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Van der Waals (vdW)-layered materials, such as graphite, exhibit unique mechanical properties owing to their structural and mechanical anisotropies. This study reports the development of a mechanical model that reproduces the characteristics of the nonlinear and reversible bending deformation of vdW-layered materials, while taking into account the microscopic mechanism of the discrete interlayer slips. The vdW-layered material was modeled as a stack of interacting discrete deformable layers (semi-discrete layer model), and the interlayer interaction was modeled using a cohesive zone model that reproduced the localized interlayer slip. Using the finite-element method, out-of-plane bending deformation analyses were performed on the cantilevers of the highly oriented pyrolytic graphite (HOPG) and MoTe2, and the validity of the model was verified by comparing it with the experimental results. The model accurately reproduced the loading and unloading behaviors in the experiments for the submicron HOPG cantilevers or the large nonlinear and reversible deformation with a hysteresis loop. Furthermore, the model reproduced well the characteristics of the bending experiments for the micro-MoTe2 cantilevers, or the intermittent decrease in stiffness during the loading process and deformation restoration during the unloading process. These results demonstrated that the designed semi-discrete layer model can be universally applied to reproduce the bending deformation characteristics of a variety of vdW-layered materials and can be employed to effectively elucidate the underlying deformation mechanisms. [ABSTRACT FROM AUTHOR]

Purpose: To examine the stresses caused by different All-on-4 surgical techniques—conventional, a combination of monocortical and bicortical, bicortical, and nasal floor elevation—on the implant and the surrounding bone using 3D finite element analysis (FEA). Materials and Methods: A 3D bone model of the atrophic maxilla was created based on CT imaging of the fully edentulous adult patient. All implants used in the models were 4 mm in diameter, and the length was 13 mm in the anterior and 15 mm in the posterior. Implants were applied to four different atrophic maxillary models with the All-on-4 technique: anterior and posterior monocortical implants in the first model, anterior monocortical and posterior bicortical in the second model, anterior and posterior bicortical in the third model, and anterior and posterior bicortical with nasal floor elevation in the fourth model. Eight linear analyses were performed by applying force from both vertical and 45-degree oblique directions to the four models prepared in our study. Results: When the cortical and cancellous bone around the anterior implants was examined, it was observed that the oblique and vertical loading conditions and the stresses around the implant were similar in all models. When the posterior implants were examined, model 1 (ie, anterior and posterior monocortical implants) showed the greatest oblique compression, vertical compression, and vertical tension forces. According to the Von Mises stress (VMS) analysis results for anterior and posterior implants, higher values were observed in model 1 compared to models 3 and 4 under oblique and vertical forces. It was observed that bicortical placement of the implants reduced the stresses on the bone and implant-abutment system but had no significant effect on the stress on the bar. Conclusions: According to the results of our study, in the All-on-4 technique, bicortical placement of the implants reduced the stresses on the bone and implant when the anatomical limitations allowed. In addition, nasal floor elevation can be applied in the atrophic maxilla in appropriate indications. [ABSTRACT FROM AUTHOR]

Wrinkling, creasing, and folding are frequent phenomena encountered in biological and man-made bilayers made by thin films bonded to thicker and softer substrates often containing fibers. Paradigmatic examples of the latter are the skin, the brain, and arterial walls, for which wiggly cross sections are detected. Although experimental investigations on corrugation of these and analog bilayers would greatly benefit from scaling laws for prompt comparison of the wrinkling features, neither are they available nor have systematic approaches yielding to such laws ever been provided before. This gap is filled in this paper, where a uniaxially compressed bilayer formed by a thin elastic film bonded on a hyperelastic fiber-reinforced substrate is considered. The force balance at the film–substrate interface is here analytically and numerically investigated for highly mismatched film–substrates. The onset of wrinkling is then characterized in terms of both the critical strain and its corresponding wavenumber. Inspired by the asymptotic laws available for neo-Hookean bilayers, the paper then provides a systematic way to achieve novel scaling laws for the wrinkling features for fiber-reinforced highly mismatched hyperelastic bilayers. Such novel scaling laws shed light on the key contributions defining the response of the bilayer, as it is characterized by a fiber-induced complex anisotropy. Results are compared with finite element analyses and also with outcomes of both existing linear models and available ad hoc scalings. Furthermore, the amplitude, the global maximum and minimum of ruga occurring under increasing compression spanning the wrinkling, period doubling, and folding regimes are also obtained. [ABSTRACT FROM AUTHOR]

This study investigates an axial extension mode magnetoelectric antenna designed for near-field communication in dielectric cluttered environments. The antenna configuration consists of two magnetostrictive Metglas-polymer composites bonded on opposite sides of a PZT-5A actuator, creating a dumbbell configuration. Operating at its 88 kHz mechanical resonance, the antenna emits electromagnetic radiation in the near field by applying an AC voltage to the piezoelectric material, generating an acoustic wave that propagates through the volume and induces oscillating magnetizations. The design uses a system of uncoupled models: an electrostatic finite element model to predict strain that feeds into a Landau–Lifshitz–Gilbert micromagnetic model to predict magnetic moment changes and, subsequently, a dipole model to forecast near-field radiation characteristics. Measurements were conducted on the antenna's impedance, quality factor, mechanical resonance, transmitted magnetic signal strength, and radiation patterns, with variations in the bias magnetic field, frequency, and applied voltage. The results exhibit a strong correlation with model predictions, and the radiated signal strengths compare favorably with those of state-of-the-art pacemaker communication devices. Computational parametric studies using Galfenol and Terfenol-D suggest the potential for up to a three order of magnitude reduction in the antenna's volume, which is critical for implanted medical devices. [ABSTRACT FROM AUTHOR]

Alternating current (ac) losses in conductor-on-rounded-core (CORC) cables of YBCO high-temperature superconducting (HTS) tapes are a significant challenge in HTS power applications. This study employs two finite element analysis (FEA) models to investigate the contributions from different ac loss components and provide approaches for reducing ac losses in cables. An FEA model based on the T-A formulation treats the cross section of thin superconducting layers as 1D lines and, therefore, only can predict the ac loss generated by the perpendicular magnetic field. In contrast, the model based on H-formulation can be performed on the actual 2D rectangular cross section HTS tapes to provide the total ac losses generated by magnetic fluxes penetrating from both the edges and surfaces of HTS tapes, although this model requires more computing time and memory. The 1D and 2D simulation models were validated by cross comparing the results from both models and by comparing sub-section and full cross section models. Subsequently, two models relate cable design and operational parameters to the surface and edge losses of a two-layer CORC cable by considering the (1) relative contributions of edge and surface losses to the overall ac losses; (2) effect of the current distribution between inner and outer HTS layers on ac losses; (3) impact of the tape alignment on ac losses in each HTS layer; (4) influence of the thickness of HTS layers on ac losses; (5) effect of size and number of inter-tape gaps on ac losses; and (6) contribution frequency on the ac losses. The research results given in this paper are therefore not only valuable to suggest strategies for reducing ac loss in multi-layer cables but also for developing more accurate and effective methods to calculate ac loss in CORC HTS cables. [ABSTRACT FROM AUTHOR]

