Low Shear Strain Research Articles

Heat Transfer of Casson Nanofluid Flow Between Double Disks: Using Buongiorno Model

Purpose: Fluid thermal efficiency is crucial in major industrial sectors. Traditional fluids often lack the heat transmission needed for various operations. To address this, researchers introduced metallic and non-metallic nano additives, creating a new type of fluid called Nanofluid. This article explores the squeezing flow of Casson nanofluid between parallel disks, considering suction/injection, thermophysical impacts, thermal radiation, and chemical reaction. Methodology: The study uses the Buongiorno nanofluid theory to analyze thermophoresis and Brownian motion, reducing partial differential equations to ordinary differential equations. Numerical technique (shooting approach) is employed to solve these equations, and the results are presented graphically. Conclusions: The study reveals that axial velocity decreases as the Casson fluid parameter increases. Near the intersection point of the velocity field with varying magnitudes of the linear thermal convection parameter, radial velocity increases. It is observed that the thermal field intensifies with a higher linear thermal convection parameter. Additionally, elevated values of the thermal radiation parameter lead to an increase in temperature distribution estimates. Applications of Current Model: Casson fluid, classified as a non-Newtonian fluid, exhibits characteristics of both an elastic solid at low shear strain and a Newtonian fluid at high stress. It is characterized by infinite viscosity at zero shear rate and infinite viscosity at infinite shear rate. Examples of Casson fluids in everyday life include tomato juice, human blood, soup, and orange juice.

A test on methods for Mc estimation and spatial-temporal distribution of b-value in the eastern Tibetan Plateau

Seismic b-value is one of the most important parameters for seismological research and seismic hazards assessment, while the accuracy of the b-value largely depended on the completeness of seismic catalog. This article compares eight methods for estimating the minimum magnitude of completeness (Mc). The results indicate that the modified maximum curvature method (MMAXC), exhibits greater stability and accuracy, closely approximating the standard Mc obtained from the synthetic seismic catalogs. We then calculate the b-value using the instrumental seismic catalog from 2000–2023 in the eastern Tibetan Plateau. The results indicate that the five major earthquakes occur in regions with lower b-value. In addition, the temporal evolution of b-value before and after major earthquakes exhibits a common trend of decreasing before earthquakes, and increasing after earthquakes, which may reflect the stress accumulation and release during earthquakes. Combining the results of maximum shear strain rate and b-value, we identify five regions characterized by low b-value and high shear strain rate, indicating a higher potential seismic hazard in the future.

Tissue adhesive, ROS scavenging and injectable PRP-based 'plasticine' for promoting cartilage repair.

Platelet-rich plasma (PRP) that has various growth factors has been used clinically in cartilage repair. However, the short residence time and release time at the injury site limit its therapeutic effect. The present study fabricated a granular hydrogel that was assembled from gelatin microspheres and tannic acid through their abundant hydrogen bonding. Gelatin microspheres with the gelatin concentration of 10 wt% and the diameter distribution of 1-10 μm were used to assemble by tannic acid to form the granular hydrogel, which exhibited elasticity under low shear strain, but flowability under higher shear strain. The viscosity decreased with the increase in shear rate. Meanwhile, the granular hydrogel exhibited self-healing feature during rheology test. Thus, granular hydrogel carrying PRP not only exhibited well-performed injectability but also performed like a 'plasticine' that possessed good plasticity. The granular hydrogel showed tissue adhesion ability and reactive oxygen species scavenging ability. Granular hydrogel carrying PRP transplanted to full-thickness articular cartilage defects could integrate well with native cartilage, resulting in newly formed cartilage articular fully filled in defects and well-integrated with the native cartilage and subchondral bone. The unique features of the present granular hydrogel, including injectability, plasticity, porous structure, tissue adhesion and reactive oxygen species scavenging provided an ideal PRP carrier toward cartilage tissue engineering.

