Shear Components Research Articles

Research on the dynamic characteristics and disaster mechanism of anti-slide short pile-supported slopes

The terrain in Southwest China is predominantly mountainous with many slopes requiring reinforcement. This region also experiences frequent rainfall and earthquakes, which can trigger landslides. Therefore, studies on slope reinforcement are crucial. In this study, we present a case study of a slope stabilization project along the Yunyang–Fengjie Expressway in Chongqing, focusing on the seismic performance of anti-slide short pile-supported slopes. By inputting the Wenchuan earthquake wave and gradually increasing the amplitude of the seismic wave, we examined the failure evolution process of an anti-slide short pile-supported slope. The experiments revealed that the failure mode of the slope comprised tensile and shear components, with tensile cracks occurring at the crest, and shear cracks developing in the remaining fractured sections. The anti-slide short piles effectively redirected the downward extension of shear cracks. As the seismic activity intensified, shear cracks propagated along the weak interlayer towards the toe of the slope. When the cracks approached the intersection of the anti-slide short piles and weak interlayer, they were impeded by the piles, altering their development path along the weak interlayer. This change caused the cracks to extend towards the top of the anti-slide piles, ultimately causing overall failure. The bending moment of the anti-slide piles under the seismic action primarily followed a parabolic shape, with the maximum value occurring near the weak interlayer.

Does helical plating for proximal humeral shaft fractures benefit bone healing? -an in silico analysis in fracture healing.

Helical plating is an established alternative to straight plating for humeral shaft fractures in order to prevent iatrogenic radial nerve damage. However, a previous biomechanical investigation indicated differences in fracture healing for helical plating due to a potential shift of interfragmentary movements compared to straight plating. Therefore, fracture healing simulations were performed to assess any differences in bone healing of helical vs. straight plating. A systematic workflow for fracture healing analytics was created, covering essential steps of bone modelling, implant modelling, finite element modelling, fracture healing simulation and result analysis. Computational humerus models with an AO12C2 fracture and straight and helical osteosynthesis were created. An established fracture healing model was used to simulate callus formation over 112days under physiological loading. The predicted tissue differentiation and interfragmentary movement (IFM) was tracked over the entire simulated healing course. Helical plating resulted in larger interfragmentary movements for compression and shear components, and in a greater proportion of near and far cortical movement. Vascularization and tissue formation were deferred, but cortical bridging was achieved. Helical plating resulted in slightly deferred bone healing due to larger interfragmentary shear movements. Considering the advantage of helical plating in clinical context, a slightly deferred bone healing is justifiable.

Stretchable Included-Formulation Free Vibration Responses of Origami Graphene Auxetic Metamaterial Reinforced Plate

A more accurate kinematic model is extended in this work for vibrational analysis of a nanocomposite plate reinforced with graphene origami subjected to mechanical and thermal loading. The stretching part of transverse deflection is included in the kinematic relations in addition to the shear and bending components to arrive at a general formulation. The Hamiltonian procedure is extended to derive the governing equations of motion. The parametric results are obtained using the analytical method for investigating the impact of graphene origami reinforcement such as foldability and content as well as geometric parameters on the natural frequency responses. The results of this work can be used for the design of optimized structures and systems with high stiffness and low density applicable in multi-field loading conditions. As a novel conclusion, one can conclude that accounting thickness stretching leads to a decrease in natural frequencies because of more deformability and consequently a decrease in structural stiffness of stretchable plate.

Crystallographic texture of aluminium alloy samples produced with additive friction stir-deposition

The crystallographic texture formation in AK9ch aluminum alloy (9.6% Si; 0.3% Mg; 0.1% Fe; 0.1% Mn, the rest – Al) specimens manufactured using the Additive Friction Stir Deposition (AFS-D) technology at room temperature is investigated. The analysis was conducted using inverse pole figures (IPFs) obtained by X-ray diffraction methods. The results reveal the presence of shear, torsion, deformation, and recrystalization texture com-ponents in both types of specimens. The texture of horizontal and vertical samples differs in the set of texture components and the character of their dispersion. The texture intensity of both types of specimens is ill defined. This testifies to the possibility to manufacture AK9ch alloy components using AFS-D technology with reduced anisotropy.