This study investigates acoustic radiation forces on spherical objects generated by Bessel beams in a viscous fluid. Radiation forces on elastic spheres and shells of different materials are examined using viscid expression with the thermoviscous correction included, and the results are then compared with numerical simulations based on the finite element method. The Stokes drag force for zero-order Bessel waves was theoretically derived, and in turn, a practical example of negative radiation forces is proposed and investigated together with the gravity, the buoyancy, and the drag force from acoustic streaming. It is found that the negative pulling force exists even including the positive forces from the other sources; however, the parameter regions for pulling forces are reduced especially for small objects. This work helps the further study of particle manipulations by acoustic Bessel beams in viscous fluids and also guides the experimental realization of acoustic tractor beams. [ABSTRACT FROM AUTHOR]

This paper proposes a layer-by-layer acoustic travel time approximation method based on ray theory for total focusing method (TFM) imaging in carbon fiber reinforced polymer (CFRP) laminates. The method considers the anisotropy in every monolayer and heterogeneity of CFRP, which approximates the path of propagation as straight in the whole material. The application of this method to TFM imaging is called TravelTimeAppro-TFM. In comparison to isotropic-TFM and Dijkstra-TFM, the experimental results indicated that TravelTimeAppro-TFM outperforms isotropic-TFM in terms of imaging amplitude gain with a maximum gain of 4.67 dB. On the other hand, this approach reduces the computational work compared to Dijkstra-TFM. The proposed method demonstrates significant improvements in both focusing performance and the speed of calculation. This paper also investigates the effective angular range of the layer-by-layer acoustic travel time approximation method through experimental and finite element simulation analysis. [ABSTRACT FROM AUTHOR]

Time–frequency non-stationarity is a ground motion characteristic which is frequently neglected in current seismic design and research. This paper studies its impact on the seismic response of high-speed railway simply supported bridge (HSRSSB). A method for generating time–frequency stationary earthquakes (TFSEs) and time–frequency non-stationary earthquakes (TFNSEs) using wavelet packet transform is proposed. A finite element model of a three-span HSRSSB is established using OpenSees. The seismic response is obtained through non-linear dynamic time history analysis, and the fragility curves of bridge components and system are calculated through incremental dynamic analysis. Finally, the reasons for the differences are analyzed by comparing the differences in seismic response of bridge, component fragility and system fragility under two groups of ground motion. The results show that the time–frequency non-stationarity of ground motion has an effect on the bridge response and fragility under strong earthquakes. TFNSE will lead to larger ground motion response, and the damage probability of bridge components and systems is higher. The reason is related to the damage and period extension of bridges under ground motion. Structures with prolonged period anti-seismic measures need to pay attention to this effect. [ABSTRACT FROM AUTHOR]

Stiffness degradation of track–bridge systems under earthquake excitations can lead to track dynamic irregularity, impacting the safety of train operations post-earthquake. In this paper, the nonlinear time-history analysis of CRTS II track–bridge system model established by ANSYS finite element analysis software is carried out under the action of transverse random earthquake. The train–track–bridge system model considering the stiffness degradation caused by earthquake is established by MATLAB, and the earthquake-induced track dynamic irregularity sample library is constructed. The probability distribution mode of the power spectral density sample of the earthquake-induced track dynamic irregularity is explored and the calculation method based on the probability guarantee rate is proposed. The influence of structural damping ratio, train running speed and train type on the power spectral density curve of the earthquake-induced track dynamic irregularity is analyzed. The results show that the power spectrum samples of track dynamic irregularity conform to the hypothesis test of a normal distribution. The power spectral density of earthquake-induced dynamic irregularity primarily consists of medium and low-frequency components. When the structural damping ratio increases from 0.03 to 0.04, 0.04 to 0.05, 0.05 to 0.06, and 0.06 to 0.07, the variation gradients are 0.1701, 0.1240, 0.1034 and 0.0999, respectively, which indicates that the structural damping ratio has a significant effect on the power spectral density of earthquake-induced irregularity, and the impacts of train speed and train type on the power spectral density of near-fault earthquake-induced irregularity are minimal. [ABSTRACT FROM AUTHOR]

Basal and prismatic slips induced by thermoelastic stresses during the growth of 4H-SiC are investigated by using the finite element method (FEM) and considering factors such as the crystal diameter, temperature, and off-axis angle. It is found that with the increase of the crystal diameter from 6 to 8 inches, the prismatic slip more likely occurs, leading to a higher density of basal plane dislocations (BPDs). However, the basal slip hardly changes. The temperature difference, rather than the growth temperature, is the primary factor contributing to the increase in the slip stresses. The stresses of the basal slip are significantly affected by a small off-axis angle, whereas those of the prismatic slip are not unaffected until the off-axis angle reaches 30 degrees. The mechanism for the decrease of the density of BPDs along the growth direction in an 8 inch 4H-SiC crystal is elucidated. We verify that the prismatic slip in an 8 inch 4H-SiC crystal contributes more to the BPD formation than the basal slip. [ABSTRACT FROM AUTHOR]

This research aims to establish a systematic framework for parametric identification of materials undergoing high temperatures and high strain rates. While advanced testing equipment, such as the Gleeble physical simulator, can produce controlled measurements of specimens under various conditions, significant challenges remain in determining the parameters of constitutive relations. Temperature gradients inevitably arise during Gleeble testing, leading to nonuniform strain distribution caused by complex thermal–mechanical coupling. Although finite element analysis of Gleeble testing can be performed, such simulations are computationally expensive, making brute-force optimization to minimize the difference between experimental data and finite element simulation across the parametric space infeasible. Furthermore, since the related constitutive relations are semi-empirical in nature, the ground truth of the constitutive parameters is generally unknown. In this context, a single-objective optimization based on a number of testing conditions may yield biased results or become trapped in local minima. In this research, we employ finite element analysis simulating Gleeble operation as the foundation, leveraging a suite of computational intelligence tools to address these challenges. We first develop a multi-response Gaussian process surrogate model, trained using a relatively small amount of finite element data, to rapidly emulate the forward analysis. We then implement a multi-objective optimization approach using simulated annealing to individually minimize the differences between experimental results and emulations under various testing conditions. AISI 9310 steel and the Johnson–Cook model are adopted for methodological demonstration. The development of the finite element model, Gaussian process surrogate model, and inverse optimization is detailed, and the results obtained are discussed. This framework can be extended to the parametric identification of other materials and heat treatment conditions using Gleeble testing. [ABSTRACT FROM AUTHOR]

Precision systems have extensively employed compliant mechanisms. Nevertheless, its utilization in vibration-assisted polishing has not garnered much interest. Therefore, this study presents a novel framework for a mechanism that adheres to two degrees of freedom. The mechanism that has been constructed exhibits a symmetrical design, enabling it to extract comparable performances in two directions. The proposed construction incorporates a novel combination of a three-lever amplification mechanism and a parallelogram to improve both the stroke and resonant frequency. The output amplification ratio is calculated by the graphical scheme method. The pseudo-rigid-body model, the free-body diagram, and the Lagrange method are all used together in this study to look into kinetostatics and dynamics. The water cycle algorithm is used to conduct structural optimization based on mathematical models. The prototype is fabricated by CNC milling, and physical tests are conducted. According to the findings for the resonant frequency, the analytical results well match the finite element analysis (FEA) results with an error of 8.44%. Besides, the measured resonant frequency was determined approximately 486 Hz, while the FEA yielded a result of 460.4 Hz. The discrepancy between the FEA and experimental results is 5.26%. The utilization of the design mechanism holds promise for the application of vibration-assisted polishing. [ABSTRACT FROM AUTHOR]

