Shear Strain Rate Research Articles

How Steady is Interseismic Crustal Deformation in Northeast Japan? Evidence From an Integrated Analysis of Centennial Geodetic Data

AbstractWe analyze conventional horizontal geodetic data (triangulation and trilateration) and GPS data from 1890 to 2009 in NE Japan to investigate interseismic deformation over a centennial time scale and to determine if a previously reported decadal strain rate decrease preceding the 2011 Tohoku‐oki earthquake had started prior to the beginning of GPS observations. Analysis of conventional geodetic data shows that the maximum shear strain rate was relatively constant from 1894 to 1984 within one standard deviation, and it is comparable to observations during the GPS era. The conventional geodetic data does not support extrapolation of the strain rate deceleration prior to the 2011 Tohoku‐oki earthquake to epochs before the beginning of GPS observations in the mid‐1990s. Our favored interpretation suggests a transient increase in strain rate followed by a return to the long‐term rate prior to the 2011 earthquake. However, poor temporal resolution and uncertainties in the conventional geodetic data allow for other interpretations, including the possibility of multiple decadal transients during the interseismic period prior to the 1990s. Integration of our results with observations of vertical deformation and physical modeling of mechanical processes at the subduction zone is essential to better understand the tectonic as well as seismological implications of the observations.

Universal scaling law of glass rheology.

The similarity in atomic/molecular structure between liquids and glasses has stimulated a long-standing hypothesis that the nature of glasses may be more fluid-like, rather than the apparent solid. In principle, the nature of glasses can be characterized by the dynamic response of their rheology in a wide rate range, but this has not been realized experimentally, to the best of our knowledge. Here we report the dynamic response of shear stress to the shear strain rate of metallic glasses over a timescale of nine orders of magnitude, equivalent to hundreds of years, by broadband stress relaxation experiments. The dynamic response of the metallic glasses, together with other 'glasses', follows a universal scaling law within the framework of fluid dynamics. The universal scaling law provides comprehensive validation of the conjecture on the jamming (dynamic) phase diagram by which the dynamic behaviours of a wide variety of 'glasses' can be unified under one rubric parameterized by the thermodynamic variables of temperature, volume and stress in the trajectory space.

A shape-change model for isolated K-feldspar inclusions within a shear zone developed in the Teshima granite, Ryoke metamorphic belt, Japan: Estimation of the duration of deformation in a natural shear zone

A shear zone developed in the Teshima granite in the Ryoke metamorphic belt of Japan contains isolated K-feldspar inclusions showing various shapes within deformed host quartz grains. We present a shape-change model for isolated K-feldspar inclusions, which is a mathematical equation that considers stress, inclusion size, temperature, and the duration of deformation. To calculate the shape-change pattern (i.e., the aspect ratio and size of inclusions) with respect to deformation duration using the model, we used values for deformation temperature (~500–600 °C) and paleo-stress (90 ± 10 MPa) estimated from deformed quartz microstructures within the shear zone. Shape-change patterns were obtained by calculating the model at the estimated range of temperatures with an interval of 25 °C and at the estimated paleo-stress. Shape-change patterns were subsequently corrected by compensating for the effect of post-deformation annealing during exhumation of the shear zone. Deformation duration was estimated by identifying the shape-change pattern calculated by the model that most closely corresponded to the observed shape-change pattern for the shear zone and considering the cooling rate of the Ryoke belt. The resultant deformation duration of the shear zone is estimated as 16,500–8400 yr under conditions of T = 550 °C and σ = 90 ± 10 MPa. Shear strain in the shear zone is calculated as 50–260 by multiplying the shear strain rate by the deformation duration.

