Finite Element Method Simulation Research Articles

Vibration characteristics analysis and identification of singular configuration space in controllable pitch propeller-shaft-oil tube system: based on dynamic parameters

ABSTRACT The vibration characteristics of the oil tube, as an important part of CPP devices, are related to ship navigation safety. Dynamic parameters such as pitch lead to the offset of the natural frequency, which will increase the risk of resonance failure. To improve the reliability of the CPP, this paper considers the influence of dynamic parameters and analyses and researches the vibration characteristics of the in-shaft oil tube using theoretical and finite element simulation methods. The equivalent model of a CPP-Shaft-Oil tube system is constructed. The system's equations of motion were derived based on Hamilton's principle. The system's equations of motion are solved using the Galerkin method. The study identifies how variations in dynamic parameters lead to an offset in the system’s natural frequency, resulting in a singular configuration space. The simulation results validate the accuracy of the theoretical results. These findings offer insights for optimising the design of CPP.

Data-driven prediction of insulation properties in dielectric composites by machine learning

Abstract Materials exhibiting superior thermal and electrical insulation characteristics are highly sought after for the development of electrical power systems and electronic equipment. Nevertheless, the composition and architecture complicatedly influence the insulation performance due to the vast array of design variables. Conventional design methods approaches typically involve extensive trial-and-error experiments, necessitating substantial investment and effort to achieve optimal results. The simulation of electrical trees using the finite element method (FEM) serves as a crucial metric for assessing insulation characteristics. A prolonged evolution period of the electrical tree is indicative of superior insulation performance. This approach provides accurate simulations, albeit at a significant computational cost. In this study, we introduce a machine learning (ML) model that enables the precise and efficient prediction of the development time of electrical trees in dielectric composites. The linear and nonlinear ML models are thoroughly trained, including both ElasticNet and a multi-layer perceptron, leveraging a dataset constructed from FEM simulations. The ElasticNet model demonstrates minimal prediction errors, offering a viable substitute for the FEM model and significantly improving the accuracy of predictions. In addition, an analysis is conducted to determine the influence of each input feature on the predictive outcomes, providing critical insights that facilitate and improve the design process of dielectric composites. To substantiate its effectiveness, the ElasticNet model has been employed to forecast existing experimental outcomes, thereby confirming its practicality and dependability.

Investigation of the mechanical anisotropy of the hot isostatic pressing Mar-M247 produced via laser powder bed fusion (LPBF): A perspective on grain characteristics

Abstract The anisotropy in mechanical properties of additively manufactured (AM) superalloys, closely related to grain morphology, grain boundaries, and precipitated phases, impedes their aerospace applications. In this study, the influence of grain characteristics on the mechanical anisotropy of HIP (hot isostatic pressing)/ HT(heat treatment) LPBF (laser powder bed fusion) Mar-M247 superalloy was investigated via experimental and finite element (FE) simulation methods. The results indicate that the mechanical properties along the build direction (XZ plane) are superior to those perpendicular to it (XY plane) at multiple temperatures. Particularly, the elongation along the build direction is nearly twice that perpendicular to it. HIP treatment effectively eliminates cracks in the alloy. Grain characteristics reveal columnar grains along the build direction and equiaxed grains perpendicular to it. The Representative Volume Element (RVE) results and the fracture analysis results show that columnar grains exhibit uniform stress distribution, resulting in higher elongation and crack initiation within grains, whereas equiaxed grains show stress concentration at triple junction boundaries, leading to crack initiation and alloy fracture.

