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Research on evaluating highway bridge performance through vehicle-bridge interaction (VBI) analysis has made significant advancements. However, when assessing driving comfort, using vehicle acceleration instead of human acceleration poses challenges in accurately representing comfort. First, the paper proposes a finite element analysis method for human-vehicle-bridge spatial interactions (HVBSIs). Then, the importance of wheel path roughness difference is explored when assessing driving comfort. Furthermore, a new method for evaluating driving comfort that includes human and vehicle vibration responses has been proposed, and a simulation example of the steel-concrete composite beam bridge (SCCBB) is used to verify the effectiveness of the proposed method. The results demonstrate that the HVBSI analysis method effectively simulates the interconnected vibrations of the human body, the spatial vehicle model, and the three-dimensional (3D) bridge model. Differences in wheel path roughness significantly impact the roll vehicle vibration responses, which are crucial in driving comfort analysis. The driver's body vibration response is essential for evaluating driving comfort, and its inclusion leads to increased comfort indices values. In comparison to traditional methods, the overall vibration total value (OVTV) increases by a maximum of 109.04%, and the level of weighted vibration ( L e q ) increases by a maximum of 6.74%. This leads to an upgrade from grade IV to grade V in terms of comfort level, indicating a reduced comfort. [ABSTRACT FROM AUTHOR]

For the rolling process from rectangular blank to profiled ring, there is a lack of simple and rapid prediction method for geometric size. Based on the constant volume principle and the discrete idea from slab method, a rapid prediction model (RPM) describing the exact geometry of ring is established, and a simplified prediction formula for the section shape of profiled ring in the rolling filling process is proposed. This method is used to analyze the rolling process of typical profiled ring, and the results are compared with the rolling experiment, the finite element model (FEM), and the formula model (FM). The results show that this method has higher prediction accuracy than the constant volume formula method and higher calculation efficiency than the finite element method. The rapid prediction method proposed in this paper is of great significance for improving the analytical efficiency of profiled ring rolling. [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 0–300Hz for the metro monolithic track bed, which is 0–194.5Hz; the calculation of FEM shows that the range of band gap is 0–193.7Hz. 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]

Recent progress in additive manufacturing, also known as 3D printing, has offered several benefits, including high geometrical freedom and the ability to create bioinspired structures with intricate details. Mantis shrimp can scrape the shells of prey molluscs with its hammer-shaped stick, while beetles have highly adapted forewings that are lightweight, tough, and strong. This paper introduces a design approach for bioinspired lattice structures by mimicking the internal microstructures of a beetle's forewing, a mantis shrimp's shell, and a mantis shrimp's dactyl club, with improved mechanical properties. Finite element analysis (FEA) and experimental characterisation of 3D printed polylactic acid (PLA) samples with bioinspired structures were performed to determine their compression and impact properties. The results showed that designing a bioinspired lattice with unit cells parallel to the load direction improved quasi-static compressive performance, among other lattice structures. The gyroid honeycomb lattice design of the insect forewings and mantis shrimp dactyl clubs outperformed the gyroid honeycomb design of the mantis shrimp shell, with improvements in ultimate mechanical strength, Young's modulus, and drop weight impact. On the other hand, hybrid designs created by merging two different designs reduced bending deformation to control collapse during drop weight impact. This work holds promise for the development of bioinspired lattices employing designs with improved properties, which can have potential implications for lightweight high-performance applications. [ABSTRACT FROM AUTHOR]

The advantages of adjustable angle phase-shifting and great expansibility make the linear phase-shifting transformer a novel type of power conversion device with a wide range of potential applications. However, during the procedure, there is a lot of noise. For the purposes of transformer design and vibration and noise reduction, it is crucial to investigate its electromagnetic vibration and noise. In this paper, the radial electromagnetic force wave considering the influence of the end effect as the source of the noise of the linear phase-shifting transformer was deduced and calculated. Based on this, the spectrum and space–time properties of the radial electromagnetic force waves were simulated and verified. Additionally, a finite element model was created using the Ansys Workbench 2022R1 platform to study the electromagnetic vibration and noise of the linear phase-shifting transformer. A joint simulation of the electromagnetic, structural, and sound fields was then performed. First, the transformer's natural frequency was determined by modal analysis. After that, the transformer's structure and the results of the transient electromagnetic field computation were combined and a harmonic response analysis was conducted to determine the vibration acceleration spectrum. Finally, in order to solve the sound pressure field, the transformer's boundary vibration acceleration was coupled to the air domain. Furthermore, an analysis was conducted to determine the noise distribution surrounding the linear phase-shifting transformer. The joint simulation findings demonstrate that the linear phase-shifting transformer's resonance, which produces larger electromagnetic vibration and noise, is indeed caused by the radial electromagnetic force. Simultaneously, the impact of the LPST core's fixed components on the electromagnetic vibration and noise of the core was examined. [ABSTRACT FROM AUTHOR]

Timely wear evaluation is crucial in maintaining the functionality of bridge expansion joints (BEJs), ultimately ensuring the safety of bridges. Despite the significance of traffic load simulation (TLS) in simulation-based evaluation methods, existing TLS approaches face challenges in accurately modeling in situ traffic flow at a high fidelity. This paper presents a novel methodology and its application for evaluating the wear performance of BEJs, employing a Transformer-enhanced TLS approach. Initially, a tailored dataset is crafted for data-driven car-following modeling, leveraging an established spatial-temporal traffic load monitoring system. High-fidelity TLS with a mean absolute error (MAE) of 0.1738 m/s is then achieved using Transformer modules equipped with an attention mechanism. To evaluate the final wear life of BEJs, transient dynamic analysis and a calibrated finite element model of the bridge are employed to extract cumulative displacement. Additionally, a surrogate model is developed to depict the relationship between the hourly traffic weight on the entire bridge deck and the cumulative displacement of BEJs, yielding an impressive R-squared value of 0.96619. Comparative results demonstrate the superior performance of our proposed TLS approach over other data-driven approaches, with the linear model derived from our TLS approach outperforming the model generated by the conventional Monte Carlo-based TLS approach. To conclude, our proposed TLS emerges as a comprehensive and precise methodology for the wear evaluation of BEJs. [ABSTRACT FROM AUTHOR]

