Ratio Of Shear Stress Research Articles

Relationship Between Lateral/Basal Shear Stress Ratio and Structural Vergence of Thrust Wedges: Results From Analogue Modeling and Implications for the Origin of Eastern Sichuan–Xuefeng Fold‐Thrust Belt in South China

AbstractThrust wedges are common in nature, but not all of their origins can be properly explained by the classic Coulomb wedge theory, which considers only a 2D perspective. A few analogue models, however, revealed that lateral shear stress (inherent in both analogue models and nature) may strongly affect the development of thrust wedges and the lateral/basal shear stress (τs/τd) ratio might have controlled the structural vergence of thrust wedge, suggesting that origin of thrust wedges needs to be considered from a 3D perspective. The origin of the Eastern Sichuan–Xuefeng fold‐thrust belt (ESXFTB), which is characterized by two oppositely vergent thrust systems at different crustal levels and may contain another large purely backward‐vergent thrust wedge on the world, is still problematic. Revealing the relationship between τs/τd ratio and structural vergence may prompt a deep understanding of the origin of thrust wedges as well as the ESXFTB. This relationship, however, is still not very clear due to the lack of systematic experiments. For these reasons, we performed systematic experiments of two types of analogue models under different τs/τd ratios. Our model results revealed, for the first time, that structural vergence of thrust wedges lying on a weak décollement may progressively change from frontward (when τs/τd <0.09) to dual (when τs/τd = 0.09–1.15) and then to backward (when τs/τd >1.15) and the two oppositely vergent thrust systems in the ESXFTB can be produced simultaneously by the single northwestward Mesozoic shortening probably due to their apparently different τs/τd ratios.

Predicting transition with algebraic intermittency function

An algebraic intermittency function is developed for “laminar-to-turbulent” transition flow within the framework of Bradshaw stress–intensity factor (ratio of principal shear-stress over turbulent kinetic energy in the boundary layer), which is parameterized with a “flow-structure-adaptive” variable (eddy-to-laminar viscosity ratio). Naturally, the intermittency inherits the “flow-structure-adaptive” character and captures various transition phenomena like bypass, separation-induced, and natural transitions when incorporated in an undamped eddy-viscosity transport equation. An additional viscous-production term is added with the eddy-viscosity transport equation to ensure proper generation of eddy-viscosity at the viscous sublayer when computing separation-induced transition over a low-Reynolds number airfoil. Splitting the intermittency into low and elevated free-stream turbulence intensities has the potential to avoid the “trial-and-error” inconsistency involved in most of the correlation-based transition models for precise computations. The results demonstrate that the proposed algebraic intermittency model is rational and feasible.

A Threshold Model of Tailings Sand Liquefaction Based on PSO-SVM

The liquefaction of tailings sand caused by seismic loads is a major problem in ensuring the safety of tailings ponds. Liquefaction may cause uncontrolled fluidized failure of the dam body, causing considerable damage to the lives, property and environment of people downstream. In this paper, a prototype tailings sand is used as the material to consider the main factors affecting liquefaction (i.e., dynamic load, soil quality, burial and static conditions). By embedding acceleration, pore pressure and earth pressure sensors in the rigid design of the self-designed rigid model box, different types of seismic waves of different ground motion amplitudes (PGA) were induced in a shaking table test of tailings sand liquefaction. The seismic intensity, waveform (class II, III and IV seismic waves) and active earth pressure of the PGA characterizing dynamic factors were obtained, and the static factors were characterized. The dynamic shear stress ratio, the peak acceleration of the earthquake, the pore pressure of the drainage factor and the buried depth (overlying effective pressure) characterize the soil conditions. SPSS software was used to analyze the factor dimension reduction, and the most suitable factors for factor analysis were obtained. Particle Swarm Optimization (PSO) was used to optimize the parameters, and the improved PSO-SVM algorithm was compared with the existing genetic algorithm (GA) and grid node search (GS). The algorithm used in this paper is fast and has a relatively high accuracy rate of 92.7%. The established threshold model method is of great significance to predict the liquefaction of tailings sand soil under the action of ground motions and to carry out safety managemenin advance, which can provide a certain reference for the project.

