Deformation Of Layer Research Articles

Influence of the Composition of Asphalt Granular Concrete Mixture on the Deformation of the Coating Layer During the Construction of the Road Pavement

Statement of the problem. The introduction of cement into the composition of the bitumen emulsion at the stage of preparation affects not only the strength of the layer, but also the properties of the asphalt granular concrete mixture, which must be taken into account when developing technological processes for compaction. Under the action of the compacting load, taking into account the content of cement in the binder material, the deformability and rigidity of the compacted layer change. The change in the rigidity of the layer affects the choice of parameters of compacting machines. Therefore, whiledeveloping a pavement technology using asphalt-granular concrete mixes using combined binders, it is necessary to establish the effect of cement content on the deformability and rigidity of the compacted layer. Results. The results on the influence of the cement content in the combined binder in the asphalt-granular concrete mix on the deformability of the layer under the action of the compacting load are presented. Dependences were obtained to determine the residual deformation and rigidity of the mix layer under the action of a load, taking into account the layer thickness and cement content. Conclusions. The use of a combined binder (bitumen emulsion and cement), depending on the cement content, leads to a decrease in the deformability of the layer of asphalt granular concrete mixture up to 40 %, regardless of the size of the granulate fractions and the thickness of the layer during laying, as well as an increase in the rigidity of the layer from 1.8 to 2.1 times, which must be taken into account when choosing the parameters of the rollers in the compaction process.

Effects of Inhomogeneous Gas Diffusion Layer Properties on the Transportation Phenomenon and Performances of Proton-Exchange Membrane Fuel Cells.

The encapsulation of the proton-exchange membrane fuel cell (PEMFC) is an essential step of fuel cell stack assembly. The selection of the assembly pressure is very important to the stack performance and life. Based on that, this paper presents a method to describe the internal physical deformation of the gas diffusion layer (GDL) after inhomogeneous pressure by using user-defined functions (UDFs). The results show that the transmission difference caused by the nonuniform GDL deformation can be clearly seen by the UDFs method, and there is an obvious transition of GDL at the interface of the channel and the rib. A three-dimensional single-channel PEMFC model is established, and an optimal assembly pressure range is obtained, between 1.5 and 2.0 MPa. The maximum thermal stress inside the cell occurs in the middle of the membrane electrode assembly and decreases as the assembly pressure increases. Furthermore, the influence of rib-channel ratios is discussed. Compared to the fuel cells with ratios of 2:1, 2:3, and 1:2, the one with 1:1 exhibits the maximum current density and the highest power density.

Experimental Study on Surface Microscopic Characteristics of scCO2-MQL Milled γ-TiAl Alloy

γ-TiAl alloy has high specific strength and excellent low-temperature resistance, but its cutting performance is poor. In this study, the four aspects of residual stress, plastic deformation, surface phase transformation, and work hardening were analyzed via experiments involving supercritical carbon dioxide minimum quantity lubrication (scCO2-MQL) and dry milling of γ-TiAl alloy. The results show that the residual stresses generated during the milling process can be significantly improved under the scCO2-MQL condition and correspondingly reduced in depth from the surface, while the plastic deformation layer is significantly reduced, and the maximum reduction of β-phase volume fraction is 12.43% under the scCO2-MQL condition compared with the dry cutting condition. With increasing cutting speed in the range of 30–90 m/min, the depth of the hardened layer gradually decreased, while increasing the feed rate caused increased microhardness.

Study on dynamic response of cushion layer-reinforced concrete slab under rockfall impact based on smoothed particle hydrodynamics and finite-element method coupling

