4,619 results
Search Results
2. Interplay between structural scales and fracture process zone: experimental and numerical analysis on paper as a model material.
- Author
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Villette, François, Dufour, Frédéric, Baroth, Julien, Rolland du Roscoat, Sabine, and Bloch, Jean-Francis
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NUMERICAL analysis , *FINITE element method , *YOUNG'S modulus , *STOCHASTIC analysis , *SURFACE energy , *RANDOM fields , *BRITTLE materials - Abstract
This work deals with fracture mechanisms in quasi-brittle materials, focusing on the characterization of the Fracture Process Zone (FPZ) of specimens under tensile load. Particularly, paper was used as model material. Experiments were conducted on notched and unnotched specimens. Based on an image analysis of these observations, a stochastic finite element model was developed, using both a nonlocal stress-based approach and a discretized random field modeling of the Young's modulus. The proposed methodology allowed characterizing the damage zone and the size of the FPZ, analyzing the influence of the mesostructure, composed of flocs (fiber aggregates where the basis weight is larger than the average one) and antiflocs (complement of flocs). The area of the active FPZ and the normalized stress drop were linked using a surface energy dissipated in the active FPZ. The stress drop, until limiting value, increased with the width of the active FPZ. Finally, a relationship between the surface energy and the nonlocal internal length was established. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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3. Author's response to "Discussion on the paper by Schoeftner, J., "A verified analytical sandwich beam model for soft and hard cores: comparison to existing analytical models and finite element calculations", Acta Mech, 234, 2543–2560 (2023)" by Lorenzo Bardella
- Author
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Schoeftner, Juergen
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SANDWICH construction (Materials) , *FINITE element method , *WOODEN beams - Abstract
It is pointed out that the Levinson-Reddy beam theory should not be used as a higher-order model for the core, although it considers cross-sectional warping: this beam model is applicable for zero shear stress conditions at the core-skin-interfaces only, which is usually not the case for sandwich structures. The resulting sandwich beam model in [[2]] is a special solution from the Krajcinovic-Bardella derivation, which allows for richer kinematics because it considers zig-zag kinematics. Author's response to "Discussion on the paper by Schoeftner, J., "A verified analytical sandwich beam model for soft and hard cores: comparison to existing analytical models and finite element calculations", Acta Mech, 234, 2543-2560 (2023)" by Lorenzo Bardella. [Extracted from the article]
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- 2023
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4. Thermographical Analysis of Paper During Tensile Testing and Comparison to Digital Image Correlation.
- Author
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Hagman, A. and Nygårds, M.
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CARDBOARD , *PAPER analysis , *THERMOGRAPHY , *TENSILE tests , *DIGITAL image correlation , *DEFORMATIONS (Mechanics) - Abstract
The thermal response in paper has been studied by thermography. It was observed that an inhomogeneous deformation pattern arose in the paper samples during tensile testing. In the plastic regime a pattern of warmer streaks could be observed in the samples. On the same samples digital image correlation (DIC) was used to study local strain fields. It was concluded that the heat patterns observed by thermography coincided with the deformation patterns observed by DIC. Because of its fibrous network structure, paper has an inhomogeneous micro-structure, which is called formation. It could be shown that the formation was the cause of the inhomogeneous deformations in paper. Finite element simulations was used to show how papers with different degrees of heterogeneity would deform. Creped papers, where the strain at break has been increased, were analysed. For these paper it was seen that an overlaid compaction of the paper was created during the creping process. During tensile testing this was recovered as the paper network structure was strained. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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5. Predictive field-oriented control of three-phase permanent magnet linear synchronous actuators.
- Author
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Erfanimatin, Mohammad, Saeedi, Suorena, and Sadighi, Ali
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PERMANENT magnets , *PREDICTIVE control systems , *ACTUATORS , *MAGNETIC flux density , *MANUFACTURING processes , *FINITE element method , *SYNCHRONOUS electric motors - Abstract
Three-phase linear synchronous actuators play a pivotal role in precision motion control applications such as lithography machines and laser material processing stages. Achieving superior tracking performance is paramount in the design of motion control systems, prompting the utilization of advanced control algorithms. In this study, a novel approach is presented to enhance the tracking capability of a three-phase permanent magnet actuator by introducing a predictive field-oriented control system. The primary contribution of this paper lies in the comprehensive design and implementation of the predictive field-oriented control system. Initially, actuator modeling is conducted in the rotating reference frame (d–q frame) and finite element analysis is performed to determine key electrical quantities, including magnetic flux densities and inductances. To address the challenges posed by time-varying sinusoidal electrical signals, a field-oriented control methodology is proposed. Notably, the novelty of this work is underscored by a distinct emphasis on the predictive control strategy employed in the system. The predictive controller is implemented on a 32-bit ARM Cortex microcontroller, showcasing the practical viability of the proposed approach. Experimental results substantiate the effectiveness of the proposed method in achieving precise trajectory tracking. This paper contributes to the field by providing a rigorous analysis of a three-phase permanent magnet actuator and introducing a predictive field-oriented control system. The methodology outlined here enhances tracking capabilities and signifies a substantial advancement in the broader landscape of precision motion control systems. Thus, this work adds valuable insights to the existing body of knowledge in the domain, while offering a notable contribution to the field. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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6. Twin variant selection criteria in magnesium alloy: a review.
- Author
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Liu, Zhe, Xin, Renlong, and Huang, Xiaoxu
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MAGNESIUM alloys , *STRAINS & stresses (Mechanics) , *FINITE element method , *SHEARING force , *TRACE analysis , *FACTOR analysis - Abstract
Twinning is an important deformation mechanism for magnesium alloys, which has a significant impact on the texture evolution and mechanical properties. Pre-twinning deformation has been considered as an effective method for texture regulation. For each twinning mode, there are six crystallographically equivalent variants. Properly identifying the activated twin and understanding its variant selection criteria are essential for the development of high-performance magnesium alloys. As summarized in this paper, the observed twin variant by the commonly employed electron backscatter diffraction technique can be identified by several approaches, including misorientation analysis, trace analysis and matrix method. Schmid factor analysis was commonly performed to explain the selection of twin variants. To broaden the application scope under complex stress state, a generalized Schmid factor was derived by introducing a stress tensor. The efficiency of Schmid criteria to assess twin variant selection was confirmed to be influenced by the type of the applied stress. To consider the local effect on twin activation, in particular twin-twin transfer and slip-induced twinning, displacement gradient tensor calculation and geometrical compatibility factor analysis have been employed. It was demonstrated that local strain accommodation played a critical role in selecting the variants of cross-boundary twins in magnesium alloys. Assisted with crystal plasticity finite element modeling, the resolved shear stress on twinning and a composite Schmid factor combining the global Schmid factor and geometrical compatibility factor were obtained to better explain the activated twin variants in magnesium alloys. All the above-mentioned Schmid law based criteria and some energy based criteria as well are summarized in this paper. Their applications in evaluating twin variant selection in magnesium alloys are critically reviewed and discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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7. Jetting Phenomenon in Cold Spray: A Critical Review on Finite Element Simulations.