The selective laser melting (SLM) technique is progressively changing the traditional manufacturing processes due to rapid molding and high forming accuracy. However, the density and microstructure induced by the process parameters have a significant influence on the material properties. In general, these process parameter windows are obtained experimentally based on the energy density requirements of the material. The combination of schemes is often huge in number, which is a time-consuming and laborious process. On the other hand, the fluctuations in molten pool temperature influence the printing quality of the part, resulting in differences in performance. The orthogonal experimental design method was used to determine the macroscopic properties of SLM-ed AlSi10Mg parts in this work. Combining the density and mechanical properties, the optimal process parameter window was deduced, and the influence of critical process parameters was investigated via range analysis. The optical microscope (OM) and scanning electron microscope (SEM) observations were used to correlate the microstructure to macroscopic properties. The influence mechanism of layer thickness and volumetric energy density (VED) variation on the molten pool morphology was investigated by the finite element method. The knowledge of optimized process parameters is essential for SLM-ed parts with better mechanical properties, which could more accurately guide the structural design. [ABSTRACT FROM AUTHOR]

In order to improve the high grinding temperature and low machining efficiency during the grinding process of nickel-based superalloy, an internal cooling wheel (ICW) with the abrasive arranged in phyllotaxy was prepared to improve machined surface integrity and reduce grinding temperatures. Firstly, two sizes of ICW were designed, and the influence of abrasive particle arrangement on grinding performance was studied using the finite element method. Secondly, based on computational fluid dynamics methods, the finite element model of the grinding zone was established, and the influence of the size of the grinding wheel and the arrangement of abrasive on the heat transfer performance and flow characteristics of the grinding fluid in the grinding zone were investigated. In a specific range, small diameter wheel (SDW) with phyllotaxy arrangement shows advantages in heat transfer performance and fluid flow compared to large diameter wheel (LDW). Finally, the grinding test of Inconel 718 superalloy was studied. The result shows that compared with the ordered arrangement, the LDW and SDW with phyllotaxy arrangement both obtained lower grinding temperatures, decreased by 20.83% and 22.86%, and smaller surface roughness values, decreased by 30.07% and 33.94%. The SDW with a larger distribution angle can obtain lower grinding temperature and slightly better workpiece surface integrity. [ABSTRACT FROM AUTHOR]

The present paper describes an inverse analysis technique to obtain material flow stress law from experimental measurements of rolling torque. This was developed by coupling a mathematical model of rolling, able to predict rolling torque, with a mathematical optimizer which minimizes the difference between experimental values and model prediction in terms of torque using an objective function. It is known that FEM is able to well predict forming loads and material behavior in the rolling process with high accuracy. For this reason, numerical tests were performed using FEM in order to obtain rolling torque values in place of experimental measurements, to validate the developed strategy. [ABSTRACT FROM AUTHOR]

For large flexible parts with initial deformation, the springback deviation of a product often occurs with the release of the fixture constraints after assembly. Different final constraint states of product leads to different springback deformation. In order to solve the problem that the classical method of influence coefficient (CMIC) is single to the final constraint states of the product in the assembly deviation modeling of flexible parts, an improved method of influence coefficient (IMIC) based on unit displacement response is proposed in this paper, which can meet the assembly springback deviation analysis of the product under any final constraint states. On this basis, a modeling method of assembly deviation of large flexible parts is proposed, which can accurately and efficiently predict the assembly deviation of flexible parts with initial deformation. Through case comparison and analysis, the IMIC has the same calculation accuracy as the CMIC, and the analysis steps of deviation model based on the IMIC are reduced by 66.67% and the analysis time is shortened by 54.17%, which proves the efficiency of the method proposed in this paper. Compared with the CMIC, the method proposed in this paper is more applicable and universal. [ABSTRACT FROM AUTHOR]

How to choose appropriate tool parameters has always been a challenge in the cross-wedge rolling (CWR) process, as different tool parameters affect the instantaneous metal deformation pattern and effective strain, thereby affecting the geometric dimensions and mechanical properties of the formed workpiece, especially for CWR steel balls with both radial and axial forming degrees of freedom. This paper proposed four novel forms of forming angle design for CWR dies and different sizes of spreading angles. The effect of different tool parameters on the deformation characteristics of CWR steel balls was analyzed using a combination of theoretical modeling and finite element (FE) simulation analysis. The analysis indicated that the axial deformation parameters increased linearly while the radial deformation parameters increased exponentially during the CWR process. The steel balls obtained from equal or small arc-forming angles had better roundness and filling than those obtained from fixed forming angle and large arc forming angle. When the forming angle is fixed, the larger the spreading angle, the more metal volume participates in deformation per unit time, and the more severe the deformation. Finally, tool parameters with a fixed forming angle of 30° and an equal arc forming angle, as well as a spreading angle of 8°, were selected for comparative experiments on steel balls forming. The experimental results indicated that the size accuracy of steel balls obtained by an equal arc-forming angle was relatively high, and a larger spreading angle could improve forming efficiency significantly, which verified the reliability of FE simulation simultaneously. [ABSTRACT FROM AUTHOR]

Aramid fiber–reinforced polymer composite (AFRPC) is popular in aerospace and defense industries owing to its superior thermal and mechanical properties. However, its intricate hexagonal cellular structure and the material's heterogeneous, soft, and brittle characteristics lead to significant surface defects, such as burr formation, wall tearing, roughness, dimensional inaccuracies, and uncut fibers during traditional machining. Such poor machining quality issues notably affect the operational lifespan and functional performance of its sandwich structural components. To address these issues, the rotary ultrasonic assisted machining (RUSAM) process has been introduced. To thoroughly investigate the RUSAM of AFRPC using various cutting tools, a 3D finite element model was developed and validated. This paper mainly investigates the effect of various machining parameters such as vibration amplitude (VA), cutting width (CW), feed rate (FR), and spindle speed (SS) on the cutting force, surface morphology, burr formation, and burr height during RUSAM of AFRPC structure by plane and toothed disc cutters. The burr height was found to decrease with the increase of spindle speed (60.82% and 71.00%) and vibration amplitude (78.15% and 82.32%), whereas increase with cutting width ( 149.81 % and 321.16%) and feed rate (156.53% and 314.83%) during RUSAM by plane and toothed disc cutters, respectively. The pattern of variation of burr height with machining parameters was found similar to that of the cutting force. Significance analysis based on 4 levels, 4 factors orthogonal L 16 ( 4 4 ) experiments revealed the cutting width to be the most influential parameter on the burr height and cutting force followed by the spindle speed, feed rate, and vibration amplitude during RUSAM of the AFRPC core by the disc cutters. Up to 62.54 % reduction in burr height was realized by rotary ultrasonic assisted machining compared to the conventional machining. Under specified operating conditions, the disc cutter generates a higher but less number of burr as compared to the toothed disc cutter without any tearing defects. 3–10% and 5–20% burrs were observed during rotary ultrasonic assisted machining compared to 20–50% and 40–70% burrs during conventional machining of AFRPC structure by plane and toothed disc cutters, respectively. This experimental research will be extremely useful to comprehend the burr formation mechanism and optimize the machining parameters for enhanced surface morphology of AFRPC structures. [ABSTRACT FROM AUTHOR]

