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Circular saw blades, a large diameter-to-thickness ratio tool, are widely used in the aerospace and transportation sectors. However, it is limited due to its thinning tendency and weak stiffness. In this study, a novel tool tensioning technique was developed using the ultrasonic surface rolling process (USRP) to improve the tool performance of circular saw blades by changing the microstructure and residual stress distribution. Archimedean spiral curve textures were successfully created on both sides of a circular saw blade using an ultrasonic rolling experimental platform. The results show that USRP induced a gradual change in the dislocation structure from a microstrip mixing pattern to a lamellar band structure, accompanied by an increase in high-angle boundaries and a decrease in dislocation cell size. These textures result in a "low–high-low" trend in the radial residual stress distribution along the radius of the circular saw blade, and this residual stress variation improves the tool dynamic performance of the circular saw blade by more than 10% based on real-time x-direction (feed direction) cutting vibrations. In addition, a rolling tensioning evolution mechanism is proposed to explain how the synergistic effect of ultrasonic vibration and rolling force generates the residual stress field. This study elucidates the evolutionary mechanism of USRP-induced tensioning of thin circular saw blades, paving the way for a high-quality, cost-effective tensioning process. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the possibility of predicting the yield curves of sandstones considering only a few key mechanical parameters, and more importantly microstructural properties. Porous rocks are modeled as a set of 2D circular grains subjected to radial and axial stresses that reflect the external forces applied on the material. The contact between individual grains define local planes. The sample is assumed to yield at the inception of nonlinear response on one of these planes, when local stresses reach either shear, tensile, or compressive limit values. A Mohr–Coulomb criterion is considered, with a tensile cutoff and a limitation on the maximum allowable shear stress. The parameters of the developed yield equations are then divided into two groups. The first category relates to the microstructure of the material: porosity, grain radius, intergranular contacts radius, and intensification factor. The second category contains a set of four mechanical properties: the cohesion, the friction angle, the maximum shear, and the compressive limit. While the first set differs from one sandstone to another, the second one is assumed to be the same for all sandstones showing similar mineral compositions. The experimental data for five sandstones, Berea, Boise, Darley Dale, Diemelstadt, and Rothbach, are gathered from the literature. The mechanical parameters are calculated based on Rothbach sandstone experimental data. Satisfactory predictions of the yield limits for the remaining sandstones are obtained from their microstructural characteristics. [ABSTRACT FROM AUTHOR]

Ceramic matrix composites (CMCs) have been widely used in aerospace thermal-structures due to their excellent high-temperature performance. It is essential to understand the damage evolution of CMCs. However, in previous research work, the effect of thermal stress induced damage during CMCs fabrication on tensile response was often ignored. A damage evolution model that considers axial and radial thermal stresses to predict tensile response of unidirectional ceramic matrix composites was proposed in this study. The average relative errors between the current prediction and experimental data in the literature were calculated as 1.64 % and 1.91 %, validating this approach. Meantime, the damage evolution laws of interface debonding and the critical stress of matrix cracking in the Budiansky–Hutchinson–Evans (BHE) model were corrected to satisfy the discontinuous interfacial shear stress. According to the experimental data, the current model predicted critical stresses of matrix cracking better than the BHE model, with error rate reductions of 6.52 % and 15.38 %. [ABSTRACT FROM AUTHOR]

Cold expansion is a mechanical method for creating residual stresses. This method is a proven technique to increase the fatigue life, and checking the residual stress on it, is of particular importance. A cold expansion process is widely used to generate beneficial residual stresses into an annular region around the hole. In the present research work, AA 6016-T6 and AA 1100 aluminum alloys which are two strain rate sensitive materials, were subjected to cold expansion process with different mandrel velocities. In fact, the effect of mandrel velocity on the created residual stresses has been investigated. The constants of the Johnson-Cook material model have been determined for them and the process has been investigated, experimentally and numerically. The obtained results revealed that the values of the residual stresses created in the sheets depend on the velocity of the process especially at the edge of the sheets holes. By increasing the mandrel velocity from 5 to 500 mm/min, depending on the distance from the hole to the edge of the sheet, it is possible to enhance the hoop residual stress by 37.3–41.2% in AA 1100 aluminum alloy and by 37.6–38.1% in AA 6016-T6 aluminum alloy. This research showed that in all cases, the radial residual stresses created around the holes are negative. Also, it was cleared that due to the existence of material constraints and the movement of the sheet material, the amount of hoop residual stress created in the mid-thickness is more than the exit face and in the exit face is also more than the entrance face, exactly unlike the size of their zones. [ABSTRACT FROM AUTHOR]

Critical velocities of a three-layer composite tube subjected to a uniform internal pressure moving at a constant velocity are obtained in closed-form expressions. A Love–Kirchhoff thin shell model including the rotary inertia and material anisotropy effects is used in the formulation. The composite tube is made of three perfectly bonded cylindrical layers of dissimilar materials, each of which can be orthotropic, transversely isotropic, cubic or isotropic. Closed-form formulas for the critical velocities are first derived for the general case by incorporating the effects of material anisotropy, rotary inertia and radial stress. Specific formulas are then obtained for composite tubes without the rotary inertia effect and/or the radial stress effect and with various types of material symmetry for each layer as special cases. It is also shown that the current model for three-layer tubes can be reduced to those for single- and two-layer tubes. To illustrate the newly derived formulas, an example is provided for a composite tube consisting of an isotropic inner layer, an orthotropic core, and an isotropic outer layer. All four critical velocities of the composite tube are computed using the new closed-form formulas. Three values of the lowest critical velocity of the three-layer composite tube are analytically obtained from three sets of the new formulas, which agree well with the value computationally determined by others. [ABSTRACT FROM AUTHOR]

Negative compressibility (NC) refers to the counterintuitive behaviour where a material expands when subjected to compressive stress. In rock mechanics, NC can be linked to failure. During the onset of failure, a slight increase in amplitude of mean compressive stress from axial loading, with constant radial stresses, can lead to dilation due to microcrack growth and grain sliding. Post-peak softening then results in reduced deviator stress as axial compressive strain amplitude increases. This study unveils a novel form of NC in poroelastic materials containing microcracks with liquid bridges, a phenomenon distinct from known failure mechanisms. This new manifestation of NC is associated with changes in the capillary force of the liquid bridge, leading to the NC of a microfracture without failure occurring. To validate the new concept of NC in rocks during elastic deformation, we formulated a theoretical model and conducted laboratory experiments on partially saturated Mancos shale. The experiments involved the simultaneous increase in amplitude of confining (axial and radial) stresses and pore pressure in the gas phase by equal magnitudes. We observed extensional volumetric strains during compression at constant net stress, indicating negative shale stiffness. Using a micromechanical model, we simulated liquid bridge hysteresis in microfractures by coupling the wettability, interfacial tension, and elastic properties of the rock, liquid, and gas phases. Theoretical modelling reveals that capillary forces may dominate over elastic forces under specific conditions defined by two dimensionless parameters. This study enhances our understanding of the static and dynamic response of the overburden at partial saturation with free gas that may contribute to carbon storage and monitoring efforts. Moreover, the concept of negative compressibility and liquid bridge phenomena has potential applications in underground hydrogen and ammonia storage. Understanding microfracture behaviour under varying pressures is crucial for developing safe and efficient storage solutions for these emerging energy carriers. Highlights: Novel finding: Porous materials with microcracks and liquid bridges can exhibit negative compressibility due to capillary force changes. Two dimensionless parameters define conditions when capillary forces dominate over elastic forces, producing negative compressibility. Experiments on partially saturated Mancos shale show negative compressibility during elastic deformation, not linked to failure mechanisms. Significance: Insights gained have implications for carbon storage, subsurface hydrogen and ammonia storage. [ABSTRACT FROM AUTHOR]

