Transverse Direction Research Articles

Unveiling the effect of strain path-dependent microstructural evolution on the electrochemical behavior of cold-rolled [FeNi]69Cr15Mn10Nb6 high-entropy alloy

In the present work, [FeNi]69Cr15Mn10Nb6 high-entropy alloys (HEAs) were subjected to a heavy cold-rolling process at ambient temperature through two distinct routes, namely unidirectional cold-rolling (UCR) and multistep cross cold-rolling (MSCCR). This was done to investigate the effect of strain path-dependent microstructural evolution on the electrochemical behavior of the alloys in a 0.5 M H2SO4 solution. The as-homogenized specimen displayed a two-phase microstructure with [FeNiNb]-rich dendrites distributed in a nearly homogenous face-centered cubic (FCC) high-entropy alloy matrix. It was found that the [FeNiNb]-rich dendrites elongated, broke down, and elongated along the rolling direction in both processing routes. In the MSCCR-processed specimen, the dendrites exhibited a smaller average size with a more uniform distribution compared to the UCR sample, which was mainly ascribed to the elongation mechanisms in the normal and transverse directions during the MSCCR route. Electrochemical studies demonstrated a decrease in corrosion current density due to high imposed strains in the UCR. Meanwhile, a more positive trend was observed in MSCCR processing. Consequently, achieving uniformly distributed small dendrites and uniform grain refinement through the MSCCR route provided ideal conditions for forming passive layer with superior protection properties.

Numerical simulation of thermal and stress fields for multilayer and multi-pass weaving WAAM of magnesium alloy

Purpose A 3D finite element (FE) model based on the double ellipsoidal heat source was developed to investigate the evolution of temperature and stress fields during the multilayer and multi-pass wire and arc additive manufacturing (WAAM) process. This paper aims to investigate the evolution of temperature and stress fields during the multilayer and multi-pass wire and arc additive manufacturing (WAAM) process by developing a 3D finite element (FE) model based on the double ellipsoidal heat source. Design/methodology/approach Experimental thermal cycle curves and residual stresses were obtained by thermocouples and X-ray diffraction, respectively. The validity of the model was verified by the corresponding experimental results. Findings The deposition process of the upper pass led to the partial remelting of the lower deposited pass. The thermal process of the current-deposited pass alleviated the stress concentration in the previous-formed passes. A more uniform temperature distribution could be obtained by using the reciprocating deposition path. Compared to the reciprocating deposition path, the peak values of the transverse and longitudinal tensile residual stresses of the deposited sample under the unidirectional deposition path were reduced by 15 MPa and increased by 13 MPa, respectively. The heat conduction in the deposited passes could be improved by extending the inter-pass cooling time appropriately. With an increase in the inter-pass cooling time, the longitudinal residual stress in the middle region of sample along longitudinal and transverse directions showed increase and decrease–increase trends, respectively, while the transverse residual stress exhibited decrease trend. Originality/value This study enhances the understanding of temperature and stress fields evolution during the multilayer and multi-pass cold metal transfer-WAAM processes of magnesium alloy and provides the reference for parameter optimization.

Wood Cell Wall Nanoengineering toward Anisotropic, Strong, and Flexible Cellulosic Hydrogel Sensors.

Achieving highly ionic conductive hydrogels from natural wood remains challenging owing to their insufficient surface area and low number of active sites on the cell wall. This study proposes a viable strategy to design a strong and anisotropic wood-based hydrogel through cell wall nanoengineering. By manipulating the microstructure of the wood cell wall, a flexible cellulosic hydrogel is achieved through Schiff base bonding via the polyacrylamide and cellulose molecular chains. This results in excellent flexibility and mechanical properties of the wood hydrogel with tensile strengths of 22.3 and 6.1 MPa in the longitudinal and transverse directions, respectively. Moreover, confining aqueous salt electrolytes within the porous structure gives anisotropic ionic conductivities (19.5 and 6.02 S/m in the longitudinal and transverse directions, respectively). The wood-based hydrogel sensor has a favorable sensitivity and a stable working performance at a low temperature of -25 °C in monitoring human motions, thereby demonstrating great potential applications in wearable sensor devices.