Ultra-high birefringence in dual semi-circular core circular-cladding holey fiber for polarization maintaining applications

Holey Fibers have attracted considerable attention due to their capacity to customize optical properties, leading to advancements in a variety of fields such as telecommunications, sensing, and laser systems. In this work, we introduce a novel design of Dual Semi-Circular Core Modified Circular Cladding Holey Fiber (DSCMC-HF), which demonstrates exceptional optical performance for polarization-maintaining applications. At the 1550 nm wavelength, the proposed fiber achieves an impressive birefringence of 0.2132, significantly exceeding that of traditional polarization-maintaining fibers. Additionally, the beat length is reduced to 7.27 × 10⁻6 m, improving polarization stability in fiber-based systems. The nonlinear coefficients for x and y polarization, 44.18 and 63.42 W⁻1 km⁻1 respectively, highlight the fiber’s potential in nonlinear optical applications. Furthermore, with effective areas of 2.936 and 2.046 μm2 for x and y polarization, and numerical apertures of 0.4546 and 0.5217 respectively, the fiber exhibits excellent light confinement and propagation characteristics. Finite Element Method simulations were employed to analyze the optical properties of the proposed design, ensuring accurate evaluation of its performance. These superior optical properties, combined with the novel dual semi-circular core structure, make the proposed DSCMC-HF design a strong candidate for advancing polarization-sensitive devices, fiber lasers, and high-speed telecommunications systems.

Reduction of thermal instability of soliton states in coupled Kerr-microresonators

Kerr-microresonator frequency combs in integrated photonics waveguides are promising technologies for next-generation positioning, navigation, and timing applications, with advantages that include platforms that are mass-producible and CMOS-compatible and spectra that are phase-coherent and octave-spanning. Fundamental thermal noise in the resonator material typically limits the timing and frequency stability of a microcomb. The small optical mode volume of the microresonators exaggerates this effect, as it both increases the magnitude and shortens the timescale of thermodynamic fluctuations. In this work, we investigate thermal instability in silicon nitride microring resonators as well as techniques for reducing their effects on the microcomb light. We characterize the time-dependent thermal response in silicon nitride microring resonators through experimental measurements and finite element method simulations. Through fast control of the pump laser frequency, we reduce thermal recoil due to heating. Finally, we demonstrate the utility of a coupled microresonator system with tunable mode interactions to increase the stability of a soliton against thermal shifts.

Active control of target scattered sound fields in ocean environments using virtual sensing.

Active control of scattered sound fields is essential for low-frequency acoustic stealth of underwater targets. However, the ocean waveguide environment introduces challenges, such as multipath effects and non-uniform sound speed distribution, that degrade the performance of existing active scattering control methods. This paper proposes an active scattering control method applicable to ocean waveguide environments. The method employs an improved virtual sensing technique suitable for multi-incidence scenarios to obtain free-field far-field predictions, which are then combined with ocean environmental parameters to estimate the far-field pressure distribution in the waveguide. These distributions are subsequently used to design the weight vector for the secondary source array. Additionally, the paper explores active control strategy when environmental parameters are unknown. Finally, the proposed method is validated through finite element method simulations, performing active control of the scattered field of a cylinder in both isovelocity and depth-dependent channels. The simulation results demonstrate the feasibility and effectiveness of the proposed method.

Advanced oral breviscapine sustained-release tablets for improved ischemic stroke treatment.

Advanced oral breviscapine sustained-release tablets for improved ischemic stroke treatment.

Displacement monitoring and multimodal frequency identification of long-span bridges utilizing PPP-RTK

Abstract Accurate displacement monitoring and precise identification of multimodal frequencies in large-span bridges are critical for ensuring structural safety and operational stability. Precise Point Positioning Real-Time Kinematic (PPP-RTK), capable of delivering instantaneous centimeter-level positioning accuracy without reliance on nearby reference stations, has gained widespread application across various domains. This study investigates the feasibility and effectiveness of PPP-RTK for structural health monitoring (SHM) of long-span bridges in complex urban environments and proposes a robust approach for reliable multimodal frequency identification based on PPP-RTK-derived displacement time series. The performance of PPP-RTK was validated using three networks comprising 11 stations in Wuhan and its surrounding areas, where three representative models for generating local single-difference slant ionospheric and tropospheric delay products were systematically evaluated. The proposed methodology was subsequently applied to the Wuhan Yingwuzhou Yangtze River Bridge for SHM. Experimental results demonstrate that PPP-RTK achieves positioning accuracy and multimodal frequency identification capabilities comparable to those of Real-Time Kinematic (RTK). Furthermore, the proposed frequency identification method exhibits exceptional performance in detecting the first six modal frequencies, showing remarkable consistency with reference values obtained from finite element method (FEM) simulations and experimental calibration. Notably, the proposed method significantly outperforms conventional approaches in terms of accuracy and reliability. These findings underscore the potential of PPP-RTK as a viable alternative technology for SHM of long-span bridges, offering a promising solution for accurate displacement monitoring and structural frequency identification in complex urban settings.