Carbon fiber-reinforced polymer Please check Affiliations if captured/presented correctly.(CFRP) composites are essential in aerospace, automotive, and civil engineering due to their strength-to-weight ratio, stiffness, thermal stability, and corrosion resistance. However, drilling CFRPs is challenging due to anisotropy, heterogeneity, and sensitivity to cutting forces, often causing delamination, burr formation, tearing surface ca[vities, and roughness. This review examines advancements in drilling techniques, analyzing their mechanisms, benefits, and limitations to improve hole quality and minimize damage. Finite element modeling (FEM) plays a crucial role in optimizing drilling by predicting thrust forces, torques, and damage, with recent advancements enhancing damage reduction. The review explores the influence of drilling parameters on thrust force, torque, temperature, and various damage types in CFRP composites. This review proposes strategies to optimize these parameters, including tool geometries, deburring techniques, pilot holes, and variable feed rates, while emphasizing sustainability for environmental and efficiency benefits. It analyzes research shortcomings, outlines future directions, and focuses on sustainable methods like cryogenic cooling, MQL, and compressed air cooling to reduce energy use, tool wear, and emissions. Future research should reveal the mapping mechanism between these parameters and CFRP hole-making quality, proposing an optimized, sustainable drilling strategy to reduce defects and improve hole quality. [ABSTRACT FROM AUTHOR]

In this paper, the effect of heat input on the temperature of bobbin tool friction stir welding (BT-FSW) joint in 16-mm-thickness 6061-T6 aluminum alloy plate is investigated by means of COMSOL Multiphysics 5.6 multi-physics field simulation software and K-sheathed thermocouple. Furthermore, the effect of heat input on the microstructure and mechanical properties of the joint is explored through the use of confocal laser scanning microscope (CLSM), electron back scatter diffraction (EBSD), and hardness and tensile measurements. The thermal impact factor (f) is regarded as a representation of heat input, and the experimental results show that when the f-value increases from 1.5 to 2.5, the simulated peak temperature increases from 426.85 to 467.85 °C, and the simulated temperature is higher about 10℃ than the measured temperature. Hole-type defects are observed at the junction of advancing side (AS) thermal-mechanically affected zone (TMAZ) and stirred zone (SZ) of the joint when f-value is 2, and the size of the defect increases when f-value is 2.5. The average grain size and the degree of recrystallization of SZ increase, but the dislocation density decreases as the f-value increases. Comparing the microhardness curves of the three groups of joints, it is found that the microhardness of each region decreases with the increase of f-value, with the microhardness of SZ decreasing from 88 to 72 HV. The tensile strength of the joints decreases from 225 to 199 MPa, the elongation increases from 8.33 to 10.32%, and the fracture morphology changes from equiaxial dimple to parabolic dimple. [ABSTRACT FROM AUTHOR]

During manufacturing of a solid oxide cell stack, tolerances on the metallic interconnects affect contact pressure distribution in the active area, which is known to influence electrical contact resistance. Finite Element Methods may be used to analyze the effects of these tolerances, however, due to complex interconnect designs and large number of contacts in a stack, such simulations are computationally expensive. In this work, with an aim to reduce computational cost, the homogenization approach is investigated for thermal expansion and relaxation behavior on interconnect contacts during operation while considering their dimensional variability. This is achieved by designing a novel constitutive material model and implementing it into the finite element framework. The output of this model is then used to evaluate the contact resistance at the SOC contacts, creating a theoretical framework to determine contact losses in a stack considering tolerance distributions on the interconnect contacts. • Tolerances on interconnects studied using homogenization approaches. • Constitutive equations representing tolerances as material properties. • Contact pressure at operational temperatures considering dimensional variability. • Effects of thermal expansion, temperature dependent moduli and creep/relaxation. • Finite element approach to calculate contact resistance at interconnect. [ABSTRACT FROM AUTHOR]

The design of a helicopter is an intricate and challenging process. Decisions made during the preliminary design phase can significantly impact subsequent design stages, making it crucial to base these decisions on a solid foundation. A range of methods, including hand calculations, finite element analyses, and experimental tests, can be employed to establish the conceptual design parameters. However, these methods often come with the drawbacks of being time-intensive and costly, especially when testing various structures during the early design phase. To address this issue, this study introduces an artificial neural network-based design tool to evaluate the static structural characteristics of a helicopter's horizontal stabilizer. The tool was built in Python using the Keras library. The required database for the training of the artificial neural network model was established using finite element analyses of the horizontal stabilizer subjected to the aerodynamic load for diverse design variables. The model's performance was evaluated, and the model's outputs were compared to the results derived from the finite element analyses. Moreover, the Hammersley sampling methodology was employed to reduce the size of the database without compromising on accuracy. The study also assessed the impact of decreasing the amount of data fed into the network model. [ABSTRACT FROM AUTHOR]

Volcanoes in extensional environments may show gradual subsidence over decades during quiescent periods, due to various processes such as magma withdrawal, cooling, contraction, plate spreading and viscoelastic response. If significant rheological anomalies reside in volcano roots, due to the presence of magma and hot rock, they can influence the style of deformation. We use Finite Element Method (FEM) models to explore how strain localization due to extension can lead to volcano deflation. We apply rheological models comprising an elastic layer overlying a viscoelastic domain and include local up‐doming regions of low viscosity material beneath volcanic centers. The models reveal a localized subsidence above the rheological anomaly, influenced by the tectonic extension, and by the up‐doming volume and its viscosity. The models suggest that plate divergence may account for 4–5 mm/yr of observed subsidence at Krafla and Askja volcanic systems (KVS and AVS, respectively) in North Iceland. Plain Language Summary: Extensional stretching may have an important effect on the ground deformation observed at volcanic systems located along a divergent boundary. The physical properties of the crust are altered by the presence of hot material and/or geothermal activity at central volcanoes, compared to the surrounding rocks. We use a two‐layer model consisting of an elastic crustal volume overlying a viscoelastic layer, which locally reaches shallower depth (referred to up‐doming material), to investigate such crustal properties beneath volcanic systems. We explore a wide range of viscosity values in the up‐doming material and elastic layer thickness. The models, applied to investigate observed ground deformation at the Krafla and Askja volcanic systems, suggests that regional stretching with realistic material properties in the crust beneath the volcanic system, fits quite well the observed deformation satellite data at Krafla volcanic system in the 2015–2018 observations, but only a minor contributor to the Askja deformation pattern in the same period. Our modeling approach suggests that any extensive magmatic system undergoing stretching should feature subsidence in relation to the presence of hot material/magma mush beneath volcanic systems. Key Points: Gradual deflation (mm to cm per year) over decades has been observed at the Krafla and Askja volcanic systems in IcelandNumerical models show that deflation is induced by stretching across volcanic systems and dependent on their crustal rheological anomaliesFor the 2015–2018 period, an extensional model can broadly explain observed deflation at Krafla, but only ∼25%−30% at the Askja caldera [ABSTRACT FROM AUTHOR]