Highlights: A relaxation test data set is reinterpreted with a focus on radial strain Specimens loaded below the crack damage stress contracted more than predicted by elasticity theory The rate of lateral contraction increased when the stress had dropped by between 50% and 80% of the total stress relaxation observed at the end of the test One specimen loaded just above crack damage changed from dilation to contraction at the transition from primary to secondary relaxation [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to investigate the thermoelastic interactions in a homogeneous, transversely isotropic infinite medium with a spherical cavity in the context of two temperature Lord-Shulman (2TLS) generalized theory of thermoelasticity considering Eringen's nonlocal theory and memory dependent derivative (MDD). Memory-dependent derivative is found to be better than fractional calculus for reflecting the memory effect which leads us to the current investigation. Design/methodology/approach: The governing field equations of the problem are solved analytically using the eigenvalue approach in the transformed domain of Laplace when the cavity's boundary is being loaded thermomechanically. Using MATLAB software the numerical solution in real space-time domain is obtained by Stehfest method. Findings: Numerical results for the different thermophysical quantities are presented in graphs and the effects of delay time parameter, non-local parameter and two temperature parameters are studied thereafter. The outcomes of this study convince that the displacement u, conductive temperature ϕ, thermodynamic temperature θ are concave upward whereas radial stress τrr is concave downward for every choice of delay time parameter ω, two temperature parameter η and non-local parameter "ζ". As a specific instance of our findings, the conclusions of an equivalent problem involving integer order thermoelasticity theory can be obtained, and the corresponding results of this article can be readily inferred for isotropic materials. Originality/value: The novelty of this research lies in the adoption of generalized thermoelastic theory with memory dependent derivative and Eringen's nonlocality for analyzing the thermoelastic interactions in an infinite body with spherical cavity by employing eigenvalue approach. It has applications to many thermo-dynamical systems. [ABSTRACT FROM AUTHOR]

A new interpretation of failure of frozen clay in tension is presented, through a unique test programme applying 'triaxial tension', in which the axial stress was reduced to negative values while zero or positive radial stress was maintained. The limit strength is determined by a meeting point of two competing mechanisms – strain hardening in shear, and progressively degrading tensile strength as the shear deformation disturbs the soil structure. In some conditions, the limit strength observed in tension is actually given by the shear resistance limit, not by a true tensile strength. This interpretation is successful in explaining apparently unclear confining stress dependency of the observed failure envelopes at low stresses. The influence of the pre-freezing effective stress, post-freezing total stress and pre-freezing pore-water pressure on the strength was also investigated. The tensile strength degradation was formulated by using the specific work input to estimate the operational tensile strength and the strain at which a tensile rupture occurs. Cooling after shear deformation apparently healed the damage and recovered the initial tensile strength, allowing the stress–strain curve to significantly overshoot the proposed tensile strength line. To explain the combined influence of shear and temperature history on the tensile strength–work relationships will require further study. [ABSTRACT FROM AUTHOR]

The potential for pile tip damage and extrusion buckling has become an increasing concern for the offshore wind industry following the trend toward the use of large-diameter thin-walled pile foundations, either as monopiles or as part of a jacket structure. Extrusion buckling may be triggered by an initial pile tip fabrication imperfection or pile damage during transport and handling. It may also be triggered during driving through strong heterogeneous sediments. Numerical analysis of the problem requires advanced and computationally expensive techniques because of the three-dimensional, dynamic and large-deformation nature of the pile and soil deformations. The problem is addressed here by combining coupled Eulerian–Lagrangian simulations with geotechnical centrifuge model test data in dry dense sand. Both approaches consider pre-dented piles with the objective of estimating the soil strength, characterised by the cone resistance, at which minor initial damage will start to propagate. Simplified analysis of structural dent propagation and radial stresses generated in the soil during advance of a deformed pile led to a simple calculation procedure to assess the potential for extrusion buckling. Reasonably good agreement was achieved between the proposed calculation method, numerical simulations and centrifuge tests data, rendering the approach a valuable screening tool for practical application. [ABSTRACT FROM AUTHOR]

Based on experimental data, this study presents a model of the dynamic growth of a thermally grown oxide (TGO) in thermal barrier coatings (TBCs) during thermal cycling. The model was solved using the finite element method. The thermal stress results of the model were compared with experimental results to verify the accuracy of the model. The stress analysis revealed that the combined effect of radial tensile stress and circumferential compressive stress can lead to the delamination of TBCs in a buckling form, which can induce the formation of cracks in TBCs along the axial direction. This observation was consistent with the conclusions drawn from the experimental results. Crack initiation and propagation result from the action of the maximum shear and radial stresses. In addition, the relationship between buckling failure and microscopic cracks was investigated. Thermal cycling induces radial and circumferential cracks, leading to buckling, delamination, and ultimate coating failure as the radial and circumferential cracks interact at the interface. [ABSTRACT FROM AUTHOR]

Considering the energy consumption of the crushed zone caused by blasting, the energy dissipation characteristics were investigated through theoretical calculation and a plug-in for calculation of energy reduction was made. As a result, an improved CDEM method suitable for studying blast-induced crack propagation was proposed. The improved CDEM method was then used to numerically simulate the blast-induced crack propagation under three different in-situ stress conditions: uniaxial in-situ stress, biaxial equal in-situ stresses and biaxial unequal in-situ stresses. It was found that the in-situ stress conditions had significant effects on the distribution of the blast-induced cracks, the evolution of blast-induced stresses and the propagation of the blast-induced cracks. At the uniaxial in-situ stress condition, the vertical in-situ stress reduced the tip stresses of the horizontal crack and inhibited the propagation of the horizontal crack. At the biaxial equal in-situ stress condition, the peak radial stresses and circumferential stresses of the gauging points decreased gradually with the increase of in-situ stresses. In particular, the circumferential stresses of the gauging points gradually changed from tension to compression with an increasing in-situ stress. At the biaxial unequal in-situ stress condition, there were different inhibitions on crack propagation in the horizontal direction and the vertical one. [ABSTRACT FROM AUTHOR]

AbstractA semi-analytical numerical non-stationary creep analysis of constant and variable thickness rotating disks made of polyamide 66 under mechanical and thermal loads is presented using Mendelson’s method of successive approximation. The material properties are time, temperature, and stress-dependent, which vary along the disk’s radius due to effective stress variation and temperature distribution and are represented by Burger’s model. A non-homogeneous differential equation in terms of radial displacement with variable and time-dependent coefficients was established using equilibrium, strain-displacement, and stress-strain relations. First, the initial thermo-elastic stresses at zero time were calculated using the Galerkin method and Hermitian elements. The history of stresses and strains was then calculated using Burger’s viscoelastic model and Prandtl-Reuss relations. To validate the results, an analysis of a disk with constant thickness made of PVDF material was also carried out using the same method employed in this study. Very good agreement of the results was observed in both elastic and creep conditions. Creep analysis was performed for PA66 disks of constant and variable thickness conditions, and the results were compared together. It has been found that the radial displacements and effective stresses are increasing with time for both disks. However, effective stresses and radial displacements of variable-thickness disks are much lower than constant-thickness disks. [ABSTRACT FROM AUTHOR]