A trivalent ferrite ferrofluid compound’s rheological response to angular frequency, magnetic induction and shear induction of chain clusters

At low and high temperatures in the presence and absence of magnetic fields, the effects of shear rate, angular frequency, and shear strain on the rheological characteristics of zinc ferrite ferrofluid is investigated. Chemical co-precipitation was used to create a zinc ferrite ferrofluid that was then coated with oleic acid to improve the stability of the fluid’s particles and avoid particle agglomeration. We looked at the rheological characteristics caused by the induced magnetic field, such as the shear stress, complex viscosity, storage modulus, loss modulus, relaxation modulus, viscous torque, damping factor, and figure of merit. From the analysis of time dependent relaxation modulus, a steady-state rheological system is formed at time interval beyond 50 s. As the shear and complex viscosities increase with an increase in magnetic field and a decrease in temperature, obstruction to fluid flow is produced. When a rheological system operates at low angular frequency and high shear rate, high shear stress is loaded; when it operates at high angular frequency and low shear rate, low shear stress is loaded. In the absence of magnetic field, a low viscosity 0.425 Pa.s and shear force 46 Pa were formed, while high viscosity 8.140 Pas and shear stress 168 Pa were formed when magnetic field 1.000 Tesla was applied. The oscillatory mode test demonstrates a change in structure from solid to liquid due to the establishment of a crossover point between shear strain 55 and 64%, supporting the solid–liquid phase transition behavior. The damping analysis demonstrates that the system is in fact excessively dampened, and it may now be utilized to reduce vibrations in a system. The system is really overdamped showing a maximum damping factor 2.08, according to the damping study, and can therefore be used to reduce vibrations in other systems. The fluid exhibits non-Newtonian shear-thinning behavior as shear rates increase. A high viscous torque is created at low shear strain and high angular frequency, which leads to the creation of a strong rotating magnetic field.

Slow and fast particles in shear-driven jamming: Critical behavior.

We do extensive simulations of a simple model of shear-driven jamming in two dimensions to determine and analyze the velocity distribution at different densities ϕ around the jamming density ϕ_{J} and at different low shear strain rates, γ[over ̇]. We then find that the velocity distribution is made up of two parts which are related to two different physical processes which we call the slow process and the fast process as they are dominated by the slower and the faster particles, respectively. Earlier scaling analyses have shown that the shear viscosity η, which diverges as the jamming density is approached from below, consists of two different terms, and we present strong evidence that these terms are related to the two different processes: the leading divergence is due to the fast process, whereas the correction-to-scaling term is due to the slow process. The analysis of the slow process is possible thanks to the observation that the velocity distribution for different γ[over ̇] and ϕ at and around the shear-driven jamming transition has a peak at low velocities and that the distribution has a constant shape up to and slightly above this peak. We then find that it is possible to express the contribution to the shear viscosity due to the slow process in terms of height and position of the peak in the velocity distribution and find that this contribution matches the correction-to-scaling term, determined through a standard critical scaling analysis. A further observation is that the collective particle motion is dominated by the slow process. In contrast to the usual picture in critical phenomena with a direct link between the diverging correlation length and a diverging order parameter, we find that correlations and shear viscosity decouple since they are controlled by different sets of particles and that shear-driven jamming is thus an unusual kind of critical phenomenon.

Estimating plasticity index directly from piezocone penetration tests in saturated natural soils

Plasticity index, Ip, is a relatable parameter for most geotechnical engineers, because Ip can be used to estimate other soil properties, such as internal friction angle, compression index, and low-strain shear modulus. Consequently, a method for estimating Ip directly from a piezocone penetration test (CPTU), which measures cone resistance, sleeve friction, and pore pressure would be useful for many practising geotechnical engineers. This technical note presents a method for estimating Ip profiles entirely from CPTU data. The new method has been calibrated using a case database of 258 complementary measurements taken, in natural soils, at 25 globally distributed marine sites.