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Rahmati, S., Mostaghimi, J., Coyle, T., and Dolatabadi, A.
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FINITE element method , *NUMERICAL roots , *CONTINUUM mechanics , *MATERIAL plasticity , *PLASTICS - Abstract
This paper offers a concise critical review of finite element studies of the jetting phenomenon in cold spray (CS). CS is a deposition technique wherein solid particles impact a substrate at high velocities, inducing severe plastic deformation and material deposition. These high-velocity particle impacts lead to the ejection of material in a jet-like shape at the periphery of the particle/substrate interface, a phenomenon known as "jetting". Jetting has been the subject of numerous studies over recent decades and remains a point of debate. Two main mechanisms, Adiabatic Shear Instability (ASI) and Hydrodynamic Pressure-Release (HPR), have been proposed to explain the jetting phenomenon. These mechanisms are mainly elucidated through finite element method (FEM) simulations, a numerical technique rooted in continuum mechanics. However, it is important to emphasize that FEM is limited by the equations established for analysis, and as such, its predictive capabilities are confined to those principles clearly defined within these equations. The choice of employed equations and approaches significantly influence the outcomes and predictions in FEM. While recognizing FEM's capabilities, this study reviews the ASI and HPR mechanisms within the context of CS. Additionally, this paper reviews FEM's algorithms and the core principles that govern FEM in calculating plastic deformation, which can lead to the formation of jetting. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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8. A procedure for the experimental identification of the strain gradient characteristic length.
- Author
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Rezaei, Nasrin, Riesselmann, Johannes, Misra, Anil, Balzani, Daniel, and Placidi, Luca
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STRAINS & stresses (Mechanics) , *DIGITAL image correlation , *IDENTIFICATION , *DISPLACEMENT (Mechanics) , *PARAMETER identification , *FINITE element method , *PORTLAND cement - Abstract
The aim of this paper is to propose an experimental procedure for determining the characteristic length of a strain gradient model. The identification problem is studied through a virtual pull-out test of a rigid bar along the symmetry axis of a cylindrical strain gradient elastic domain. To allow an accurate parameter identification based on measured data, we investigate the effect of the characteristic length on the mechanical fields for this problem. We see a significant sensitivity of the inflection point of the displacement profile evaluated on the cross section of the cylinder, with respect to the characteristic length. By adjusting the characteristic length of the strain gradient such that the theoretical models match best with experimental measurements of the surface displacement fields, the characteristic length of the strain gradient can be estimated. In order to allow for more efficient analysis and an almost real-time parameter identification, the initial three-dimensional (3D) problem is reduced to a one-dimensional (1D) problem by exploiting the cylindrical symmetry of the problem. As will be shown, an accurate 1D finite element method (FEM) strain gradient solution can be obtained for this simplified problem. Since the cylindrical symmetry is only true in an infinitely long cylinder, specific boundary conditions are constructed on a cylinder of finite length, which is then used for the comparison of the 1D and 3D problems. Results show, however, that the structural response at the inflection point is insensitive to whether the specific boundary conditions are considered or not, which is why the 1D model can be used for parameter identification. Since the proposed approach is methodological, it can be applied to any material. As a prototype problem in this paper, we consider the case of a bar embedded in Portland cement concrete. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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9. Reliability analysis of high core rockfill dam against seepage failure considering spatial variability of hydraulic parameters.
- Author
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Li, Yanlong, Liu, Hangfei, Wen, Lifeng, Xu, Zengguang, and Zhang, Ye
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EARTH dams , *SEEPAGE , *FINITE element method , *HYDRAULIC conductivity , *RANDOM fields - Abstract
Historically, seepage failure has always been the primary cause of failures and accidents of earth dams after overtopping. However, research on the reliability of earth dams against seepage failure remains scarce. Meanwhile, the influence of the uncertainty of the soil–water characteristic curve (SWCC) on the reliability of dams against seepage failure is still unclear. In this study, the van Genuchten–Mualem model is used to describe SWCC, and its uncertainty is characterized by discretizing SWCC fitting parameters a and n into cross-correlation lognormal random fields. Based on the random finite element method, this paper systematically studies the influence of the heterogeneity, autocorrelation, and cross-correlation of hydraulic parameters Ks, a, and n on the reliability of a dam against seepage failure. Sensitivity analysis indicates that Ks and autocorrelation distance crucially affect the reliability of the dam against seepage failure. Additionally, this paper also emphasizes and proves that considering the correlation between the hydraulic conductivity field and the critical hydraulic gradient field has a significant impact on evaluating the reliability of earth dams against seepage failure. However, this subtle but important potential characteristic has not been paid attention to in previous studies. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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10. Protection of Whipple shield against hypervelocity impact of space debris: a review.
- Author
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Singh, Pradeep Kumar and Kumar, Manoj
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SPACE debris , *HYPERVELOCITY , *EARTH'S orbit , *FINITE element method , *EQUATIONS of state - Abstract
The space debris in Earth's orbit has increased drastically due to the failure of spacecraft, rocket bodies, and mission-related objects. These objects in orbit increase the space waste and challenge other flying objects such as spacecraft. A hypervelocity impact of space debris on spacecraft structures can have a range of effects (mechanical damage and functional failure), raising significant concerns about spacecraft safety. This paper reviews the different studies on the performance and development of the Whipple shield against the hypervelocity impact of space debris. The study focuses on the impact mechanism, dynamic Fragmentation of materials, strength models, Equation of state, characteristics, and model of the debris cloud. The strength models (Steinberg–Guinan and Johnson–Cook) and Mie–Gruneisen equation of state, primarily used for hypervelocity impact applications, are thoroughly covered in this study. The study also reported the various experimental and numerical techniques for high and hypervelocity impact. The study concluded that mesh-based, mesh-free, and hybrid finite element methods are reliable for analyzing Whipple shield targets to resist hypervelocity impact. The study also observed that the two-stage light gas gun technique investigates most experimental analyses of hypervelocity impact on the Whipple shield. Alongside reviewing the abovementioned aspects, this paper also underlines the future scope of study in this paradigm. The authors strongly believe that this study provides more insights into the fundamentals and perceptions of the Whipple shield to protect the spacecraft against the hypervelocity impact of space debris. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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11. An improved mechanism for partial blowout instability of tunnel face in large slurry shield-driven tunnels.