The electromagnetic force dynamic installation (DI) method of interference fit fasteners has significant advantages in improving the quality of the assembly interface of composite structure. This study aims to investigate how improving assembly interface quality may help in achieving high‐precision interference‐fit joints in composites. Single‐lap joint specimens were prepared using electromagnetic installation technique, the fatigue life and failure behaviors of the joints under different bolt‐hole clearances were measured and analyzed experimentally. In addition, a three‐dimensional finite element model was developed to predict the radial pre‐compression stresses around the hole and the progressive failure behavior of various typical damage modes in carbon fiber‐reinforced polymer induced by the interference. The results show that the critical interference range for the DI‐composite bolted structure is 1.0%–1.2%. The fatigue life of the best interference (1.0%) and the worst interference (0%, neat fit) have a difference of 36 times in amplitude. The residual stress with uniform distribution and high amplitude reduces the stress concentration of the hole wall and improves the failure evolution of the loaded hole. The contribution of this study provides vital guidance for improving the fatigue performance of CFRP bolted structures using a novel DI method. Highlights: I = 1.0% is the critical damage‐enhancing interference size for dynamically installation interference fit bolts with electromagnetic forces.The residual stress amplitude introduced by the interference does not increase uniformly as the interference size increases. Excessive interference significantly reduces the uniformity and magnitude of residual stresses.Under subsequent cyclic loading, the fifth layer near the inlet and outlet of the extruded lower laminate appears to be the critical ply of extrusion deformation, and severe damage is concentrated in the critical ply of deformation.The decrease of stress amplitude and the variation of mean stress are the mechanisms of fatigue life enhancement in interference fit joints under external cyclic loading. [ABSTRACT FROM AUTHOR]

The mechanical and deformation behaviors of the surrounding rock play a crucial role in the structural safety and stability of tunnel shafts. During drilling and blasting construction, seepage failure and hard brittleness damage of the surrounding rock occur frequently. However, previous discussions on stress deformation in the surrounding rock did not consider these two factors. This paper adopts the theory of elastoplastic to analyze the effects of seepage and hard brittleness damage on the stress and deformation of the surrounding rock of a tunnel shaft. The seepage effect is equivalent to the volumetric force, and a mechanical model of the surrounding rock considering seepage and hard brittleness damage was established. An elastoplastic analytical formula for surrounding rock was derived, and its rationality was verified through numerical examples. Based on these findings, this study revealed the plastic zone as well as stress and deformation laws governing the behavior of surrounding rock. The results showed that the radius of a plastic zone had a significant increase under high geostress conditions, considering the hard brittleness damage characteristics of the surrounding rock. The radius of the plastic zone increased with an increase in the initial water pressure and pore pressure coefficient, and the radius of the plastic zone increased by 5.5% and 3.8% for each 0.2 MPa increase in initial water pressure and 0.2 increase in pore pressure coefficient, respectively. Comparing the significant effects of various factors on the radius of the plastic zone, the effect of support resistance inhibition was the most significant, the effect of the seepage parameter promotion was the second, and the effect of the hard brittleness index promotion was relatively poor. The hard brittleness index and water pressure parameters were positively correlated with the tangential and radial stresses in the surrounding rock, and the radial stresses were overall smaller than the tangential stresses. The deformation of the surrounding rock was twice as large as the initial one when hard brittleness damage and seepage acted together. These findings can provide a reference for the stability evaluation of the surrounding rock in tunnel shafts. [ABSTRACT FROM AUTHOR]

This study investigates the dynamic response of an infinite structure comprising two coaxial cylinders employing the one-relaxation-time generalized thermoelastic diffusion model. The inner cylinder, serving as a cavity, possessing a radius a, while the outer cylinder has radius b. The inner cylinder is insulated and experiencing a localized thermal load with thickness 2 h. The outer cylinder, with radius b, is also experiencing to a localized thermal load with width 2 h, and its surface exhibits no traction. Additionally, the structure experiences the influence of a solenoidal body force. The analysis of this problem employs a combination of Laplace transform, inverse Laplace transform, and exponential Fourier transform techniques. Numerical analysis of the resulting solutions reveals the variations in temperature, displacement, radial stress, concentration, and potential fields as a function of the radial coordinate. Results indicate a minimal impact of the time interval on the temperature distribution, while displacement and radial stress exhibit significant time-dependent behavior. These findings highlight the significance of incorporating thermoelastic diffusion theory in the analysis of real-world engineering problems. [ABSTRACT FROM AUTHOR]

Swelling soft rock (SSR) exhibits obvious characteristics of swelling deformation and damage after being immersed. However, there is no systematic description of the mineral composition and mechanical response after immersion. This study proposed a discrete element modeling and calibration method for SSR based on the X-ray diffraction tests, expansion tests, and uniaxial compression tests in the laboratory. The damage of composite minerals model under continuous immersion time were simulated, and the swelling and strength weakening of SSR after immersion were quantitatively characterized. The results show that the proportion of clay minerals is the main factor that causes the mechanical property decay of rock after immersion. With the increase of immersion time, a large number of radial stress concentration areas and fractures would be formed around the agglomeration locations of swelling clay minerals. The uniaxial compressive strength and elastic modulus decrease exponentially with immersion time. In terms of energy, the boundary energy required for the model to load up to failure and the total strain energy stored are negatively correlated with the immersion time. However, friction dissipation energy is positively correlated with it. The numerical calculation results provide valuable references for studying the meso-mechanical behavior and failure modes of SSR after immersion. [ABSTRACT FROM AUTHOR]

An analytical solution is presented for spherically symmetric growth of a fluid-saturated, poroelastic inhomogeneity inclusion embedded within a compressible elastoplastic matrix. A fluid source at the center causes the inclusion growth. The solution considers full poroelastic coupling of the inclusion pore fluid flow and solid phase deformation while solving for large deformation of the matrix via incremental elastoplasticity with associated flow rule and modified Mohr-Coulomb or Drucker-Prager yield models. Results obtained from the compressible (drained) solution are compared against the previously published solution pertaining to incompressible (undrained) matrix. Drained deformation is found to generally cause larger deviatoric stress, less compressive radial and hoop stresses, as well as faster growth of the plastic region, in the matrix. An example case study shows that compared with the undrained case, the drained matrix reaches the same elastoplastic strain with substantially smaller volume of injected fluid inside the embedded inclusion. The solution may be used as a proxy model of caprock integrity problem in CO2 geo-sequestration applications and further as a rigorous benchmark to verify the related numerical solvers. [ABSTRACT FROM AUTHOR]

Products coated with flexible film can be stored in wound rolls after the winding process. However, if the roll product experiences excessive internal stress, it can lead to various defects in the coated layer. To alleviate the stress within the wound roll, a taper tension profile is utilized to progressively reduce tension as the winding length increases. As a substantial amount of web is wound onto the core, the moment of inertia of the wound roll increases. It has been observed that, as the winding length increases, the tension control performance of the taper tension tends to deteriorate. We propose an advanced taper tension profile to enhance tension control performance and validates the effectiveness of this profile through winding experiments. It was observed that, compared to the parabolic taper tension, maximum tension error could be reduced by approximately 16.1 % throughout the winding process. This reduction in tension error enables the preservation of the radial stress reduction effect of the taper tension, resulting in a 13.3 % decrease in the maximum radial stress compared to the parabolic taper tension. The proposed taper tension profile contributes to a more uniform quality of the coated layer, especially as the maximum winding length is extended. [ABSTRACT FROM AUTHOR]