Studies on surface roughness and axial thrust force of drilled holes in Mg-Zn-Ca bio-medical alloy

Mg-Zn-Ca alloy is a promising candidate for orthopaedic implants such as bone plates and screws, as it has a similar mechanical strength and elastic modulus to bone, and it degrades in the body without causing toxicity or inflammation. Drilling studies are necessary to optimize the drilling process parameters, to evaluate the machinability and surface integrity of Mg-Zn-Ca alloy, and to ensure the effective and efficient drilling for various applications in the medical and engineering fields. The present experimental study emphasizes the influence of Ca content, biofriendly coolants and their combined effect with standard drill bits on the surface quality and axial thrust force in the drilling operation of Mg-Zn-Ca alloy. The drilling parameters such as cutting speed, feed rate, standard tools, bio-compatible coolants were optimized with respect to the amount of Ca in the Mg-Zn alloy. The axial thrust force and average surface roughness of drilled holes were considered as response of the experiments. The drilled surfaces were measured for average surface roughness in the transverse direction along the centre path of the drilled hole and a qualitative analysis was also carried out using advanced confocal microscope. The results revealed that the cutting speed among continuous factors significantly influenced the axial thrust force and average surface roughness. The effect of categorical factors was assessed using a regression based ranking method. The results of statistical analysis revealed that high speed steel, and vegetable oil offered improved surface quality, whereas the coconut oil showed low axial thrust force. The liquid nitrogen showed high value of axial thrust force and average surface roughness due to the brittleness induced by cryogenic coolant before drilling operation.

Stress Analysis of Pressing Joint of Two Conical Pipes – Part 2

Abstract The paper presents a strength analysis of a pressed joint of two conical pipes with the aim of finding out whether this method of connection is suitable for telecommunication masts. In this paper, a solution using an engineering approach and a finite element method (FEM) numerical analysis for transversal direction will be compared.

Bending properties and deformation micromechanisms of near-α titanium alloy sheets/foils considering initial texture characteristics and size effect

Clarifying the bending deformation behaviour of metal foils is essential for meeting the lightweighting requirements of metal honeycomb structures. This study selected Ti65 alloy specimens with various thicknesses and initial α-phase textures to conduct room-temperature three-point bending experiments. A detailed comparative analysis was performed on the bending deformation behaviour of Ti65 alloy sheets and foils. It reveals that in the foil specimens, the weakening effect of surface layer grains is significant. Under the influence of size effects, the springback angle of Ti65 alloy foils with coarse α-phase grains decreases markedly. Additionally, through various methods, including global Schmid factor analysis, lattice rotation analysis, and crystal plasticity finite element method simulations, the specific relationship between α-phase texture and the bending performance of Ti65 alloy foils was thoroughly investigated. The rolling process influences the bending performance of Ti65 alloy by determining the α-phase texture. Unidirectionally rolled Ti65 alloy products exhibit a transverse α-phase texture, which predisposes them to form transverse texture α-phase macrozones during bending. In contrast, cross-directionally rolled Ti65 alloy foils possess a basal α-phase texture biased toward the transverse direction. This not only helps avoid the formation of macrozones but also ensures coordinated deformation across the foil, resulting in superior bending performance.

Topological protection revealed by real-time longitudinal and transverse transport measurements

Topology is essential for achieving unchanged (or protected) quantum properties in the presence of perturbations. A challenge facing the application is the variable protection levels displayed in real systems associated with the reconstructive behaviors of the dissipationless modes. Despite various insights on potential causes of backscattering, the edge-state-based approach is incomplete because the bulk states also contribute indispensably. This study investigates sample-scale reconstruction where dissipationless modes are global objects instead of being restricted to the sample edge. An integer quantum Hall effect hosted in a Corbino geometry is adopted and brought to the verge of a breakdown. Two independent and simultaneous detections are performed to capture transport responses in both longitudinal and transverse directions. The real-time correspondence between orthogonal results confirms two facts. 1. Dissipationless modes undergo frequent reconstruction in response to electrochemical potential changes, causing dissipationless current paths to expand transversely into the bulk while preserving chirality. A breakdown only occurs when a backscattering emerges between reconstructed dissipationless current paths bridging opposite edge contacts. 2. Topological protection is subject to an interplay of disorder, electron-electron interaction, and topology. The proposed reconstruction mechanism qualitatively explains the robustness variations, beneficial for protection optimization.