Transmission error (TE) is a significant parameter related to gears vibration widely investigated by many authors using different approaches. However, in previous studies, spur and helical gears were mainly examined. There is a lack of studies addressed to double helical and herringbone gears and a comparison among several types of gearing with parallel axes. In this paper, spur, helical, double helical, and herringbone gears are analyzed in terms of static transmission error (STE), contact pressure and tooth root stress. Static contact analyses were conducted using the finite element method (FEM) which is often considered a tool for validating other methods and approaches. Moreover, three variants of boundary conditions of each gear type are introduced, including flexible shafts and the effect of a tip relief modification at sole gears, without shafts, was analyzed. In addition, a concept of a compact test rig intended for STE measurements at low loads was presented. The results have shown, among other things, significant influence of the shaft stiffness and boundary conditions on meshing characteristics. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of an open hole on the stability of a compressed laminated composite plate. The study was carried out in two ways: using experimental tests and numerical analysis. As a result of the experiment, the buckling form and path of the plate were recorded. The form of buckling was determined using the ARAMIS non-contact measurement system. The critical load value was determined from the working path using the approximation method. The experimental results were verified by numerical analysis based on the finite element method. FEM investigations were carried out in terms of a linear eigenproblem analysis. This allowed the bifurcation load and the corresponding buckling form of the numerical model of the plate to be determined. Investigating the effect of the hole in the compressed plate at a critical state showed high agreement between the proposed test methods. No clear effect of the hole size on the buckling of the plate was observed. In contrast, a clear effect of the hole on the critical load value was determined. The maximum decrease in the critical load value was 14%. The same decrease was observed for the stiffness of the post-critical characteristics. It was shown that the [45|−45|90|0]s composite plate had more than three times lower strength compared to [0|−45|45|90]s and [0|90|0|90]s. The novelty of this article is the development of a research methodology based on new interdisciplinary research methods for describing the influence of the central hole on the stability of compressed composite plates. The ABAQUS system was used for the numerical analysis. [ABSTRACT FROM AUTHOR]

Using metal additive manufacturing processes can make up for traditional forging technologies when forming complex-shaped parts. At the same time, metal additive manufacturing has a fast forming speed and excellent manufacturing flexibility, so it is widely used in the aerospace industry and other fields. The fatigue strength of metal additive manufacturing is related to the microstructure of the epitaxially grown columnar grains and crystallographic texture. The crystal plasticity finite element method is widely used in the numerical simulation of the microstructure and macro-mechanical response of materials, which provides a strengthening and toughening treatment and can reveal the inner rules of material deformation. This paper briefly introduces common metal additive manufacturing processes. In terms of additive manufacturing fatigue, crystal plasticity simulations are summarized and discussed with regard to several important influencing factors, such as the microstructure, defects, surface quality, and residual stress. [ABSTRACT FROM AUTHOR]

Despite the fact that there is an existing body of literature addressing the computation of Coupling Loss Factors (CLFs) via the Finite Element Method (FEM), no publications have sufficiently taken into account real structural joints in their approach. Previous research has focused on academic cases of trivial connections, rarely involving more than two steel plates. To enable Statistical Energy Analysis (SEA) on a real ship, a methodology for determining CLFs for non-trivial systems is proposed, considering realistic boundary conditions and irregularities that can occur in marine structures. Based on the method, a library of CLFs is created by selecting the tested connections to enable modelling of about 90% of the acoustic paths on an existing jack-up vessel. Boundary conditions were set by introducing spring elements with a stiffness calibrated to the type of connection and taking the adjacent structure into account. In previous works, CLFs were determined for basic connections of rectangular plates. The lack of scantling variations, ignoring discontinuities and only defining parallel edges in the considered models, lead to the overestimation of energy transmission in real structures. To consider the influence of the above, random deviations from the initial stiffness of the springs at individual edges and point restraints at random points are introduced in this paper. [ABSTRACT FROM AUTHOR]

Microwave-induced thermoacoustic imaging (MTI) has the advantages of high resolution, high contrast, non-ionization, and non-invasive. Recently, MTI was used in the field of breast cancer screening. In this paper, based on the finite element method (FEM) and COMSOL Multiphysics software, a three-dimensional breast cancer model suitable for exploring the MTI process is proposed to investigate the influence of Young's modulus (YM) of breast cancer tissue on MTI. It is found that the process of electromagnetic heating and initial pressure generation of the entire breast tissue is earlier in time than the thermal expansion process. Besides, compared with normal breast tissue, tumor tissue has a greater temperature rise, displacement, and pressure rise. In particular, YM of the tumor is related to the speed of thermal expansion. In particular, the larger the YM of the tumor is, the higher the heating and contraction frequency is, and the greater the maximum pressure is. Different Young's moduli correspond to different thermoacoustic signal spectra. In MTI, this study can be used to judge different degrees of breast cancer based on elastic imaging. In addition, this study is helpful in exploring the possibility of microwave-induced thermoacoustic elastic imaging (MTAE). [ABSTRACT FROM AUTHOR]

Vibrating flip-flow screens are widely employed in the deep screening processes of coal washing, solid waste treatment, metallurgy, and other fields, playing a crucial role in enhancing product quality and production efficiency. The screen surface and material movement of vibrating flip-flow screens are highly complex, and there is currently insufficient understanding of their screening mechanism, limiting further optimization and application. In this paper, the Discrete Element Method (DEM), Finite Element Method (FEM), and Multi-Body Dynamics (MBD) were integrated to establish a numerical coupling model for vibrating flip-flow screens, considering material loads, screen surface deformation, and screen machine dynamics. The Response Surface Method was utilized to analyze the significant impact of relative amplitude, tension amount, amplitude of driving screen frame, vibration frequency, and screen surface inclination on screening efficiency and material velocity. The results indicate that the most significant factor influencing the screening of flip-flow screens is the screen surface inclination. Based on a BP neural network, a five-degree-of-freedom inclination surrogate model for flip-flow screens was established. The whale algorithm was employed for multi-objective optimization of the surrogate model, resulting in a screen surface inclination distribution that meets the requirements of different operating conditions. [ABSTRACT FROM AUTHOR]

• Dynamic modelling of soft tissue deformation based on the dynamic model decomposition. • No prior knowledge of the system governing equation is required. • Construct a reduced-order model by extracting the essential features of the full model. This paper studies a new approach to dynamic modelling of soft tissue nonlinear deformation behavior based on dynamic model decomposition. This approach derives the deformation relationship between two continuous time points from correlated system snapshots. Subsequently, it constructs a reduced-order system by extracting most relevant information via thin-singular value decomposition to capture dynamic characteristics of the full-order deformation system. Unlike the existing methods which mainly rely on the establishment of complex constitutive equations for governing soft tissue deformation, the proposed method conducts tissue deformation directly from measured samples without involving constitutive governing equations. Simulation results show that the proposed method not only achieves real-time performance, but also sustains similar accuracy as the nonlinear finite element method. [ABSTRACT FROM AUTHOR]