- Author
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Liu, Wei, Zhang, Xuanyang, Wu, Ben, and Huang, Yucheng
- Subjects
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COHESION , *TUNNELS , *FINITE element method , *SLURRY , *TUNNEL design & construction - Abstract
In the tunneling driven by large diameter slurry shield (SS), the working face is at risk of passive failure when the overburden is insufficient or the support pressure is excessive. This paper examines the partial progressive failure of the tunnel face by developing a hybrid mechanism which incorporates the failure zone into the complex movement. The failure blocks include a translational and a rotational one, and a spatial discretization technique is used to construct the velocity discontinuity between the blocks to ensure compatibility. To identify the failure extent of the face, the incipient failure origination is introduced. A kinematic approach is utilized to determine the upper bound solution for support pressure. By optimizing, the minimum support pressure is searched and the failure mechanism is gained in response. Additionally, this study performs the parametric analysis to discuss the influences of the factors such as frictional angle, cohesion, overburden depth, ground surface surcharge, and slurry weight on incipient failure origination as well as support pressure. The numerical analysis included in the framework of finite element limit analysis is carried out for verification. This paper ends with the validation of the current solution by re-examining the previous case. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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12. Three-Dimensional Simulation for Radon Migration in Fractured Rock Masses: A Computational Modeling Approach.
- Author
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Feng, Shengyang, Wang, Wenhao, Liu, Yong, Hong, Changshou, Wang, Hong, and Yang, Rong
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THREE-dimensional modeling , *RADON , *ROCK deformation , *FRACTAL dimensions , *NANOFLUIDICS , *FINITE element method , *DIFFUSION coefficients - Abstract
Numerical simulation of radon migration in fractured rock masses is crucial for environmental radon pollution protection, radon tracing technology and the co-exploitation of coal and uranium resources. This paper proposed a novel model based on a fractal discrete fracture network (DFN) to simulate radon migration in fractured rock masses. The paper provided a detailed method for determining the locations of three-dimensional fractures using the multiplicative cascade process. The governing equations for radon migration in fractures and the rock matrix were established and numerically solved using the finite element method. The study developed open-source software DFNRn (Discrete Fracture Network model for Radon migration), which was publicly available on GitHub. The software simulated radon migration in a fractured rock mass with a domain size of 100 m. The results demonstrate that fluid convection in fractures drives radon migration, which is dominant compared to the diffusion process. The accuracy of our proposed model was verified by comparing it with the measured data of the fractured rock. Furthermore, the study investigated the relationship between the percolation threshold of the fracture density P 32 ′ and the key parameters of the DFN. The results show that P 32 ′ decreased with the fractal dimension Df (1.4 ≤ Df ≤ 1.9) and normalization constant α (1.4 ≤ α ≤ 1.8) and is not correlated with the length exponent a (1.2 ≤ a ≤ 2.8). P 32 ′ decreased with the mean orientation angle and has no correlation with the Fisher constant. The radon source term of the rock matrix has the greatest impact on radon migration in fractured rock masses compared to the radon diffusion coefficient and permeability. Highlights: A new approach is proposed to model radon migration in fractured rock masses. An open-source software DFNRn was developed and is publicly available on GitHub. The procedure of the multiplicative cascade method in 3D space is given in detail. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
13. An efficient latent map multi-fidelity Kriging model and adaptive point-selected strategy for reliability analysis with time-consuming simulations.
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Tong, Cao, Zhang, Qi, Cui, Can, Jin, Xiaolei, Chen, Zixuan, and Dong, Xinyue
- Subjects
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KRIGING , *FINITE element method , *ACTIVE learning , *LEARNING strategies - Abstract
Reliability analysis can be particularly challenging when performance functions require time-consuming simulations. Such simulations often involve multiple fidelity sources. This paper aims to enhance the efficiency of reliability analysis by leveraging multiple sample datasets with varying sources of fidelity. Firstly, this paper extends the GP model to integrate multiple low fidelity data into high fidelity predictions. In order to consider the correlations among data from different fidelity sources, the latent space representation from LMGP is introduced into the correlation matrix of different fidelity data. This multi-fidelity GP model is referred to as a latent map multi-fidelity Kriging (LMmfK). The effectiveness of LMmfK is validated through 1-dimensional analytical test and 8-dimensional Borehole test. Secondly, based on LMmfK, this paper proposes an active learning point-selected strategy suitable for scenarios with multiple fidelity sources, referred to as mfUEFF. The mfUEFF strategy intelligently selects the best data points from multiple fidelity sources, leveraging the benefits of both global improvement and local uncertainty. This integration enhances the efficiency and accuracy of reliability analysis. Two classic cases demonstrate that the proposed reliability method demonstrates superior computational accuracy and efficiency compared to other reliability methods. Finally, this paper applies the proposed method to the static reliability analysis of gears, involving time-consuming finite element models. Engineering application demonstrates that this method significantly improves efficiency, especially in scenarios with multiple fidelity sources. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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14. Wear prediction model of hot rolling backup roll based on FEM + ML algorithm.