Shear Band-Induced Internal Surface Structures in a Vitreloy Bulk Metallic Glass Deformed by High-Pressure Torsion.

In the present investigation, high stability Vitreloy Zr44Ti11Cu10Ni10Be25 bulk metallic glass has been subjected to severe shear deformation by high-pressure torsion for 0.1 revolutions under an applied pressure of 4 and 8 GPa. The fully glassy nature of the as-cast glass has been confirmed by X-ray powder diffraction and differential scanning calorimetry. Deformation-induced surface features on an internal plane of the deformed disk-shaped specimens were studied in detail at the macroscopic level by optical reconstruction method and at microscopic scales by white-light optical profilometry. Shear and compressive strain components were measured based on surface changes and it was determined that compressive strain gradient with 0.2-0.4 strain change builds up toward the disk edge, while only part of the nominal shear deformation occurs in the disk interior. The effect of strain localization in the Vitreloy bulk metallic glasses has been quantified by a surface distortion model based on simple shear. The model was then validated experimentally by the reconstructed z-profiles.

Aseismic creep and strain partitioning accommodating the Nubia-Eurasia oblique convergence in northern Africa from InSAR analysis

The northern Africa region faces significant seismic and tsunami hazards, driven by the ongoing convergence between the Nubian and Eurasian plates. Using radar interferometry (interferometric synthetic aperture radar, InSAR) analysis, we provide constraints on the interseismic behavior of tectonic structures within the region between ∼2°W and ∼11°E using the first InSAR-derived regional-scale maps of east-west and vertical velocity components. Despite the unresolved N-S−oriented motions due to inherent limitations to the InSAR technique, our millimeter-per-year level velocity maps reveal three distinct domains of strain accommodation along the plate boundary. In Western Tell, both onshore and offshore folds and thrusts accommodate frontal collision, regularly generating large reverse earthquakes, such as the Ms 7.3 El Asnam earthquake of 1981. In the Eastern Tell, deformation is widely distributed from the Saharan Platform to the northern coastlines. In the Central Tell, we identify the predominantly aseismic behavior of the 500-km-long Ghardimaou-North-Constantine fault, marked by a shallow locking depth (<5.1 ± 0.5 km) and standing out as one of the slowest (<2.5 mm/yr) continental strike-slip faults ever detected with geodetic data. Strain partitioning diverts most of the shear component of the oblique convergence into this major inland structure, thereby making the offshore thrusts and folds the principal sources of seismic hazard.

Enhancing Epoxy Composites with Graphene and Graphene Oxide: Thermal and Mechanical Insights

AbstractThis paper shows the graphene and graphene oxide nanoflakes as the 0.1, 0.5, 1, 2, and 4 wt.% reinforcement of epoxy‐resin matrix to enhance the thermal and mechanical characteristics of the composite. Experimental measurement of the glass transition temperature and thermal expansion coefficient indicated that the addition of nanostructural filler improving the glass transition temperature about ~12 °C for nanocomposite filled carbon‐based nanoparticles for both heating and cooling cycles compared to the bare epoxy resin. Young's elastic modulus measured by nanoindentation and the stress versus strain curves for different weight fractions of graphene nanoflakes additives during uniaxial compression and tension considered were obtained from the experiments. The distributions of logarithmic strain field for the transverse, axial and shear components on the nanocomposites sample surfaces, during the uniaxial tension process for quasi‐static strain rates, were analyzed. The tensile strengths show improvement for nanocomposites with less than 1 % weight fraction of carbon‐based nanoparticles. The compressive yield stress increased to a maximal value (at the recorded peak on the curve) for an epoxy nanocomposite having 2 wt.% oxidized graphene flakes, where both parameters were enhanced with the oxidized form of graphene for the more effective dispersion in the epoxy resin matrix over the bare graphene filler.