Intrinsic dependence of welding quality and recrystallization on the surface-contacted micro-asperity scale during ultrasonic welding of Cu–Cu joints

Substantial shear deformation induced by high-frequency friction at the interface is inseparable from recrystallization and welding quality during ultrasonic welding. In this study, we prepared welding surfaces with various micro-asperity scales to analyze the comprehensive effects of deformation heat, shear strain and strain rate on the recrystallization and welding quality. Smaller surface-contacted micro-asperities with a size of 16.03 nm led to a surge in the low angle grain boundaries and recrystallization grains before the formation of a complete weld, which drastically increased the load carry capacity by 139% for joints welded at 1500 J comparing with larger micro-asperities. Molecular dynamics simulation indicated that weld formation involved a dynamic process, including micro-connection, tear, fracture, flattening and weld spread, and the reduction in the micro-asperity scale accelerated the flattening process and aggravated shear deformation at the intimate contact positions. According to the calculation model of recrystallization induced by the shear deformation, smaller micro-asperities promoted the coupling between high shear strain and low strain rate, and maximum shear strain of 1.57 and minimum average strain rate of 346/s were obtained simultaneously, which decreased critical recrystallization strain and enlarged the dynamic recrystallization regions during ultrasonic welding.

Survival estimates across five life stages of redfin (Perca fluviatilis) exposed to simulated pumped-storage hydropower stressors.

The global prevalence of pumped-storage hydropower (PSH) is expected to grow exponentially as countries transition to renewable energy sources. Compared to conventional hydropower, little is currently known regarding PSH impacts on aquatic biota. This study estimated the survival of five life stages (egg, two larval stages, juvenile and adult) of redfin (European) perch (Perca fluviatilis) following passage through a PSH facility during the pumping phase. This was achieved by simulating the individual stressors expected to occur during passage through a 2000-MW PSH facility using laboratory-simulated (shear strain and extreme compression) and modelling (blade strike, BS) approaches. Our results indicate that redfin could survive the shear, pressure and BS stressors expected within the PSH facility, but impacts varied among life stages. Juvenile survival was >70% across all shear strain rates, while the survival of eggs and larvae declined markedly as strain rate increased. All life stages had high survival when exposed to rapid compression and BS. The high survival of redfin to the stressors tested suggests the PSH facility could facilitate the passage of redfin during the pumping phase from the lower to the higher elevation reservoir. This outcome would be welcomed in situations where the species is native, but could have adverse implications for the conservation of native biota where the species is considered a pest.

Оценка моделей давления флуктуаций потока для расчета кавитирующих течений

A numerical study is performed to simulate the cavitating flow, evaluating the applicability of different flow fluctuation pressure (FFP) models such as the Singhai FFT model, the modified Singhal FFT model, the shear strain model, and the present shear strain-vorticity model. The axisymmetric blunt-body with the availability of experimental data is selected for the simulation purpose. According to the results, the first three FFP models produce nearly similar pressure coefficient Cp distribution on the blunt-body. On the other hand, the numerical results indicate the influence of both turbulent shear strain rate and the vorticity in the flow. A slightly better prediction of the cavitation mechanisms such as the flow parameter Cp and cavity length is thus produced with the present shear strain-vorticity model.

Geometry Influence on Fracture Behavior of Lap-Shear Solder Joints

Single lap-shear (SLS) specimens of 63Sn37Pb solder joints were prepared with three different adherend thicknesses at three varying joint lengths. The fracture force was measured at a shear strain rate of 0.01 s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> for different geometries. The elastic–plastic fracture mechanics (EPFM) theory was used to find the energy dissipated in each case using a finite element model (FEM), and the fracture energy was obtained by cohesive zone modeling (CZM). Both 2-D and 3-D models were used to explain the variations in fracture energy by the level of constraint on the joint. Also, the plastic zone area and stress distribution along the solder layer were calculated at the moment of fracture. A phase angle definition was proposed and compared in different solder lengths to show its influence on fracture energy. It was concluded that the fracture energy was influenced by the local phase angle and plastic zone area at the moment of fracture. The effect of adherend thickness on fracture load was significant especially for long joints (i.e., lengths of 6.35 and 12.7 mm). The observations on the crack path showed that the crack was initiated near one of the adherends and tended to propagate within the intermetallic compound (IMC) layer. Also, the planar fracture surface was observed in all the specimens except for the short solder joints (i.e., with the length of 2.54 mm).