Tensile strength characterization of brittle materials by means of uniaxial tensile tests is often unfeasible, as most samples form chips during specimen preparation, leading to unacceptable geometric deviations. For this reason, the disc specimens used in Brazilian tests to determine indirect tensile strength are preferred. Despite its influence on the induced stress field and the location of the failure initiation point, the actual stress distribution along the contact is still under debate. In the present work, the complex variable method is used to develop a new analytical formulation based on the simplest possible shear stress distribution along the disc boundary that fulfils elastic equilibrium. Based on this formulation, an integration method is used to obtain the stress field generated inside specimens—elastic discs—that are subjected to distributed shear forces on their contact rims. An application of this method to the Brazilian test case is performed, proving that shear and frictional forces can be considered simultaneously. Furthermore, a mathematical procedure to simultaneously consider radial and shear stress distributions along the loaded boundary is developed to determine any possible stress field for relevant practical applications. The results confirm that shearing significantly increases stress in the vicinity of the contact area, which may explain the wedge failure pattern sometimes observed in real test specimens. Additionally, the proposed formulation guarantees that if failure is initiated in the centre of the specimen, the applied shear stress distribution no longer influences the indirect tensile strength of the material, although it influences the final test output if failure is initiated at any other point along the vertical diameter. [ABSTRACT FROM AUTHOR]

Copyright of Nuclear Safety is the property of Nuclear & Radiation Safety Center and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Structures made of fiber-reinforced polymer (FRP) bars encased in seawater and sea-sand concrete (SSC) have received significant attention in recent years owing to the high corrosion resistance of FRP, and the environmental friendliness and economic advantage of SSC. However, studies on their long-term bonding performance, particularly in cold coastal environments, are limited. This study investigates the feasibility of using polyvinyl alcohol (PVA) fibers to improve the resistance of normal-strength SSCs to seawater freeze–thaw cycles (FTCs). The interlaminar shear, flexural, and tensile properties of bare glass-FRP (GFRP) and basalt-FRP (BFRP) bars and their bond behaviors in the designed SSC with good seawater freeze‒thaw durability were studied. The failure modes and microstructural tests revealed a bonding-deterioration mechanism. The test results revealed that the chloride ions in seawater, SSC-encased alkalinity, and FTCs adversely affected the mechanical properties of the saturated GFRP and BFRP bars. Additionally, the effect of FTCs was greater than that of SSC alkalinity. The deterioration of the BFRP was marginally more severe than that of the GFRP because the corrosion at the basalt fiber–resin interface caused interface and resin cracking, and thereby increased ice expansion during freezing. Seawater FTCs reduced the bond strength and residual bond strength, and increased the corresponding slippages of the SSCs with GFRP and BFRP bars. This is attributed to the degraded resin-rich surface layer of the bar and radial cracking of the cement matrix at the bonding interface. The radial cracking was caused by the hoop and radial stresses generated by the radial expansion of the saturated bar during freezing. These exceeded the tensile strength of the deteriorated concrete after seawater FTCs. The bond degradation of the BFRP–SSC was marginally more severe than that of the GFRP–SSC owing to the larger extent of cracking in the bar and cement matrix. [ABSTRACT FROM AUTHOR]

A dimensionless discrete state-space mathematical model is proposed for stress analysis of an axially-symmetric saturated poroelastic circular plate being loaded by temperature rise of one of the flat faces. Computation of stress by means of this model is free from a need for differentiation. The curves of thermal postbuckling, thermal nonlinear bending, radial stress, circumferential stress and resultant radial force have been achieved by means of six state-space variables and differential quadrature procedure. The effects of loading temperature, boundary conditions, porosity, pore distribution and fluid pore pressure on the thermal post buckling and nonlinear bending phenomena have been investigated. The critical postbuckling thermal load has been determined by means of a numerical algorithm that does not converge to trivial solution because it starts from a relatively great numerical thermal load. Contrary to the governing equation in usual form, the governing equations in state space together with the state equations equalize the number of the governing assembled difference equations and that of the unknowns, and eventually do not require to apply the so-called auxiliary extra boundary conditions at the nodes adjacent to the boundary nodes. As another advantage, in state-spatial viewpoint, there is not any necessity for computing the coefficients of derivatives with order higher than unity. [ABSTRACT FROM AUTHOR]

It is well known that the roughness of a wall plays a crucial role in determining the passive earth pressure that is exerted on a rigid wall. While the effects of positive wall roughness have been extensively studied in the past few decades, the study of passive earth pressure with negative wall friction is rarely found in the literature. This study aims to provide a precise solution for negative friction walls under passive wall conditions. The research is initiated by adopting a radial stress field for the cohesionless backfill and employs the concept of stress self-similarity. The problem is then formulated in a way that a statically admissible stress field be developed throughout an analyzed domain using a two-step numerical framework. The framework involves the successful execution of numerical integration, which leads to the exploration of the statically admissible stress field in cohesionless backfills under negative wall friction. This, in turn, helps to shed light on the mechanism of load transfer in such situations so that reliable design charts and tables be provided for practical uses. The study continues with a soft computing model that leads to more robust and effective designs for earth-retaining structures under various negative wall frictions and sloping backfills. [ABSTRACT FROM AUTHOR]

Modern conditions of mineral deposit development are characterized by more stringent requirements as to the environmental impacts of production and the increased volume of blasting operations near populated areas. The importance of the study is due to the need of developing energy-efficient technologies for crushing rocks, finding safe ways to intensify the coal degassing processes and reducing the intensity of methane inflow into the mined-out space. The Smoothed Particle Hydrodynamics numerical method used in this work allows adequately calculating nonlinear dynamic problems arising during blasting development of mineral deposits, while the use of most other computer modeling methods to solve these problems causes significant computational difficulties. The paper presents the results of a study of the nature of variations in the rock displacement velocity and the stresses and parameters of the radial crack propagation zone from the distance to the charge during blasting operations in monolithic and fractured massifs. [ABSTRACT FROM AUTHOR]

High-voltage cables are the main arteries of urban power supply. Cable accessories are connecting components between different sections of cables or between cables and other electrical equipment. The stress in the cold shrink tube of cable accessories is a key parameter to ensure the stable operation of the power system. This paper attempts to explore a method for measuring the stress in the cold shrink tube of high-voltage cable accessories based on ultrasonic longitudinal wave attenuation. Firstly, a pulse ultrasonic longitudinal wave testing system based on FPGA is designed, where the ultrasonic sensor operates in a single-transmit, single-receive mode with a frequency of 3 MHz, a repetition frequency of 50 Hz, and a data acquisition and transmission frequency of 40 MHz. Then, through experiments and theoretical calculations, the transmission and attenuation characteristics of ultrasonic longitudinal waves in multi-layer elastic media are studied, revealing an exponential relationship between ultrasonic wave attenuation and the thickness of the cold shrink tube. Finally, by establishing a theoretical model of the radial stress of the cold shrink tube, using the thickness of the cold shrink tube as an intermediate variable, an effective measurement of the stress of the cold shrink tube was achieved. [ABSTRACT FROM AUTHOR]

The phenomenon of peripheral rock instability is more common in crushed bedrock roadways, and the fundamental reason for this lies in the significantly different characteristics of its peripheral rock stress field. Taking the newly dug belt inclined shaft of PingDingShan TianAn Coal Co., Ltd. No. 6 Mine as the engineering background, a mechanical model of a broken perimeter rock roadway was established by using classical rock mechanics theory. Stress distribution around the roadway of the broken perimeter rock medium was systematically analyzed, and radial and tangential stress formulas of the broken perimeter rock were deduced. Through the formula calculation, it was deduced that there was a stress drop in the intact surrounding rock outside the disturbed zone, and the radial stress of the intact surrounding rock in its deep part was relatively increased, while the tangential stress was relatively decreased. The existence of crushed surrounding rock increased the minimum principal stress and decreased the maximum principal stress of the unfractured surrounding rock, which proves that a well-maintained disturbed zone can play a lining role. Thus, a "U-shaped steel + inverted arch + bottom arch linkage beam + floor bolt compensation" support program was proposed. This joint support program easily forms a closed support structure, which is more effective in controlling the deformation of tunnel perimeter rock. The support structure can effectively resist the deformation of the surrounding rock and enhance bottom drum resistance. Through numerical simulation, it was concluded that the horizontal displacement of the two gangs was reduced by 70%, and the displacement of the top and bottom plates was reduced by 77% after optimization of the support, which effectively controlled the stability of the broken surrounding rock. [ABSTRACT FROM AUTHOR]