- Author
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Lu, Jia, Hao, Luhan, Wang, Pengfei, Huang, Huagui, Li, Xu, Hua, Changchun, Su, Lihong, and Deng, Guanyu
- Abstract
The wear of backup rolls will have a great impact on the quality of the shape of hot rolled strip sheet. In order to overcome the limitations of the finite element method (FEM) in calculating backup roll wear in terms of efficiency and accuracy, this paper proposes a tandem FEM + ML hybrid model to optimise the predictive effect of the finite element method (FEM) on backup roll wear. Firstly, a backup roll wear model based on FEM is established. Secondly, in order to select the optimal machine learning (ML) algorithm as the finite element error compensation model, three types of finite element error compensation models were established based on the random forest (RF) algorithm, the radial basis function (RBF) neural network algorithm, and the particle swarm optimisation support vector machine (PSO-SVM) algorithm. Finally, the three types of finite element error compensation models were connected in series with the FEM model to compare the prediction performance of the three types of FEM + ML models on backup roll wear. The numerical experimental results show that the FEM + PSO-SVM model can better predict the wear of the backup roll, and the PSO-SVM algorithm is the most suitable for building the finite element error compensation model. It is proved that the FEM + ML model proposed in this paper can effectively improve the accuracy and computational efficiency of the FEM model for predicting backup roll wear without adding microelements. In addition, among the hot rolling parameters, the rolling force has the greatest influence on the backup roll wear, and excessive rolling force for a single pass should be avoided to slow down the backup roll wear. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
15. Analysis method useful for calculating various interface stress intensity factors efficiently by using a proportional stress field of a single reference solution modeling.
- Author
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Oda, Kazuhiro, Ashikari, Shunsuke, and Noda, Nao-Aki
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CRACK propagation (Fracture mechanics) , *FINITE element method - Abstract
This paper has proposed an efficient analysis method to calculate interface stress intensity factors (SIFs) based on a proportional stress field of a reference problem whose exact solution is available. In the previous proportional methods, the same crack length and the same element size were applied to both reference and unknown problems so that the same FEM error can be produced. Therefore, when analyzing many unknown problems, the conventional method needs to analyze many reference problems at the same time. Since this approach is time-consuming, this paper considers how to calculate many crack lengths efficiently by using only one single reference solution modeling. For this purpose, several general relations of SIFs are derived for the unknown and the reference problems when both crack length and element size are different. To analyze many unknown problems accurately by using a single reference solution modeling, how to choose the most suitable element dimension of the reference model is clarified. The proposed method is especially useful for crack propagation analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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16. Soft Computing-Based Models for Estimating the Ultimate Bearing Capacity of an Annular Footing on Hoek–Brown Material.
- Author
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Keawsawasvong, Suraparb, Sangjinda, Kongtawan, Jitchaijaroen, Wittaya, Alzabeebee, Saif, Suksiripattanapong, Cherdsak, and Sukkarak, Raksiri
- Subjects
- *
NONLINEAR regression , *FINITE element method , *PROCESS capability , *REGRESSION analysis - Abstract
The finite element limit analysis solution presented in this paper offers novel approaches for estimating the ultimate bearing capacity of annular foundations on Hoek–Brown criterion. The study examines the effects of five of dimensionless parameters, including the ratio of internal to external radii, the depth ratio, the adhesive factor, the yield parameter, and the geological strength index, on the findings of bearing capacity as well as the processes of collapse. Furthermore, one of the soft-computing regression methodologies, the multi-objective evolutionary polynomial regression analysis (MOGA-EPR) method, is utilized along with the requirement of the FELA outcomes as input data. This paper provides accurate limit-state predictions for annular footings on diverse rock masses using the MOGA-EPR model. By using the MOGA-EPR approach, the findings are highly precise and trustworthy, empowering designers to choose the best annular foundation design for various Hoek–Brown material varieties. Moreover, this study extends its scope by encompassing the application of multiple linear regression, multiple nonlinear regression, and artificial neural network models for an extensive comparative analysis. The amalgamation of these models widens the evaluative framework, fostering a more comprehensive exploration of predictive capabilities and insights into the stability assessment of annular footings across rock mass conditions. Through this multifaceted approach, a holistic comprehension emerges, thereby enhancing the decision-making process pertaining to the design of annular foundations within diverse Hoek–Brown material contexts. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
17. The Analysis of the Fracturing Mechanism and Brittleness Characteristics of Anisotropic Shale Based on Finite-Discrete Element Method.
- Author
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Li, Hongtao, Chapman, David N., Faramarzi, Asaad, and Metje, Nicole
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BRITTLENESS , *RADIOACTIVE wastes , *SHALE , *RADIOACTIVE waste disposal , *DISCRETE element method , *FRACTURE mechanics , *FINITE element method - Abstract
Shale anisotropy characteristics have great effects on the mechanical behaviour of the rock. Understanding shale anisotropic behaviour is one of the key interests to several geo-engineering fields, including tunnel, nuclear waste disposal and hydraulic fracturing. This research adopted the finite discrete element method (FDEM) to create anisotropic shale models in ABAQUS. The FDEM models were calibrated using the mechanical values obtained from published laboratory tests on Longmaxi shale. The results show that the anisotropic features of shale significantly affect the brittleness and fracturing mechanism at the micro-crack level. The total fracture number in shale under the Uniaxial Compressive Strength (UCS) test is not only related to the brittleness of shale. It is also strongly dependent on the structure of the shale, which is sensitive to shale anisotropy. Two new brittleness indices, BIf and BICD, have been proposed in this paper. The expression for BIf directly incorporates the number of fractures formed inside of the rock, which provides a more accurate frac-ability using this brittleness index. It can be used to calculate the frac-ability of rocks in projects where there are concerns about fractures after excavation. Meanwhile, BICD links brittleness to the CD/UCS ratio in shale for the first time. BICD is easy to obtain in comparison to other brittleness indices because it is based on the Uniaxial Compressive Strength test only. In addition, it has been shown there is a relationship between tensile strength and the crack damage strength in shale. Based on this, an empirical relationship has been proposed to predict the tensile strength based on the Uniaxial Compressive Strength test. Highlights: Through the use of FDEM simulations, the fracturing mechanics of shale, fracturing behaviour, and brittleness of shale have been investigated from a micro-scopic viewpoint taking shale anisotropy into account. Two new brittleness indices are proposed. One relies on the number of fractures in the shale to reflect the shale's frac-ability, and the other uses strength parameters that can be easily obtained from UCS tests. This paper proposes an empirical relationship to predict the tensile strength of rocks based on UCS tests. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