Study and comparison of the bending response of porous advanced composite plates under thermomechanical loads using different materials

This research focuses on the study and comparison of the thermomechanical bending behavior of porous advanced composite plates, particularly functionally graded materials (FGM), where the presence of porosity significantly influences their structural performance. A refined shear deformation theory is developed to analyze the bending response of porous FGMs under thermomechanical loads. The proposed model introduces a novel transverse shear function, separating transverse displacements into bending and shear components. This innovative approach simplifies the analysis, requiring fewer unknowns and eliminating the need for shear correction factors, thereby reducing computational costs compared to traditional theories such as first-order shear deformation theory (FSDT), higher-order shear deformation theory (HSDT), sinusoidal shear deformation theory (SSDT), and quasi-3D theory. The study examines the bending response of porous FGMs composed of various materials, including FGM 1 (Aluminum/Zirconia), FGM 2 (Ceramic/Zirconia), FGM 3 (Titanium/Silicon Carbide), FGM 4 (Stainless Steel/Zirconia), FGM 5 (Copper/Alumina), and FGM 6 (Nickel/Silicon Nitride). The results derived from the proposed theory are systematically compared with those obtained from other established theories to demonstrate its accuracy and computational efficiency. This work provides valuable insights into the behavior of porous FGMs and highlights the potential of the refined shear deformation theory for future applications in structural engineering.

SUBBASE FRICTION EFFECTS ON CONCRETE PAVEMENTS

Designing, constructing, and maintammg concrete pavements under rigorous and unpredictable traffic and environmental loads is a rather formidable challenge. Several effects of the environment on concrete pavements, including the effects of moisture and temperature, have been studied. However, one very important factor, the frictional characteristics between concrete pavements and stabilized subbases, has not been adequately researched. This paper presents findings of a study researching the frictional effects of stabilized and unstabilized subbases. The study was funded by the Texas State Department of Highways and Public Transportation and the Federal Highway Administration and conducted by the Center for Transportation Research at The University of Texas at Austin. The paper first discusses the concepts of subbase friction, including defining that it consists of three components - an adhesion, or gluing, component between the concrete pavement and the subbase; a bearing component that is influenced by the surface texture of the subbase; and a shearing component which is induced by the movement of the slab across the subbase. The paper then covers the results of a literature search on the topic of subbase friction, which found, among other facts, that the frictional effects of stabilized subbases have not been adequately pursued until this study, and that, according to one report, the frictional effects of cement stabilized subbases are very large, on the order of 28 psi and higher. Then, experiments on several subbases, in the form of push off tests, are discussed. These experiments were performed on cement stabilized, asphalt stabilized, lime treated clay, flexible, sand-stabilized shell, and untreated clay subbase materials and resulted in frictional restraint - movement graphs. The experimentation found that, on all but the cement stabilized subbases, the maximum frictional restraints ranged between 0.6 psi on an untreated clay subbase to 3.4 psi on a flexible subbase. However, a peak frictional restraint on the cement stabilized subbase could not be found without exceeding the testing equipment's maximum load capacity, and, as a result, it was conservatively estimated that the maximum frictional restraint of the subbbase was 15.4 psi, 4-1/2 times larger than the flexible subbase's maximum frictional restraint. Results and implications from the experiments are then presented in the paper. Discussion will include the observation that, for stabilized subbases, the failure planes resulting from the push-off tests were within the subbases itself, not at the slab-subbase interfaces. From the experimentation, it was also found that slab thickness, or overburden pressure, was not a significant factor in the frictional effects of stabilized subbases, the flexible subbase, and the sand-stabilized shell subbase. Since the 1986 AASHTO Guide for Design of Pavement Structures assumes that slab thickness does affect the frictional properties of all subbases, as shown in its use of coefficients of friction, the Guide should be modified to account for this fact. In addition, results of testing on two asphalt stabilized subbase layers indicated that the subbase's thickness and internal temperature do have substantial effects on the subbase's frictional properties. It was also found that the asphalt stablized subbase's surface texcture does not significantly affect the frictional restraint. Results of using the indirect tensile testing of subbase cores to estimate subbase friction are also presented. The paper concludes with a discussion of how subbase friction could affect design of concrete pavements.