The roles of stress state and pre-straining on Swift effect for an extruded AZ31 Mg alloy

The Swift effect of Mg alloy is sensitive to initial texture. However, dislocation slip is the main deformation mechanism during torsion of Mg alloy. The underlying relation of Swift effect and dislocation slip is still not clarified. The effect of stress state and pre-straining on Swift effect was studied experimentally during free-end torsion for an extruded AZ31 alloy. The free-end torsion was performed with axial tension and compression stress which is lower than yield stress. It is found that the transition of axial deformation from contraction to elongation occurs when the axial stress changes from negative to positive. The pre-dislocations introduced by pre-tension promote axial shortening during torsion. While the pre-twins introduced by pre-compression are inhibition of axial shortening. The change of axial deformation is attributed to competition between twinning and prismatic slip. The axial shortening of extruded Mg alloy is generated by tensile twinning leading to c -axis strain. In contrast, the axial elongation can be generated by the activation of prismatic slip. The magnitude of axial strain generated by twinning is larger than that by prismatic slip. Moreover, the occurrence of detwinning results in axial elongation at low shear strain.

Assessment of sustainable expanded glass granules for enhancing shallow soil stabilization and dynamic behaviour of clay through resonant column tests

In geotechnical engineering applications such as artificial slope fills, backfill for retaining walls and embankments are required to be as light as possible, yet more durable and provide drainage. Recently, the use of waste materials in stabilization applications is preferred due to both a more sustainable environment and economic advantages. In this study, expanded glass granules, used in lightweight and stabilization material such as autoclaved aerated concrete, were mixed with clay at various ratios (by mass 1 – 2% and by volume 2.5 – 5 – 7.5 – 10 – 15%) and their dynamic properties such as initial shear modulus, damping ratio and modulus reduction were investigated under various effective pressures comparatively using resonant column/torsional shear test (RCTS). Considering the shear modulus results of the mixtures by mass (1–2%) and by volume (2.5–5 − 7.5%), it is observed that low and medium shear strain amplitude (0.001–0.05%) were observed to be higher in the range of up to 40% and 10% compared to the reference sample. In addition, it was calculated that the density of the mixed specimens (2.5–5 − 7.5%) with high shear modulus were up to 6.2% lower than the reference sample. The study concludes that the use of expanded glass granules (by mass 1–2%, by volume 2.5, 5%) is experimentally satisfactory for shallow soil stabilization in geotechnical applications where the presented boundary conditions are valid.

Assessment of strength and low-strain shear modulus of bio-cemented sand considering MICP treatment

Assessment of strength and low-strain shear modulus of bio-cemented sand considering MICP treatment

Continuous Evaluation of Shear Wave Velocity from Bender Elements during Monotonic Triaxial Loading.

Few researchers have attempted to experimentally evaluate the low-strain shear wave velocity (Vs) of specimens undergoing large strain deformations. They report that the Vs is practically unaffected by the strains, and the reasons behind this behavior are not fully understood. This study presents the continuous measurement of low-strain Vs with bender elements (BE) during monotonic shearing of two sand specimens in a triaxial device. The results are analyzed using a micro-mechanical model based on contact theory. The results of this study confirm that the Vs values from BE measurements are unaffected by an increase in axial strains that are induced by a separate mechanism. The micro-mechanical model predictions of Vs agree well with the results of this study and with the results of previous studies. They show that the mean effective stress and increase in inter-particle stiffness controls the low-strain stiffness despite a global increase in strains during monotonic loading.

Superimposed structures, incremental strain and deformation path from field data to modelling: A case study from the Alpi Apuane metamorphic core complex (NW Tuscany, Italy).

In this study, superimposed folds and antitaxial strain fringes are investigated to unravel the deformation path of the core zones of the Alpi Apuane metamorphic complex (northwest Tuscany Italy). Detailed field mapping combined with microstructural analyses is used together with computer-modelling of a complex strain fringe system to disclose the main steps of the Alpi Apuane syn-metamorphic deformation history. A comparison between natural investigated fibres and those produced by paraffine wax experiments provides details of the relative core-object-fringe rotation allowing new insight on the growth kinematics of strain fringes. The results of our analyses show that our composite fringe system is characterized by a first set of fibres to be related with the main composite axial planar foliation of regional scale isoclinal non-cylindric folds. This first set of fibre fringes records a local non-coaxial strain with an absolute core-object rotation (relative to an external reference frame represented by the main foliation) of 140° and a calculated shear strain (γ) of about 4. The second set of fringes, developed after the tilting of the main foliation and the first fringe-set in a sub-vertical orientation, records a lower absolute rotation of the core-object (25°), a lower shear strain (γ) of about 1.4 and a coaxial strain associated with the vertical shortening. This part of the composite fringe system and the related structures may relate to the switch from the crustal scale contractional regime to the extensional one, which characterized the development of the inner northern Apennines orogen.