Customized design of mechanical properties for irregular lattice structures with variable in-plane wall thickness

Abstract Irregular lattice structures offer the potential to unlock a wider spectrum of properties and innovative functional spaces. The in-plane wall thickness of the lattice, as a critical structural parameter, decisively governs the mechanical performance of irregular lattice structures, yet current research on in-plane wall thickness optimization remains notably insufficient. Herein, we propose a robust data-driven framework to design novel irregular lattice structures with user-defined Poisson's ratio and Young's modulus. This framework involves the creation of a comprehensive dataset of irregular lattice structures, constructed through a randomized strategy that incorporates diverse stretching and bending dominance. Based on the deformation characteristics of the structures, we analyze the impact of in-plane wall thickness on the mechanical properties of the unit cell. Furthermore, the inverse design process, employing genetic algorithms, effectively and precisely facilitates the generation of irregular lattice structures, thereby achieving customized targets for Young's modulus and Poisson's ratio. Specific inverse design cases are validated through finite element method simulations and uniaxial tensile tests. By spatially assembling two distinct lattice structures, facial patterns were designed to form a “smiling face” and a “surprised face” under compression, demonstrating the capability of the proposed irregular structures in regulating deformation configurations. This research demonstrates its potential for practical applications in material science and engineering.

Numerical simulation and flexural strength analysis of jute/epoxy laminated composites using ANSYS workbench

The increasing demand for environmentally sustainable yet mechanically efficient materials has driven interest in natural fiber-reinforced composites, particularly jute-based laminates. While jute fibers offer biodegradability and cost-effectiveness, their limited mechanical performance necessitates further study for structural applications. This research aims to evaluate the flexural behavior of jute/epoxy laminated composites using numerical simulation with ANSYS Workbench 2022 and validate the findings through experimental testing. The primary objectives are to (1) analyze the impact of jute fiber layer configurations on stress distribution and deformation behavior, (2) determine the correlation between the number of fiber layers and flexural strength, and (3) verify the accuracy of the numerical model using experimental data. The composite specimens were fabricated with one to four woven jute layers, following ASTM D790 standards, and tested using a three-point bending setup. Finite Element Method (FEM) simulations were conducted to evaluate stress distribution and identify optimal configurations. Results showed that increasing the number of jute layers significantly reduced stress concentrations and enhanced load-bearing capacity. A four-layer composite exhibited a 31.5% improvement in flexural strength compared to a single-layer configuration. Furthermore, numerical predictions closely matched experimental values, with deviation margins between 1.63% and 2.16%, confirming the model's reliability. These findings highlight the potential of jute/epoxy laminates as sustainable structural materials and demonstrate the effectiveness of FEM-based simulations in optimizing composite designs. Future research should explore hybridization strategies and environmental durability to further enhance performance for industrial applications

32 dB modal gain in Er:LiNbO3 waveguide amplifiers with Er,Yb:Al2O3 cladding layer via bidirectional pumping scheme