Evolution of Basal Force Fluctuations and Seismic Signals of Granular Flows and Their Proxy: Insights From Laboratory Flume Experiments

AbstractThe forces exerted by geophysical granular flows on Earth's surface, and the resulting seismic signals, can be used to monitor natural geohazards and understand their dynamic evolution and characteristics. Substantial research has focused on linking basal force fluctuations and seismic signals to granular flow dynamics. However, the mechanisms behind the generation and evolution of seismic signals remain incompletely understood. In this study, we conducted laboratory flume experiments to gain insights into the evolution and characteristics of basal force fluctuations and seismic signals and explored their relationship with the macroscopic properties of granular flows. Our results show that the shear and normal components of basal force fluctuations exhibit different behavior during flow evolution, which are related to variations in flow velocity fluctuations. As the granular flow moves downstream, shear basal force fluctuations decrease due to weakening velocity fluctuations, whereas normal force fluctuations increase. Similar to basal force fluctuations, seismic signals follow a generalized Pareto distribution. Basal force fluctuations and seismic signals are strongly nonlinearly related to the bulk flow properties, indicating that thicker, denser and faster flows generate stronger basal force fluctuations and more intense seismic signals. However, particle size significantly influences this relationship. We demonstrate that the inertial number, characterizing the macroscopic rheological properties of granular flows, can unify basal force fluctuations and seismic signals across different particle sizes, exhibiting a negative correlation on the temporal scale. This implies that the macroscopic rheological behavior of granular flows may provide critical insights into the mechanisms of generation and evolution of seismic signals.

Motorcycle Chain-Sprocket Injuries – A Preventable Mishap

Fingertip injuries are common due to their frequent interaction with the environment during exploratory and manipulative activities. Motorcycle chain injuries occur when a hand gets trapped between the chain and sprocket, leading to various injuries ranging from nailbed damage to amputations of single or multiple digits. These injuries often happen during cleaning or repairs and are referred to as sprocket injuries, chain-sprocket injuries, bike chain injuries, or motorcycle chain injuries. Injuries can occur while tensioning the chain, reapplying derailed chains, oiling, and cleaning when the wheels are rotating. There is a noticeable difference in cleaning methods between professionals and the inexperienced. Patients typically present with injuries sustained while cleaning the chain with the engine idling. These injuries are characterized by compression forces, shear, and rotational components, leading to single-level injuries. The presence of cleaning reagents and lubricants on the chain and sprocket at the time of injury often contaminates the wounds, complicating treatment. Chain-sprocket injuries differ from other machine injuries, which typically involve multiple levels of injury. Treatment options depend on the degree of injury and the structures involved, with priorities being to maintain the length of the digits and nail bed. Replantation and revascularization procedures are possible but challenging due to the larger zone of vessel damage. Prevention measures include proper training and awareness, especially for amateurs. Learning and visualizing the correct cleaning techniques from experts can help reduce the incidence of these injuries. An average motorcycle chain cleaning kit is cost-effective, but precautionary measures must be followed to avoid injuries.

Shear capacity model of RC beams based on MCMC approach and reliability analysis

The research question revolves around accurately predicting the shear capacity of RC beams and enhancing the reliability of such prediction models. This study aims to refine the accuracy of the RC beam shear capacity model. To augment the safety margin, the enhanced model underwent further calibration through a reliability analysis. The shear strength models, rooted in Bayesian theory’s Markov Chain Monte Carlo (MCMC) method and the Modified Compressive Field Theory (MCFT), were introduced. A research database was curated from test data of 782 RC beams sets under shear stress. From this database, six mechanism models were juxtaposed with the MCMC models for comparison. To meet the desired reliability indexes ([Formula: see text] = 3.2, 3.7, 4.0) in these models, resistance factors ([Formula: see text]) were incorporated. Both the Monte Carlo and First Order Second Moment (FOSM) methods were employed for the reliability analysis, considering inherent model errors and the probability distribution of primary variables. The effect of different elements on the target reliability index was assessed using a tornado diagram. Findings showed that the refined shear model displayed minimal variance when benchmarked against models from existing literature and national codes, yielding a Vtest/ Vcal ratio close to 1.0. The shear components aligned with established mechanical mechanism. Depending on various operational conditions and load combinations, resistance factors fluctuated from 0.377 to 0.516 in the RC beams without stirrup, while resistance factors fluctuated from 0.479 to 0.621 in the RC beams with stirrup. Key determinants, such as the inherent uncertainty in computing model, the live loads, and the cylinder compression strength, significantly influenced the reliability index.