The interaction between the surrounding rock and the support structure in a circular water conveyance tunnel with lining comprises two main aspects: internal and external hydraulic pressures, and the contact load between the post-excavation lining and the surrounding rock. There is currently no reasonable calculation method to consider both factors simultaneously. Therefore, by utilizing the assumption of smooth contact between the surrounding rock and the lining, an analytical model for a circular water conveyance tunnel with lining is developed through the complex function method. Smooth contact indicates continuity of radial contact stress, coordination of radial displacement, and the absence of shear stress transmission. Considering the inner and outer boundary stress conditions of the lining, two sets of undetermined analytical functions are established, corresponding to internal and external water pressure, as well as the contact stress between the surrounding rock and the lining. Ultimately, the stress and displacement components at any point within the surrounding rock and lining can be derived under the conditions outlined in this study. The analytical model elucidates the mechanism of load transfer within the circular water conveyance tunnel with lining, considering the combined effects of internal and external water pressure and excavation loads. Of particular note, it quantifies the restrictive impact of external water pressure on lining hydrofracturing when subjected to high internal water pressure. Additionally, the model offers a theoretical foundation for designing and assessing support structures for use in long-distance water conveyance projects. [ABSTRACT FROM AUTHOR]

Copyright of Coal Geology & Exploration is the property of Xian Research Institute of China Coal Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The most influential effect of installing pressure-grouted micropiles is the increase of the radial stresses in the surrounding soil, which subsequently increases the micropile load capacity. The Increased Ks Approach has been extensively utilized in the literature for simulating this effect within finite element-based software, such as PLAXIS, and has been deemed reasonably suitable. However, this paper aims to outline the principal limitations of this approach and introduce an alternative method—the Cavity Expansion Approach—that can accurately simulate the expansion of micropiles during installation. A case study involving the installation and loading of both single and group micropiles was simulated using FE modelling to assess the efficacy of the proposed method. The findings indicate that the Increased Ks Approach results in an unrealistic stress field around the micropile following installation, with the micropile retaining a straight shape with the drill bit's initial diameter. Conversely, the Cavity Expansion Approach was found to produce reasonable stress fields, characterized by uneven increases in radial and hoop stresses within a confined zone extending up to a distance of 9 Dmp from the micropile. When implemented using prescribed pressures, the Expansion Approach yields tapered micropiles featuring rough, corrugated surfaces. [ABSTRACT FROM AUTHOR]

Epoxy impregnated superconducting coils have better structural integrity and thermal stability. However, for REBa 2 Cu 3 O 7 − δ (REBCO, RE=Rare earth) coils, the mismatch of thermal expansion coefficients between epoxy and REBCO tapes is a serious problem. In this work, the temperature distribution, stress evolution during the cooling process, critical current distribution, and delamination sites inside REBCO coils impregnated using Stycast 2850FT have been studied. We measured the temperature distribution and the hoop strain in the penultimate turn of impregnated coils during the cooling process and analyzed the thermal stress evolution. No damage was observed for coils with the ratio between outer and inner diameter R o / R i < 1.93. The delamination behavior occurred in coils with R o / R i > --> 2.37 , where the coils even exhibited a two-stage delamination. The delamination mechanism of REBCO coils was proposed from three aspects: the mechanical analysis, the critical current degradation, and the microscopic analysis. In this work, we found that the actual delamination behavior may appear earlier than the steady-state temperature, and temperature distribution will push the radial stress peak toward the inner radius of the coil, making the inner turn more susceptible to delamination. Multiple delamination locations were accurately predicted and confirmed. The measured compressive hoop strain first increased from − 4212 μ ε to − 4684 μ ε with the increase in R o / R i and then decreased to − 3835 μ ε obviously due to delamination. This work reveals in detail the delamination mechanism in impregnated REBCO coils, which is of great significance for the development of damage-free coils. [ABSTRACT FROM AUTHOR]

Laboratory model tests were conducted on artificially structured clays using self-developed equipment to better understand the penetration mechanism of jacked piles in structured clays. Two artificially structured clays with the same initial void ratio but different structured strengths, along with one unstructured clay, served as foundation soils for model tests. Cement and salt were selected to simulate the bonding force and macroporous fabric between soil particles in artificially structured clays. The microstructure and mechanical behavior of artificially structured clay samples were analyzed using a scanning electron microscope and a triaxial apparatus. This analysis aimed to evaluate the efficacy of the current method utilized in preparing structured clays and elucidate the evolution mechanism of pile response in structured clays in relation to soil cells. The findings showed that increased confining pressures lead to a more pronounced impact of soil structure on pile jacking force. Unlike the pile shaft, soil structure played a more crucial role in influencing the pile end during jacking, primarily due to the shear-induced structure degradation of clays close to the pile shaft. The axial force and shaft resistance of piles significantly increased with higher cement content. Simultaneously, the mobilization of the increased pile shaft resistance enhanced the nonlinearity in the distribution of axial force along the pile shaft. The pore-water pressure and total radial stress at the pile–soil interface, located 150 mm from the pile toe, experienced respective increases of 1.27 and 1.38 times as the cement content of model soils increased from 0% to 4%. [ABSTRACT FROM AUTHOR]

The reliable anchorage of carbon fiber-reinforced polymer (CFRP) tendons is a critical issue influencing the stable bearing capacity of bridge cables. This study introduces a novel CFRP single-strand extrusion anchoring structure, where the strand is compressed at its end. By integrating this with internal cone filler wrapping, we create a CFRP multi-strand cable composite anchoring system. This innovative design not only minimizes the overall dimensions of the anchoring system but also significantly improves its anchoring efficiency coefficient. An axisymmetric model was developed using ANSYS finite element software. The radial stress distribution and anchorage efficiency coefficient in the anchorage zone of Φ7 CFRP bar and Φ13.6 extrusion die were analyzed with varying parameters, such as chamfering, outer diameter, and length of the extrusion sleeve, and were validated through static load anchorage tests. The results indicate that the highest anchoring efficiency is achieved when four extrusion sleeves with a chamfer angle of 5°, an outer diameter of Φ14.4, and a length of 15 mm are connected in series, reaching a coefficient of 61.04%. Furthermore, this study proposes an anchorage structure where multiple extrusion sleeves are connected in series and sequentially compressed to overcome the limitations of increasing anchorage length for enhancing the anchorage coefficient. The test results demonstrate that with equal total anchorage length, connecting four 15 mm extrusion sleeves in series enhances the anchorage efficiency coefficient by 24.98% compared to a single 60 mm extrusion sleeve structure. [ABSTRACT FROM AUTHOR]

Tunneling in sandy dolomite strata often faces hazards such as collapse, water inrush, and water-sand inrush, seriously threatening the safety of tunnel construction. There are currently limited studies on the mechanical behaviors of sandy dolomite tunnels. In view of this, an analytical solution for tunneling in sandy dolomite strata is derived in this study, and then parametric analysis is performed to analyze the mechanical response of rock mass in sandy dolomite tunnels. The results demonstrate five tunnel sidewall stress scenarios according to the different lateral pressure coefficients (λ). Varying λ values impact stress distribution and tunnel stability, with extreme values posing risks of instability. Tunnel safety is greatly reduced when rock stress approaches the plastic limit. At different internal friction angles, cohesion, and initial rock stresses, radial stress decreases gradually as the radius increases. The stress values under different conditions tend to be similar, while the effects of internal friction angle, cohesion, and initial rock stress on stress in the elastic zone decrease with increasing distance from the center of the tunnel. Under different internal friction angles and cohesion, the plastic zone radius increases with increasing distance from the excavation surface, and a larger internal friction angle and cohesion lead to an increase in stress. The stress and cohesion of a rock mass significantly affect the plastic zone radius, and an increase in tunnel excavation radius also leads to an increase in the radius of plastic zone. These findings provide a reference and insight for similar geotechnical engineering practices in the future. [ABSTRACT FROM AUTHOR]