This paper presents an effort to address urgent issues associated with semitruck platooning. The weigh-in-motion data were first examined to determine the characteristics of naturally formed semitruck platoons. A safety-based two-vehicle platoon model was then utilized to determine the critical headways for assessing the safety of semitruck platooning in various driving scenarios. The possibilities for passenger vehicles to cut into semitruck platoons were assessed using actual vehicle headway data. Finally, the potential impacts of semitruck platooning on typical interstate highway pavements were assessed using finite element analysis. Most semitruck platoons consist of two to three vehicles. An optimal platoon gap of 0.94 s was identified for connected and automated semitruck platooning. The potential impacts of truck platooning on concrete pavement were negligible for a platoon gap greater than 0.2 s. The maximum possible impact was less than 4% in terms of the service life reduction for interstate asphalt pavement. [ABSTRACT FROM AUTHOR]

This paper focuses on electromagnetic and loss analyses of an induction machine using the subdomain method. The proposed method derives an analytical solution for each subdomain using electromagnetic theory. On the basis of the derived analytical solution, electromagnetic performances are calculated and copper loss, iron loss, and rotor loss are derived. The validity of the proposed method was verified by comparing the analysis and loss analysis results with the finite element analysis results. In particular, the loss analysis results were input into an equivalent thermal analysis model, thermal analysis was performed, and the results were compared with those measured in the actual model. The reliability of the proposed method was verified through analysis and experimental results. [ABSTRACT FROM AUTHOR]

In this paper, an electromagnetic analysis method is proposed to improve force characteristics by using spring permanent magnets (PMs) along the axial and circumferential directions of a linear oscillatory generator (LOG). For accurate electromagnetic analysis, a detailed analysis model of the LOG is developed, and the governing equations of each subdomain are derived based on Maxwell's equations and electromagnetic theory. Analytical solutions of the magnetic vector potential in each subdomain are derived using boundary conditions. The reliability of the proposed method is verified through a comparison with the results of a two-dimensional finite element analysis (FEA). In particular, the force characteristics depending on the spring PM is effectively derived by considering the three-dimensional (3D) circumferential and axial end effects. The proposed analysis method is used to determine the thickness of spring PM that transforms the detent force of the LOG with the spring PM into restoring force. The reliability of the proposed analysis method is verified through comparison with the results of a 3D FEA. [ABSTRACT FROM AUTHOR]

In urban combat, sub-millimeter inert metal powder is used to replace fragments in explosive bombs, which can effectively reduce collateral damage. In order to investigate the damage effect of high-speed metal particles on the human body, a particle ring filled with a charge was designed to create an explosion-driven particle cloud for the penetration ballistic gelatin. The particle ring was made of polytetrafluoroethylene (PTFE) and sub-millimeter tungsten powder. The dispersion properties of the particle cloud driven by the explosion were studied with high-speed photography and ballistic gelatin. Furthermore, the numerical simulation models of particle-penetrating gelatin based on the experimental results were established with the finite element method. The influences of the particle size and velocity on the penetration depth and cavity diameter was obtained. The relationship between the critical interference distance of the cavity and the distance between particles was determined. This paper provides references and theoretical support for the design of low collateral damage ammunition based on inert metal powder. [ABSTRACT FROM AUTHOR]

This paper introduces the Julia programming language as a dynamic, cost-effective, and efficient framework for implementing structural analysis packages. To achieve this, the finite element method was implemented for plane frames addressing the elastic instability problem through the Finite Element Method (FEM). Julia is a language open source, multiplatform, high-level and high-performance for technical and scientific computing, its compiler allows you to achieve speeds comparable to languages such as C and FORTRAN, but with more productive development dynamics due to its programming flexibility. Benchmarks between Julia and MATLAB are employed to discuss the processing costs, the programming techniques and paradigms used for computational performance. The results demonstrate that Julia performed the same analysis as the language used for comparison in 88.40% of the time, in addition to the fact that in loops comparisons case it reached 41.7% of the time for iteration, confirming its significant potential as a development tool of computational packages for structural analysis and scientific computing in general. [ABSTRACT FROM AUTHOR]

In this paper, we construct a new two-grid algorithm of the finite element method for the Schrödinger equation in backward Euler and Crank–Nicolson fully discrete schemes. On the coarser grid, we solve coupled real and imaginary parts of the Schrödinger equation. On the fine grid, real and imaginary parts of the Schrödinger equation are decoupled, and we solve the elliptic equation about real and imaginary parts, respectively. Then, we obtain error estimates of the exact solution with the two-grid solution in the H 1 -norm and carry out two numerical experiments. [ABSTRACT FROM AUTHOR]

Surface integrity influences the material fatigue performance significantly, but most micromechanical models based on crystal plasticity only consider the microstructure of the matrix. In this paper, a crystal plastic finite element modeling method was proposed, which simultaneously considered surface roughness, residual stress, and gradual microstructure. It was verified through multiaxial fatigue experiments of materials processed by different multistage machining processes. The results show that larger axial residual compressive stress and smaller grain size can lead to higher multiaxial fatigue life. The existence of residual compressive stress causes the location of material crack initiation to decrease from the surface layer to the subsurface layer. The proposed model can predict the multiaxial fatigue life of materials within a 50% error band. Highlights: A crystal plasticity model considering surface integrity was established.The multiaxial fatigue life of turning specimens is higher than that of grinding.The residual compressive stress cause crack initiation at the subsurface layer.A fatigue life prediction method was proposed within a 50% error band. [ABSTRACT FROM AUTHOR]

In this paper, a dynamic interaction model of the coupled system of railway bridge, foundation, subsoil, ballast, track, and high-speed train is presented, with special emphasis on the longitudinal interaction between the track and the bridge structure, taking into account the flexibility of the ballast. After a description of the model of this interaction system, the equations of motion are given separately for each subsystem. The discretization of the bedded rails is performed by two different approaches. In the first approach, the deflection of the rails is expanded into the eigenfunctions of a finitely long bedded beam representing the rails. In the second, simplified approach, the track response is represented by a superposition of the static deflection of the infinitely long bedded beam due to a concentrated load. The coupling of the bridge structure with the track is achieved by a component mode synthesis technique, which in the first approach leads to a representation of the equations of motion in state-space. A discrete substructure technique is used to couple this subsystem with the train model. The two presented strategies are verified by comparison with results of a finite element model of this interaction system. Several application examples reveal the influence of the horizontal track–bridge interaction and other modeling parameters on the dynamic bridge response. [ABSTRACT FROM AUTHOR]