Numerical simulation of flow pattern for non-Newtonian flow in agitated thin film evaporator

Agitated thin film evaporator (ATFE) is a new type of high-efficiency evaporator where a film is forced to form through a rotating scraper and the high-viscosity non-Newtonian flow materials can be evaporated smoothly. The flow distribution and transmission mechanism of the material in the evaporator directly determine the evaporation efficiency and power consumption of the evaporator. Unlike previous study that was based mainly on Newtonian flow, this paper establishes a three-dimensional computational fluid dynamics model of ATFE for non-Newtonian flow with different viscosities, and systematically probes the flow field distribution characteristics and film forming mechanism in the evaporator. The results show that the flow field distribution characteristics of low-viscosity non-Newtonian flow are similar to those of Newtonian flow, the material can form a uniform and continuous liquid film on the wall; as the viscosity increases, the uniformity and continuity of the liquid film gradually deteriorate. Through studying the flow field distribution and transmission form of the materials, and combining the liquid film distribution, velocity distribution, shear strain rate distribution, and viscosity distribution, it is found that the shear field and viscosity distribution formed by the internal structure and operating state of the evaporator are the key to the good film formation. In addition, it is proposed that the bending of the leading edge of the scraper can assist the spreading of high viscous fluid liquid film, and the best bending angle is explored. This research provides theoretical guidance and basis for the design and application of ATFE.

Multiscale Approaches Including ANN and M5P-Tree with SI and OBJ Assessment Tools to Predict the Shear Thinning of Bentonite Drilling Muds Modified with Clay Nanosize at Various Elevated Temperatures

Improving the flowability behavior of the water-based drilling mud (WBM) using bentonite under high-temperature conditions is significant in the drilling borehole operations. In this study, the influence of bentonite and clay nanoparticle (CNP) contents on the non-Newtonian fluid (rheology) properties such as initial shear stress and fluid’s resistance to flow (viscosity) under high-temperature conditions were tested and quantified. The shear stress and shear strain rate relationships of WBM were simulated using two new rheological models of the vapor pressure and modified Hoerl models, and the modeling outcomes were validated with the Herschel–Bulkley (HB) model. This study also analyzed and formulated more than 268 data sets, including observational data and data obtained from previously published studies ranging with bentonite in the drilling muds from 2% to 8% (%wt. of water), 0% to 1% of CNP (%wt. of bentonite), and heating temperatures were ranging from 25°C to 100°C. The HB rheological model predicted initial shear stress better than the other two rheological models depending on several statistical assessments. The initial shear stress of drilling muds can be predicted well based on bentonite, CNP contents, and temperature using various simulation techniques. According to several statistical tests, the nonlinear regression and artificial neural network (ANN) performed stronger than other model techniques to predict the yield stress of WBM as a function of bentonite, CNP contents, and temperature.

Assessment of Flow Fluctuation Pressure Models for Simulating the Cavitating Flow

A numerical study is performed to simulate the cavitating flow, evaluating the applicability of different flow fluctuation pressure (FFP) models such as the Singhai FFT model, the modified Singhal FFT model, the shear strain model, and the present shear strain-vorticity model. The axisymmetric blunt-body with the availability of experimental data is selected for the simulation purpose. According to the results, the first three FFP models produce nearly similar pressure coefficient Cp distribution on the blunt-body. On the other hand, the numerical results indicate the influence of both turbulent shear strain rate and the vorticity in the flow. A slightly better prediction of the cavitation mechanisms such as the flow parameter Cp and cavity length is thus produced with the present shear strain-vorticity model. Keywords: Cavitation, turbulent fluctuation, shear strain, voticity, homogeneous model.

Plasticity resource of high-chrome 08Kh13N4M1F steel when pressing

The use of pipes made of high-chromium steel grades in developing oil and gas fields is an important task. The unique properties of the material make pipes indispensable under certain operating conditions in comparison with the same pipes made of carbon, low-alloy and alloy steel grades. However, at the same time, they have a reduced ductility during hot forming. In this work, in order to assess the probability of cracking during hot pressing of pipes made of high-chromium steel grades, the developed method of constructing diagrams of the plasticity of metals and alloys in the hot state for 08Kh13N4M1F steel grade is used. The technique was implemented using a modern testing complex Gleeble 3800. Compression, tensile and torsion tests were carried out at various temperatures. For each test, an assessment of the accumulated degree of deformation was carried out. The obtained data were put into the QForm 3D software package. Based on the processing of the computer simulation results, dependences were obtained that describe the change along the deformation zone when pressing of the stress state index, the intensity of the shear strain rates, and the temperature of the metal being pressed. On the basis of the data obtained, the curves of the dependence of the degree of plastic resource utilization on the deformation temperature were constructed. A metallographic study of 08Kh13N4M1F steel grade revealed the formation of &delta;-ferrite at hot deformation temperatures, which made it possible to draw conclusions about the most rational pressing temperature. The developed technical proposals, which ensure a decrease in the likelihood of cracking on the surface of hot-pressed pipes, were tested using computer modeling of the pressing process and during experimental pressing.