Lithium niobate on insulator (LNOI) holds substantial promise for applications in integrated photonic systems. Waveguide amplifiers are fundamental photonic components within integrated photonic platforms. In this paper, we report a high-gain erbium-doped lithium niobate (Er:LiNbO3) waveguide amplifier coated with an erbium and ytterbium co-doped aluminum oxide (Er,Yb:Al2O3) cladding layer. The ridge waveguide dimensions and cladding thickness were optimized via finite element method (FEM) simulations of electric field distributions, with further analysis of the impacts of optical confinement factor (Γ) and effective mode area (A eff ) on device performance. This paper further validates the advantages of a bidirectional pumping scheme in suppressing amplified spontaneous emission (ASE) and reducing noise figures (NF). Numerical simulations based on an Er3+-Yb3+ co-doped theoretical model demonstrate that under an Er3+ concentration of 3×1020 cm−3, Yb3+ concentration of 2.7×1021 cm−3, and a signal power of −30 dBm, the amplifier achieves a modal gain of 32 dB. This work establishes a theoretical foundation for the monolithic integration of compact Er3+-Yb3+ co-doped waveguide amplifiers on the LNOI platform through systematic optimization of waveguide dimensions and doping ratios.

Design of high group velocity dispersion optical fiber assisted by cascaded neural networks

The growing demand for high-speed optical communication requires advanced dispersion management to suppress pulse broadening and nonlinear effects. This work proposes a dual-core optical fiber with ultrahigh group velocity dispersion, optimized using cascaded deep neural networks. By leveraging the anti-crossing between the LP01 mode in the central core and the LP02 mode in a side core, controlled mode coupling enables dispersion enhancement. Finite element method simulations show that a dual-core fiber design derived from the standard G.652 fiber achieves an ultrahigh chromatic dispersion of approximately 11,000ps/(nm⋅km) at the 1550 nm wavelength window, with tunable bandwidth via core spacing adjustment. This methodology establishes a paradigm for AI-driven photonic device design, offering significant potential for advancing optical communication and ultrafast laser technologies.

Design simulation of high-homogeneity portable MRI magnet array using global optimization algorithm and equivalent currents model.

High-field magnetic resonance imaging (MRI) systems offer high sensitivity and resolution but are costly and bulky, limiting their widespread use, particularly in remote areas. Conversely, portable MRI systems have emerged as a complementary technology, promising enhanced accessibility. This study introduces a novel optimization method combining an analytical model with a highly convergent global optimization algorithm to enhance the design of portable MRI permanent magnet arrays. The approach aims to significantly improve the efficiency of the magnet design process, thereby advancing the homogeneity of portable MRI magnet array. The proposed approach begins with the calculation of initial magnetic field distributions using current element principles. This is followed by the development of an advanced analytical model based on matrix algebra. The consistency between the calculated results of the analytical model and the results from finite element method (FEM) simulations is then evaluated to assess the reliability of the magnetic field calculations across various magnet array configurations. The integration of the analytical model with the improved grey wolf optimization (IGWO) algorithm enhances the optimization process, leading to magnet array configurations with improved homogeneity. FEM simulations agree with the analytical model, revealing a computational error with an average root mean square error (RMSE) of 0.4% in the magnetic field map. The calculation speed of analytical model is at least 200 times higher than that using FEM-based software with uncompromised accuracy. The optimization process successfully yields a permanent magnet array with exceptional homogeneity (1080ppm) and strong field strength (79.5 mT) across a 0.2m diameter of spherical volume (DSV). Moreover, this is accomplished while maintaining a lightweight (129kg) and compact design (interior diameter: 0.31m). The IGWO model has been shown to outperform the benchmark genetic algorithm (GA) model, which is currently used for magnet design in MRI. This study introduces a novel optimization method that significantly enhances the design of portable MRI permanent magnet arrays. By integrating an analytical model with the IGWO algorithm, this method enhances the efficiency of magnet design compared to traditional FEM. This method addresses the limitations of traditional magnet optimization techniques, which are often susceptible to local optima. The results indicate that this method can play a crucial role in developing MRI systems with high homogeneity.