The identification of frequency zones where waves propagate freely (i.e., propagation zones) and where they are attenuated (i.e., attenuation zones) in a railway track, plays an important role in a number of applications, such as nondestructive testing, structure-borne noise prediction, and vibration control. This paper presents a numerical model based on the wave finite element method to study wave propagation and attenuation in periodic supported rails. The model involves postprocessing of element matrices of a rail span (i.e., rail segment between two supports), which is modeled using three-dimensional finite elements meshed through the cross section. The model uses solid elements to capture the complex cross-sectional deformation of the waves and considers the dimensions of the periodic supports. In order to obtain accurate results, the stiffness and the damping coefficients of the supports are calibrated through a finite element model updating procedure that utilizes the modal parameters and the attenuation coefficients obtained from experiments. The results demonstrate that the proposed model is capable of (i) capturing the classic vibrational modes (i.e., vertical and lateral bending), (ii) describing the complex cross-sectional deformation and the mode conversions, and (iii) obtaining the wave propagation and attenuation regions of periodic supported rails. [ABSTRACT FROM AUTHOR]

A flexure hinge composed of elliptical and hyperbolic hybrid configurations is developed and analyzed in this paper. The analytical models of compliance, rotation accuracy, and maximum stress of the flexure hinge are established, and the correctness of the models is validated by finite element analysis and experiments. The influence of structural parameters on compliance and rotation accuracy is discussed. The concept of compliance stress ratio is proposed to assess the deformation capacity of flexure hinges when subjected to the same stress, which provides a basis for quantitatively comparing the comprehensive performance of flexure hinges. The performance of the hybrid flexure hinge is compared with that of elliptical, hyperbolic, and circular flexure hinges by taking the compliance accuracy ratio and the compliance stress ratio as the performance evaluation indexes. The results show that the hybrid flexure hinge combines the advantages of hyperbolic and elliptical hinges and has a balanced performance in compliance, rotation accuracy, and low stress. The designed hybrid flexure hinge is suitable for the support structure of fast steering mirrors, which provides a valuable reference for the engineering optimization design of flexure hinges. [ABSTRACT FROM AUTHOR]

This paper presents a novel plasticity-based formulation for three-dimensional (3D) topology optimization of continuum structures. The proposed formulation addresses the optimization problem by combining mixed rigid-plastic analysis with density-based topology optimization, resulting in a volume minimization approach. Unlike conventional stress-constrained topology optimization methods that rely on linear elastic structural analysis, our developed formulation focuses on enhancing the loading capacity of the designed structures based on the plastic limit theory, leading to more cost-effective designs. To improve computational efficiency, we employ the smoothed finite element technique in our proposed method, enabling the utilization of linear tetrahedral elements for 3D mesh refinement. Moreover, the final formulation of our developed method can be efficiently solved using the advanced primal–dual interior point method, eliminating the need for a separate nonlinear finite element structural analysis. Numerical examples are presented to demonstrate the effectiveness of the proposed approach in offering enhanced design possibilities for continuum structures. [ABSTRACT FROM AUTHOR]

The deep drawing process of thick sheet metal for vessel production is carried out by applying a tractrix die with the absence of a blank holder, which has economic benefits for industrial production. The main aim of the paper is the development of a reliable numerical thermo-mechanical model of a silicon brass vessel manufactured by a deep drawing process in a tractrix die and a subsequent ironing process, which includes the previous assembly of the dies with reinforcing rings that creates the required prestresses. The testing of the mechanical properties of silicon brass CuZn24Si was carried out by a standard uniaxial tensile test, thus a flow curve was determined to describe the material behaviour. The initial temperatures of the environment, blank and tools were measured with an infrared thermal imager. A comprehensive finite element stress analysis of the deformable tools was carried out for the assembly phase of the dies, and for workpiece and tools in the deep drawing and ironing processes. The comparison of measured and numerically estimated temperatures had a good agreement, so the developed numerical model was confirmed and validated. This research study demonstrates how different process parameters can be investigated through a reliable and precise numerical model with complementary experimental research for the optimization of industrial technology. [ABSTRACT FROM AUTHOR]

This paper is concerned with a class of nonlinear multi-term time fractional wave equations. Based on the Galerkin finite element method (FEM) in space and the L 2- 1 σ formula in time, combined with the corresponding fast algorithm, an efficient fully discrete scheme is constructed. The unconditional optimal convergence property in H 1 -norm of the proposed scheme is discussed by utilizing the time-space splitting technique. Furthermore, the optimal L 2 -norm convergence and the H 1 -norm superconvergence results of the method are obtained. Finally, several illustrative numerical experiments are performed to verify the theoretical results. Compared with the existing works, studying the convergence of FEMs for the nonlinear fractional wave equation is a great challenging task, and there are significant differences in research approaches. [ABSTRACT FROM AUTHOR]

In this paper, we present a new error analysis of a class of charge-conservative finite element methods for stationary inductionless magnetohydrodynamics (MHD) equations. The methods use the standard inf-sup stable Mini/Taylor–Hood pairs to discretize the velocity and pressure, and the Raviart–Thomas face element for solving the current density. Due to the strong coupling of the system and the pollution of the lower-order Raviart–Thomas face approximation in analysis, the existing analysis is not optimal. In terms of a mixed Poisson projection and the corresponding estimate in negative norms, we establish new and optimal error estimates. In particular, we prove that the method with the lowest-order Raviart–Thomas face element and Mini element provides the optimal accuracy for the velocity in L 2 -norm, and the method with the lowest-order Raviart–Thomas face element and P 2 − P 1 Taylor-Hood element supplies the optimal accuracy for the velocity in H 1 -norm and the pressure in L 2 -norm. Furthermore, we propose a simple recovery technique to obtain a new numerical current density of one order higher accuracy by re-solving a mixed Poisson equation. Numerical results are provided to verify the theoretical analysis. • New and optimal error analysis of charge-conservative finite element methods are established. • A simple recovery technique is proposed to obtain a new current density with higher accuracy. • Numerical examples are provided to verify the theoretical findings. [ABSTRACT FROM AUTHOR]