Estimation of stresses in 1D structures via inverse wavenumber analysis

The ANR ITHERATE project proposes to develop identification procedures of residual stresses in additive manufacturing via in-situ and non destructive methods using the wide band wave response of structures. This work presents a proof on concept on one-dimensional waveguides, as a preliminary results to more complex configurations. An original experimental setup is implemented using a cylindrical lens to optically amplify the vibrations of the structure in the transverse direction, allowing to resolve the wave propagation with a high-speed low-resolution camera. The dispersion of the wave velocity with the frequency, obtained via high-resolution wavenumber analysis (HRWA), is compared to predictions given by the acousto-elastic theory. In particular, the effects of the quasi-static initial stress and the elasticity of the material can be separated and estimated seperately via an inverse method that is independent from the boundary conditions and applied loads. Interestingly, this wave-based estimation does not necessitate an a-priori knowledge of the material constitutive law, overcoming the limitations of most stress estimation techniques of the state of the art, that are based on a measurement of the strain. Finally, perspectives for the generalization of the method to more complex situations, as plates under thermal loads, will be presented.

Strong Strain Hardening Induced by {11–22} Twins of Hexagonal Titanium upon Low-Temperature Deformation Along the Transverse Direction

Strong Strain Hardening Induced by {11–22} Twins of Hexagonal Titanium upon Low-Temperature Deformation Along the Transverse Direction

Entropy analysis of MHD hybrid nanofluid in a rotating channel filled with porous material

This study investigates entropy generation of MHD hybrid nanofluid in a rotating channel filled with porous material. The hybrid nanofluid, which uses Cu and alumina nanoparticles along with water as the base fluid, has been used. The hybrid model equations were solved numerically using MATLAB’s ode15s which employs Runge-Kutta–Fehlberg scheme. Effects of entropy generation and other system variables were investigated. Parametric analysis reveals that, hybrid nanofluids show better heat transport capacities with a higher Nusselt number than Cu–water and alumina-water nanofluids. Thus, because of its improved thermal characteristics, the hybrid nanofluid transfers more heat, which makes it a better option for applications that need effective heat dissipation. The results show that, increasing the Biot number reduces temperature, while hybrid nanofluids yield a higher Bejan number, indicating more efficient heat transfer with minimized entropy generation. The study identifies increased friction between fluid and porous media as the cause of temperature rise with higher porous media resistance and shape factor parameters. It is also depicted that, the rate of entropy generation decreases as the Biot number Bi rises, this happens as a result of the channel’s temperature gradient being less pronounced at higher Bi, which reduces thermal irreversibility and, in turn, entropy generation. The findings also demonstrate that the presence of a magnetic field reduces axial velocity while increasing transverse velocity. Consequently, skin friction increases in the axial direction and decreases in the transverse direction. In addition, the increase of rotational parameter has been found to reduce skin friction to the greatest extent. These findings underscore the potential of hybrid nanofluids in optimizing thermal systems by reducing entropy generation and enhancing heat transfer efficiency.

Ultrasonic Vibration-assisted Tube Extrusion Shear Expansion (UVaTESE): A Novel Process to Manipulate the Texture of AZ31 Magnesium Alloy