Modeling cyclic behavior of unbound aggregates using two-surface plasticity theory

Various empirical rutting models have been proposed to predict the permanent deformation of aggregate base/subbase layers in pavements. Nevertheless, an analytical model is required for large-scale finite element simulation of the pavement structure. A two-surface plasticity theory is used to predict the long-term cyclic behavior and provide path-dependent material responses of aggregates. The deviatoric stresses for each aggregate were determined based on the shear stress ratio and the shear strength properties at source and engineering gradations. The proposed rutting model was optimized and validated via repeated load triaxial tests using 11 aggregates. The numerical results demonstrate that the proposed model accurately describes aggregates with low-level permanent strain and thus enables the yield surface, long-term shear strain, and path-dependent resilient modulus to be assessed. Overall, the proposed physics-based modeling approach can help understand and predict the deformation behavior of aggregates subjected to moving-wheel loads.

Water saturation effects on mechanical performances and failure characteristics of rock-concrete disc with different interface dip angles

The mechanical performance of rock-concrete interface is greatly affected by water and dip angles in many rock or concrete engineering projects. To investigate the coupled effects of water saturation and dip angle on the mechanical performances and failure characteristics of rock-concrete interface, series of Brazilian splitting tests were carried out on rock-concrete bi-material disc specimens containing a rough interface. During the test, the interface dip angle θ is set to 0°, 15°, 45° and 90°, respectively. A high-speed camera was used to capture the whole failure process, and the displacement field on the specimen surface was also analyzed. The test results show that regardless of dip angle, the peak load of sample decreases after water saturation. The loss percentages of peak load are very close around 20% when the interface dip angles are 0°, 45° and 90°. However, the reduction of peak load is the most dramatic at the 15° dip angle. When the specimen becomes saturated, its stiffness unexpectedly increases at the dip angle of 0° which is followed by a significant drop at 15°, and finally tends to no obvious change. The stress state at the interface of rock-concrete disc under radial compressive load is discussed. The strength weakening degree of rock-concrete disc specimen by water has a very strong correlation with the ratio of shear stress to tensile stress at the interface. The weakening of water on the bearing capacity of rock-concrete structure is the most obvious at θ≈18.43°.

Experimental study on static characteristics of the Yellow River silt under (triaxial) consolidated undrained conditions

The siltation of reservoirs and rivers in the Yellow River Basin and the occurrence of flood disasters are mainly caused by silt transportation. The Yellow River silt being applied to practical production will help solve the problem of siltation in the Yellow River. In this paper, the consolidated undrained (CU) test of the Yellow River silt is carried out by using GDS triaxial apparatus. The effects of confining pressure, relative density and loading rate on the stress-strain relationship, strength parameters, generalized shear stress ratio and pore water pressure variation of the Yellow River silt are explored. The results show that, under the same axial strain, the deviator stress increases with the increase of confining pressure and relative density, and decreases with the increase of loading rate; compared with the relative density, the effect of the confining pressure and loading rate on the generalized shear stress ratio is insignificant. The friction angle is affected by relative density and confining pressure in varying degrees, but less by loading rate. The secant modulus and initial tangent modulus increase with the increase of confining pressure and relative density. The pore water pressure first increases to the positive peak value, and then decreases to a negative value gradually with the increase of axial strain under most conditions. The pore water pressure variation is affected by the confining pressure and relative density obviously, while affected by the loading rate insignificantly.

Hemodynamics derived from computational fluid dynamics based on magnetic resonance angiography is associated with functional outcomes in atherosclerotic middle cerebral artery stenosis.