We present an application of stable finite element (FE) approximations of convection-diffusion initial boundary value problems (IBVPs) using a weighted least squares FE method, the automatic variationally stable finite element (AVS-FE) method [1]. The transient convection-diffusion problem leads to issues in classical FE methods as the differential operator can be considered a singular perturbation in both space and time. The stability property of the AVS-FE method, allows us significant flexibility in the construction of FE approximations in both space and time. Thus, in this paper, we take two distinct approaches to the FE discretization of the convection-diffusion problem: i) considering a space-time approach in which the temporal discretization is established using finite elements, and i i) a method of lines approach in which we employ the AVS-FE method in space whereas the temporal domain is discretized using the generalized- α method. We also consider another space-time technique in which the temporal direction is partitioned, thereby leading to finite space-time "slices" in an attempt to reduce the computational cost of the space-time discretizations. We present numerical verifications for these approaches, including numerical asymptotic convergence studies highlighting optimal convergence properties. Furthermore, in the spirit of the discontinuous Petrov-Galerkin (DPG) method by Demkowicz and Gopalakrishnan [2–6] , the AVS-FE method also leads to readily available a posteriori error estimates through a Riesz representer of the residual of the AVS-FE approximations. Hence, the norm of the resulting local restrictions of these estimates serves as error indicators in both space and time for which we present multiple numerical verifications in mesh adaptive strategies. [ABSTRACT FROM AUTHOR]

Suspenders play a crucial role in transmitting loads from the bridge deck to the main cable in a suspension bridge. They are susceptible to fatigue due to repeated dynamic loads, particularly traffic loads. Traffic Load Models (TLMs), typically created using Monte–Carlo simulation and Weigh-In-Motion (WIM) data, are employed to evaluate this fatigue. However, these models often overlook practical vehicle trajectories and spatio-temporal distribution, which compromises the precision of fatigue assessments. In this study, we introduce a novel 2D Intelligent Driver Model (2D-IDM) that incorporates actual vehicle trajectories, with a particular focus on transverse vehicle movement. This enhancement aims to improve the fidelity of existing TLMs. To provide a clear, qualitative, and quantitative understanding of the effects of fatigue evaluation with or without actual trajectory characteristics, we have structured this paper as a comparative study. We compare our proposed model, denoted as TLM S-3, with two observation-based models (O-1 and O-2) and two simulation-based models (S-1 and S-2). We conducted an experimental case study on a long-span suspension bridge, where the actual traffic load trajectory was obtained using a WIM-Vision integrated system. To calculate fatigue damage considering both longitudinal and transverse directions, we established a multi-scale Finite Element Model (FEM) using solid element types to simulate the bridge girder. This model can generate the stress influence surface of the bridge and has been verified in both static and dynamic aspects. Our detailed comparative analysis demonstrates the consistency of the proposed 2D-IDM with the actual measured traffic load trajectories. This indicates that our approach can enhance the fidelity and precision of fatigue evaluations for bridge suspenders. [ABSTRACT FROM AUTHOR]

Aiming at the current low degree of mechanization of pomegranate sprouting tiller pruning in China, all relying on manual pruning, this paper designs a PLC-based pomegranate sprouting tiller removal machine. This machine adopts the identification method of wireless map transmission, the sprouting tiller removal method of multi-cylinder cooperative operation, and the MCGS configuration to realize the interaction between the user and the system, which realizes the displacement and angle compensation of the end-effector under complex conditions to realize the all-around accurate removal of the pomegranate sprouting tiller. The performance test and finite element analysis showed that the device could remove up to 74.62% of sprouting tillers, and the damage rate was as low as 18%. This meets the requirements of pomegranate plantations for the removal of emergent tillers. [ABSTRACT FROM AUTHOR]

The machining accuracy of CNC machine tools is significantly affected by the thermal deformation of the feed system. The ball screw feed system is extensively used as a transmission component in precise CNC machine tools, responsible for converting rotational motion into linear motion or converting torque into repetitive axial force. This study presents a multi-physical coupling analysis model for the ball screw feed system, considering internal thermal generation, intending to reduce the influence of screw-induced thermal deformation on machining accuracy. This model utilizes the Fourier thermal conduction law and the principle of energy conservation. By performing calculations, the thermal source and thermal transfer coefficient of the ball screw feed system are determined. Moreover, the thermal characteristics of the ball screw feed system are effectively analyzed through the utilization of finite element analysis. To validate the proposed analysis model for the ball screw feed system, a dedicated test platform is designed and constructed specifically to investigate the thermal characteristics of the ball screw feed system in CNC machine tools. By selecting specific CNC machine tools as the subjects of investigation, a comprehensive study is conducted on the thermal characteristics of the ball screw feed system. The analysis entails evaluating parameters like temperature field distribution, thermal deformation, thermal stress, and thermal equilibrium state of the ball screw feed system. By comparing the simulation results from the analysis model with the experimental test results, the study yields the following findings: The maximum absolute error between the simulated and experimental temperatures at each measuring point of the feed system components is 2.4°C, with a maximum relative error of 8.7%. The maximum absolute error between the simulated and experimental temperatures at the measuring point on the lead screw is 2.0°C, with a maximum relative error of 6.8%. The thermal characteristics obtained from the steady-state thermal analysis model of the feed system exhibit a prominent level of agreement with the experimental results. The research outcomes presented in this paper provide valuable insights for the development of ball screw feed systems and offer guidance for the thermal design of machine tools. [ABSTRACT FROM AUTHOR]

In light of the growing safety concerns associated with lithium-ion batteries integrated in electric automobiles, there is an escalating need to explore the mechanical behavior of lithium-ion batteries under diverse loading conditions using finite element simulations. In this paper, a homogenized finite element model was proposed to predict the material behavior of pouch lithium-ion cells using finite element simulations under various loading conditions. This homogenized model consisted of four layers of solid elements wrapped by shell elements, and it was made to consider especially the porosity and the pressure sensitivity of a pouch cell. The material properties of this homogenized model were calibrated based on the out-of-plane compression, in-plane confined compression, and 3-point bending test data for a single cell. The simulations using the model exhibited good agreement with the experimental load-displacement data not only for a single cell but also for two stacked cells. Additionally, the effects of the pouch and the vacuum on the mechanical behavior were examined. [ABSTRACT FROM AUTHOR]

This paper proposes an analytical model of the double-stator spoke-type permanent magnet vernier machine (DSSTVM) using the subdomain method (SDM), which can be used to calculate the magnetic field distribution and corresponding electromagnetic parameters of the DSSTVM. The whole field domain is divided into several subdomains according to the magnetic characteristics of each region, within which Laplace's and Poisson's equations are solved accordingly in terms of magnetic vector potential (MVP). Then, the corresponding magnetic flux density distribution, back electromotive force (EMF), and electromagnetic torque of the DSSTVM can be obtained. Ultimately, finite element analysis (FEA) is adopted to validate the proposed analytical model's effectiveness for quickly predicting the no-load and on-load performances of the DSSTVM. [ABSTRACT FROM AUTHOR]