We study experimentally and theoretically the influence of size effects and structural factors on the dielectric and ferroelectric properties of the dense ferroelectric composites. The composites have the form of the tape-casted films with 28 vol% of nanosized or submicron BaTiO 3 particles dispersed in the polyvinyl butyral. We measured and analyzed the temperature dependences of the capacitance and dielectric losses in the temperature range (−200 – +200)oC and frequency range (102–105) Hz. The nonmonotonic temperature dependences of dielectric permittivity of the studied composite films have a wide plateau-like maxima located between 80oС and 160oС, in contrast to the relatively sharp maximum near the Curie temperature (∼124oC) observed in the fine-grained and coarse-grained ceramics, sintered from the same nanosized or submicron BaTiO 3 particles at 1250oC. The shift of the dielectric permittivity and losses maxima (in more than 40oC) and their strong frequency dispersion do not agree with the behavior expected for the systems with a weak interaction between ferroelectric particles and a polymeric matrix. In contrast, we reveal the relaxor-like behavior of the composite dielectric response. To explain the observed results, we propose the analytical model, which considers the strong dipole-dipole cross-interaction of the BaTiO 3 particles in the dense nanocomposite. The analytical model is corroborated by the structural studies of the BaTiO 3 nanosized and submicron particles by X-ray phase analysis and static 137Ba NMR spectra, as well as by the finite element modelling of the composite polar properties, which confirms the strong cross-interactions between the dipole moments of single-domain nanoparticles and/or between the domain walls of different submicron polydomain particles. The obtained results may be useful for development of cheap and flexible lead-free dense ferroelectric nanocomposites with relaxor-like behavior of the dielectric response, which are promising for non-volatile memory and energy-saving elements, modulators, electrical converters and piezoresistive elements. [ABSTRACT FROM AUTHOR]

Dispersant is critical in the ceramic vat photopolymerization (VP) due to its decisive impact on ceramic particle dispersion and suspension stability. However, the mechanisms by which dispersants influence photopolymerization of suspension remain underexplored. In this paper, the effects of the dispersants' refractive index and absorption coefficient on the light intensity distribution within suspension was investigated using a finite element method (FEM) simulation. The results indicate that the absorption coefficient is the primary influencing factor; as the absorption coefficient increases, the light transmittance of the suspension significantly decreases. Additionally, the photopolymerization performances of Al 2 O 3 ceramic suspensions formulated with different dispersants were investigated. We found the mechanisms by which dispersants influence photopolymerization behavior: by affecting light absorption through absorption coefficient and by directly impacting the polymerization reaction through functional groups. The study successfully achieved VP 3D printing of high-precision ceramic architectures with micron-sized features via dispersant optimization. This paper provided a new insight into optimizing fabricating resolution in ceramics VP 3D printing. [ABSTRACT FROM AUTHOR]

Background: While measuring meniscal extrusion quantitatively is an early risk factor for knee osteoarthritis (KOA), the biomechanics involved in this process are not well understood. This study aimed to investigate the effects of varying degrees of medial and lateral meniscal extrusion and their material softening on knee osteoarthritis progression. Methods: Finite element analysis (FEA) was utilized to simulate varying degrees of meniscal extrusion (1–5 mm) in 72 knee joint models, representing progressive meniscal degeneration and material softening due to injury. Changes in von Mises stress of the cartilage and menisci and the load distribution on the tibial plateau's meniscus and cartilage were studied under balanced standing posture in both healthy and injured knees, and statistical analysis was performed using Spearman correlation. Results: Compared to healthy knees, peak stress in medial compartment tissues increased by over 40% with 4 mm of medial meniscus extrusion, and in lateral compartment tissues with 2 mm of lateral meniscus extrusion. Meniscus extrusion reduced the contact load between the meniscus and femoral cartilage but increased it between the tibial and femoral cartilages, with a maximum increase up to fivefold. Spearman correlation analysis indicated that meniscal extrusion significantly affected peak stress and contact loads in the respective knee compartment (p < 0.001), with a lesser impact on the opposite compartment. Notably, medial meniscal extrusion also significantly increased peak stress in the lateral tibial cartilage (p < 0.05). Conclusions: The quantitative analysis revealed that meniscal extrusion significantly affected the biomechanics of soft tissues within the same compartment, with limited impact on the opposite side. Specifically, Medial extrusion beyond 4 mm significantly affected the biomechanics of the medial compartment, while lateral extrusion over 2 mm had a similar impact on the lateral compartment. Meniscal softening, without altering joint contact characteristics, primarily affected the biomechanics of the meniscus itself, with minimal impact on other soft tissues. [ABSTRACT FROM AUTHOR]

Highlights This paper propose a random fiber distribution generation algorithm based on lattice partition, which addresses the issue of limited increase in fiber volume fraction caused by the random movement of fibers in previous methods. By partitioning the representative volume element (RVE) window into lattices and moving fibers directionally, the proposed algorithm significantly increases the number of fibers within the RVE window. The generated fiber distribution achieves a fiber volume fraction of up to 80%, with an average execution time of 243.4 s. The influence of algorithm parameters on the randomness of fiber distribution is examined through statistical analysis of the generated distributions. Finite element models with various parameters are established to predict the elastic properties of the composites. The average relative error between the predicted values and the experimental results is 8.6%, demonstrating the effectiveness of the proposed algorithm. This algorithm offers a simple and effective approach for generating fiber distributions in the numerical study of the micromechanics of composites. A new lattice‐partition method is proposed to generate fiber distributions. The fiber volume fraction of generated fiber distribution is up to 80%. The randomness of fiber distribution is analyzed through statistical analysis. The algorithm predicts elastic properties with an average relative error of 8.6%. [ABSTRACT FROM AUTHOR]

Confined brick masonry structures have garnered considerable attention as an effective solution for earthquake-prone regions due to their robust construction, efficient wall-to-column connections, and optimised utilisation of material strength. Within the realm of building design and construction, openings play a pivotal role, serving as essential elements for facilitating natural light and fresh air into the structure. However, the presence of openings within confined brick masonry walls causes a significant reduction in their seismic resistance. Hence, striking the right balance between these openings and structural strength is crucial. For this purpose, it is necessary to investigate the influence of size, shape, and position of the openings in confined brick masonry walls on their seismic performance. In this work, a comprehensive finite element macro-model is adopted that treats the wall and tie members as a unified system. A concrete damage plasticity approach is employed to predict damage progression in confined brick masonry walls. Using a pushover analysis in finite element framework, the ultimate strength, stiffness, and energy absorption capacity of confined brick masonry with different types of openings is assessed. Furthermore, a parametric study is conducted incorporating various scenarios, such as aspect ratios of confined brick masonry walls, diverse shapes of opening and variations in the positions of windows, doors, and combinations of both openings. Based on the results, simplified equations are developed to facilitate analytical estimation of ultimate strength, along with recommendations for optimising opening shape, size, and placement to enhance the design of confined brick masonry walls with openings. The study highlights that larger openings in confined brick masonry walls diminish ultimate strength, stiffness, and energy dissipation due to reduced load distribution and increased stress concentrations. Openings smaller than 10% of the masonry area maintain load paths, but larger openings require additional support. Rectangular openings with greater height than width exhibit superior performance. Furthermore, the positioning of windows significantly influences wall strength, with placements farther from the loading point proving favorable. Door placement also impacts ultimate strength, with central placement compromising stiffness. Combining window openings with a centrally located door maintains consistent ultimate strength but affects stiffness. Overall, this research contributes to a better understanding of the seismic behaviour of confined brick masonry structures with openings, offering valuable insights for engineers and architects working in regions susceptible to seismic activity. [ABSTRACT FROM AUTHOR]