18. Dynamic response of open doubly curved sandwich shells with soft core subjected to a moving force.
- Author
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Sadripour, Saman, Jafari-Talookolaei, Ramazan-Ali, and Malekjafarian, Abdollah
- Subjects
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SANDWICH construction (Materials) , *SHEAR (Mechanics) , *CRITICAL velocity , *DEGREES of freedom , *FINITE element method , *FIBER orientation - Abstract
This paper presents a forced vibration analysis of open doubly curved sandwich panels subjected to a moving constant force. In this paper, the effect of softness of the core is considered by implementing a semi-layerwise theory. To this aim, the first-order shear deformation theory is adopted for the face sheets and a higher-order theory which was obtained based on 3D elasticity theory is considered for the core. The presented formulation is general and as the deepness parameter is accounted in the strain–displacement relations, the formulation can be used for a wide range of deep as well as shallow doubly curved shells. To obtain the dynamic response of the system, the finite element method (FEM) along with the Newmark method is used. The proposed element is a higher-order one with nine nodes and each node has fifteen degrees of freedom. The effect of various parameters such as length-to-thickness ratio, in-plane aspect ratio, boundary conditions, lamination scheme, and fiber orientation angles on the dynamic response of the structure is examined. Additionally, the critical velocity of the force at which the structure experiences maximum dynamic deflection is obtained in each case. The results show that as the length-to-thickness ratio of the structure increases, the dynamic magnification factor curve increases with respect to non-dimensional velocity. This study provides insights into the dynamic behavior of doubly curved sandwich panels with soft cores and can aid in the design of such structures for specific applications. The results of this study can also serve as a benchmark for future studies on the forced vibration behavior of doubly curved sandwich panels. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
19. Eccentricity fault detection in synchronous reluctance machines.
- Author
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Hooshmandi Safa, Hossein and Abootorabi Zarchi, Hossein
- Subjects
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RELUCTANCE motors , *ECCENTRICS (Machinery) , *AIR gap flux , *FAST Fourier transforms , *SYNCHRONOUS electric motors , *FINITE element method - Abstract
This paper introduces a novel index for static eccentricity (SE) fault diagnosis in synchronous reluctance motors (SynRMs). Although SynRMs with rotor barriers under SE have been modeled in a few papers, any indices for the fault detection have not yet been reported. The proposed index is a specific frequency pattern in the motor current, which can also determine the fault severity. A novel analytical magnetic field investigation is applied to ascertain the proposed index. An accurate nonlinear numerical method is proposed for the motor inductances calculation. The model considers the rotor flux barriers, magnetic saturation, and the stator slots effect. The air gap flux density and the motor current are then achieved. The fast Fourier transform is exploited as a signal-processing tool to calculate motor current spectra. Then, a two-dimension time-stepping finite element method is used to attest of the proposed numerical model. Effectiveness of the proposed index is verified by simulation and experimental tests. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
20. A new approach for fast field calculation in electrostatic electron lens design and optimization.
- Author
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Hesam Mahmoudi Nezhad, Neda, Ghaffarian Niasar, Mohamad, Hagen, Cornelis W., and Kruit, Pieter
- Subjects
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ELECTROSTATIC fields , *FINITE difference method , *BOUNDARY element methods , *FINITE element method , *ELECTRON optics - Abstract
In electron optics, calculation of the electric field plays a major role in all computations and simulations. Accurate field calculation methods such as the finite element method (FEM), boundary element method and finite difference method, have been used for years. However, such methods are computationally very expensive and make the computer simulation challenging or even infeasible when trying to apply automated design of electrostatic lens systems with many free parameters. Hence, for years, electron optics scientists have been searching for a fast and accurate method of field calculation to tackle the aforementioned problem in the design and optimization of electrostatic electron lens systems. This paper presents a novel method for fast electric field calculation in electrostatic electron lens systems with reasonably high accuracy to enable the electron-optical designers to design and optimize an electrostatic lens system with many free parameters in a reasonably short time. The essence of the method is to express the off-axis potential in an axially symmetrical coordinate system in terms of derivatives of the axial potential up to the fourth order, and equate this to the potential of the electrode at that axial position. Doing this for a limited number of axial positions, we get a set of equations that can be solved to obtain the axial potential, necessary for calculating the lens properties. We name this method the fourth-order electrode method because we take the axial derivatives up to the fourth order. To solve the equations, a quintic spline approximation of the axial potential is calculated by solving three sets of linear equations simultaneously. The sets of equations are extracted from the Laplace equation and the fundamental equations that describe a quintic spline. The accuracy and speed of this method is compared with other field calculation methods, such as the FEM and second order electrode method (SOEM). The new field calculation method is implemented in design/optimization of electrostatic lens systems by using a genetic algorithm based optimization program for electrostatic lens systems developed by the authors. The effectiveness of this new field calculation method in optimizing optical parameters of electrostatic lens systems is compared with FEM and SOEM and the results are presented. It should be noted that the formulation is derived for general axis symmetrical electrostatic electron lens systems, however the examples shown in this paper are with cylindrical electrodes due to the simplicity of the implementation in the software. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
21. Powder bed fusion integrated product and process design for additive manufacturing: a systematic approach driven by simulation.
- Author
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Dalpadulo, Enrico, Pini, Fabio, and Leali, Francesco
- Abstract
This paper presents a computer-based methodology to support the design for additive manufacturing of metal components. Metal additive manufacturing, and in particular powder bed fusion systems, are playing a prominent role in the industry 4.0 scenario. The state of the art concerning design methods and tools to support design for additive manufacturing is reviewed by the authors. The key phases of product design and process design to achieve lightweight functional designs and reliable processes are deepened, and the computer-aided technologies to support the approaches implementation are described. Indeed, the state of the art design for additive manufacturing general workflow can be enriched by holistic approaches, use of numerical simulation, and integration and automation between the required tasks. The paper provides a methodology based on the systematic use of numerical simulation to achieve the optimization of both products and associated processes. To take advantage of the holistic perspective, the approach relies on the use of integrated product-process design platforms, allowing to streamline the digital process chain. Product design is based on the systematic integration of topology optimization and automatized tools for concept development and selection and subsequent product simulation driven design refinement. Process design is based on a systematic use of process simulation to prevent manufacturing flaws related to the high thermal gradients of metal processes and minimize residual stress and deformations. This is achieved by working on both the build cycles layouts and the 3D models' distortion compensation. An automotive use case of product and process design performed through the proposed simulation-driven integrated approach is provided to assess the actual method suitability for effective re-designs of additive manufacturing high-performance metal products. The bridged gaps are systematically outlined, and further developments are discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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22. Electromagnetic Modeling Using Adaptive Grids – Error Estimation and Geometry Representation.