This note presents the application of the mobilisable strength design (MSD) method to the monitoring results of the multi-propped excavation in the south area of the British Library Euston, constructed in a highly overconsolidated stiff clay deposit. The MSD method is an energy-based approach (a nonlinear finite-element method for a single-degree-of-freedom soil-wall system) introduced to develop a simplified design methodology that satisfies both ultimate and serviceability limit states. Wall displacement predictions based on the MSD method are compared with considerable field monitoring data. The sensitivity of the method to reasonable variations in input parameters is considered. A spreadsheet and python code demonstrating the MSD analysis from this paper are provided in the online supplement alongside details of the mathematical formulation. [ABSTRACT FROM AUTHOR]

Although the classical four-point probe method usually provides adequate results, it is in many cases inappropriate for the measurement of thin sheet resistance, especially in the case of a buried conductive layer or if the surface contacts are oxidized/degraded. The surface concentration of dislocation defects in GaN samples is known to challenge this kind of measurement. For the GaN sample presented in this study, it even totally impaired the ability of this method to even provide results without a prior deposition of gold metallic contact pads. In this paper, we demonstrate the benefits of using a new broadband multifrequency noncontact eddy current method to accurately measure the sheet resistance of a complicated-to-measure epitaxy-grown GaN-doped sample. The benefits of the eddy current method compared to the traditional four-point method are demonstrated. The multilayer-doped GaN sample is perfectly evaluated, which will allow further development applications in this field. The point spread function of the probe used for this noncontact method was also evaluated using a 3D finite element model using CST-Studio Suite simulation software 2020 and experimental measurements. [ABSTRACT FROM AUTHOR]

A suction bucket foundation is a new type offering high construction efficiency, precise positioning, cost-effectiveness, and environmental friendliness. It has been extensively employed in marine resource development, particularly in offshore wind power and oil and gas extraction. It usually involves multiple suction bucket conduit rack platforms during offshore construction projects. Accurately predicting the sinking penetration resistance and determining the suction value is crucial during the construction of the suction bucket foundation, as it ensures the safe sinking of the platform foundation to the designated depth. This paper examines the feasibility of the suction bucket foundation's sinking, sinking penetration resistance, suction value, and self-weight penetration depth, using the offshore wind farm guiding frame platform foundation project in Yangjiang, Guangdong Province, as a basis of analysis. The measured data is analyzed using the API specification static equilibrium analysis method, ABAQUS finite element analysis, and data mining techniques. The suction drum base platform's sinking process was monitored for negative pressure and penetration resistance. These observed values were compared to theoretical and finite element calculations. Results demonstrated that the API specification's theoretical calculations and finite element analyses effectively predict sinking penetration resistance, the suction force value, and the penetration depth for self-gravitational penetration. On-site engineering data fit these theoretical calculations, and finite element analyses well. The findings from this study have enriched the engineering application database of the suction drum foundation, providing a valuable reference for the design and construction of similar projects and establishing the groundwork for further promotion and application. [ABSTRACT FROM AUTHOR]

Additive Manufacturing (AM) processes are known as revolutionary manufacturing processes that fabricate a part using a 3D model layer upon layer. These techniques gained more attention from various industries due to their advantages like low waste material. Also, these processes can produce any part with high degrees of complexity in a short period of time. The Fused Deposition Modeling (FDM) process is a material extrusion-based technique which works by extruding a fine molten polymeric filament through a heated nozzle on the heated platform named printer bed. In this method, some important manufacturing parameters play a crucial role in controlling the mechanical properties and quality of the final fabricated part. However, all printed specimens through the FDM process should be tested based on the standards under some critical circumstances. Thus, in the current research paper, five and three test speeds are considered in tensile and fracture testing procedures, respectively to evaluate how these speeds can affect the mechanical and mode I fracture properties. Also, as the FDM specimens present elastic–plastic behavior, the critical value of J-integral is assumed as a fracture assessment and calculated from the finite element analysis. Among the mechanical properties, ultimate tensile strength is affected significantly by the test speed. For instance, the ultimate tensile strength of FDM specimens is 39.02, 38.58, 42.33, 48.09, and 52.11 for test speeds of 2, 4, 6, 8, and 10 mm/min, respectively. But vice-versa results are detected for the mode I fracture behavior and corresponding values of J for the FDM-PLA specimens. Finally, experimental and numerical results together with comprehensive discussions about the considered speeds and obtained results are reported. [ABSTRACT FROM AUTHOR]

Tooth flank fracture (TFF) and tooth interior fatigue fracture (TIFF) usually occur on case-harden gears in electromechanical coupling systems, both starting from the core caused by metal fatigue. The cracks propagate rapidly compared with the total life of a gear, so that it is necessary to detect and identify the faults in time when they take place in order to avoid danger. In this paper, the time-varying mesh stiffness model of two types of faults is established by the potential energy method and validating by the finite element method. Based on the stiffness model, the influence of faults on the electromechanical system and their fault characteristics are analyzed, which provides a theoretical basis for the health detection of electromechanical coupling systems. The results indicate that in the early stage of the three faults, i.e., tooth root fracture, tooth interior fatigue fracture, and tooth flank fracture, it is hard to discriminate the faults. But after the second stage, the faults can be distinguished by the vibration amplitude, frequency band components, and phase diagrams. The TFF can be discerned into different stages by frequency domains and phase diagrams. When the fracture occurs completely, three faults can be easily distinguished by the time domain and phase diagram. In the frequency domain, the TRF can also be distinguished from the other two faults by referring to the sideband component near the meshing frequency. [ABSTRACT FROM AUTHOR]

To maximize the capabilities of nano- and micro-class satellites, which are limited by their size, weight, and power, advancements in deployable mechanisms with a high deployable surface area to packaging volume ratio are necessary. Without progress in understanding the mechanics of high-strain materials and structures, the development of compact deployable mechanisms for this class of satellites would be difficult. This paper presents fabrication, experimental testing, and progressive failure modeling to study the deformation of an ultra-thin composite beam. The research study examines the deformation modes of a post-deployed boom under repetitive pure bending loads using a four-point bending setup and bending collapse failure under eccentric buckling. The material and fabrication challenges for ultra-thin, high-stiffness (UTHS) composite boom are discussed in detail. The continuum damage mechanics (CDM) model for the beam is calibrated using experimental coupon testing and was used for a finite element explicit analysis of the boom. It is shown that UTHS can sustain a bending radius of 14 mm without significant fiber and matrix damage. The finite element model accurately predicts the localized transverse fiber damage under eccentric buckling and buckling stiffness of 15.6 N/mm. The results of the bending simulation were found to closely match the experimental results, indicating that the simulation accurately shows deformation stages and predicts damage to the material. The findings of this research provide a better understanding of the structure characteristics with the progressive damage model of the UTHS boom, which can be used for designing a complex deployable payload for nano-micro-class satellites. [ABSTRACT FROM AUTHOR]