Microstructural and textural modification of columnar calcite under increasing shear strain (Evia Island, Greece)

We studied the microstructural and textural modification of columnar calcite naturally deformed at increasing shear strain. The studied marbles were sampled from different structural levels of the Basal Unit of the Cycladic Massif on Evia Island, Greece. The marbles have experienced high pressure metamorphism at peak temperatures around 350 °C. The long axes of the columnar calcite grains and their c-axes were originally oriented normal to the foliation and were subsequently rotated during exhumation. The obliquity of the long axes of relict calcite grains with respect to the foliation was used to infer shear strain. Electron backscatter diffraction (EBSD) analysis was used to characterize the marble microstructure as well as the crystallographic preferred orientations (CPO) and misorientations in calcite. Recrystallization of calcite was active from very low shear strains (0.1) and mylonitization (∼60% area fraction of recrystallized grains) took place at shear strains >∼4. Subgrain rotation was the dominant recrystallization mechanism in calcite in all samples. Differential stress and strain rate did not show any systematic variation with increasing shear strain. A shear strain of up to ∼4 was not enough to produce a strong CPO in calcite.

Formation of dislocation structures during cyclic deformation in near-[001] multiple-slip-oriented copper single crystals

Dislocation structures in [001]-oriented copper single crystals have historically been studied at relatively low plastic shear strain amplitudes (γpl). Herein, the dislocation structure is investigated across a wide γpl range of 1.7 ∙ 10−4–1.7 ∙ 10−2. When γpl < 1.5 ∙ 10−2, the dislocation structure comprised a labyrinth with a set of parallel (100) and (001) walls. However, as γpl approached 1.5 ∙ 10−2, the dislocation structure changed to a cell structure to accommodate the higher plastic strain. The formation plane of the cell boundary depends on which slip system is activated as the primary slip system.

Dynamic Properties of Calcareous Sands from Urban Areas of Abu Dhabi

Abu Dhabi (ABD) has recently developed its national building code that mandates dynamic analysis of large structures to seismic loadings. Large strain dynamic properties such as shear modulus (G) and damping ratio (D) of local undisturbed calcareous sands are not available. Designers are compelled to choose degradation models from studies on calcareous sands of other regions that are usually reconstituted. This research presents for the first time large strain dynamic properties of calcareous sands of urban ABD. Undisturbed samples are collected from different areas of urban ABD and are tested in cyclic triaxial (CT) devices fitted with bender elements (BE). The dynamic properties as functions of confinement are curve fitted with power models, whereas their variation with shear strain level is curve fitted with hyperbolic models. The results are compared with findings of previous studies on calcareous and silica sands. The results indicate that dynamic properties of all samples degrade with shear strain at almost the same rate irrespective of their spatial distribution. The proposed degradation models can therefore be used in dynamic analyses. The results from this study show smaller rates of degradation in dynamic properties compared to other studies on similar sands. The change in low-strain shear wave velocity (Vs) with confinement is significant among the tested samples; therefore, a site-specific evaluation of Vs is recommended. The dynamic properties of calcareous sands of ABD and previous studies however exhibit larger degradation with shear strain and a smaller increase in confinement compared to silica sands.

MR Elastography-Based Shear Strain Mapping for Assessment of Microvascular Invasion in Hepatocellular Carcinoma.