A shear and elongational decomposition approach of the rate-of-deformation tensor for non-Newtonian flows with mixed kinematics

We propose a novel approach for non-Newtonian viscoelastic steady flows based on a decomposition of the rate-of-deformation tensor which here, in a simplified version, leads to an anisotropic generalised Newtonian fluid-like model with separated treatment of kinematics pertaining to shear and extensional flows. Care is taken to assure that the approach is objective and does not introduce spurious effects due to dependence on a specific reference frame. This is done by separating the rate-of-deformation tensor into shear and elongational components, with the local scalar shear and elongation rates being the second invariant of each tensor separately, and by modifying the method used to separate the rate-of-deformation tensor so that it becomes independent of superimposed rigid rotations, thus satisfying the principle of material indifference. We assess the model with two test cases: planar contraction flow, often employed to evaluate numerical methods or constitutive equations and for which experimentally observed corner vortex enhancement and pressure drop increase are seldom found in numerical simulations; and flow past confined or unconfined cylinders, for which experiments indicate a drag increase due to elasticity and most predictions give a drag decrease. With our anisotropic model, incorporating additional elongational-flow-related terms, large vortices and accentuated pressure drop coefficients can be predicted for the contraction problem and enhanced drag coefficient for the cylinder problems. This is the first work where problems of non-Newtonian fluid mechanics are solved numerically with separation of strain rate into shear and elongational components.

Modeling and mechanism of the mechanical interlocking for the carbon fiber/epoxy interphase

Modeling and mechanism of the mechanical interlocking for the carbon fiber/epoxy interphase

The Lattice Strain Distribution in GexSn1-x Micro-Disks Investigated at the Sub 100-nm Scale

The local lattice distortion in a crystal, the lattice strain, greatly influences the physical mechanisms underlying the operating principles of semiconductor devices. For example, strain is widely used in the bandgap engineering of group IV-based optoelectronic devices to improve their performance. In the case of GeSn-based light emitters, optimization of the lattice strain allowed the demonstration of optically pumped lasing at room temperature [1] and cw operation in an electrically pumped µ-disk laser [2], thanks to its beneficial effect on the "directness" of the bandgap, leading to increased material gain. It is therefore of paramount importance to characterize the strain with high sensitivity and sub-micron spatial resolution.Here we show how scanning X-ray diffraction microscopy, a recently developed model-free method based on synchrotron radiation [3,4], can be used to fully determine the landscape of mechanical deformation and stoichiometry fluctuation in a lithographically fabricated Ge1-xSnx/Ge suspended µ-disk, a structure of the same type as that used to demonstrate the first GeSn laser [5].The full strain tensor of the entire microstructure, including all normal and shear components, is tomographically reconstructed with a lateral resolution of less than 100 nm and a sensitivity to strain variations of the order of 10-4. By comparing the lattice deformation in different sections of the microdisk, we observe a marked difference between the central pillar region in contact with the virtual Ge substrate and the free-standing outer rim where the Ge layer has been removed. Interestingly, although the misfit dislocation network at the GeSn/Ge relaxed heterointerface in the rim region has been removed during the fabrication process, we observe that a "fossilized" footprint of the dislocations is still present in the strain landscape of the layer. We attribute this to stoichiometric fluctuations that we measure in the Ge1-xSnx alloy generated by dislocation-driven strain fields during epitaxial growth, which are unaffected by etching and in turn generate a local strain field.We then exploit the symmetries of both the microdisk and the Ge1-xSnx material system itself. This allows us, for the first time, to calculate maps of the surface normal stress in an alloyed epitaxial thin film, which is traditionally difficult to impossible to disentangle from stoichiometric fluctuations in diffraction-based data, and is a key piece of information to evaluate in epitaxial layer growth.We complement the synchrotron experiments with electron microscopy and dedicated finite element method (FEM) simulations of both elastic and plastic relaxation processes in the model system, finding excellent agreement between experiment and theory. Furthermore, the effects of strain on the band structure are predicted in the light of the measured local variations in strain and composition.[1] A Elbaz, et al. Nature Photon. 14, 375 (2020)[2] L. Siedel et al. Nature, submitted (2024)[3] C. Corley-Wiciak et al. ACS Appl. Mater. & Interfaces 15, 3119 (2023)[4] C. Richter et al. Phys. Rev. Applied 18, 064015 (2022)[5] S Wirths, et al. Nature Photonics 9, 88 (2015)