Abstract In the rockfall prevention and control project, the reinforced concrete (RC) slab and sand (gravel soil) soil cushion layer are commonly used to form the protection structure, thereby resisting the rockfall impact. Considering that the oversized deformation of the cushion layer under impact load using the finite element simulation cannot converge, this article establishes a numerical calculation model using smoothed particle hydrodynamics–finite-element method coupling (SPH–FEM). First, the standard Lagrange finite-element mesh is established for the whole model using ABAQUS, and then the finite-element mesh of the soil cushion layer is converted to SPH particle at the initial moment of the calculation, and finally the calculation results are solved and outputted. The results indicate that, compared with the results of the outdoor rockfall impact test, the relative errors of the rockfall impact force and the displacement of the RC slab are within 10%, which proves the rationality of the coupling algorithm; moreover, in terms of the numerical simulation, the SPH–FEM coupling algorithm is more practical than the finite element for reproducing the mobility of the rockfall impacting the sand and soil particles. In addition, at an impact speed of less than 12 m·s−1, the cushion layer is able to absorb more than 85% of the impact energy, which effectively ensures that the RC slab is in an elastic working state under small impact energy and does not undergo destructive damage under large impact energy; the peak impact force of the rockfall is approximately linear with the velocity, and the simulated value of the peak impact force is basically the same as that of the theoretical value of Hertz theory; the numerical simulation is good for reproducing the damage process of the RC slab in accordance with the actual situation. The SPH–FEM coupling algorithm is more justified than the FEM in simulating the large deformation problem, and it can provide a new calculation method for the design and calculation of the rockfall protection structure.

Improvement in Fatigue Strength of Chromium–Nickel Austenitic Stainless Steels via Diamond Burnishing and Subsequent Low-Temperature Gas Nitriding

Chromium–nickel austenitic stainless steels are widely used due to their high corrosion resistance, good weldability and deformability. To some extent, their application is limited by their mechanical characteristics. As a result of their austenitic structure, increasing the static and dynamic strength of the components can be achieved by surface cold work. Due to the tendency of these steels to undergo intercrystalline corrosion, another approach to improving their mechanical characteristics is the use of low-temperature thermo-chemical diffusion processes. This article proposes a new combined process based on sequentially applied diamond burnishing (DB) and low-temperature gas nitriding (LTGN) to optimally improve the fatigue strength of 304 steel. The essence of the proposed approach is to combine the advantages of the two processes (DB and LTGN) to create a zone of residual compressive stresses in the surface and subsurface layers—the enormous surface residual stresses (axial and hoop) introduced by LTGN, with the significant depth of the compressive zone characteristic of static surface cold working processes. DB (both smoothing and single-pass hardening), in combination with LTGN, achieves a fatigue limit of 600 MPa, an improvement of 36.4% compared to untreated specimens. Individually, smoothing DB, single-pass DB and LTGN achieve 540 MPa, 580 MPa and 580 MPa, respectively. It was found that as the degree of plastic deformation of the surface layer introduced by DB increases, the content of the S-phase in the nitrogen-rich layer formed by LTGN decreases, with a resultant increased content of the ε-phase and a new (also hard) phase: stabilized nitrogen-bearing martensite.

Influence of thickness on porous lining when the inclined channel walls are bounded by a deformable porous layer

This paper deals with the viscous fluid flow in an inclined channel bounded by a deformable porous layer. The coupled phenomenon of fluid movement and solid deformation in the porous layer was considered. The governing equations were obtained for the fluid velocity, solid displacement and temperature distribution in the deformable porous medium. Analytical solutions were obtained for solid displacement, fluid velocity, velocity in the free flow region and temperature distributions. The results were analysed for different physical parameters using graphs. The results revealed that the effect of the thickness of the porous layer was significant on solid displacement and fluid velocity. The solid displacement decreased by increasing the volume fraction of the fluid and the thickness of the porous layer. Since the drag coefficient was the ratio of fluid viscosity to the permeability of the porous material, it follows that the enhancement in drag reduces the permeability of the bounding porous layer. The flow in the blood vessels (capillaries) is surrounded by a tissue layer which is modelled as a deformable porous medium.

Seismic performance of soft rock tunnel under composite support conditions

In order to effectively improve the seismic and impact resistance performance of soft rock tunnels, a composite support method was proposed and validated in the paper. The UDEC (Universal Distinct Element Code) model of soft rock layers was established, and the movement and subsidence characteristics of the roof and floor of the rock layers under impact loads was simulated and calculated. As a result, a composite support scheme with good cushioning performance was proposed. The top and sides of the tunnel were supported by a combination of anchor rods of different lengths and metal mesh, reinforced by steel beams and vibration absorbing filler around. The anchor rod was designed as a segmented loading structure, and can be set to different preloading forces based on the internal deformation of the rock layer. The dynamic response testing scheme was designed, and the results indicate that the segmented loading anchor rod has a significant buffering effect on the response to impact load, and can provide reasonable tension feedback at different stages. Research has found that when the water cement ratio is 0.5-1.5, the curing efficiency and strength are both higher. In order to compare the seismic performance of composite support and traditional constant resistance anchor rod support, local blasting experiments were conducted. Based on a blasting vibration tester, a data detection and transmission system were designed to obtain the vibration speed of the tunnel roof during the vibration process. The research results show that composite support can reduce the maximum vibration by more than 40 %, stabilize the fragmentation coefficient at 1.38, and have a very significant vibration reduction effect.