Greater hemodynamic stresses initiated the anterior communicating artery aneurysm on the vascular bifurcation apex

ObjectiveTo investigate hemodynamic stresses associated with the anterior communicating artery (Acom) aneurysm formation using computational fluid dynamics (CFD) analysis. MethodsThree-dimensional geometries of the anterior cerebral artery (ACA) bifurcations in 20 patients with Acom aneurysms and 20 control subjects were used for CFD analysis to investigate hemodynamic stresses including the total and dynamic pressure, wall shear stress (WSS), vorticity and strain rate. ResultsAt the direct flow impinging center on the bifurcation apex, the total pressure was the maximal but decreased quickly from the impinging center to both daughter branches. The WSS, dynamic pressure, vorticity and strain rate were the minimal at the direct impinging center but increased rapidly and reached the peaks at both daughter branches. The ACA bifurcation angle was significantly (P < 0.001) greater in patients with than without Acom aneurysms (144.2° ± 4.1° vs. 105.1° ± 3.2°). Most aneurysms (70% and 85%, respectively) were deviated to the smaller daughter branch or to the daughter branch forming a smaller angle with the A1 segment of ACA, where the hemodynamic stresses were significantly (P < 0.05) greater than those on the contralateral daughter branch. After aneurysm formation, the hemodynamic stresses on the aneurysm dome were all significantly decreased compared with at the aneurysm initiation site with aneurysm virtual removal (P < 0.001). ConclusionFormation of the Acom aneurysm is closely associated with and is to decrease the locally abnormally enhanced hemodynamic stresses.

Research on a mechanical model of magnetorheological fluid different diameter particles

Abstract In this paper, the chain structure of magnetorheological fluid (MRF) magnetic particles was studied and analyzed, the mechanical model of MRF with different diameter ferromagnetic particles was established, silicone oil-based MRF with different particle volume fractions was prepared, the shear properties of the MRF were tested, and the theoretical and experimental data were compared. The experimental results show that the shear stress is stable with the increase of shear strain rate under the action of the magnetic field, and it has a shear thinning effect. The shear stress increases linearly with the increase of particle volume fraction. The shear stress increases with the increase of magnetic induction intensity. After data analysis and in the case of control variables, the average error of improved theoretical data and experimental data is lower than that of previous theoretical data and experimental data, which verifies that the improved theory (mechanical model) has a certain accuracy.

Rheological and Flow Behaviour of Yolk, Albumen and Liquid Whole Egg from Eggs of Six Different Poultry Species.

Liquid egg products are one of the basic raw materials for the food industry. Knowledge of their rheological and flow behaviour in real technical elements is absolutely necessary for the selection of suitable technological equipment for their processing. In this article, the rheological properties of liquid egg products were determined. Eggs from six different species of poultry are used: domestic hen (Gallus gallus domesticus) hybrid Hisex Brown; Japanese quail (Coturnix japonica); German carrier goose (Anser anser f. domestica); domestic ducks (Anas platyrhynchos f. domestica); domestic guinea fowl (Numida meleagris f. domestica); and domestic turkeys (Meleagris gallopavo f. domestica). Liquid egg products showed pseudoplastic behaviour in range of shear strain rates from 0.2 up to 200 s−1 and at the temperature of 18 °C. Thus, the flow curves were constructed using the Ostwald-de Waele rheological model, with respect to the pseudoplastic behaviour of liquid egg products. According to the values of the coefficients of determination (R2), the sum of squared estimate of errors (SSE) and the root mean square error (RMSE), this model was appropriately chosen. Using the consistency coefficient K, the flow index n and the adjusted equations for the flow rate of technical and biological fluids in standard pipelines, the 3D velocity profiles of liquid egg products were successfully modelled. The values of the Reynolds number of the individual liquid egg products were calculated, and the type of flow was also determined. A turbulent flow has been detected for some liquid egg products.