- Author
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Spitzer, Klaus
- Subjects
- *
COMPUTATIONAL electromagnetics , *FINITE element method , *ELECTROMAGNETIC fields , *GEOMETRY , *GEOPHYSICS - Abstract
This review paper addresses the development of numerical modeling of electromagnetic fields in geophysics with a focus on recent finite element simulation. It discusses ways of estimating errors of our solutions for a perfectly matched modeling domain and the problems that arise from its insufficient representation. After a brief outline of early methods and modeling approaches, the paper mainly discusses the capabilities of the finite element method formulated on unstructured grids and the advantages of local h-refinement allowing for both a flexible and largely accurate representation of the geometries of the multi-scale geomaterial and an accurate evaluation of the underlying functions representing the physical fields. In summary, the accuracy of the solution depends on the geometric mapping, the choice of the mathematical model, and the spatial discretization. Although the available error estimators do not necessarily provide reliable error bounds for our complex geomodels, they are still useful to guide grid refinement. Therefore, an overview of the most common a posteriori error estimators is given. It will be shown that the sensitivity is the most important function in both guiding the geometric mapping and the local refinement. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
23. Mechanical Properties of Concentric Three-Phase HTS Cable Based on Laminated Theory.
- Author
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Feng, Bin, Ding, Kaizhong, and Zhu, Jiahui
- Subjects
- *
CABLES , *HIGH temperature superconductors , *FINITE element method , *CRITICAL currents , *ELECTROMAGNETIC forces , *SUPERCONDUCTING magnets - Abstract
High-temperature superconducting (HTS) cable, with massive current carrying capability and low electric power loss, is always at the cutting edge of the strong electric fields. The concentric three-phase HTS cable usually subjects to the impact of electromagnetic and mechanical forces. The forces will lead to the shape change of the cable, which may damage the cable and cause the degeneration of the critical current (Ic). In this paper, an analysis model of stress-strain and bending properties of the 10 kV/1 KA cable based on laminated theory is built. Laminated beam theory can simplify REBCO superconducting tape and concentric three-phase HTS cable to analyze stress-strain distribution. A finite element method (FEM) simulation model is established to analyze the critical bending radius of the HTS cable. Meanwhile, the normalized of the critical current of the cable is obtained at different bending radii. The analysis results will provide the theoretical basis for cable pipelaying and line relay protection in grid. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
24. Effect of axial load and shear span on seismic performance of CFT columns reinforced with end-fixed ultra-high strength rebars.
- Author
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Cai, Gaochuang, Wen, Yue, Malla, Prafulla B., Fujinaga, Takashi, and Si Larbi, Amir
- Subjects
- *
CONCRETE-filled tubes , *STEEL framing , *AXIAL loads , *REINFORCING bars , *MATERIAL plasticity , *FINITE element method , *STEEL bars - Abstract
A hybrid frame with resilient members and energy dissipation devices is proposed as a solution to address the issues of the safety and post-earthquake repairability of concrete structures in earthquake-prone zones. This paper experimentally investigates the seismic performance of concrete-filled square steel tube (CFT) columns reinforced with low-bond ultrahigh-strength steel (LBUHSS) bars, which are proposed for the hybrid frames. 8 large-scale specimens with different types of LBUHSS bars, axial load ratios, and shear span ratios were tested. The results show that the use of LBUHSS bars significantly improved the seismic behavior of the CFT columns, including improving the deformation capacity and bearing capacity of the columns and controlling their post-earthquake residual displacements, especially at the large deformation stages of the columns. The cumulative damage and plastic deformation of the specimens decreased with the introduction of the steel bars. The shear-span ratio and axial loads both have a significant influence on the seismic behavior of columns. A simplified finite element analysis model was proposed and applied for a parametrical analysis. Based on the study, two simplified calculation models were proposed to predicate the peak and ultimate deformation of the reinforced CFT columns. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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25. A measure for seismic multiple bends and shear damage patterns of RC rigid-frame bridge tall piers.
- Author
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Mei, Zhu, Liu, Yang, Wu, Bin, Bursi, Oreste S., Lu, Da-gang, and Paolacci, Fabrizio
- Subjects
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CONTINUOUS bridges , *BRIDGE foundations & piers , *GROUND motion , *FINITE element method , *SEISMIC response , *REINFORCED concrete , *HYBRID computer simulation - Abstract
Reinforced concrete (RC) rigid-frame bridges with tall hollow piers were widely constructed in Southwestern China, an earthquake-prone area. For such bridges, the seismic damages may be underestimated if multiple bends of tall piers are overlooked using a conventional damage measure such as the drift ratio. Moreover, the seismic damage assessment can be inaccurate if tall piers' shear damages are ignored using the sectional curvature as a damage measure. Along these lines, this paper proposes a novel seismic damage measure, the piecewise drift ratio (PDR), involving both shear effects and multiple-bend deformations; it has been validated by hybrid tests and analyzed employing fragility curves. Damage state limits represented by the PDR are estimated through statistical analysis of the 40 existing tests of hollow piers. To validate the PDR, a finite element model of an RC rigid-frame bridge with two tall piers was established and adequately calibrated based on model-updating hybrid simulations. To comprehensively evaluate the PDR, ground motions were selected and grouped into four categories by identifying their first two-class nature frequency and their amplitude ratio; to determine fragility curves, both the spectral acceleration at the fundamental period with 5% damping, Sa(T1, 5%), and the peak ground acceleration have been adopted as intensity measures. Results show the effectiveness of the proposed PDR, provide a more severe ground motion for assessment, and reveal the high exceedance probability of the complete damage state of tall piers under some potential seismic scenarios. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
26. Measurement and Processing of Road Irregularity for Surface Generation and Tyre Dynamics Simulation in NVH Context.
- Author
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Rapino, Luca, La Paglia, Ivano, Ripamonti, Francesco, Corradi, Roberto, Di Lione, Riccardo, and Baro, Simone
- Subjects
- *
PAVEMENTS , *FINITE element method , *TESTING equipment - Abstract
Nowadays, finite element tyre models are often used to perform vehicle NVH (noise, vibration, harshness) simulations. To account for the specific operating conditions, a road surface must be properly included in the model. This paper deals with a methodology to experimentally evaluate and process road irregularity measurements, so as to generate a road surface input. These surfaces are used to simulate the tyre/road interaction at the footprint, which is modelled as a contact surface in finite element tyre models. For this reason, a linear profile of the road surface is not suitable for these simulations and the whole surface must be considered. Starting from the measurements taken through a test equipment specifically designed to carry laser sensors and scan road profiles, the Power Spectral Density (PSD) of a specific track is estimated and then interpolated considering piecewise functions. Finally, a model to generate a road surface starting from the measured PSD is developed, discussed and validated. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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27. Seismic performance of a new type of prefabricated bridge pier with cast-in-place UHPC jacketing.