A wearable three-axis force sensor based on deep learning technology for plantar measurement

A challenge in the measurement of plantar shear stress measurement is the absence of wearable and comfortable monitoring devices. In this paper, a wearable three-axis force sensor based on end-to-end deep learning technology is developed for plantar shear stress monitoring. The sensor can convert the three-axis stress it experiences into image signals through the deformation of the pattern layer embedded in the elastomeric probe. These images and three-axis stresses are fed into a convolution neural network for training, establishing a mapping relationship between images and three-axis forces. The prepared sensor has the advantages of small size (1.62 cm3), light weight (1.68 g), and flexibility, which make it possible to form a sensor array in the shoe without affecting the comfort of the wearer. By synchronizing with an action camera, the sensor array can provide real-time three-axis stress in different plantar regions for each frame of motions such as walking, running, playing football or basketball. This work contributes to the advancement of gait analysis, the clinical diagnosis of foot diseases, and the evaluation of athletic training.

Modeling extrusion process and layer deformation in 3D concrete printing via smoothed particle hydrodynamics

We developed a computational framework to simulate the intricate processes of extrusion and layer deformation in 3D concrete printing (3DCP). A novel two-dimensional (2D) virtual printing scheme is proposed that enables direct prediction of cross-sectional shape, releasing simulations from the constraint of rectangular nozzles inherent in traditional 2D models. The proposed scheme accurately captures significant lateral deformation, previously ignored by conventional 2D models. It is noteworthy that, for the first time, the effect of time-dependent yield stress on layer deformation is considered by introducing the structuration rate. Further, to leverage advantages in avoiding mesh generation and additional interface tracking, a weakly compressible smoothed particle hydrodynamics (SPH) method incorporating the regularized Bingham model is equipped in the proposed framework. The simulated cross-sectional shapes exhibit excellent consistency with experimental results and outperform existing numerical results across various nozzle heights, printing velocities, and extrusion velocities. Our exploration of rheological parameters reveals that the final layer deformation is influenced by the yield stress, while its deformation rate is affected by the plastic viscosity. The proposed virtual printing framework emerges as a promising tool for enhancing predictability and efficiency in the printing process.

Tree-Level Chinese Fir Detection Using UAV RGB Imagery and YOLO-DCAM

Achieving the accurate and efficient monitoring of forests at the tree level can provide detailed information for precise and scientific forest management. However, the detection of individual trees under planted forests characterized by dense distribution, serious overlap, and complicated background information is still a challenge. A new deep learning network, YOLO-DCAM, has been developed to effectively promote individual tree detection amidst complex scenes. The YOLO-DCAM is constructed by leveraging the YOLOv5 network as the basis and further enhancing the network’s capability of extracting features by reasonably incorporating deformable convolutional layers into the backbone. Additionally, an efficient multi-scale attention module is integrated into the neck to enable the network to prioritize the tree crown features and reduce the interference of background information. The combination of these two modules can greatly enhance detection performance. The YOLO-DCAM achieved an impressive performance for the detection of Chinese fir instances within a comprehensive dataset comprising 978 images across four typical planted forest scenes, with model evaluation metrics of precision (96.1%), recall (93.0%), F1-score (94.5%), and AP@0.5 (97.3%), respectively. The comparative test showed that YOLO-DCAM has a good balance between model accuracy and efficiency compared with YOLOv5 and advanced detection models. Specifically, the precision increased by 2.6%, recall increased by 1.6%, F1-score increased by 2.1%, and AP@0.5 increased by 1.4% compared to YOLOv5. Across three supplementary plots, YOLO-DCAM consistently demonstrates strong robustness. These results illustrate the effectiveness of YOLO-DCAM for detecting individual trees in complex plantation environments. This study can serve as a reference for utilizing UAV-based RGB imagery to precisely detect individual trees, offering valuable implications for forest practical applications.