To investigate the relationship between fluid-attenuated inversion recovery (FLAIR) vascular hyperintensity (FVH), hemodynamics, and functional outcome in atherosclerotic middle cerebral artery (MCA) stenosis using a computational fluid dynamics (CFD) model based on magnetic resonance angiography (MRA), according to a modified Rankin Scale (mRS) at 3 months. A total of 120 patients with 50-99% atherosclerotic MCA stenosis were included. The training and internal validation groups were composed of 99 participants and 21 participants, respectively. Demographic, imaging data, and functional outcome (mRS at 3 months) were collected. Hemodynamic parameters were obtained from the CFD model. The FVH score was based on the number of territories where FVH is positive, according to the spatial distribution in the Alberta Stroke Program Early Computed Tomography Score (ASPECTS). The prediction models were constructed according to clinical and hemodynamic parameters using multivariate logistic analysis. The DeLong test compared areas under the curves (AUCs) of the models. The multivariable logistic regression analysis showed that the National Institute of Health Stroke Scale (NIHSS) at admission, hypertension, hyperlipidemia, the ratio of wall shear stress before treatment (WSSRbefore), and difference in the ratio of wall shear stress (WSSR) were independently associated with functional outcome (all P<0.05). In the training group before treatment, the AUC of model 1a (only clinical variables) and 2a (clinical variables with addition of WSSRbefore) were 0.750 and 0.802. After treatment, the AUC of model 1b (only clinical variables) and 2b (clinical variables with addition of difference in WSSR) were 0.815 and 0.883, respectively. The AUC of models with hemodynamic parameters was significantly higher than the models based on clinical variables only (all P<0.05, DeLong test). In the internal validation group before treatment, the AUC of the model (clinical variables) was 0.782, and that of the model (clinical variables and WSSRbefore) was 0.800. After treatment, the AUC of the model (clinical variables) was 0.833, and that of the model (clinical variables and difference in WSSR) was 0.861. There were no significant differences between the good and the poor functional outcome group concerning FVHbefore scores before treatment (0.30±0.81 vs. 0.26±0.97; P=0.321) and FVHafter scores after treatment (0.08±0.39 vs. 0.00±0.00; P=0.244). Hemodynamics was associated with functional outcomes in patients with ischemic stroke attributed to atherosclerotic MCA stenosis, while FVH was not. Hemodynamic parameters were of great importance in the prediction models.

Mechanistic study of Mg-Mn-Al extrusion alloy with superior ductility and high strength

Because of the special crystallization structure (hexagonal close-packed structure), it is difficult to achieve the synergy between strength and ductility in Mg alloys. High strength can be obtained through alloying addition or low-temperature deformation, but these methods usually cause the extremely poor ductility (less than 5%). Meanwhile, solid solution treatment or considerable alloying addition, such as RE, Li, can probably possess the superior ductility, whereas these techniques commonly result in the insufficient strength (poor than 100 MPa). However, Mg 1Mn binary alloy developed in our previous work extruded at a low temperature exhibiting the superior ductility (38.8%) with medium yield strength (204.3 MPa) has been recommended as one of the candidates to improve the strength-ductility synergy in Mg alloys. In this paper, a low-alloyed Mg-1Mn-1Al alloy has been developed to overcome the disequilibrium between strength and ductility. The alloy has a superior elongation capacity (~ 32%) and a reasonably high tensile yield strength (~ 280 MPa) at room temperature. The reasonably high yield strength of the alloy can be dominantly attributed to the refined DRXed grains based on the Hall-Petch relationship, intensified basal texture leading to the basal slip activity difficultly, a great number of nano-scaled Al 8 Mn 5 secondary particles pinning the dislocation motion through the dispersion hardening and the multi-heterogeneous microstructure inducing bask-stress strengthening as dislocation pile-up. The superior elongation capacity of the alloy can be mainly explained as the ultra-fined microstructure through reducing the critical resolved shear stress (CRSS) ratio between prismatic slip and basal slip that favors prismatic slip activity to accommodate basal slip. • Extremely refined Mg-1Mn-1Al alloy is fabricated through the low-temperature extrusion process. • Al addition significantly affects the texture and mechanical properties of Mg-1Mn alloy. • Mg-1Mn-1Al extrusion alloy shows a superior elongation capacity (~ 32%) and a reasonably high tensile yield strength (~ 280 MPa).