ABSTRACT A nonlinear variational auto‐encoder (NLVAE) is developed to reconstruct the plane strain stress field in a solid with embedded cracks subjected to uniaxial tension, uniaxial compression, and shear loading paths. Latent features are sampled from a skew‐normal distribution, which allows encoding marked variations of the features of the stress field across the load steps. The NLVAE is trained and tested based upon stress maps generated with the finite element method (FEM) with cohesive zone elements (CZEs). The NLVAE successfully captures stress concentrations that develop across the loading steps as a result of crack propagation, especially when enhanced disentanglement is emphasized during training. Some latent variables consistently emerge as significant across various microstructure descriptors and loading paths. Correlations observed between the evolution of fabric descriptors and that of their significant stress latent features indicate that the NLVAE can capture important microstructure transitions during the loading process. Crack connectivity, crack eccentricity, and the distribution of zones of highly connected opened cracks versus zones with no cracks are the fabric descriptors that best explain the sequences of latent features that are the most important for the reconstruction of the stress field. Notably, the distributional shape, tail behavior, and symmetry of microstructure descriptor distributions have more influence on the stress field than basic measures of central tendency and spread. [ABSTRACT FROM AUTHOR]

The mechanical properties of negative stiffness (NS) metamaterial could be customized and tuned in a wide range for various requirements, achieving programmable performances by the design from the aspect of structure and material. This work investigates the viscoelastic NS metamaterial based on double curved beams using a combined approach of experiments, simulations, and analytical modeling with an emphasis on multistage loading bearing and programmable energy absorption ability. Numerical simulations are first implemented based on the finite element models of three types of metamaterial cells, which provide comparisons of load bearing and energy absorption properties. Further, the effects of geometric parameters of multistage metamaterial element and the mechanisms are analyzed. An analytical discrete model is then innovatively developed to provide straightforward understandings of the geometric effects and reveal the role of viscoelasticity by examining the instantaneous loading responses and rate-dependent behaviors. Experimentally, we fabricate the metamaterial samples using 3D-printing technique and perform compression tests to validate the properties based on different boundary conditions, loading rates and cyclic loading and unloading. Results of this work show the potential of wide programmable room for mechanical properties through structure and functional material design, such as multistage load bearing capacity and energy absorption ability. [ABSTRACT FROM AUTHOR]

The scaled boundary finite element method (SBFEM) is implemented in ABAQUS through the user subroutine interface. The accuracy of the proposed method and computer program are verified by using two benchmark examples. With the coupled SBFEM and standard finite element method (FEM), the dynamic interaction model of concrete dam – reservoir – foundation considering the geometrical nonlinearity of transverse joints is established using the viscous-spring absorbing boundary conditions. The overlaying element technique is applied to define the contact interface of transverse joints. The dynamic characteristics and linear seismic response of the Koyna gravity dam have been analyzed using polyhedral elements. Finally, nonlinear seismic analysis of the NG5 arch dam has been conducted. The calculated results are in good agreement with those of ABAQUS built-in elements. Moreover, numerical examples demonstrate that proposed method has high computational accuracy and can be applied to the dynamic analysis of complex engineering structures. [ABSTRACT FROM AUTHOR]

This study uses the finite element method to investigate partially infilled reinforced concrete frames under monotonic loading. A FE model of a fully infilled frame was validated against an existing experimental model and was used for further study on partially infilled frames. The study analyzes fourteen models with varying infill heights and conducts a parametric study on infill strength and aspect ratio. Results show that partial infill improves initial lateral stiffness and strength, forming a single off-diagonal compression strut. An implied macro model for estimating initial lateral stiffness is proposed. Study found, stronger infill causes plastic deformation in the column. [ABSTRACT FROM AUTHOR]

Earthquake damage to engineering structures often occur in near-fault areas. Near-fault ground motion is characterized by high-energy velocity pulses, long action period, and strong destructiveness. This paper forces on the seismic analysis of a multi-tower super high-rise building that subjected to near-fault ground motions. The interactions between each tower makes the internal forces and dynamic responses much complex and totally different from single-tower super high-rise buildings. However, currently, multi-tower buildings in China are usually regarded as multiple single-tower buildings, and then separately designed based on the relevant provisions in seismic code for single-tower buildings. The mutual influence between the towers is almost not taken into account. Seismic response history analysis was carried on a three-tower super high-rise building using finite element method. Various near-fault and far-fault ground motions and high-energy velocity pulses were used as inputs. Through calculation of inter-story drift ratio and maximum displacement, the quantitative seismic fragility analysis was conducted for the main tower and sub-tower structures. The results show that the responses from near-fault ground motions to the structure are much greater than those from far-fault ground motions. The damage probabilities of various damage levels for near-fault ground motions are 12.5% higher than far-fault ground motions averagely. A further analysis reveals that the velocity pulses are the main factor causing structural damage in near-fault ground motions. [ABSTRACT FROM AUTHOR]

Skin flap transplantation is the most commonly used method to repair tissue defect and cover the wound. In clinic, finite element method is often used to design the pre-operation scheme of flap suture. However, the material parameters of skin flap are uncertain due to experimental errors and differences in body parts. How to consider the influence of material parameter uncertainty on the mechanical response of flap suture in the finite element modeling is an urgent problem to be solved at present. Therefore, the influence of material parameter uncertainty propagation in skin flap suture simulation was studied, Firstly, the geometric model of clinical patient's hand wound was constructed by using reverse modeling technology, the patient's three-dimensional wound was unfolded into a flat surface by using curved surface expansion method, yielding a preliminary design contour for the patient's transplant flap. Based on the acquired patient wound geometry model, the finite element model of flap suture with different fiber orientations and different sizes was constructed in Abaqus, and the uncertainty propagation analysis method based on Monte Carlo simulation combined with surrogate model technology was further used to analyze the stress response of flap suture considering the uncertainty of material parameters. Results showed that the overall stress value was relatively lower when the average fiber orientation was 45°. which could be used as the optimal direction for the flap excision. when the preliminary design contour of the flap was scaled down within 90%, the stress value after flap suturing remained within a safe range. [ABSTRACT FROM AUTHOR]

Diamond rope saws are one of the important tools for cutting large structures in deep water, and exploring their ability to remove steel materials is a prerequisite for improving cutting efficiency. In this paper, based on the observation results of an optical profilometer on the surface morphology of diamond beads, using statistical theory to analyse the data on the spatial parameters of abrasive grains, a method of three-dimensional digital characterisation of diamond beads based on the spatial description of the coordinate system of the column is proposed. Based on the above research, the theoretical models for material removal prediction and the finite element simulation model of diamond bead cutting steel material are established to analyse the removal ability of steel material under different cutting conditions with the synergistic effect of multiple abrasive grains in the process of diamond beads cutting steel material. Experiments were used to perform error analysis on the theoretical model, optimise the cutting parameters and correct the theoretical model for material removal. The results show that the cutting speed of 21 m/s and the feed speed of 1 mm/min resulted in a low theoretical and real removal error and less bead wear, which is favourable for continuous cutting. This current work provides a theoretical basis for the intelligent monitoring of the cutting process state of underwater diamond rope saws. [ABSTRACT FROM AUTHOR]

