with real applications, the current structure is reinforced by a novel viscoelastic substrate with four variables. With the aid of the complex shear modulus of ER material, the shear modules corresponding to the ER core of the current sandwich structure are modeled. Employing first-order shear deformation theory (FSDT) as well as Hamilton’s principle, the equations of motions for the current sandwich structure are presented. The differential quadrature method (DQM) with the weighted linear sum function of the amounts at each separated point in the throughout allowable input range for solving the governing equations using boundary conditions is presented. Finally, the influence of various physical along with geometrical parameters on the frequency performance and absorbed energy capacity of the sandwich axisymmetric curved panel are discussed in detail.