AZ31 magnesium (Mg) alloy prepared via the extrusion process forms an immensely strong {0001} basal texture, therefore there is a necessity to improve the existing extrusion process to achieve a weakening of the {0001} basal texture of the AZ31 Mg alloy. In this study, a novel process called UVaTESE is proposed. The Mg alloy texture and slip system activation at four ultrasonic vibration (UV) frequencies have been simulated via ABAQUS-VUMAT and VPSC, individually. The simulation results indicate that UV is capable of diffusing the {0001} basal texture of the Mg alloy along the extrusion direction (ED) and transverse direction (TD) and significantly improves the activation of pyramidal slip <c+a>. The simulations are verified experimentally, and the {0001} basal texture of AZ31 Mg alloy has the identical tendency to disperse along ED and TD. Prismatic slip <a> and pyramidal slip <c+a> jointly lead to diffusion of the grain basal texture along the TD, while grains with basal texture diffused along the ED are controlled by both basal slip <a> and pyramidal slip <c+a>. UV has a positive effect on the grain refinement as well as on the homogeneity of AZ31 Mg alloy. The proportion of dynamic recrystallization (DRX) of AZ31 Mg alloy is proportional to the frequency of UV, and it is noteworthy that the mechanism of DRX behavior is not affected by UV. This novel process provides a fundamentally innovative approach to the preparation of Mg alloys and magnesium-aluminum (Mg-Al) composite tubes via extrusion.

Moisture effects on the transverse compressive behaviour of single flax fibres

Studying the effects of moisture on the mechanical behaviour of single flax fibres, particularly in the transverse direction, is of key importance for the reliable use of biobased composites exposed to varying humidity levels. In this study, the apparent transverse Young’s modulus evolution of single flax fibres is recorded through repeated compressive load/unload cycles conducted at three Relative Humidity (RH) levels— 40%, 60%, and 80%. No significant changes in the apparent Young’s modulus, determined from the unloading, were observed during transverse compression cycling or under increasing humidity conditions. The absence of apparent softening with the rise in RH is attributed to the expression of two antagonistic mechanisms: wall softening due to plasticisation and structural stiffening linked to fibre compaction. Intriguingly, a noteworthy transverse stiffening is recorded at 40% RH following the humidification and drying of the fibre. This outcome is ascribed to a hornification phenomenon.

In-plane properties of an in-situ consolidated automated fiber placement thermoplastic composite

Automated fiber placement (AFP) has been employed to manufacture aerospace structures for decades, recently focusing on thermoplastic composites (TPC). The in-situ consolidation AFP of TPCs is pursued as an energy-efficient additive manufacturing (AM) approach for fabricating composite structures. This work compares the in-plane mechanical properties of in-situ consolidated coupons with those of compression molded counterparts to provide new insights into their failure mechanics and processing-structure relationships. Tensile and compressive properties along the fiber and transverse directions, in-plane shear properties, and short beam strength were measured for all samples. Failure modes and mechanics in tested coupons were related to AFP defects and processing, i.e., resultant crystallinities, fiber misalignment, matrix mechanical properties, porosity, and fiber–matrix interfacial strength. The findings of this study can be used to guide the manufacturing of future TPC structures and potentially open new avenues for applications where post-processing is not feasible or reduced mechanical performance is acceptable.

Range-dynamical low-rank split-step Fourier method for the parabolic wave equation.

Numerical solutions to the parabolic wave equation are plagued by the curse of dimensionality coupled with the Nyquist criterion. As a remedy, a new range-dynamical low-rank split-step Fourier method is developed. The integration scheme scales sub-linearly with the number of classical degrees of freedom in the transverse directions. It is orders of magnitude faster than the classic full-rank split-step Fourier algorithm and saves copious amounts of storage space. This enables numerical solutions of the parabolic wave equation at higher frequencies and on larger domains, and simulations may be performed on laptops rather than high-performance computing clusters. Using a rank-adaptive scheme to optimize the low-rank equations further ensures the approximate solution is highly accurate and efficient. The methodology and algorithms are demonstrated on realistic high-resolution data-assimilative ocean fields in Massachusetts Bay for two three-dimensional acoustic configurations with different source locations and frequencies. The acoustic pressure, transmission loss, and phase solutions are analyzed in the two geometries with seamounts and canyons across and along Stellwagen Bank. The convergence with the rank of the subspace and the properties of the rank-adaptive scheme are demonstrated, and all results are successfully compared with those of the full-rank method when feasible.