Towards the Optimization of Apodized Resonators

Bulk Acoustic Wave (BAW) resonators are essential components in modern RF communication systems due to their high selectivity and quality factor. However, spurious resonances caused by Lamb wave mode propagation along the in-plane directions degrade the filter performance. Traditional Finite Element Method (FEM) simulations provide accurate modeling but are computationally expensive, especially for arbitrarily shaped resonators and solidly mounted resonators (SMRs), whose stack of materials is composed of many thin layers of different materials. To address this, we extend a previously published model (named the Quasi-3D model), which employs the Transmission Line Matrix (TLM) method, enabling efficient simulations of complex geometries with more precise meshing. The new approach allows us to simulate different geometries, and we will show several apodized geometries with the aim of minimizing the lateral modes. In addition, the proposed approach significantly reduces the computational cost while maintaining high accuracy, as validated by FEM comparisons and experimental measurements.

Resonance Behaviors of the Plate-Structured Rock with Minute Defects Under the Action of Multiple Types of Excitations

Plate-structured rocks are prevalent in rock engineering applications such as stratified formation and underground gas storage, and the breakage driven by dynamic loads is significantly influenced by resonance. However, the current literature discloses a research gap regarding the theoretical analysis of the natural frequency of porous and cracked rock under vibro-impact conditions. In this study, we develop and verify an analytical model for predicting the natural frequencies of plate-structured rock with minute pores and cracks, thus an idealized solid plate model is available to explore the resonance behaviors. First, Nur’s model is incorporated into the plate vibration model to quantify the porosity effects on the natural frequency of rock. Subsequently, considering the porous rock presented by the micro-CT slice image, the crack propagation resulting from the increasing penetration depth of the cutting tool is visualized by the discrete element method (DEM). The effects of rock porosity and the extent of crack propagation evaluated by porosity on the vibration characteristics of plate-structured rock are explored by employing Nur’s model, and the analytical solutions of natural frequency demonstrate agreement with the finite element method (FEM) simulation results. Next, a forced vibration plate model is used to obtain the amplitude–frequency responses and the distributions of the maximum principal stress under the normal-direction uniform excitations. Finally, the resonance effects of multiple distributions of vibration excitation on the plate model are explored by the FEM. The results indicate that the crack propagation induced by shallow penetration depths exerted a limited influence on the natural frequencies, thereby confirming the engineering applicability of the plate vibration model. Based on the model validation, an idealized solid plate is employed to investigate the resonance behaviors under multi-directional excitations with diverse spatial distributions. The vibration model of the plate demonstrates its extensive applicability and potential in optimizing rock-breaking efficiency in engineering practices.

Localized Sound-Integrated Display Speaker Using Crosstalk-Free Piezoelectric Vibration Array.

Beyond visual quality, features like sound and tactile feedback have become essential to enhancing user experience, resulting in more immersive, realistic displays. Multisensory displays engaging multiple senses are increasingly in demand. Panel-integrated piezoelectric speakers represent a major advancement in audio-visual technology, merging sound generation with display panels to enable compact, versatile designs in thin, flexible formats. However, challenges like sound crosstalk between exciters and non-uniform frequency responses often compromise audio quality. To address these issues, frame-based sound vibration isolation strategies are explored to localize surface vibrations and reduce interference across multiple exciters. Through experimental measurements and Finite Element Method (FEM) simulations, it is found that increasing frame height and width, along with using materials with different acoustic impedance for the diaphragm, significantly improved frequency response uniformity and reduced Total Harmonic Distortion (THD). These enhancements simplify speaker response compensation, ensuring reliable, high-quality sound output. As demonstrated on a practical 13-inch OLED display, these results confirm that vibration-isolated, localized sound in multi-array exciters overcomes prior limitations, advancing the acoustic performance of piezoelectric panel speakers. This study provides valuable insights for future developments in thin, flexible, display-integrated audio systems, offering new possibilities in immersive, multisensory user experiences.