The friction-induced microstructures changes of 18Cr-8Ni austenitic stainless steels with different grain sizes

Abstract The friction and wear performance, wear morphology and friction-induced subsurface microstructural characteristics of 18Cr-8Ni austenitic stainless steels with coarse-grained (CG), heterogeneous ultrafine-grained (HUFG), and nano/ultrafine-grained (NG/UFG) microstructures after dry sliding wear under room temperature were studied. The results reveal that HUFG steel with a good match between hardness and plasticity exhibits the best wear performance, followed by CG steel, while NG/UFG steel with the highest hardness exhibits the poorest wear performance. From the element distribution map, the contents of O and Si in the delamination and wear debris are relatively high. O is relatively evenly distributed on the whole wear surface of HUFG steel, and there is a continuous oxide layer on its wear surface. After the wear test, the hardness increment near the wear surface of the CG sample is the largest, and the depth affected by sliding is the largest, followed by the HUFG sample, and those of the NG/UFG steel are the smallest. The repeated frictional shear stress causes the formation of cracks between the mechanical mixed layer and the plastic deformation layer, and the continuous expansion of cracks can help oxygen elements diffuse deeply, causing the deformation layer materials to fall off.

Graphite nucleation on (Al, Si, Mg)-nitrides: Elucidating the chemical interactions and turbostratic structures in spheroidal graphite cast irons

The ubiquitous (Al,Si,Mg)-nitride has been the focus of recent investigations of spheroidal graphite irons. In particular, because they have been systematically found in the nucleus of graphite spheroids. Despite having a similar crystal structure as graphite, their lattice parameter is vastly different. Since the crystallographic match is mainly used to justify the potential of nucleation sites, challenges have been encountered to explain the mechanism of graphite nucleation in this type of inclusion (microparticle). The present work reports the structure, composition, and interactions of these (Al,Si,Mg)-nitrides with graphite and other compounds, such as (Zr,Ti,Nb)-carbonitrides. The latter were the only inclusions with Zr that could be found, while the former inclusion could also be found in the core of graphite. The results confirm that the graphite layers close to the surface of the (Al,Si,Mg)-nitrides have a turbostratic structure. Organized graphite layers are only observed far away from the nitride nucleus. Density functional theory simulations of this interface showed that the interaction between the first graphene layers and the (Al,Si,Mg)-nitrides has a covalent nature, which could explain the turbostratic structure of the inner part of the graphite nodule. Therefore, nucleation of graphite on nuclei with a large lattice mismatch (low planar misfit) may be facilitated by the covalent bonding of carbon atoms on this substrate. These results explain the observed disorder at the interface as well as the deformation of the graphene layers.

Nano-protrusions in intercalated graphite: understanding the structural and electronic effects through DFT.

Complex phenomena characterize the intercalation of ions inside stratified crystals. Their comprehension is crucial in view of exploiting the intercalation mechanism to change the transport properties of the crystal or obtaining a fine control of crystal delamination. In particular, the relationship between the concentration and nature of intercalated ions and surface structural modifications of the host stratified crystal is still under debate. Here, we discuss a theoretical effort to provide a rationale for some structural changes observed on the highly oriented pyrolytic graphite (HOPG) surface after electrochemical treatment in perchloric and sulphuric acid solutions. The formation of the so-called nano-protrusions on the basal plane of intercalated graphite was previously observed with scanning tunneling microscopy (STM). In this work, we employed both STM and density functional theory (DFT) simulations to elucidate the physical and chemical mechanisms driving the emergence of these nano-protrusions. The DFT results show that, in a bilayer graphene system, the presence of a single ion can generate a nano-protrusion with 2.49 Å height and 21.27 Å width. In the deformed area, the C-C bond length is stretched by about 2.5% more than the normal graphene bond. These values are of the same dimensional scale as those reported in previous STM experimental results.25 However, the simulated STM images obtained by increasing the amount of intercalated ions per area suggest that the presence of more than one ion is needed for the deformation of the uppermost graphite layer during the early stages of intercalation. In contrast, in a multilayer graphene system, no significant surface deformation is detected when ions are intercalated between the third and fourth layers. Charge analysis indicates an altered distribution of the charges as a consequence of the intercalation. The charge transfer from graphene layers to the intercalated ions results in a surface layer more prone to oxidation.