Permanent deformation and particle crushability of calcareous sands under cyclic traffic-induced loadings through simple shear apparatus

Permanent deformation and particle crushability of calcareous sands under cyclic traffic-induced loadings through simple shear apparatus

Theoretical model for analysis of elastic constants in orthotropic materials considering shear stress

Nowadays, a general theoretical model to describe the mechanical behavior of anisotropic or orthotropic materials is still an open challenge. In this study, we propose a new theoretical model to determine the elastic constants of these materials considering the shear components of the stress tensor. To analyze the consistency of new approach in biaxial stress state on thin films, we used data reported in the literature, based in the $\sin^2 \psi$ technique. For the first time, the shear modulus value equal to $G_{xz} = 0.3 GPa$, for a polycrystalline Au thin film, was calculated, in addition to other elastic constants. Finally, we demonstrate that the new proposal theoretical model considering shear stress can be useful to determine elastic constants in orthotropic materials from experimentally measured data.

Direct calculation of the eddy viscosity operator in turbulent channel flow at Re τ = 180

This study aims to quantify how turbulence in a channel flow mixes momentum in the mean sense. We applied the macroscopic forcing method (Mani & Park, Phys. Rev. Fluids, 2021, 054607) to direct numerical simulation (DNS) of a turbulent channel flow at $Re_\tau =180$ using two different forcing strategies that are designed to separately assess the anisotropy and non-locality of momentum mixing. In the first strategy, the leading term of the Kramers–Moyal expansion of the eddy viscosity is quantified, revealing all 81 tensorial coefficients that essentially characterise the local-limit eddy viscosity. The results indicate the following: (1) the eddy viscosity has significant anisotropy, (2) Reynolds stresses are generated by both the mean strain rate and mean rotation rate tensors associated with the momentum field and (3) the local-limit eddy viscosity generates asymmetric Reynolds stress tensors. In the second strategy, the eddy viscosity is quantified as an integration kernel revealing the non-local influence of the mean momentum gradient at each wall-normal coordinate on all nine components of the Reynolds stresses over the channel width. Our results indicate that while the shear component of the Reynolds stress is reasonably reproduced by the local mean gradients, other components of the Reynolds stress are highly non-local. These results provide an understanding of anisotropy and non-locality requirements for closure modelling of momentum transport in attached wall-bounded turbulent flows.

Characterize the influences of hydraulic fracturing on preventing rock burst from the stress and vibration fields

The thick and hard roof (THR) is a significant factor that induces rock burst incidents. Traditional deep-hole blasting methods struggle to effectively relieve pressure for the high-level THR on a large scale. Although the horizontal staged hydraulic fracturing technology can crack high-level rock stratas, its impact on roof fracture still needs to be clarified, and there need to be more effective methods to evaluate its pressure relief effect. This paper conducted a comparative engineering test of local hydraulic fracturing pressure relief and load reduction on the working face to address this gap. The key layer theory and mine earthquake distribution were used to identify potential hazards of rock strata and the fracturing strata. Revealed the spatial and temporal evolution rules of microseisms induced by mining work, the failure mechanism of high-energy mine earthquakes, the evolution characteristics of source mechanical parameters, and the evolution characteristics of the stope stress field. The results indicate that after fracturing microseisms during mining presented exhibit a uniform distribution of high frequency and low energy. The fracture fragmentation of the roof rock was reduced, and the range of mining disturbance was minimized. High-energy mine earthquakes induced by mining are transferred to the goaf. Simultaneously, the corner frequency and stress decrease while the rupture radius and the shear component of the failure mechanism increase. The integrity of the THR is compromised, and fracture propagates and slips along the pre-crack. The roof of the working face experiences localized pressure, with decreased periodicity and intensity, reducing the overall static load level of the coal seam under the fracturing area. The research findings serve as a valuable reference for further investigations into the mechanism and risk assessment of hydraulic fracturing in preventing and controlling rock burst.

Prediction of shear capacity of RC columns and discussion on shear contribution via the explainable machine learning

Prediction of shear capacity of RC columns and discussion on shear contribution via the explainable machine learning