Energy drives the large deformation of soft rock tunnels, which is a nonlinear mechanical behavior of surrounding rock. This study aims to develop an analytical model for analyzing the energy conversion and absorption processes involved in tunneling. First, an analytical approach is presented for analyzing the energy conversion of the surrounding rock and energy absorption properties of the yielding support system during tunnel excavation. Subsequently, a comprehensive parametric investigation is conducted using the analytical model to investigate the impact of support pressure, tunnel radius, and initial stress on the energy conversion and dissipation of the surrounding rock. Similarly, the effect of support installation time, tunnel radius, and initial stress on the energy absorption properties of the yielding support system is explored. The results reveal that energy is input into the surrounding rock at the outer boundary through radial stress work. A portion of the energy is converted into elastic strain energy of the surrounding rock. Simultaneously, the plastic deformation of the surrounding rock consumes some of the input energy. Subsequently, the remaining energy flows from the excavation boundary as rock pressure work. Installing yielding components in the support system significantly enhances its maximum energy absorption capacity, which may be raised by up to 30 times. Moreover, the earlier the support installation time, the larger the tunnel radius, and the higher the initial stress, the more energy the yielding elements of the support system absorb. Highlights: Proposed an analytical model to characterize energy conversion in large deformation tunnels with yielding support. Quantitatively analyzed the energy conversion and dissipation properties in the surrounding rock. Explored the energy absorption characteristics of yielding support in large deformation tunnels. [ABSTRACT FROM AUTHOR]

The technology of combining a negative Poisson's ratio (NPR) anchor cable with a double-layer truss support technology (N-DTST) is a new support technology for deeply buried tunnels. To evaluate the stability of the surrounding rock support after the application of this new support technology in the Sichuan–Tibet Railway tunnels, geomechanical model tests were conducted for the first time. A model test loading system with intelligent numerical control and automated analysis was developed to reveal the changing patterns of displacement and stress in the surrounding rock of tunnels. The test results revealed the following: (1) After the burial depth exceeds 800 m, the tunnel undergoes large deformations with displacements greater than 37.5 mm, and the traditional anchor cable support fails; (2) In the burial depth range of 800–2,000 m, the new support technology can control the surrounding rock deformation, and the surrounding rock displacement is less than 10 mm; (3) After the tunnel excavation, the radial stress decreases and the tangential stress concentrates. When the burial depth is greater than 800 m, the radial stress compensation provided by the anchor cable no longer meets the stability of the tunnel surrounding rock, and the new support technology can provide high stress to support the deeply buried tunnel; (4) After the burial depth exceeds 2,000 m, butterfly-shaped damage occurs on the tunnel surface, the truss structure inside the tunnel is damaged, and the support structure fails, so it is recommended to carry out reinforcement support at the arch shoulder. The research results verify the effectiveness of the new support technology and provide an important reference for the support of the surrounding rock in deeply buried tunnels. Practical Applications: Common Poisson's ratio anchors/ropes or shotcrete are widely used in tunnels as the core support structure. They often fail to meet the requirements of fractured rock, expansive rock, and high-ground-stress soft rock tunnels because they cannot adapt to the large deformation characteristics of the catastrophic rock mass. Based on this, this paper proposed a new support technology: an anchor rod/rope with a negative Poisson's ratio material combined with a double-layer three-dimensional truss for joint support of the tunnel. To verify the feasibility of this technology, the research and development team developed a new design for the structure. To verify the feasibility of this technology, a large-scale geomechanical model test system was developed, and a comparative model test was conducted using this test system in combination with the ground stress environment of the Sichuan–Tibet Railway to verify the effectiveness of the new support technology proposed in this paper, which provides a reference for the world's deep buried tunnel support technology. [ABSTRACT FROM AUTHOR]

The semi‐underground double‐storey squat silo (SUDSSS) is a new type of silo with the advantages of preserving grain quality. In this paper, a numerical model of SUDSSS was constructed using solid elements. The proposed numerical model was validated by test results of an experimental underground silo, and the results demonstrated that: (1) Before and after backfilling, the radial and circumferential stress of the underground storey reached their maximum at 2/3 from the bottom and 2/3 from the ground surface, respectively; (2) As the height of grain storage increases, the silo wall stress in the overground storey increases. From the top of the underground storey up to 1/4 height of the overground storey, the stress of silo wall increases. (3) For the underground storey, the maximum stress occurs at 1/3 of the way from the apex of bottom cone. Practical applications: The semi‐underground double‐storey squat silo is a new grain storage device proposed by this paper, which consists of two layers. The lower layer is located in the ground and can utilize the shallow ground temperature to realize the green and low‐temperature storage of grain, the upper layer is conducive to the turnover of grain, which can ensure the quality of grain storage. The new silo has the advantages of saving land, energy saving and carbon reduction. Based on the silo, this paper investigates the stress–strain properties of the silo before and after soil backfilling during the construction stage, and obtains the change pattern of the static mechanical properties of the silo. This paper analyses the mechanical properties of semi‐underground double‐storey squat silo under different storage conditions at the grain storage stage, and studies the change patterns of the mechanical properties of the silo body under different storage heights. [ABSTRACT FROM AUTHOR]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rock salt is a potential medium for underground storage of energy resources and radioactive substances due to its physical and mechanical properties, distinguishing it from other rock media. Designing storage facilities that ensure stability, tightness, and safety requires understanding the geomechanical properties of rock salt. Despite numerous research efforts on the behaviour of rock salt mass, many cases still show unfavourable phenomena occurring within it. Therefore, the formulation of strength criteria in a three-dimensional stress state and the prediction of deformation processes significantly impact the functionality of storage in salt caverns. This article presents rock salt's mechanical properties from the Kłodawa salt dome and a statistical analysis of the determined geomechanical data. The analysis is divided into individual mining fields (Fields 1–6). The analysis of numerical parameter values obtained in uniaxial compression tests for rock salt from mining Fields 1–6 indicates an average variation in their strength and deformation properties. Upon comparing the results of Young's modulus (E) with uniaxial compressive strength (UCS), its value was observed with a decrease in uniaxial compressive strength (E = 4.19968·UCS2, R-square = −0.61). The tensile strength of rock salt from mining Fields 1–6 also exhibits moderate variability. An increasing trend in tensile strength was observed with increased bulk density (σt = 0.0027697·ρ − 4.5892, r = 0.60). However, the results of triaxial tests indicated that within the entire range of normal stresses, the process of increasing maximum shear stresses occurs linearly ((σ1 − σ3)/2 = ((σ1 + σ3)/2)·0.610676 + 2.28335, r = 0.92). A linear relationship was also obtained for failure stresses as a function of radial stresses (σ1 = σ3·2.51861 + 32.9488, r = 0.73). Based on the results, the most homogeneous rock salt was from Field 2 and Field 6, while the most variable rock salt was from Field 3. [ABSTRACT FROM AUTHOR]