Exploring the dynamics of grain growth and coarsening in polycrystalline materials through finite-element method and multiphase-field simulation

Exploring the dynamics of grain growth and coarsening in polycrystalline materials through finite-element method and multiphase-field simulation

Enhancing lithographic accuracy by mitigating overlay errors via mask-induced thermal and mechanical optimization

As technology nodes continue to shrink, the demand for higher lithographic accuracy in integrated circuit fabrication intensifies. To address the limitations of traditional compensation methods, this study proposes a mask-induced thermal and mechanical optimization approach to mitigate overlay errors, thereby enhancing lithographic precision in emerging techniques such as nanoimprint lithography (NIL) and surface plasmon lithography (SPL). This approach integrates stress application schemes with localized thermal effects, resulting in a range of compensation strategies based on mask-induced thermal-mechanical coupling. Through mathematical modeling and moment balance assumptions, the technique leverages the linear superposition property for overlay error compensation and identifies 20 key compensation parameters through statistical analysis and optimization algorithms. Experimental validation demonstrates that the compensation effectiveness for completely random, linear, quadratic, and higher-order overlay errors reaches 89.18%, 93.05%, 64.75%, and 53.89%, respectively. In 24 rounds of random testing, the average compensation in theXandYdirections was 91.98%, showing strong stability and consistency. Furthermore, finite element method simulations validate the model, revealing a residual overlay error compensation of less than 0.2 nm, with a calculation-to-validation discrepancy under 0.9%, confirming the model's accuracy. This technology provides a reliable solution for overlay error compensation in emerging lithographic techniques like lensless SPL and NIL and offers valuable insights for future research in extreme ultraviolet lithography and deep ultraviolet lithography, with potential applications in integrated circuit lithography and further validation across various mask types and complex exposure areas.

A low cost Flame-Retardant 4 material accelerometer for low-frequency vibration detection

Abstract Low-frequency vibrations of large buildings and bridges caused by factors such as earthquakes can lead to structural damage, therefore monitoring their vibration characteristics is of great importance for the safety of society. The fabrication of conventional silicon based microelectromechanical system (MEMS) accelerometers involves microfabrication processes, resulting in escalated production costs. In this paper, we present an innovative area-variable capacitive accelerometer that can be achieved by low-cost and rapid fabrication. The accelerometer uses flame resistant 4 (FR4) glass epoxy laminate material as the substrate of the accelerometer. And it
is optimized through theoretical analysis and ANSYS finite element method (FEM) simulation. It utilizes a cost-effective PCB production process to fabricate the metal electrodes, which are used to form the capacitive array for sensing, and CNC machining for the spring-mass structure. Experimental results demonstrate that the accelerometer achieves a high sensitivity of 1290 mV/g, a quality factor of 224, a fundamental frequency of 8.3 Hz, and also exhibits a low repeatability error of 2.27%, and a low nonlinearity of 2.52%. In addition, the accelerometer demonstrate good temperature stability and resistance to metal interference. The proposed design and processing methodology offer a cost-effective solution for the realization of low-frequency vibration monitoring.

A Novel Ultrasonic Sampling Penetrator for Lunar Water Ice in the Lunar Permanent Shadow Exploration Mission

This paper presents an ultrasonic sampling penetrator with a staggered-impact mode, which has been developed for the extraction of lunar water ice. A comparison of this penetrator with existing drilling and sampling equipment reveals its effectiveness in minimizing disturbance to the in situ state of lunar water ice. This is due to the interleaved impact penetration sampling method, which preserves the original stratigraphic information of lunar water ice. The ultrasonic sampling penetrator utilizes a single piezoelectric stack to generate the staggered-impact motion required for the sampler. Finite element simulation methods are employed for the structural design, with modal analysis and modal degeneracy carried out. The combined utilization of harmonic response analysis and transient analysis is instrumental in attaining the staggered-impact motion. The design parameters were then used to fabricate a prototype and construct a test platform, and the design’s correctness was verified by the experimental results. In future sampling of lunar water ice at the International Lunar Research Station, the utilization of the ultrasonic sampling penetrator is recommended.