Flow and arrest in stressed granular materials.

Flowing granular materials often abruptly arrest if not driven by sufficient applied stresses. Such abrupt cessation of motion can be economically expensive in industrial materials handling and processing, and is significantly consequential in intermittent geophysical phenomena such as landslides and earthquakes. Using discrete element simulations, we calculate states of steady flow and arrest for granular materials under the conditions of constant applied pressure and shear stress, which are also most relevant in practice. Here the material can dilate or compact, and flow or arrest, in response to the applied stress. Our simulations highlight that under external stress, the intrinsic response of granular materials is characterized by uniquely-defined steady states of flow or arrest, which are highly sensitive to interparticle friction. While the flowing states can be equivalently characterized by volume fraction, coordination number or internal stress ratio, to characterize the states of shear arrest, one needs to also consider the structural anisotropy in the contact network. We highlight the role of dilation in the flow-arrest transition, and discuss our findings in the context of rheological transitions in granular materials.

Dense shearing flows of soft, frictional cylinders.

We perform discrete numerical simulations at a constant volume of dense, steady, homogeneous flows of true cylinders interacting via Hertzian contacts, with and without friction, in the absence of preferential alignment. We determine the critical values of the solid volume fraction and the average number of contacts per particle above which rate-independent components of the stresses develop, along with a sharp increase in the fluctuations of angular velocity. We show that kinetic theory, extended to account for a velocity correlation at solid volume fractions larger than 0.49, can quantitatively predict the measured fluctuations of translational velocity, at least for sufficiently rigid cylinders, for any value of the cylinder aspect ratio and friction investigated here. The measured pressure above and below the critical solid volume fraction is in agreement with a recent theory originally intended for spheres that conjugates extended kinetic theory, the finite duration of collisions between soft particles and the development of an elastic network of long-lasting contacts responsible for the rate-independency of the flows in the supercritical regime. Finally, we find that, for sufficiently rigid cylinders, the ratio of shear stress to pressure in the subcritical regime is a linear function of the ratio of the shear rate to a suitable measure of the fluctuations of translational velocity, in qualitative accordance with kinetic theory, with an intercept that increases with friction. A decrease in the particle stiffness gives rise to nonlinear effects that greatly diminishes the stress ratio.

Equivalent-linear seismic ground response analysis in Palu area

The 7.5 Mw Palu earthquake on September 28, 2018, was caused by the Palu Koro fault. This earthquake produced forceful wave propagation in the soil layer and generated enormous surface damage in Balaroa, Petobo, and Jono Oge. Estimations of soil amplification at a specific location are helpful as guidance for infrastructure development. This study examined the effect of local soil in modifying the one-dimensional linear soil response in Balaroa, Petobo, and Jono Oge regions, considering the data of various sites in those regions. The soil response was observed to obtain the synthetic input motion and its effects in the time history of surface acceleration, the ratio of shear stress to effective vertical stress to spectrum response time, and the Fourier amplitude versus frequency ratio. Amplification is standard for ground acceleration, which considers the strong ground motion with the acquired frequency and duration of the content. The results showed that the peak of ground acceleration amplification factors for Balaroa, Petobo, and Jono Oge was around 1.49, 2.05, and 1.27 times, respectively. With a lack of information at the particular site, designers will use the response spectrum obtained along the soil layer to develop earthquake-resistant geotechnical structures in locations close to Palu.

Abstract 12046: Can We Better Predict Type a Aortic Dissection?