- Author
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Zhang, Zhe, Zou, Pan, Deng, En-Feng, Wang, Shi-Bo, Pang, Yu-Yang, Xue, Hong-Tao, Men, Shao-Rong, and Liu, Dong-Xu
- Subjects
- *
PIERS , *BRIDGE foundations & piers , *BRIDGE design & construction , *FINITE element method , *FAILURE mode & effects analysis - Abstract
Accelerated bridge construction (ABC) is prevalent all over the world attributable to its technical advantages including the higher construction efficiency, less traffic disruption, and higher construction quality. Grouting sleeves (GS) and grouting corrugated pipes (GCP) are the traditional connection methods of ABC in high seismic regions, with the disadvantages of uncompacted grouting and high requirement of construction accuracy. To this end, this paper developed a new type of prefabricated concrete bridge pier connected with ultra-high performance concrete (PCBP–UHPC) jacketing to solve the problems. To validate the seismic performance of the proposed innovative bridge pier, quasi-static tests on three full-scale specimens PCBP–UHPC, PCBP–GS, and PCBP–GCP were carried out. The results indicated that the failure mode of specimen PCBP–UHPC was similar to that of specimens PCBP–GS and PCBP–GCP with the characteristics of longitudinal steel yielding and concrete crushing at the base of the hollow pier. The obvious plastic hinge outward shifting could be observed during the loading for specimen PCBP–UHPC. The positive ultimate load of specimen PCBP–UHPC was 636.33 kN, which was 14.8% and 13.3% higher than those of specimens PCBP–GS and PCBP–GCP, respectively. In addition, a refined finite element model (FEM) was established by ABAQUS to provide an in-depth understanding on the failure mechanism of the proposed PCBP–UHPC. The parametric analyses were conducted to reveal the influence of the socket depth and axial compression ratio on seismic performance of the proposed PCBP–UHPC. The results indicated that the socket depth had little effect on seismic performance of the prefabricated pier, while the ultimate load bearing capacity of specimen PCBP–UHPC increased to some extent as the increase of the axial compression ratio. The present research work provides an innovative prefabricated bridge pier and a comprehensive experimental–numerical understanding on its seismic performance, which is beneficial for its engineering application. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
28. Synergy of LIDAR and hyperspectral remote sensing: health status assessment of architectural heritage based on normal cloud theory and variable weight theory.
- Author
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Guo, Ming, Shang, Xiaoke, Zhao, Jiawei, Huang, Ming, Zhang, Ying, and Lv, Shuqiang
- Subjects
- *
POINT cloud , *REMOTE sensing , *LIDAR , *FINITE element method , *SURFACES (Technology) , *MODEL theory - Abstract
Architectural heritage health assessment is the basis of scientific repair and maintenance. However, existing methods do not adequately take into account the fuzziness, randomness and uncertainties unique to architectural heritage assessment. In this paper, a new evaluation model of VM-NCM is constructed by combining variable weight theory and normal cloud model theory. The model enables the combination of qualitative ratings and quantitative calculation, deals with the fuzziness in the assessment process, and resolves the randomness and reflects the uncertainty to a certain extent. Based on constructing the index system combining qualitative and quantitative indexes, the structural index values are acquired by the synergistic coupling of the fine laser point cloud model and finite element structural analysis model. The acquisition of surface index values is completed by the hyperspectral intelligent detection technology of surface materials and diseases. These reduce the generation of ambiguous information in the index detection process. An evaluation study is conducted using the Yingxian wooden pagoda in China as an example. The results show that this method takes into account the fuzziness and randomness in the evaluation process, and obtains more scientific and reliable evaluation results, which provides a research paradigm for assessing the architectural heritage health status. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
29. Flexibility prediction of thin-walled parts based on finite element method and K-K-CNN hybrid model.
- Author
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Li, Wangfei, Ren, Junxue, Shi, Kaining, Lu, Yanru, Zhou, Jinhua, and Zheng, Huan
- Abstract
Elastic deformation in thin-walled parts during machining is affected by the coupling of force and flexibility. Obtaining flexibility information along machining tool paths is crucial for online monitoring of this deformation. However, the current finite element method (FEM) is limited by mesh nodes, hampering its ability to accurately determine flexibility along tool paths. To overcome this limitation, this paper proposes a method that combines FEM with the surrogate model to predict flexibility accurately at any position on thin-walled parts' surfaces. The surrogate model is the hybrid model K-K-CNN based on two K-nearest neighbor (KNN-KNN) algorithms and a convolutional neural network (CNN) model. Initially, an initial dataset containing positions and flexibility of mesh nodes is generated automatically through secondary development of ABAQUS. Then, the K-K-CNN hybrid model is introduced and trained on this dataset to calculate flexibility accurately at any position on the surface of thin-walled parts. The hybrid model employs a CNN to address the nonlinear spatial correlation issue in flexibility prediction. Moreover, the hybrid model incorporates two KNN algorithms to alleviate the overfitting challenge stemming from the straightforward input features and extensive dataset size. In comparison to traditional deep learning models, the K-K-CNN hybrid model presents notable benefits in predicting flexibility for complex thin-walled parts at any given position, which affirms its robustness and accuracy. The proposed prediction method for flexibility can provide high-quality data-driven information for monitoring the elastic deformation of thin-walled parts. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