To evaluate the potential of MR elastography (MRE)-based shear strain mapping to noninvasively predict the presence of microvascular invasion (MVI) in hepatocellular carcinoma (HCC). Fifty-nine histopathology-proven HCC patients with conventional 60-Hz MRE examinations (+/-MVI, n = 34/25) were enrolled retrospectively between December 2016 and October 2019, with one subgroup comprising 29/59 patients (+/-MVI, n = 16/13) who also underwent 40- and 30-Hz MRE examinations. Octahedral shear strain (OSS) maps were calculated, and the percentage of peritumoral interface length with low shear strain (i.e., a low-shear-strain length, pLSL, %) was recorded. For OSS-pLSL, differences between the MVI (+) and MVI (-) groups and diagnostic performance at different MRE frequencies were analyzed using the Mann-Whitney test and area under the receiver operating characteristic curve (AUC), respectively. The peritumor OSS-pLSL was significantly higher in the MVI (+) group than in the MVI (-) group at the three frequencies (all p < 0.01). The AUC of peritumor OSS-pLSL for predicting MVI was good/excellent in all frequency groups (60-Hz: 0.73 (n = 59)/0.80 (n = 29); 40-Hz: 0.84; 30-Hz: 0.90). On further analysis of the 29 cases with all frequencies, the AUCs were not significantly different. As the frequency decreased from 60-Hz, the specificity of OSS increased at 40-Hz (53.8-61.5%) and further increased at 30-Hz (53.8-76.9%), and the sensitivity remained high at lower frequencies (100.0-93.8%) (all p > 0.05). MRE-based shear strain mapping is a promising technique for noninvasively predicting the presence of MVI in patients with HCC, and the most recommended frequency for OSS is 30-Hz. • MR elastography (MRE)-based shear strain mapping has the potential to predict the presence of microvascular invasion (MVI) in hepatocellular carcinoma preoperatively. • The low interface shear strain identified at tumor-liver boundaries was highly correlated with the presence of MVI.

On the enhanced hardening ability and plasticity mechanisms in a novel Mn-added CoCrNi medium entropy alloy during high-pressure torsion

Microstructure and texture evolution during high-pressure torsion (HPT) of a novel Mn-added CoCrNi medium entropy alloy (Co33Ni33Cr19Mn15) is investigated for the first time. The alloy exhibited a rapid rise in hardness at relatively low shear strains (γ≤20). It is attributed to an extensive dislocation activity to achieve saturation in dislocation density of ~1016 m−2, combined TWIP and TRIP effects and microstructural refinement. At higher shear strain, hardness increased at much reduced rates owing to saturation of dislocation density, twin fault probability and the TRIP effect, besides continued grain refinement for severe nano-structuring led to subsequent strengthening. The FCC phase showed remarkable stability except a small degree of initial deformation-induced HCP martensitic transformation in an early stage of HPT. The ideal shear texture components were observed at low shear strain, and these continued to evolve up to 5 turns of HPT processing. For similar HPT processing conditions, the studied alloy showed superior hardness (~650 Hv) compared to a wide spectrum of FCC materials, which is ascribed to a combination of the strengthening mechanisms of Taylor hardening, the TRIP and TWIP effects and Hall-Petch strengthening resulting from the nano-structured grains having an average size of ~35 nm.

Floor response spectra analysis of a nuclear reactor considering uncertainties in soil parameters

Floor response spectra of the nuclear reactor building are an important part of the seismic analysis and design of the whole reactor system. Uncertainties exist in the calculation of floor response spectra considering soil-structure interaction effect due to uncertainties in soil parameters. Stochastic models of shear wave velocity, shear modulus reduction, and damping ratio were built, and random samples were generated via Monte Carlo simulation, according to the survey data of 2 MW Thorium Molten Salt Reactor-Liquid Fuel 1 by the China Earthquake Administration. Site response analysis carried out using an equivalent linear methodology was performed to study the influence of uncertainties in different soil parameters on surface response spectra. The coefficient of variation (Cv) was calculated via generating and enveloping random samples of low strain shear modulus to count for uncertainties in soil parameters, unlike many studies which take Cv as code’s minimum requirement of 0.5 directly. Floor response spectra considering uncertainties in soil parameters were calculated by the time-domain method using Cv. The results indicate that the uncertainty of shear wave velocity has the most significant influence on the surface response spectra. Floor response spectra have increased significantly after considering uncertainties in soil parameters, and the behavior of taking Cv as 0.5 like other studies is not conservative enough to consider uncertainties in soil parameters. Soil uncertainties have not been considered thoroughly in the calculation of floor response spectra in past studies, and this paper addresses this knowledge gap via Monte Carlo simulation. The findings will be used to perform floor response spectra analysis considering uncertainties in soil parameters.