Introduction: Type A aortic dissection is seen as a progression of aneurysmal dilation, but 60% of patients in the iRAD registry had a maximum aortic diameter (MAD) &amp;lt 55mm. Hypothesis: We theorized that a simplified marker for vessel instability (aortic ratios) and shear stress may improve predictability of dissection compared to maximal aortic diameter (MAD) alone. Methods: Retrospective cohort analysis of all patients who underwent open ascending aortic intervention at Waikato Hospital, New Zealand between 2014-2019, comparing dissection and non-dissection patients. MAD measured in mm; vessel instability as a ratio of MAD to 9 standardized points using ACCF/AHA guidelines; shear stress using MAD to height ratio. Reciever-operator-curve analysis to determine cut-off values for all markers; correlation with dissection assessed using logistic regression for propensity matched cohorts. Results: An entire cohort of 215 patients, 78 (36.3%) dissection patients, the median age at intervention 63.3 years, 52 (24.2%) females, with dissection and non-dissection patients well matched for size (Figure 1a). A diameter of &gt;55mm was only seen in the 33.3% of dissections (n=26/78, Figure 1b), and was not a predictor of dissection (OR 1.88, 95%CI 0.64-5.51). Sinus of Valsalva (SoV) to MAD ratio above 1.06 (cut-off value) was associated with OR 4.49 of dissection (95%CI 1.46-13.81); other vessel instability and shear stress ratios weren’t significant (Figure 1c). Compared to MAD, SoV:MAD ratio had greater sensitivity (0.33 vs. 0.73), lower number-needed-to-treat (17.9 vs. 2.7) and superior area-under-curve in ROC analysis (0.54 vs. 0.71) (Figure 1d). Conclusions: Aortic diameter remains poorly correlated to aortic dissection; SoV:MAD ratio has greater sensitivity, discrimination, and is better correlated with dissection.

Entrance flow of unfoamed and foamed Herschel–Bulkley fluids

The present study investigates extrusion processing of unfoamed and foamed cocoa butter (CB) crystal-melt suspensions (CMSs) with varying crystal volume fraction ΦSFC. Capillary rheometry derived flow curves were fitted with the Herschel–Bulkley–Papanastasiou (HBP) model, and the derived yield stress to wall shear stress ratio τ0/τw of CB CMSs was compared for the various ΦSFC. Foamed CB CMSs behaved fluidlike for ΦSFC≤11.9% and according to a brittle porous solid for ΦSFC>11.9%. The dimensionless entrance pressure loss nen/α as a function of dimensionless shear stress τ∗ was higher for foamed compared to unfoamed CB CMSs at ΦSFC≤11.9% and lower for foamed compared to unfoamed CB CMSs at ΦSFC>11.9%. The ΦSFC dependent difference in nen/α was attributed to the crystal confinement in the die entrance flow, which is increased in the case of elastic gas bubble deformation and decreased in the case of plastic gas pore collapse. The computational fluid dynamics simulated flow of unfoamed and foamed CB CMSs through an abrupt circular 20:1 contraction with the HBP model was compared with the experimental results from quantitative entrance flow visualization (QEFV). Furthermore, the QEFV derived half center incidence angle θ as well as the entrance flow shear and elongational rates γ˙ef and ϵ˙ef were derived and used to establish a model predicting the Bagley entrance pressure loss ΔPBag and calculate an entrance flow characteristic shear and elongational viscosities ηefs and ηefe.

Micromechanical Modeling of Unidirectional CFRP Composites with Proportional Stressing

In this paper, we present a computational micromechanical analysis of unidirectional (UD) carbon fiber-reinforced plastics (CFRPs) using representative volume elements (RVEs). The RVEs consist of randomly distributed fibers, matrix, and interfaces between the fibers and matrix. Periodic boundary conditions (PBCs) and proportional stressing are implemented to facilitate micromechanical analysis of the composites under controlled stress states. In particular, the failure mechanisms of the RVEs under combined transverse and in-plane shear stressing are investigated. The ratio of in-plane shear stress over transverse stress is kept constant during each simulation. By varying this ratio, the mechanical responses of composites under different stress states are systematically studied and the failure envelopes for different fiber volume fractions are extracted. We find the failure envelope converges as the fiber volume fraction increases. The framework developed in this study can be extended to different stress states allowing us to conveniently examine the failure criteria for UD CFRP composites comprehensively.