The study uses FEM to analyze the creep behavior of a rotating FGM disc made of Al-SiCp. The disc thickness and SiCp reinforcement in the disc are assumed to vary according to the exponential functions of the disc radius. The yielding and creep behavior of the disc material are described by Tresca's criterion and threshold stress-based law, respectively. The disc is assumed to rotate at constant angular velocity under free-free boundary conditions. The disc domain is discretized radially using 3-noded one-dimensional elements with quadratic shape functions. Galerkin's approach has been used to derive the expressions for stresses and strain rates in the disc. For numerical computation of the creep results, a MATLAB code has been developed corresponding to the FE formulation. The creep results estimated using the FE approach are noticed to be in excellent agreement with those obtained using the analytical technique (continuum mechanics approach), experiment results, and commercial FE software. The study reveals that with the increase in SiCp gradient in the disc, the elastic as well as creep components of the tangential stress (near the inner radius) and the radial stress increase significantly, though the tangential stress exhibits a sizable decrease toward the outer radius. The increase in SiCp gradient results in a significant reduction in the steady-state radial and tangential strain rates in the disc, besides resulting in a relatively more uniform distribution of the strain rates, which is desirable for reducing distortion in the disc. The study indicates that the rupture time of the FGM disc could be enhanced significantly by employing a steeper SiCp gradient in the rotating disc. [ABSTRACT FROM AUTHOR]

Previous studies found that the strengthening mechanism of piles in composite foundation is related to the cross sectional shape of piles. However, the mechanism of plum blossom cast-in-place pile (plum blossom pile), as a novel kind of pile, strengthening mechanism is still unclear. In the present study, based on the transparent soil model test technique and Coupled Eulerian–Lagrangian (CEL) approach, single pile penetration tests were conducted. The load-vertical displacement characteristics of composite foundation and the variation of soil around piles are analyzed, and compared with circular piles with same cross sectional area. The results show that the ultimate bearing capacity of plum blossom pile is 1.45 times that of circular pile with the same cross sectional area. The compaction transition zone is observed in the soil around the plum blossom pile during the penetration process, and the radial distance of the compaction transition zone around the plum blossom pile is about 1.5 times that of the circular pile with the same cross sectional area. With the help of geotechnical engineering infinite element software Abaqus/Explicit, the variation of the mean pressure, radial stress and vertical stress of the soil around the plum blossom pile, and the evolution of the compaction transition zone and stress of soil around the pile are analyzed. With the penetration of plum blossom pile, the compaction transition zone at the pile side gradually increases, and the load can be transferred to a wider range in the composite foundation through the pile side compacting the soil around the pile. The research results can provide technical guidance for the design of the plum blossom pile composite foundation. [ABSTRACT FROM AUTHOR]

The interior of a high-voltage cable causes a state of extrusion due to thermomechanical effects; the resulting stress and deformation can easily lead to the destruction of the cable structure. Aiming at the problem, we establish an electromagnetic–thermal–force field model of a high voltage cable. By considering the influence of temperature on the material properties, a bidirectional couple simulation of electromagnetic and thermal fields is established. The thermal load excitation is introduced into the structural field, and the simulation calculation of thermal strain and thermal stress of the axial and radial layers is realized. The influence of ambient temperature, load current, and circulating current defect factors on the thermal–force characteristics of each layer of the cable is studied. The results show that the response of the insulating layer to the thermomechanical effect is the most significant, and its characteristic change law shows the nonlinear trend. In addition, the thermal strain of the cable has an approximate axial symmetry; the axial thermomechanical effect is significantly higher than the radial direction. The maximum axial and radial deformations of the cable when running at full load are 1.21 and 0.16 mm respectively. Among the three influencing factors, the impact of circulating current defects on the thermomechanical effect of cables is the most obvious. The thermomechanical effect of the cable approximately is positively related to the square of the circulating current defect factors, the load current, and the ambient temperature. [ABSTRACT FROM AUTHOR]

Background The distribution of subchondral bone density in a joint represents stress that is applied to the joint. Knowing this information is important for understanding the pathophysiology of osteoarthritis (OA). In the elbow, however, this has not been studied before. Questions/purposes (1) Is advanced-stage elbow OA associated with more radially distributed subchondral bone density than earlier stages? (2) What demographic (age and sex) and radiographic (osteophyte location and carrying angle) factors are associated with increased radial shift in subchondral bone density? Methods Between March 2001 and December 2021, we treated 301 patients for elbow OA. We considered patients with plain radiographs and conventional CT scans as potentially eligible. Thus, 68% (206 patients) were eligible; a further 27%(80 patients)were excluded because of a history of any injury or surgery or known inflammatory joint disease, leaving 42% (126 patients) for analysis here. Their mean 6 standard deviation age was 60 6 10 years. Early OA with minimal joint space narrowing and osteophyte formation was found in 33% (42 of 126) of patients, and advanced OA was found in the remaining 67% (84 of 126). Three-dimensional distal humerus subchondral bonemodels were derived from CT images, and in the central intraarticulating portion, we measured the subchondral bone density in two different sites: where it articulates with the radius (SBDrad) and with the ulna (SBDulna). We further defined the SBDratio as the percent ratio of SBDrad to SBDulna. We also evaluated osteophyte severity based on its size at the radiocapitellar and ulnotrochlear joints, and alignment through measuring the carrying angle on radiographs. To assess interobserver reliability, two orthopaedic surgeons took measurements independently from each other. All measurements had excellent intraoberver and interobserver reliabilities. Then, we compared the subchondral bone parameters between early and advanced OA and performed a multivariable analysis of the factors associated with subchondral bone parameters, including age, sex, osteophyte location, and carrying angle. Results Radial versus ulna subchondral bone density (SBDratio) was modestly higher in patients with advanced OA (118% 617%) than in patients with early OA (109%6 17%, mean difference 9% [95% CI 2.3% to 15.3%]; p = 0.01). With increasing radial deviation in subchondral bone density, cubitus valgus had amodest association (b = 0.466 0.23; p = 0.04) and severe osteophytes at the radiocapitellar joint had a large association (± = 9.51 6 3.06; p = 0.002). Conclusion According to subchondral bone density distribution, stress concentration was more radially deviated in patients with the advanced stages of elbow OA than in those with the early stages. We also found that an increase in carrying angle is associated with radial deviation of stress. Afuture study that examines longitudinal changes in the subchondral bone density might be required to confirm changes in stress concentration with OA progression. Clinical Relevance This study gives us insight into the potential pathophysiology of elbow OA in relation to elbow alignment. Although debridement of osteophytes in the ulnotrochlear joint is the most frequently performed procedure in patients with advanced elbow OA, our finding suggests that some patients with an increased carrying angle might benefit from management of the radiocapitellar joint as well, or from being informed of the future development of OA in the radiocapitellar joint, because stress at this site can be increased with the advancement of OA. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai Jiao Tong University (1006-2467) is the property of Journal of Shanghai Jiao Tong University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Steel structures with light weight, high rigidity, and easy assembly have become the first choice for large-span complex building materials. At the same time, transparent materials are widely used for the sake of practicality and aesthetics. However, steel structures will be deformed due to changes in temperature, which will affect the accuracy of closure. The components are restricted from free deformation as a result of multiple statically indeterminate structures. A safety hazard will occur if the residual temperature stress is not released. At present, the strain law of open-air steel structures caused by temperature change is still unclear, and the corresponding temperature–strain model has not been established. This paper is based on the third-phase reconstruction and expansion project of Taiyuan Wusu Airport in Xiaodian District, Taiyuan City, Shanxi Province (37°45′ N, 112°38′ E, average altitude of 774 m), winter long time series temperature measured data, deduced daily temperature change laws, and the established relationship model between air temperature and steel surface temperature. Based on the measured data of long-term stress and strain in winter, the strain law of open-air steel columns under temperature change is discussed. According to the results, the air temperature can be utilized to determine the strain of the open-air steel column during winter. The determination coefficient of the temperature–stress model can reach 0.868, and the radial bending stress caused by the change in daily temperature cannot be ignored, accounting for 15.7% of the radial stress at the same time, which can provide a reference for stress calculations of similar structures. [ABSTRACT FROM AUTHOR]