Mechanical Properties of HTPB Propellant under Shear Loading at Low Temperature

AbstractA new type of shear loading fixture and tensile testing machine with a refrigeration system was utilized to conduct Hydroxyl‐terminated polybutadiene (HTPB) propellant low strain rate (0.01∼1.00 s−1) shear loading tests at low temperature (223 K∼298 K). The shear strength and shear modulus of the HTPB propellant under different loading conditions were studied, and the master curves of the shear mechanical properties were constructed. It is found that the shear strength of HTPB propellant increases with increasing of shear strain rate and decreasing of temperature. The change of shear strength with temperature and strain rate conforms to the linear double logarithmic relationship. The initial shear modulus has a good linear double logarithmic relationship with the strain rate but changes nonlinearly with the logarithmic temperature. The shift factor of HTPB propellant shear strength and initial shear modulus changes exponentially with temperature after taking logarithm. The master curve of the initial shear modulus of HTPB propellant shows an “S”‐shaped change trend, and a linear equation is used to fit the master curve of shear strength to obtain a better fitting effect.

Synergistic Effects in Coaxial Mixers: The Controlling Strategy of the Flow and Shear

AbstractSynergistic effects implying that strong flow and high shear can be obtained simultaneously were found in coaxial mixers. The flow field, axial pumping rate Qzave, and shear strain rate were studied to characterize the synergistic effect quantitatively. The indicator of synergy S was proposed to judge the goodness of synergy. The influences of the fluid viscosity, speed ratio, and rotation mode were studied. The S value becomes larger and smaller with increasing fluid viscosity for helical ribbon and pitched blade turbine impellers, respectively. The variation trend is opposite to the increase of the speed ratio. The co‐rotation mode has better mixing performance than that of the counter‐rotation mode at constant specific power.

Shear Variation at the Ice‐Till Interface Changes the Spatial Distribution of Till Porosity and Meltwater Drainage

AbstractMany subglacial environments consist of a fine‐grained, deformable sediment bed, known as till, hosting an active hydrological system that routes meltwater. Observations show that the till undergoes substantial shear deformation as a result of the motion of the overlying ice. The deformation of the till, coupled with the dynamics of the hydrological system, is further affected by the substantial strain rate variability in subglacial conditions resulting from spatial heterogeneity at the bed. However, it is not clear if the relatively low magnitudes of strain rates affect the bed structure or its hydrology. We study how laterally varying shear along the ice‐bed interface alters sediment porosity and affects the flux of meltwater through the pore spaces. We use a discrete element model consisting of a collection of spherical, elasto‐frictional grains with water‐saturated pore spaces to simulate the deformation of the granular bed. Our results show that a deforming granular layer exhibits substantial spatial variability in porosity in the pseudo‐static shear regime, where shear strain rates are relatively low. In particular, laterally varying shear at the shearing interface creates a narrow zone of elevated porosity which has increased susceptibility to plastic failure. Despite the changes in porosity, our analysis suggests that the pore pressure equilibrates near‐instantaneously relative to the deformation at critical state, inhibiting potential strain rate dependence of the deformation caused by bed hardening or weakening resulting from pore pressure changes. We relate shear variation to porosity evolution and drainage element formation in actively deforming subglacial tills.