Effect of straw reinforcement on the shearing and creep behaviours of Quaternary loess

In addition to the shearing behavior of soil, the creep character is also considered crucial in determining the long-term shear strength. This especially holds true for the loess that possesses the metastable microstructure and is prone to landslide hazards. This study explored the potential application of straw reinforcement to enhance the shearing and creep properties of the Quaternary loess. The mechanism responsible for the straw reinforcement to elevate the peak shear strength was revealed. Furthermore, three creep characters, namely attenuating creep, non-attenuating creep, and viscous flow were identified in this study. The unreinforced and reinforced specimen behaved in a different manner under identical shear stress ratio condition. The reinforced specimen was superior in limiting the particle relative movement within the shear plane than the unreinforced specimen. The chain reaction of interparticle contact loss, accompanied with excessive viscous displacement, rapid weakening of creep resistance, and eventually accelerated creep displacement, provided an evidence for the formation mechanism of slow-moving landslide. The long-term shear strength using the isochronal stress–strain relationship may be used for optimising the design of high-fill embankment works.

A unified constitutive model for pressure sensitive shear flow transitions in moderate dense granular materials

Granular shear flows exhibit complex transitional regimes that are dramatically affected by the pressure level and shear stress state. New advances in granular shear tests at low pressure have enlightened the understanding of the two granular shear flow transitions: between quasi-static and moderate shear flows, and between steady-state and transient shear flows. However, a unified constitutive model to describe these two transitions is yet to develop. In this work, a simplified and unified model is proposed based on innovative triaxial shear flow tests, using two dimensionless physical variables. Model results validated against experimental data suggest that the shear flow transition between a quasi-static to a moderate Isotach type flow state is highly pressure-dependent. At extremely low pressure, the granular viscosity becomes the primary mechanism, suppressing the quasi-static mechanism even under “quasi-static” shear rates. In transient to steady state granular flow transitions, a mobilized shear stress ratio or mobilized friction coefficient between zero and the critical state ratio for consolidated granular packings is taken into consideration. This is coupled with the mechanism of granular viscosity. These findings have not been discussed before and are of great relevance to granular mechanics as well as space and earthquake engineering.

Notch fatigue analysis and crack initiation life estimation of maraging steel fabricated by laser beam powder bed fusion under multiaxial loading

This paper deals with the notch fatigue behaviour and crack initiation life estimation in maraging steel fabricated by laser beam powder bed fusion under multiaxial loading. Tests are conducted in tubular geometries with lateral holes considering different normal stress to shear stress ratios and multiaxial loading levels. The cyclic stress–strain response at the notch-controlled process zone is simulated numerically using two alternative approaches: a generalised isotropic plasticity model with mixed isotropic-kinematic hardening, and a linear-elastic model. Both approaches demonstrated to be suitable for predicting the crack initiation sites, the directions of crack growth, and the fatigue life. Fatigue life was calculated from a SWT-based model combined with the Theory of Critical Distances. Elastic-plastic predictions led to smaller errors but slightly shifted to the non-conservative side.

Stress distribution in the walls of major arteries: implications for atherogenesis.