For photothermal therapy of cancer, it is necessary to find Ag @TiO2 core-shell nanoparticles that can freely tune the resonance wavelength within the near-infrared biological window. In this paper, the finite element method and the size-dependent refractive index of metal nanoparticles were used to theoretically investigate the effects of the core material, core length, core aspect ratio, shell thickness, refractive index of the surrounding medium, and the particle orientation on the light absorption properties of Ag@TiO2 core-shell nanospheroid and nanorod. The calculations show that the position and intensity of the light absorption resonance peaks can be freely tuned within the first and second biological windows by changing the above-mentioned parameters. Two laser wavelengths commonly used in photothermal therapy, 808 nm (first biological window) and 1064 nm (second biological window), were selected to optimize the core length and aspect ratio of Ag@TiO2 core-shell nanospheroid and nanorod. It was found that the optimized Ag@TiO2 core-shell nanospheroid has a stronger light absorption capacity at the laser wavelengths of 808 nm and 1064 nm. The optimized Ag@TiO2 core-shell nanoparticles can be used as ideal therapeutic agents in photothermal therapy. [ABSTRACT FROM AUTHOR]

The processing of dielectric materials in the radio frequency field continues to be a concern in engineering. This procedure involves a rigorous analysis of the electromagnetic field based on specific numerical methods. This paper presents an original method for analysing the process of drying wooden boards in a radio frequency (RF) installation. The electromagnetic field and thermal field are calculated using the finite element method (FEM). The load capacity of the installation is also calculated, since the material being heated in the radio frequency heating installations is placed in a capacitor-type applicator. A specific method is created in order to solve the problem related to mass, a quantity which tends to change during the drying of the dielectric. In addition, special consideration is given to issues regarding the coupling of the electromagnetic field and the thermal field, along with aspects pertaining to mass. These are implemented numerically using a program written in the Fortran language, which takes the distribution of finite elements from the Flux2D program, the dielectric thermal module, intended only for the study of RF heating. The results obtained after running the program are satisfactory and they represent a support for future studies, especially if the movement of the dielectric is taken into account. [ABSTRACT FROM AUTHOR]

Cold hole expansion is a crucial technology for enhancing the fatigue life of hole structures. This paper presents the design and optimization of a novel multi-convex hulls expansion tool for deep small holes in Inconel 718 superalloy using the finite element method (FEM) and experimental techniques. The results from the FEM model, which was used to investigate the compressive residual stress (CRS) distribution and contact force during the expansion process, indicate that the curved single convex hull (CSCH) structure is more suitable for deep small hole expansion (DSHE). However, accounting for the strength limitations of the actual expansion tool, a multi-convex hulls expansion tool structure was proposed. The FEM model was employed to compare the effects of various tool structures on the hole wall CRS distribution and the contact force during the expansion process. The obtained optimal parameters for enhancing deep small holes in Inconel 718 superalloy under high temperature and high load conditions are as follows: expansion section hull spacing l1 = 0.4 mm, taper ratio C = 0.008, number of convex hulls in the sizing section n = 10, and sizing section hull spacing l2 = 1 mm. Moreover, an optimized convex hull expansion amount allocation scheme was obtained through an experimental study. The results of the FEM simulations and experimental study demonstrate that the optimized multi-convex hulls expansion tool (with an expansion rate of 1.92%) can induce the formation of a high CRS layer and a refined surface without causing significant microcracks in the hole walls. [ABSTRACT FROM AUTHOR]

This paper focuses on the analytical procedure for determining novel exact expressions for internal forces and displacements of hemi-ellipsoidal shells formed as an axisymmetric shell of revolution under uniformly distributed load such as imposed loads. The simplest form of expressions for solutions is derived based on the linear membrane theory under symmetrical loading that is formed as a shell of revolution. The results have been validated and have a good consistency with numerical solutions from the finite-element method (FEM) which are derived based on the principle of virtual work and differential geometry. The obtained analytical exact solution is only valid for small displacements or if the response does not exceed the linearity limit. In cases of large displacements, geometrical nonlinear finite-element analysis is recommended to determine the solution. The linearity limit determination is demonstrated, and the effects of shells' geometry, thickness, and magnitude of applied loads are presented. Additionally, the linear buckling analysis has been performed. The study found that the size ratio, thickness, and support condition have a significant effect on the critical load of the first mode, and the hemispherical shells have the highest buckling resistance due to the geometry. [ABSTRACT FROM AUTHOR]

The scaled boundary finite element method (SBFEM) is a semi-analytical numerical approach based on the scaled boundary coordinates. Recently, the method which uses interpolations in both the circumferential and radial directions has also been developed based on the scaled boundary representation. However, the stress fields are always discontinuous within the S-elements by both the original SBFEM and the latter method. In this paper, a new class of quadrilateral elements with interior smoothness is constructed by extending the B-net method based on the area coordinates into the S-net method based on the scaled boundary coordinates. In the S-net method, the Bernstein bases are separately applied to discretize both circumferential and radial directions in each sub-triangle of an S-element (or quadrilateral element), and the smoothness conditions between adjacent triangles can be simply represented in the form of linear equations. Then, by using the S-net method, we obtain a new class of quadrilateral elements with interior smoothness and high-order completeness. The shape functions or interpolation bases can be obtained explicitly and determined by the same interpolation nodes of the S-element as the original SBFEM. Some numerical tests also show that the proposed elements can obtain good results. • A new class of quadrilateral FEM elements is constructed in the scaled boundary coordinates with interior C 1 continuity. • The B-net method based on the area coordinates is extended into the S-net method based on the scaled boundary coordinates. • The new elements overcome the stress singularity at the scaling centre and stress discontinuity inside the S-element. • The high-order completeness of the new elements is proved theoretically and thus the convergence is guaranteed. • The extended S-net method can construct new polygonal elements with high-order continuity. [ABSTRACT FROM AUTHOR]

This paper proposes an extended virtual element method based on the combination of the extended finite element method and the virtual element method on interface-unfitted meshes for solving elliptic interface problems. The well-posedness of the discrete problem is shown and the optimal error estimate is derived, which is independent of the location of the interface relative to the mesh and the contrast between the diffusion coefficients. Numerical experiments verify the theoretical results. [ABSTRACT FROM AUTHOR]