The suppression effect of a vertical baffle on three-dimensional swirling and chaotic sloshing in a laterally excited square-based tank

In order to systematically investigate the suppression effect of a vertical baffle on three-dimensional (3D) swirling and chaotic sloshing in a square-based tank subjected to horizontal harmonic excitation, hundreds of experiments are conducted in a clean tank and baffled tanks with three different configurations. Specifically, the vertical baffle is mounted on the tank bottom parallel to the longitudinal direction, the transverse direction, or the diagonal direction. This experimental work finds that there are four sloshing wave regimes in a clean tank—planar, square-like, swirling, and chaotic—which can be described by the asymptotic multimodal theory. Furthermore, there are only two wave regimes in a longitudinal-baffle tank, the planar and swirling regimes, and the occurrence of swirling requires that the excitation amplitude is sufficiently large. It is confirmed that the longitudinal baffle has a significant suppression effect on the swirling and chaotic motions of the sloshing waves, even though it is parallel to the direction of tank movement. Furthermore, the suppression effect of the diagonal baffle is similar to but somewhat smaller than that of the longitudinal baffle. However, when the transverse baffle is mounted on the bottom of the tank, it is difficult to excite the rotation of the sloshing wave. Therefore, the suppression effect of a bottom-mounted baffle depends largely on the included angle between the vertical baffle and the tank movement direction.

Unraveling anisotropic mechanical behaviors of lithium-ion battery separators: Microstructure insights

The mechanical properties of separators significantly affect the electrochemical stability and potential short circuit risks in lithium-ion batteries. An important aspect of their mechanical behavior is their anisotropy, which is predominantly influenced by the microstructures formed during manufacturing process. This study aims to bridge the gap between the anisotropic mechanical features of the separators and their microstructures caused by the manufacturing methods. Initially, we delve into the characterization of separators, featuring their heterogeneous components and orientated arrangement of fibers. Then, we conduct uniaxial tensile tests to measure the stress-strain relationships of separators along the machine direction (MD), diagonal direction (DD), and transverse direction (TD), revealing pronounced anisotropy in both strength and rate sensitivity. Subsequently, image processing techniques is adopted to obtain a representative configuration of separators, which is further divided into fibers and lamellae. According to the manufacturing process of separators, a viscoplastic model is used to describe the mechanical behavior of lamellae while a strengthened viscoplastic model is utilized to mimic the mechanical response of fibers. The finite element analyses underscore the dominant role of orientated fibers in determining anisotropic mechanical properties. Furthermore, we explore the effects of manufacturing and geometry parameters on the separator's anisotropic mechanical behavior. This research provides valuable insights for optimizing manufacturing parameters and enhancing safety measures for lithium-ion batteries.

Vortex-induced vibrations of three rigidly coupled circular cylinders in an equilateral-triangular arrangement

A three-cylinder system in an equilateral-triangular arrangement is a common, basic structure in the engineering field, and the rigid connection of multiple cylinders has been applied in some practical projects. In this paper, three cylinders in an equilateral triangle arrangement for a spacing ratio of 4 at Reynolds number of 200 are studied by means of numerical simulation. The vibration modes are divided into single cylinder vibration, three freely vibrating vibration and three rigidly coupled vibration. The vortex-induced vibration characteristics and aerodynamic forces and fluid–structure-interaction mechanisms are analyzed. The results show that the vibration velocity regions and the amplitude of three freely vibrating cylinders in the transverse and streamwise directions are obviously larger than that of a single cylinder. The rigid connection measures can effectively suppress the vibration velocity region and amplitude. However, this suppression effect is no better than the single cylinder. In the lock-in region, the trajectories of three rigidly coupled cylinders are regular closed shapes. The Strouhal numbers of the three cylinders are synchronous in the natural frequency in the lock-in region. The wake vortices from the upstream cylinders affect the downstream cylinders, which depends on different case and reduced velocity. The complex aerodynamic interference and parallel vortices of the wake enhance the vibration of the structure in some cases.