Fabrication of small-period neutron absorption grating by pressurized particle filling method

Neutron absorption gratings play a crucial role in neutron phase contrast imaging systems, where the fabrication of large-size and small-period absorption gratings that meet imaging requirements presents a significant challenge. The pressurized particle filling method has been successfully applied to fabricate large-size absorption gratings. Here, we investigated the feasibility of the pressurized particle filling method for fabricating small-period gratings and proposed an optimized pressurized particle filling method. The grating surface was covered with a uniform particle layer and then pressurized, utilizing the adaptive deformation of the particle layer to achieve uniform particle filling. Neutron absorption gratings with an area of 60 × 60 mm2 and periods of 8 and 4 µm were fabricated through this method. The particle filling rate and fabrication efficiency were successfully improved. In addition, the evaluation of the particle filling uniformity method by analyzing the proportion of particles on the grating surface was proposed. The better uniformity of small-period neutron absorption gratings indicated that the optimized pressurized particle filling method can achieve relatively uniform particle filling.

Evaluation of structural performance of thinasphalt pavement reinforced with wicking geotextiles over expansive soils

This research provides a comprehensive evaluation of the effects of a wicking geotextile capable of multiple functions, including separation and reinforcement and gravity and capillary suction-induced drainage for subsurface layers in flexible pavements built over expansive soils. Two test sections were designed and constructed near central Texas, which were prone to distress from cyclic moisture-induced strains related to expansive soils, during the Fall of 2018. The base layers in the first and second sections were constructed with reclaimed asphalt pavement and crushed stone aggregate, respectively, and wicking geotextiles were installed between the base and subgrade layers. The adjacent lane to the test sections was selected as the control section. Falling weight deflectometer (FWD) testing was conducted to evaluate the in-situ moduli of the pavement layers. Multiple performance indicators were selected to compare the performance of reinforced and control sections. A performance prediction software program was used to investigate the performance of the sections according to the mechanistic-empirical design and analysis approach. The results showed the rapid removal of moisture has a significant impact on controlling the permanent deformation of the pavement layer. FWD results revealed that the reinforced layer helped to improve the base and subgrade moduli values. The performance prediction results showed the wicking geotextile has the potential to be used for reinforcing the pavements constructed over expansive soil

Analysis of Implementation Plans for the ACR -PCR System on Flexible Pavement Runways at Utilization Cooperation Airport

ICAO determined that the ACR–PCR system will take effect in July 2020 and be effective in November 2024. It is very important for airports in Indonesia to make adjustments to optimize the use of pavement assets. The research aims to calculate ACR-PCR, compare it with ACN-PCN, evaluating the airside pavement structure of airport through the application of the ACR-PCR system. Case study analysis of calculations with ICAO–ACR1.32 and FAARFIELD2.0. ACN/PCN and ACR/PCR ratios are classified against pavement strength limitation criteria. Evaluation based on the criteria for permanent deformation of the subgrade layer andfatigue cracking of the asphalt layer. Tjilik Riwut airport runway PCR value 542FBXT, Radin Inten II 850FCXT, Fatmawati Soekarno 712FCXT and H. AS. Hanandjoeddin 643FCXT. Comparison of the ACR/PCR and ACN/PCNratiosshows an increase in pavement capacity of 1.4746. Based on the criteria for fatigue cracking of the asphalt layer and permanent deformation of the PCR subgrade layer at Tjilik Riwut airport 668 and 575 FBXT, Radin Inten II 1027 and629FCXT,Fatmawati Soekarno 862 and 629 FCXT, H. AS. Hanandjoeddin 675 and 560 FCXT. The structural pavement capacity of PT Angkasa Pura Indonesia airport has the opportunity to be increased in terms of flight frequency.