Shale gas is considered a crucial global energy source. Hydraulic fracturing with multiple fractures in horizontal wells has been a crucial method for stimulating shale gas. During multi-stage fracturing, the fracture propagation is non-uniform, and fractures cannot be induced in some clusters due to the influence of stress shadow. To improve the multi-fracture propagation performance, technologies such as limited-entry fracturing are employed. However, perforation erosion limits the effect of the application of these technologies. In this paper, a two-dimensional numerical model that considers perforation erosion is established based on the finite element method. Then, the multi-fracture propagation, taking into account the impact of perforation erosion, is studied under different parameters. The results suggest that perforation erosion leads to a reduction in the perforation friction and exacerbates the uneven propagation of the fractures. The effects of erosion on multi-fracture propagation are heightened with a small perforation diameter and perforation number. However, reducing the perforation number and perforation diameter remains an effective method for promoting uniform fracture propagation. As the cluster spacing is increased, the effects of erosion on multi-fracture propagation are aggravated because of the weakened stress shadow effect. Furthermore, for a given volume of fracturing fluid, although a higher injection rate is associated with a shorter injection time, the effects of erosion on the multi-fracture propagation are more severe at a high injection rate. [ABSTRACT FROM AUTHOR]

Marine gas hydrate formations are characterized by considerable water depth, shallow subsea burial, loose strata, and low formation temperatures. Drilling in such formations is highly susceptible to hydrate dissociation, leading to gas invasion, wellbore instability, reservoir subsidence, and sand production, posing significant safety challenges. While previous studies have extensively explored multiphase flow dynamics between the formation and the wellbore during conventional oil and gas drilling, a clear understanding of wellbore stability under the unique conditions of gas hydrate formation drilling remains elusive. Considering the effect of gas hydrate decomposition on formation and reservoir frame deformation, a multi-field coupled mathematical model of seepage, heat transfer, phase transformation, and deformation of near-wellbore gas hydrate formation during drilling is established in this paper. Based on the well logging data of gas hydrate formation at SH2 station in the Shenhu Sea area, the finite element method is used to simulate the drilling conditions of 0.1 MPa differential pressure underbalance drilling with a borehole opening for 36 h. The study results demonstrate a significant tendency for wellbore instability during the drilling process in natural gas hydrate formations, largely due to the decomposition of hydrates. Failure along the minimum principal stress direction in the wellbore wall begins to manifest at around 24.55 h. This is accompanied by an increased displacement velocity of the wellbore wall towards the well axis in the maximum principal stress direction. By 28.07 h, plastic failure is observed around the entire circumference of the well, leading to wellbore collapse at 34.57 h. Throughout this process, the hydrate decomposition extends approximately 0.55 m, predominantly driven by temperature propagation. When hydrate decomposition is taken into account, the maximum equivalent plastic strain in the wellbore wall is found to increase by a factor of 2.1 compared to scenarios where it is not considered. These findings provide crucial insights for enhancing the safety of drilling operations in hydrate-bearing formations. [ABSTRACT FROM AUTHOR]

This paper aims to design the fundamental basis for an Unmanned Aerial System (UAS)-driven, remote, and non-invasive current sensing application. Using the COMSOL software, the methodology presented here consists of the Computer Aided Design (CAD) for stranded Transmission Line (TL) geometries composed of 7 to 91 sub-filaments and discretized via tetrahedral-element-based meshes. The radiated Magnetic Field (MF) around each TL is then solved by means of Finite Element Analysis (FEA) after selecting the proper materials for TLs under the coil geometry analysis study. For each TL, all resultant MFs' norms are presented as tabulated data, with respect to the inducing currents. Eventually, the complex mathematical model needed to evaluate these MFs, radiated around stranded TLs, is surpassed by the scalable models designed through this study. The min/max MFs radiated around each TL resulting from the min/max injected current values are hence obtained. This would serve in the accurate choosing/positioning of magnetic-based sensors in UAS applications, reliably. Additionally, related future works are concretely presented. [ABSTRACT FROM AUTHOR]

Titanium alloys are extensively used in the manufacturing of key components in aerospace engines and aircraft structures due to their excellent properties. However, aircraft skins in harsh operating environments are subjected to long-term corrosion and pressure concentrations, which can lead to the formation of cracks and other defects. In this paper, a detection probe is designed based on the principle of alternating current field measurement, which can effectively detect both surface and buried defects in thin-walled titanium alloy plates. A finite element simulation model of alternating current field measurement detection for buried defects in thin-walled TC4 titanium alloy plates is established using COMSOL 5.6 software. The influence of defect length, depth, and excitation frequency on the characteristic signals is investigated, and the detection probe is optimized. Simulation and experimental results demonstrate that the proposed detection probe exhibits high detection sensitivity to varying lengths and depths of buried defects, and can detect small cracks with a length of 3 mm and a burial depth of 2 mm, as well as deep defects with a length of 10 mm and a burial depth of 4 mm. The feasibility of this probe for detecting buried defects in titanium alloy aircraft skin is confirmed. [ABSTRACT FROM AUTHOR]

Motion cables, which are widely used in aero-engine sensors, are critical components that determine sensor stability. Because motion cables have unique motion characteristics, the study of their mechanical properties and reliability is very important. In addition, motion cables are complex in structure and cannot be applied to conventional fixed cable research methods. In this study, a new approach is proposed to introduce the theory of anisotropic composites into a simplified cable model, so that the cable is both physically conditioned and has good mechanical properties. While applying the theory of anisotropic composites, the forces of tension and torsion are considered in a motion cable under the combined action. In this context, the reliability of the structure is the fatigue life of the cable. In this paper, the mechanical properties and fatigue life of motion cables are investigated using the finite element method at different inclination angles and fixation points. The simulation results show that there is a positive correlation between the inclination angle and the extreme stress in the motion cables, and the optimal inclination angle of 0° is determined. The number of fixing points should be reduced to minimize the additional moments generated during the movement and to ensure proper movement of the cables. The optimal configuration is a 0° inclination angle and two fixing points. Subsequently, the fatigue life under these optimal conditions is analyzed. The results show that the high-stress zone corresponds to the location of the short-fatigue life, which is the middle of the motion cables. Therefore, minimizing the inclination angle and the number of fixing points of the motion cables may increase their fatigue life and thus provide recommendations for optimizing their reliability. [ABSTRACT FROM AUTHOR]