The Structure of Field‐Aligned Current Systems as Inferred From the Multiscale Minimum Variance Analysis

AbstractAuroral field‐aligned currents (FACs) have an intrinsic complexity caused by the superposition of contributions from a broad spectrum of scales and diversity of locations. The complex FAC systems are investigated by using the multiscale minimum variance analysis. This technique provides a scale based decomposition of the FAC systems by identifying the constituting FAC elements as well as their structure. At the basis, the analysis exploits the scale dependence of the eigenvalues of the magnetic field variance matrix. The scale decomposition along the transversal (latitudinal) direction results from the scale derivative of the maximum eigenvalue. The complementary information from the scale derivative of the minimum eigenvalue helps to infer the full structure of each FAC element by providing estimates of the FAC length (longitudinal) scale. The scale derivative of minimum and maximum eigenvalues are used to identify FAC signatures associated to different types of aurora (e.g., highly extended, finite arcs, gradient regions) as well as to characterize the influence of the crossing location with respect to the FAC structures (e.g., near edge crossings). The multiscale analysis is applied to simulated FACs and to spacecraft observations made by the Swarm mission. The use with real world data illustrates the power of this analysis, whose full benefits for magnetosphere‐ionosphere coupling investigations are yet to be explored.

Effect of wall microstructure on conical hypersonic boundary layer flow

As an effective boundary layer flow control method, wall microstructure has an important application prospect in heat and drag reduction of hypersonic. In this paper, based on experimental techniques such as high-frequency pressure fluctuation testing, the effects of different microstructure configurations (V-shaped and rectangular) and distribution modes (streamwise and transverse) on the flow of hypersonic conic boundary layer under the condition of Mach 6 hypersonic incoming flow are studied. The experimental results show that compared with the flow of the smooth wall boundary layer, the wall microstructure has a greater influence on the eigenfrequency of the second-mode wave in the boundary layer, and the streamwise increases by about 20 kHz to the rectangular microstructure and decreases by about 30 kHz to the transverse rectangular microstructure. At the same time, the transverse V-shaped microstructure can increase the amplitude of the second mode in the boundary layer by 5.5 times compared with the smooth wall. For the evolution of boundary layer flow, the microstructure arranged along the flow direction will accelerate the linear development of the disturbance wave during the transition, so that the laminar flow will be transformed into turbulent flow in a shorter distance. The microstructure arranged along the transverse direction prolongs the linear development stage of the disturbance wave during the transition, so that the laminar flow turns into turbulent flow over a longer distance. Downstream of different structures, it is shown that transverse rectangular microstructure has lowest temperatures.

Aperture Field Anisotropy Control on Immiscible Displacement Patterns in Rough Fractures

AbstractTwo‐phase flow displacement in rock fractures is crucial for various subsurface mass transfer processes and engineering applications. In fractures, the displacement of a less viscous fluid by a more viscous one (i.e., viscosity ratio M &gt; 1) involves viscous forces help stabilizing the displacement front in presence of capillary pressure fluctuations. Although previous studies have reported displacement patterns in isotropic fractures, the impact of anisotropic fractures on displacement patterns has not been systematically examined. In this study, we conducted flow‐rate‐controlled drainage experiments to examine how anisotropic aperture fields affect displacement patterns. We observed the transition of displacement patterns from capillary fingering (CF) to crossover zone (CZ) to compact displacement pattern (CD) based on variations in transverse pore‐filling event (TPFE) frequency, which characterizes the competition between capillary and viscous forces. Increasing aperture correlation length in the transverse direction leads to increased TPFE frequency at a low flow rate, destabilizing displacement front. While the increasing aperture correlation length in longitudinal direction suppressed TPFE frequency, stabilizing displacement front. Therefore, the critical capillary number (CaCF‐CZ), which indicates the onset of the CF‐CZ transition, decreases as the aperture field varies from transversely to longitudinally correlated. At high flow rates, TPFEs almost disappeared, indicating that anisotropy did not affect CZ‐CD transition (CaCZ‐CD). Furthermore, we modified theoretical models of CaCF‐CZ and CaCZ‐CD by incorporating the aperture anisotropy factor, achieving a good fit with the experimental data. This study demonstrates the critical role of aperture field anisotropy in controlling two‐phase displacement patterns and provides a theoretical framework for predicting multiphase flow behavior in natural fractures.