Theory of history-dependent multi-layer generalized stacking fault energy— A modeling of the micro-substructure evolution kinetics in chemically ordered medium-entropy alloys

In this study, a chemical order related concept “history-dependent multi-layer generalized stacking fault energy” (HDML-GSFE) was proposed, and it was then demonstrated by employing the recent, very interesting multi-principal element alloy (CoCrNi medium-entropy alloys; MEA) with different chemical short-range order (CSRO) levels using a density functional theory (DFT)-based neural network interatomic potential. To demonstrate the impacts of the history dependency and interlayer (atomic interlayers of the slip system) coupling effect on the GSFE of CSRO MEAs, HDML-GSFEs were computed for different shear deformation pathways of the MEAs with different CSRO levels, such as interlayer multiple-time slipping, twin growth, and γ−ε (FCC-HCP) phase transformation. It was demonstrated that multiple-time slipping induces CSRO collapse, leading to local shear softening due to the history dependency of GSFE. In addition, it was found that the slipping of neighboring atomic interlayers is affected by the slipping resulting from the induced CSRO collapse of present interlayers because of the interlayer coupling effect of GSFE. Eventually, by employing a novel kinetic Monte Carlo (kMC) simulation method based on dislocation/disconnection loop nucleation events and using the HDML-GSFE with the history dependency and interlayer coupling effect, we proposed a laminated micro-substructure evolution that involves twinning and γ−ε phase transformations subject to a finite shear strain rate and finite temperature.

Slow slip in subduction zones: Reconciling deformation fabrics with instrumental observations and laboratory results

AbstractCataclasites are a characteristic rock type found in drill cores from active faults as well as in exposed fossil subduction faults. Here, cataclasites are commonly associated with evidence for pervasive pressure solution and abundant hydrofracturing. They host the principal slip of regular earthquakes and the family of so-called slow earthquakes (episodic slip and tremor, low to very low frequency earthquakes, etc.). Slip velocities associated with the formation of the different types of cataclasites and conditions controlling slip are poorly constrained both from direct observations in nature as well as from experimental research. In this study, we explore exposed sections of subduction faults and their dominant microstructures. We use recently proposed constitutive laws to estimate deformation rates, and we compare predicted rates with instrumental observations from subduction zones. By identifying the maximum strain rates using fault scaling relations to constrain the fault core thickness, we find that the instrumental shear strain rates identified for the family of “slow earthquakes” features range from 10−3s−1 to 10−5s−1. These values agree with estimated rates for stress corrosion creep or brittle creep possibly controlling cataclastic deformation rates near the failure threshold. Typically, pore-fluid pressures are suggested to be high in subduction zones triggering brittle deformation and fault slip. However, seismic slip events causing local dilatancy may reduce fluid pressures promoting pressure-solution creep (yielding rates of &amp;lt;10−8 to 10−12s−1) during the interseismic period in agreement with dominant fabrics in plate interface zones. Our observations suggest that cataclasis is controlled by stress corrosion creep and driven by fluid pressure fluctuations at near-lithostatic effective pressure and shear stresses close to failure. We posit that cataclastic flow is the dominant physical mechanism governing transient creep episodes such as slow slip events (SSEs), accelerating preparatory slip before seismic events, and early afterslip in the seismogenic zone.

Dynamic shearing resistance of a polymer-bonded energetic simulant: Composite of sucrose and hydroxyl-terminated polybutadiene (HTPB)

The mechanical behavior of polymer-bonded explosives (PBXs) and polymer-bonded simulants has been widely studied under normal impact. However, their shearing response under large pressures and shear strain-rates has not been explored, to the best of our knowledge. Such measurements are crucial in informing constitutive models that aim to predict hot-spot formation and ignition behavior of PBXs subject to multi-axial loading. Pressure-shear plate impact experiments have been conducted on a composite of hydroxyl-terminated polybutadiene (HTPB) binder and sucrose (an energetic simulant) under normal stresses of 3–10 GPa nominally and shear strain-rates of the order of 105 s−1. The shear strength of the composite shows a dramatic drop after reaching a critical shear strain. Such a drop could be due to fracture or localization in either of the two phases, further compounded by other mechanisms such as friction between the resulting interfaces or collapse of voids. It is also observed that the shear strength of the composite is highly pressure-sensitive, increasing from 176 to 453MPa as the normal stress increases nominally from 3 to 9.5 GPa. Comparison of the shearing behavior of the composite with that of a granular aggregate of sucrose grains at low normal stresses (∼3 GPa) indicates that the binder plays the role of a lubricant between the sucrose grains at those normal stresses. However, at normal stresses of ∼9–10 GPa, the shear strength of HTPB becomes similar to sucrose, and beyond these normal stresses, a transition in the failure mode and its location is expected.