The carbon/glass hybrid rod exhibits high tensile strength, light weight, and strong corrosion resistance. However, the bottleneck of interlayer splitting exists in the interlayer hybrid rod, severely impeding safe operation. To solve the problem of rod splitting, this paper proposed a new scheme of an intralayer carbon/glass hybrid rod. Based on the material constitutive model, a full‐scale simulation model was developed. The stress distribution and deformation of the hybrid rod were analyzed and the progressive damage mechanism of the hybrid rod was explained. The results indicated that, for the intralayer carbon/glass hybrid rod, (a) the ultimate experimental tensile load witnessed a significant increase, rising by 14.0% from 452.4 to 515.7 kN compared to the interlayer hybrid rod; (b) the numerical model predicted the tensile load of 525.9 kN, with an error of 1.9% compared to the test result, meeting engineering accuracy requirements; (c) the elastic deformation stage saw a 146.7% increase from 280.2 to 691.3 MPa in the maximum axial stress of the carbon‐fiber layer, and a 120% increase from 89.8 to 198.0 MPa in the maximum radial stress of the glass fiber layer as the tensile displacement increased from 0.16 to 0.32 mm. In conclusion, the intralayer carbon/glass hybrid rod proposed in this paper can significantly improve the tensile strength compared to the interlayer hybrid rod, which can accelerate the application of carbon/glass hybrid rods in oil and gas fields. Highlights: According to the problem of interlayer splitting in the interlayer carbon/glass hybrid rods, a novel scheme of an intralayer carbon/glass hybrid rod was proposed.Based on the material constitutive model, a full‐scale simulation model of an intralayer carbon/glass hybrid rod was developed to analyze the stress distribution and deformation response under tensile load.The dynamic progressive damage analysis method for intralayer carbon/glass hybrid rods was proposed to reveal the damage evolution mechanism. [ABSTRACT FROM AUTHOR]

This article uses polydimethylsiloxane (PDMS) to package an improved fiber Bragg grating (FBG) temperature sensor. Unlike the structure of PDMS completely enveloping fiber gratings, we utilize microfluidic processing technology to construct a microchannel with a diameter of 150 μm in the area of the fiber gratings. It eliminates the thermal stress on the fiber grating in the radial direction. Through the force analysis of the fiber gratings in the packaged sensor, it can be found that eliminating the radial thermal stress is conducive to improving the axial coefficient of thermal expansion of the fiber gratings. The temperature sensing characteristics of this structure are verified by simulation and experiment. Both theoretical and experimental results have shown that this structure can effectively improve the temperature sensitivity of the sensor. In the experiment, the temperature sensitivity of the packaged sensor is 3.5 times higher than that of the standard fiber gratings. The temperature sensitivity of the sensor is 37.6 pm/°C. It is simple to manufacture, does not pollute the environment, and can accurately monitor the temperature of the complex environment. Therefore, it is an ideal model for temperature monitoring in complex environments such as the ocean and mine. [ABSTRACT FROM AUTHOR]

The quantitative prediction and control of assembly stress are crucial for the accuracy of precision optical instruments during their manufacturing process. As a typical optical component, the multipoint bonded flat lens is widely used in precision optical instruments, in which the main assembly stress (i.e., radial adhesive stress) and its induced nonuniform stress field in the lens vary with environmental parameters and time. These factors ultimately determine the accuracy and stability of such precision instruments. Effective prediction of the radial adhesive stress is important for bonding parameter optimization and accuracy enhancement but remains difficult to obtain due to the lack of direct measurement devices and effective prediction methods. Here, a novel prediction method is presented to estimate the radial adhesive stress applied on a multipoint bonded flat lenses. First, a quantitative characterization method (QCM) is developed to concisely describe the nonuniform stress field in a lens using quantitative characterization parameters (QCPs). Then, based on the QCM and the theoretical model established in our previous work (Xiong et al., 2022), a prediction method is developed for the radial adhesive stress applied on a lens by analyzing the stress field in the lens. In this method, a backpropagation neural network is constructed to obtain the mapping relationship between the key QCPs of the stress field and the radial adhesive stress applied on the lens. Finally, an experimental verification of the prediction method is carried out. This paper proposes a novel method to predict the radial adhesive stress for multipoint bonded optical lenses, which can be adopted to monitor the variation characteristics of assembly stress in optical instruments during the entire life cycle and then further employed to optimize the bonding parameters during the lens manufacturing process. This paper attempts to construct a direct mapping relationship between assembly quality and assembly parameters for precision instruments, supporting the quantitative optimization of assembly parameters and quantitative control and prediction of assembly quality during the manufacturing and working process. [Display omitted] • A quantitative characterization method to describe the stress field in a lens is proposed. • Quantitative features of the stress field in multipoint bonded lenses are revealed. • The radial adhesive stress is predicted by analyzing the stress field in the lens. • A mapping relationship between assembly quality and assembly parameter is constructed. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive investigation of the swelling behaviour of a compacted bentonite–sand mixture subjected to hydration under constant volume conditions. Contrary to previous studies, the tested sample was isotropically compacted before being hydrated under constant volume conditions until full saturation was reached. The total axial pressure, total radial pressures at four different heights of the sample, and injected water volume were recorded over time. The experimental data reveal a complex and non-uniform evolution of the axial and radial stresses over time, as well as anisotropy of the total stresses, which persist at the saturated equilibrated state. To gain further insights, a numerical analysis was performed using an advanced hydromechanical framework for partially saturated porous media, accounting for the evolving microstructure of the material. The complex evolution of the total axial and radial pressures with time is attributed to the advancing hydration and swelling front in the sample, along with the development of irreversible strains. The good agreement between the numerical results and the experimental data enables validation of the developed framework. Implications for engineered barriers in deep geological disposal of radioactive waste are discussed. Highlights: The swelling behaviour of an isotropically compacted bentonite-based material under constant-volume conditions is investigated. Hydration of the sample generates stress heterogeneity and anisotropy, which persist at the saturated equilibrated state. Numerical modelling shows that the complex evolution of the total axial and radial pressures can be attributed to the advancing hydration and swelling front in the sample, along with the development of irreversible strains. The relationship between the local dry density and the radial stress seems to follow the global dry density-swelling pressure trend determined on small-scale samples. [ABSTRACT FROM AUTHOR]

A series of small-scale 1 g model tests were conducted using a self-designed pile driving loading model test system to investigate the effect of relative density and cross-section geometry on the development of soil stress around the pile during the penetration of X-section Cast-in-place Concrete (XCC) pile in sand. It is found that the variations of the radial stress Δσ'r/σ'v0 in the surrounding soil presented a significant "h/R effect" during the penetration of the XCC pile, indicating that the "h/R effect", which was found for circular pile during the penetration of piles, was also observed for the XCC pile. The radial stress distribution along the axial direction of the pile could be divided into three zones, i.e., the pile body region, the pile tip region, and the soil region below the pile tip. The development trend of the radial stress along with soil depth is different in each region. Additionally, the peaks of the radial stresses in the pile tip region were very sensitive to the variations of the relative density of the surrounding soils and the cross-section geometry of the piles, which increased significantly with increasing the relative density and cross-section geometry. The radial stresses Δσ'r/σ'v0 decreased exponentially as the radial distance r/R increased. The decay rates decreased with increasing the relative densities of the surrounding soils, while increased with decreasing the cross-section geometry parameter of the piles. [ABSTRACT FROM AUTHOR]