There is a correlation between the sites of atheroma development and stress points in the arterial system. Generally, pulse pressure results in stresses acting on the vascular vessel, including longitudinal stress, radial or normal stress, tangential stress or hoop stress and shear stress. This paper explores the relationship between arterial wall shear stress and pulsatile blood pressure with the aim of furthering the understanding of atherogenesis and plaque progression. We computed the magnitude of the shear stresses within the carotid bifurcation geometry of a patient and calculated the increase in shear stress levels that would occur when the blood pressure and pulse pressures rise during exertion. We also determined in which layer of the artery wall the maximum shear stress is located, and computed the shear stress at different levels within the media. We used the theory of laminate analysis, (Classical Laminate Plate Theory), to analyse the stress distribution on the carotid artery wall. Computational Fluid Dynamics (CFD) analysis was used on anatomy based on a CT angiogram of the carotid bifurcation of a patient with a 90% stenosis on the right side and 10% on the left. The pulsatile non-Newtonian blood flow with a resting blood pressure of 120/80 mmHg and an exertion pressure of 200/100 mmHg was simulated and the resultant forces were transferred to an ANSYS Composite PrepPost (ACP) model for wall shear stress analysis. A multilayer elastic, anisotropic, and inhomogeneous arterial wall (intima, internal elastic lamina, media, external elastic lamina, and adventitial layers) was modelled and the shear stress magnitudes and change over time between the layers was calculated. Shear stress in the individual composite layers is far greater than that acting on the endothelium (less than 5 Pa). At rest, the maximum variation of shear stress in the arterial wall occurs in the intima (138 Pa) and adventitia (135 Pa). The medial layer has the lowest variation of shear stress. Under severe exertion, the maximum shear stress magnitude in the intimal layer and the adjacent medial layer is near the ultimate stress level. The maximum/minimum shear stress ratios during the cardiac cycle vary most widely in the innermost part of the media, adjacent to the intima, with a four-fold ratio increase. This compares with a less than two-fold increase in all the other layers including the intima and adventitia, making the inner media the most vulnerable layer to mechanical injury. This study showed that the magnitude of exertion-induced shear stress approaches the ultimate stress limit in the intima and the immediate adjacent medial layer. The variation in stress is maximal in the inner layer of the media. These findings correlate the site of atheroma development with the most vulnerable site for injury in the media and emphasise the impact of pulse pressure. Further biological studies are required to ascertain whether this leads to injury that initiates atheroma that then precipitates an injury/healing cycle.

Behaviour evaluation of a gravelly soil–geogrid interface under normal cyclic loading

Reinforced soil structures are often subjected to both static and dynamic loads. However, experimental data concerning the interaction of soil–geosynthetic interfaces under normal dynamic loads are scarce. This paper reports on a series of large-scale direct shear tests that are used to investigate the shear behaviour of a gravelly soil–geogrid interface under normal cyclic load (NCL) conditions. The results show that the shear stress magnitude under NCL conditions is generally between the shear stresses under normal static load (NSL) conditions corresponding to the upper and lower bounds of the NCL. The upper and lower envelopes of the shear stress–displacement curve increase with increasing initial stress and amplitude. The enhancement coefficient ([Formula: see text]) is used to describe the degree of influence of the additional cyclic load on the shear stress of the interfaces. The relative time shift between the shear stress ratio ([Formula: see text]) and the normal stress ([Formula: see text]) is nearly a constant of 0.5 cycles, and the influence of the initial stress on the stress ratio is opposite to that of the amplitude. Finally, the volume change response is discussed under different normal load conditions.

Morphological and hemodynamic analysis of the patient-specific renal cell carcinoma models

Although the morbidity of renal cell carcinoma (RCC) has been increasing as the seventh most common tumours, to our knowledge, there is few studies foucsing on the hemodynamics of the renal artery (RA) with RCC. The objective of this study is to perform morphological and hemodynamic analysis of the RA and abdominal aorta artery (AAA) in the control healthy and RCC patient groups. Three-dimensional (3D) geometries are reconstructed from 18 control healthy subjects and 15 RCC patients based on Computed Tomography Angiography (CTA) images. There is higer in the lumen diameter of the RA (6.21 ± 0.89 mm) and curvature of the RA (1.2 ± 0.07) in the RCC patient group compared with the control healthy group (4.29 ± 1.08 mm, 1.1 ± 0.1), respectively. In the hemodynamic analysis, the surface area ratio (%) of low time-averaged wall shear stress (SAR-TAWSS) at the RA (10.65 ± 11.65) and AAA (48.49 ± 12.79) in the RCC patient group is significantly higher than that in the control healthy group (0.23 ± 0.22, 21.57 ± 20.5), respectively. It is found that RCC altered the morphology of the RA in the RCC patient group, which could deteriorate the hemodynamic environment of the RA and AAA. The finding in this study could enhance us to understand the progression of vascular disease caused by RCC.