B4C particle-reinforced Al matrix composite (B4Cp/Al) has excellent properties and is expected to become the mainstream of composites in the future. Due to the complex meso-structure of B4Cp/Al, this increases the difficulty of material precision machining. In addition, the current research on the PRMMCs generally focuses on SiCp/Al and the effects of machining parameters on cutting force and temperature, while the research on the effects of tool geometry parameters on material cutting is relatively rare. Therefore, the cutting mechanism of B4Cp/Al is studied by finite element simulation. Firstly, based on the meso-structure of B4Cp/Al, a three-dimensional (3D) model of the material is established. Then the mechanism of surface formation of B4Cp/Al was studied by combining cutting simulation and turning experiment. Use the simulation to study the effect of tool rake angle on material cutting surface quality. It was found that the removal mode of B4C particles, the residual stress in Al matrix after cutting, and the plastic deformation would be affected by the tool rake angle, thus affecting the cutting surface quality. After a comprehensive comparison, it is found that when the rake angle is − 5°, the cutting quality is the best. [ABSTRACT FROM AUTHOR]

ATI 718plus is a novel nickel-based high-temperature alloy that delivers superior mechanical properties and higher working temperatures compared to the In718 superalloy. In order to study the machinability of ATI 718plus, a combination of experiments and finite element simulation is used to explore the mechanism of serrated chip formation and the evolution of microstructure under high-speed cutting conditions. Firstly, the Johnson-Cook constitutive model parameters of the ATI 718plus alloy were obtained through a split Hopkinson pressure bar experiment. Secondly, we established a 2D orthogonal cutting model on the AdvantEdge FEM platform by implementing the Johnson-Cook constitutive model and damage model via a custom subroutine. Through the comparison of orthogonal cutting experimental data and finite element simulation results, we verified the accuracy of the finite element model and analyzed the mechanism of serrated chip formation. Finally, combining the multi-physics field distribution of different parameters from the finite element simulation and EBSD test results, it is revealed that the microstructural evolution mechanism during the high-speed cutting of ATI 718plus involves grain lamellar refinement induced by CDRX and grain growth induced by DDRX. The interaction of these two processes results in different forms of microstructures. Under specific cutting parameters, a superfine grain layer with a thickness of 10 µm was formed on the machined surface, which holds great referential significance for our control and improvement of the surface properties in cutting machining. [ABSTRACT FROM AUTHOR]

The machine tool spindle supported by oil-lubricated hydrostatic bearings suffers from high temperature rise when running at high speed. To overcome this issue, an improved motorized spindle supported by water-lubricated hydrodynamic spiral groove bearings is proposed in this study. The thermal model for the motorized spindle including heat generation model and heat dissipation model is established by aid of finite element method. A test prototype for the motorized spindle and an experimental device are developed to carry out the test study of the spindle thermal behavior. The temperature field and thermal deformation field of the motorized spindle are investigated by numerical simulation and experimental measurement. Finally, a comparative study is made from the thermal behavior of the proposed spindle with herringbone groove journal bearings (HGJB) and the replacement spindle with plain journal bearings (PJB), and a comparative study of HGJB lubricated by the water and by the oil is carried out. The result indicates that using the water-lubricated hydrodynamic spiral groove bearings can decrease the temperature rise of motorized spindle, and the thermal design for the proposed motorized spindle can reduce the axial thermal displacement of the spindle front end to a low level. [ABSTRACT FROM AUTHOR]

The behavior of materials under high strain rates is pivotal to their deformation during machining processes. This research focuses on numerical modeling of the dynamic behavior of aluminum alloys (AA) 7075-T6 in dry turning operation. The Johnson–Cook (J-C) constitutive equation and coefficients derived from the split-Hopkinson pressure bar (SHPB) and uniaxial tensile tests were used in numerical simulations based on finite element (FE). Numerical models were validated under different machining conditions. The numerical and experimental studies revealed the significant impact of the feed rate on the alloy's behavior, chip thickness, and chip morphology. The work confirmed that increasing the cutting speed and feed rate led to higher machining temperatures. The lowest amounts of built-up layer (BUL) and built-up edge (BUE) were observed at high cutting speed and feed rate levels. The minimum surface roughness was recorded at low feed rates and high cutting speeds. The experimental results adequately confirmed the accuracy of the FE simulations. This research indicates that strain rate hardening significantly affects AA 7075-T6 and substantially increases strength as the strain rate increases. The results of the machining simulation validated the appropriateness of the J-C damage parameters used for the material. [ABSTRACT FROM AUTHOR]

In the present work, a thermographic procedure to evaluate in-plane thermal diffusivity and parallel finite element method were applied to a metal matrix composite layer. The observed coatings were realized with copper and graphene. Graphene application is more interesting in various fields, but this innovative technology shows various issues of application like the cluster formation that reduces mechanical and physic properties of coating. In this work, the application of graphene can be made with electrodeposition, and a matrix of copper was obtained with subsequent electrodeposition processes. This innovative methodology allows to avoid the issue of cluster formation and increases the amount of graphene in the final layer. In addition, the implementation of multi-coating increases thermal diffusivity by up to 65% obtaining results difficult to reach with a single layer of graphene. In addition, a FEA simulation was carried out to observe the compliance of the numerical method aimed at predicting the thermal properties of the obtained composite. [ABSTRACT FROM AUTHOR]

Within the manufacturing industry, hole flanging is an essential process for forming local features in sheet metal. To enhance the flanging height, the diameter of the prefabricated hole should be reduced. However, the undersized diameter of the hole may result in a crack during the flanging process. Combining the electropermanent magnet (EPM) technique with the stamping process, a composite flanging method with incremental feed is proposed to improve sheet forming performance based on the superposition principle of magnetic circuits. Through a symmetric flanging model, the thickness distribution, contour, and forming height of flanging zones are simulated, measured, and found to be reasonably consistent with related theories. The results show that the built model is suitable for investigating flanging deformation behavior. Flanging processing was performed on 304 stainless steel plates with various laser cutting predrilled hole radii. Under various increment rates, the flanging inclination angle is measured and compared through finite element method (FEM) and experiment. Furthermore, when the plate thickness ratio to the prefabricated hole diameter is 0.11, the limit circular hole flanging coefficient can reach 2.22, which is an improvement of 4.83% compared to the traditional flanging process. [ABSTRACT FROM AUTHOR]