Effect of ultrasonic field on microstructure evolution in friction stir welding of dissimilar Al/Mg alloys

Understanding of the microstructure evolution and the influence of ultrasonic vibration on friction stir welding (FSW) of dissimilar Al/Mg alloys is of great significance in optimizing the process parameters and improving the joint quality. In this study, the microstructure evolutions in the weld nugget zone (WNZ) of dissimilar Al/Mg joints during FSW and ultrasonic vibration enhanced FSW (UVeFSW) were characterized and compared. It was found that ultrasonic vibration (UV) has great effect on the grains structure of the WNZ in the Mg alloy side. Specially, the exerted UV changed the main dynamic recrystallization (DRX) mechanism of grains in the Mg alloy side from continuous DRX (CDRX) to discontinuous DRX (DDRX) under lower or higher welding speeds but constant tool rotation speed. Along the thickness direction, the average grain sizes near the bonding interface in the WNZ increased first and then decreased, and the maximum grain size was located at the mid-depth of the weld. Low strain shear texture appeared more in the WNZ of the Al alloy side during FSW, while in UVeFSW more locations in the WNZ were with high strain shear textures. The application of UV field improved the DRX degree in the whole weld through promoting the entanglement, aggregation and rearrangement of dislocations.

Development of Surface Level Seismic Hazard Maps Considering Local Soil Conditions for the State of Haryana, India

Abstract An extensive ground response analysis has been carried out in order to consider the effect of local soil conditions on surface level strong ground motions in the state of Haryana, India. Non-linear approach has been adopted to analyze 81 sites drilled up to refusal covering the entire state. It has been observed that 75 sites fall under site class D (medium dense soils), 4 sites under site class C (very dense soils), whereas only 2 sites fall under site class E (loose soils) as per the provisions of National Earthquake Hazard Reduction Program (NEHRP). For the estimation of low strain shear modulus (Gmax) using SPT N-value for different type of soils, various correlations have been used due to non-availability of in-situ measured values of shear wave velocity (Vs). The standard backbone curves for clays and sands have been used in the study in the absence of site-specific shear modulus degradation and damping ratio curves. The recorded acceleration time histories of the Ms 7.0 1991 Uttarkashi earthquake, having a focal depth of 10 km with PGA (g) ranging from 0.05g to 0.31g, have been used as input motion for the analysis. Amplification factors for peak ground acceleration (PGA) and spectral acceleration (Sa) for site class D have been calculated which are found to be comparable with those reported in NEHRP provisions. However, the site-specific hazard parameters determined for the tectonic setup of the seismic study region are quite different from that suggested by Indian standard code of practice.

Modulation of morphology, water uptake/retention, and rheological properties by in-situ modification of bacterial cellulose with the addition of biopolymers

In situ modification of bacterial cellulose (BC) allows structural and morphological tuning which determines the crucial properties such as water absorption/retention and rheological behaviour. This work reports the effect of in situ modification carried out by adding two biopolymers Agar and Chitosan to the standard culture media for bacterial cellulose synthesis. The agar modified BC (Agar-BC) form a BC network with reduced pore volume, and a much denser network, leading to lesser water absorption and further lower retention time than BC. Agar-BC also demonstrates a higher storage modulus, while the yield point is observed at a lower shear strain. This indicates a behaviour similar to that of a crosslinked polymer with a low strain onset of plasticity. On the other hand, chitosan-modified BC (Chitosan-BC) also exhibits a lower pore volume with a lower densely packed structure and with lower swellability and water retention reduced to 1 h (7 h for BC). Chitosan-BC presents a lower modulus with a yield strain similar to that of unmodified BC. The water absorption-retention behaviour is discussed in detail considering the relative pore shape-size distribution, fibre dimension and surface area. The mechanism of viscoelastic deformation for each of the cases is explained.