Laboratory Evaluation of Marginal and Industrial Waste Material in Geocell-Reinforced Pavements under Cyclic Loading

Abstract The availability of quality materials for the construction of pavements has been a problem in some regions. This scarcity enforced geosynthetic materials as one of the quests for su1stainability in the pavement industry. This study attempted to stabilize marginal (tunnel muck, reclaimed asphalt pavement material) and industrial waste (zinc slag) materials by employing high density polyethylene geocell to appraise the effectiveness of geosynthetic reinforcement in enhancing the characteristics of pavement materials and mitigating their rutting. The cyclic plate load tests are performed on marginal and industrial waste material with geocell-reinforced and unreinforced base layers over black cotton soil as the subgrade. The tests were conducted following the trapezoidal loading pattern with a 0.77-Hz frequency. The geocell-reinforced pavement performance was evaluated for resilient deformation, accumulated permanent deformation, rut depth reduction, traffic benefit ratio, and base layer thickness reduction. The mechanistic empirical pavement design guide (MEPDG) permanent deformation performance (PDP) model framework was used to predict the accumulated permanent deformation in unbound granular layers and to differentiate the rutting performance in geocell-reinforced and unreinforced sections. This study determined the material constants of the MEPDG PDP model for marginal and industrial waste materials used in the pavement section for quantifying the reduction in base layer thickness.

Formation of the Naxos nested domes and crustal differentiation by convection and diapirism

The Naxos dome, in the middle of the Aegean domain, exposes the former root of the Alpine orogenic belt and represents a key natural example to investigate the development of gravitational instabilities during orogenic evolution and their impact on crustal differentiation. The Naxos dome is cored by migmatites with structures depicting second order domes with a diameter of 1–2 km nested in the first order deca-kilometer scale dome that formed at the onset of orogenic collapse. Zircon grains from the migmatites record a succession of crystallization-dissolution cycles with a period of 1–2 Myr. These features have been attributed to the development of convective and diapiric gravitational instabilities, related to thermally induced and compositional buoyancy. In this paper, we test the pertinence of this model with a thermal-mechanical numerical experiment performed with a volume of fluid method (VOF) known to preserve material phase interfaces during large deformation of viscous layers. Partial melting of the crust is modeled by strain-rate and temperature dependent viscosity and temperature dependent density. Moreover, horizontal layers with density, viscosity and heat production variations mimic more felsic or more mafic lithologies in a crust of intermediate composition. With basal heating, gravitational instabilities initiate with local segregation of the buoyant versus heavier layers, followed by diapiric upwelling of buoyant pockets of aggregated less dense material. Convection starts after 5 Myr, approximately when half of the crust has a viscosity lower than 1019 Pa s. The size of the convection cells increases as the temperature rises in the crust and reaches ∼25 km in diameter after ca. 20 Myr, which defines the size of first order domes. Some of the heterogeneous material is entrained in the convection cells with a revolution period of 1 to 3 Myr. However, most of the denser material accumulates in the lower crust, while the buoyant material segregates at the top of the convection cells and forms diapirs that correspond to second order domes, of several kilometers in diameter and nested within the first order domes. This model, which reproduces the first order characteristic dimensions of the Naxos nested domes and the periodicity of their zircon geochronological record, demonstrates the efficiency of gravitational instabilities in the formation of migmatite domes and, more generally, in the multi-scale dynamics of crustal differentiation leading to a felsic upper crust, an intermediate middle crust and a mafic lower crust.

Electrowetting hysteresis on a deformable dielectric film.

Electrowetting on dielectric (EWOD) involves actuating droplets through electrical stimulus while the droplets lie on a dielectric layer that covers the electrode. In order to activate the droplet, a higher threshold voltage is required due to electrowetting hysteresis. The effect of a deformable dielectric layer and its thickness on electrowetting hysteresis has not been studied. We demonstrate in this work that electrowetting hysteresis increases with decreasing elasticity of the dielectric layer. This is attributed to the formation of wetting ridges along the three-phase contact line and relies on electro-elastic capillary interactions. Furthermore, we demonstrate that the thickness of the dielectric film can affect electrowetting hysteresis on soft materials. In addition, we present a unique mechanism of electrowetting hysteresis reduction on soft solids by the addition of a minute amount of anionic surfactant (sodium dodecyl sulfate, SDS) to the liquid. We also demonstrate that the voltage cycle affects the electrowetting hysteresis of sessile drops on a soft dielectric layer. Dielectric layer elasticity can be used in various engineering applications, such as optofluidic displays, liquid lenses, lab-on-a-chip devices, and energy harvesting systems.

The result of tangential layered solid-state flow deformation in the middle and lower crust: The Yardoi dome in the eastern Himalayan orogenic belt

The result of tangential layered solid-state flow deformation in the middle and lower crust: The Yardoi dome in the eastern Himalayan orogenic belt