Helical milling is widely used in aerospace as a key processing technology for Carbon fiber reinforced polymer (CFRP). However, the eccentric machining characteristics lead to an unusually complex pattern of cutting force and residual stress distribution on the work-piece during helical milling processing. Based on the Hashin failure criterion, a 3D FEM model of CFRP helical milling was built for analyzing the changing law of cutting force, then the three factors and three levels orthogonal tests were used to investigate the influence of machining parameters on the axial force, radial force, and minimum principal residual stress, finally, the multi-objective optimization based on grey correlation analysis was realized. The results showed that the errors of axial force and radial force obtained by simulation and experiment were 10.68% and 12.26%, respectively. The axial force and radial force were negatively correlated to the spindle speed, positively correlated to the axial cutting depth, and uncorrelated to the feed per tooth. The minimum principal residual stress was negatively correlated to the spindle speed, positively correlated to the feed per tooth, and uncorrelated to the axial cutting depth. The degree of influence on optimization of machining parameters was: spindle speed > axial cutting depth > feed per tooth. The corresponding average grey correlation degree differences were 0.280981, 0.216859, and 0.013422, respectively. The maximum value of grey correlation degree in the orthogonal test was 0.874372, and the corresponding optimal parameters combination was the spindle speed 8000 r/min, feed per tooth 0.03 mm/z, and axial cutting depth 0.2 mm/r. [ABSTRACT FROM AUTHOR]

The current study presents superposition‐based concurrent multiscale approaches for porodynamics, capable of capturing related physical phenomena, such as soil liquefaction and dynamic hydraulic fracture branching, across different spatial length scales. Two scenarios are considered: superposition of finite element discretizations with varying mesh densities, and superposition of peridynamics (PD) and finite element method (FEM) to handle discontinuities like strain localization and cracks. The approach decomposes the acceleration and the rate of change in pore water pressure into subdomain solutions approximated by different models, allowing high‐fidelity models to be used locally in regions of interest, such as crack tips or shear bands, without neglecting the far‐field influence represented by low‐fidelity models. The coupled stiffness, mass, compressibility, permeability, and damping matrices were derived based on the superposition‐based current multiscale framework. The proposed FEM‐FEM porodynamic coupling approach was validated against analytical or numerical solutions for one‐ and two‐dimensional dynamic consolidation problems. The PD‐FEM porodynamic coupling model was applied to scenarios like soil liquefaction‐induced shear strain accumulation near a low‐permeability interlayer in a layered deposit and dynamic hydraulic fracturing branching. It has been shown that the coupled porodynamic model offers modeling flexibility and efficiency by taking advantage of FEM in modeling complex domains and the PD ability to resolve discontinuities. [ABSTRACT FROM AUTHOR]

A new failure criterion has been developed to improve modeling of orthotropic structural composites subjected to quasi-static and impact loadings. Rather than using an analytical expression that traditionally has been employed to predict failure, a point cloud failure surface is constructed in the stress/strain space using a combination of virtual and laboratory testing. These discrete points are obtained by building a micromechanical model that is subjected to uniaxial and multiaxial states of stress until the first failure of a finite element in the model is detected. The post-peak response behavior is then activated till the element meets the erosion criterion and is deleted from the model. One of the challenges in using the generated point cloud data is the ability to correctly predict when failure onset in a finite element takes place without being too conservative. Three predictive methods are compared in this paper – Approximate Nearest Neighbor (ANN), Simplified Approximate Nearest Neighbor (SANN), and Neural Network (NN). Point cloud data from a unidirectional composite, the T800-F3900, commonly used for aerospace applications, is used for comparative evaluation of these methods. The performances are first evaluated using a standalone program not connected with FE analysis. Finally, two of these methods (SANN and NN) are implemented in a commercial finite element program, LS-DYNA, and their performances are evaluated by simulating a laboratory impact test. Results indicate that the SANN and NN implementations are robust, efficient, and accurate. [ABSTRACT FROM AUTHOR]

This study investigated the thermomechanical behavior of an alumina calciner's lining, a critical component in alumina processing, often susceptible to maintenance issues arising from refractory failure due to erosion and cracking. Based on numerical analyses via the finite element method, the design of a refractory panel was modeled. Furthermore, the influence of geometric parameters and friction level between lining layers on the thermal and mechanical behavior of the system was evaluated. Key findings highlighted how the curvature changed the stress profiles, resulting in particular cracking patterns, where curved panels showed higher stress concentrations at the center of their edges. Empirical validation through in-situ crack pattern observations further validated the model's predictive capability. Additionally, the study evaluated the influence of friction coefficients on resulting stresses, showing their small effect relative to other factors. Analyses on design parameters indicated that stress levels generally increased with the size-to-thickness ratio, highlighting the trade-off between reducing installation time and ensuring structural integrity in panel design and application. An alternative for enhancing lining performance was explored by selecting the material, where decreasing the insulating thermal conductivity reduced the likelihood of failure of the castable layer. Ultimately, the computational numerical method developed in this study offers a robust framework for exploring various geometries and materials, providing engineers with a versatile tool for optimizing lining designs in various operational scenarios. • Panel curvature influenced stress distributions and cracking patterns in calciner linings. • Friction modestly affected tensile stresses; 0.5 is reasonable for simulations. • Stress levels increased with panel size-to-thickness ratio, affecting installation efficiency. • Lower insulating thermal conductivity reduced failure risk in the castable layer. • The developed method provides a framework for exploring various geometries and scenarios. [ABSTRACT FROM AUTHOR]

In order to study the dynamic response of high-speed railway bridge and its deformation law under the coupling effect of vibration load and shield tunneling, a coupling model of shield tunneling and train load is established based on the actual case of tunneling under an adjacent bridge. The deformation characteristics and dynamic response of the bridge are investigated by analyzing the deformation under different tunneling conditions and train running speeds. The results show that the maximum disturbance of the original stress field around the bridge is caused when the shield penetrates to the near side of the bridge structure, at which time, the damping effect of the ground and bridge system on the vibration load is weakened, thus intensifying the dynamic response of the bridge system, and the additional deformation caused by the vibration load is the largest; the presence of train loads during the shield excavation slightly attenuates the differential settlement of the bridge, but increases the cumulative settlement of the bridge, in addition, the additional deformation of the bridge will increase with the increase of the train running speed; the additional deformation caused by the train load within 2 m of the shield crossing on both sides of the bridge is large, so the construction should be avoided as much as possible when the train is running in this construction section. [ABSTRACT FROM AUTHOR]

With the rapid development of cities, metro transportation has also developed rapidly to solve the congestion problems caused by urban development. However, with the continuous development of metro transportation, the vibration problems caused by it have become increasingly obvious. Based on the phonon crystal theory, this paper investigates the vibration characteristics of the metro track structure. It analyzes the influence of the track structure parameters on the band gap characteristics to regulate the metro vibration band gap range. To study the band gap characteristics of metro monolithic bed track structure, establish the double-layer Euler beam model and use the plane wave expansion method (PWE) to calculate its energy band structure; use the finite element method (FEM) to calculate to get its band structure, frequency response function, and time domain analysis. The calculation of PWE shows that there is a band gap in the range of 0–300 Hz for the metro monolithic track bed, which is 0–194.5 Hz; the calculation of FEM shows that the range of band gap is 0–193.7 Hz. Fastening spacing, stiffness, and sub-slab support stiffness will have an impact on the band gap, so appropriate fastening and spacing need to be selected for effective vibration damping of the track structure. The results show that the band gap characteristics of the metro monolithic track bed can be calculated effectively and accurately by using the phononic crystal theory. [ABSTRACT FROM AUTHOR]