30. An analysis of bone drilling process using finite element analysis.
- Author
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Kim, Dong Chan, Kim, Dong Min, and Park, Hyung Wook
- Subjects
- *
CARBON fiber-reinforced plastics , *CUTTING force , *FRACTURE mechanics , *FIBROUS composites , *CARBON composites , *ARTIFICIAL joints , *BRITTLE materials , *FINITE element method - Abstract
The bone drilling process has been used in orthopedic surgical procedures to remove bones and create artificial joint holes. Heat generation due to the cutting temperature is a critical problem, which leads to permanent damage to bone tissues and thermal necrosis. Previous studies noted that the temperature changes during the drilling process depend on the cutting forces. Temperatures above 50 °C can damage the surface of the drilled hole. Machining parameters such as the feed rate affect the generation of the cutting force and temperature. Low ranges of surface velocity and feed rate significantly increase the surgery time, thereby increasing the thermal exposure time. Therefore, selecting the appropriate cutting parameters considering the machining time is essential to improve the bone surgery process. A bone cell has anisotropic material properties owing to is orientation. Bones consist of osteons and lamellae, which is analogous to the fiber and matrix in composites such as carbon fiber-reinforced polymer. The finite element (FE) method can be used to analyze the mechanism of the composites machining process, and this requires the use of a failure model. Hill's potential theory is used in the failure analysis of anisotropic materials. Although Hou's failure model yields better analysis results than Hill's theory, the former is suitable for predicting the failure of brittle materials. Bones are more ductile than composites owing to the presence of minerals and moisture. This paper proposes an FE analysis model for three-dimensional orthopedic surgical drilling to predict the cutting force. The performance of the FE model was validated by comparing the obtained results with the cutting force measured during experiments using bovine orthopedic bone. Orthopedic bone has an anisotropic structure. The structure consists of packed osteons and lamellae, reflecting a directional property similar to that of the composites structure. Therefore, the FE model considered the anisotropic material behavior with a failure criterion. The Hashin and Puck models were implemented in the FE model to analyze the failure of the osteons and lamellae, respectively. The thrust force is higher than the radial and tangential forces, which contributes to temperature increase during the drilling process. Therefore, the thrust forces obtained from the experiment and FE model at various drilling parameters were compared to validate the performance of the FE model. At a higher feed rate, the FE model yielded good prediction accuracy with a low error of approximately 3.37 %. Based on the predicted thrust force, the heat generated on the surface of the drilled hole was calculated to predict the degree of necrotic surface. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
31. Dynamic design and transmission performance analysis based on CF/PEEK composite for short flexspline harmonic drive.
- Author
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Lv, Hongzhan, Jiang, Yu, You, Jia, and Huang, Wei
- Subjects
- *
HARMONIC drives , *CARBON composites , *FATIGUE life , *FINITE element method , *COMPOSITE materials - Abstract
The short flexspline harmonic drive has the advantages of a small axial size and a compact structure. However, unlike the ordinary cup-shaped flexspline with a long cylinder, a steel flexspline with a short cylinder often leads to concentrated stress and transmission failure due to inaccurate spatial meshing. This paper proposes a harmonic drive made of carbon fiber-reinforced polyetheretherketone (CF/PEEK) composite to solve this problem. The finite element method is employed to calculate and analyze the key technical performance of the composite material and the traditional steel harmonic drive. Results indicate the good vibration characteristics, fatigue life, and excellent load capacity of the new composite harmonic drive despite sacrificing some transmission accuracy. This work provides a new research method for designing a short flexspline harmonic drive using composite materials and a theoretical basis for designing a CF/PEEK short flexspline harmonic drive. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
32. Numerical estimation of landslide runout flow–structure interactions: A case study of Zhengjiamo landslide.
- Author
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Zhang, Zelin, Feng, Fei, Wang, Tao, and Dou, Xiaodong
- Subjects
- *
LANDSLIDES , *MARINE debris , *LANDSLIDE prediction , *FINITE element method , *FIELD research , *ENERGY dissipation - Abstract
In rural areas, landslides can bury houses and result in major disasters in affected areas, which can greatly hinder local economic development and construction. When landslides occur, sliding debris can result in large impact forces, causing varying degrees of damage to building structures. Given the great harm caused by landslides, this paper studies the prediction of dynamic response characteristics of building structures under the impact of the Zhengjiamo landslide. The engineering geological background of the Zhengjiamo landslide is analyzed in detail via field investigations. Then, a numerical method is presented to simulate the runout process of the sliding debris, and the runout process and final deposition area are studied. A node-to-surface contact algorithm is adopted to transfer the displacements and contact forces between the sliding debris and the building. The building structure is simulated via the finite element method (FEM). The sliding debris is simulated via the smoothed particle hydrodynamics (SPH) method. An element erosion algorithm is adopted to simulate the destruction process. The SPH-FEM fluid–structure coupling method is implemented to simulate the landslide dynamic disaster process (the impact behavior for the building). The destruction process is considered in the interactions between the sliding debris and the building on the three-dimensional terrain. The landslide motion during each stage is analyzed, including the sliding, energy dissipation, impact, and damage to the building structure. The maximum runout of the landslide is about 280 m. The maximum stress of the impact on the building is 2 × 106 Pa. The impact speed of the sliding body is generally 16.5–24.07 m/s. On the basis of this, the disaster background, disaster status, and prediction of the landslide disaster effect are studied to provide new insights into landslide disaster prevention and reduction. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
33. Analysis for the space-time a posteriori error estimates for mixed finite element solutions of parabolic optimal control problems.
- Author
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Shakya, Pratibha and Kumar Sinha, Rajen
- Subjects
- *
FINITE element method , *CONVEX domains , *A posteriori error analysis , *SPACETIME - Abstract
This paper investigates the space-time residual-based a posteriori error bounds of the mixed finite element method for the optimal control problem governed by the parabolic equation in a bounded convex domain. For the spatial discretization of the state and co-state variables, the lowest-order Raviart-Thomas spaces are utilized, although for the control variable, variational discretization technique is used. The backward-Euler implicit method is applied for temporal discretization. To provide a posteriori error estimates for the state and control variables in the L ∞ (L 2) -norm, an elliptic reconstruction approach paired with an energy strategy is utilized. The reliability and efficiency of the a posteriori error estimators are discussed. The effectiveness of the estimators is finally confirmed through the numerical tests. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
34. Rates of robust superlinear convergence of preconditioned Krylov methods for elliptic FEM problems.
- Author
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Castillo, S. J. and Karátson, J.
- Subjects
- *
BOUNDARY value problems , *KRYLOV subspace , *FINITE element method - Abstract
This paper considers the iterative solution of finite element discretizations of second-order elliptic boundary value problems. Mesh independent estimations are given for the rate of superlinear convergence of preconditioned Krylov methods, involving the connection between the convergence rate and the Lebesgue exponent of the data. Numerical examples demonstrate the theoretical results. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
35. Mechanical electrical coupling analysis of a 3D braided composite piezoelectric energy harvester with spring support to expand the frequency domain.
- Author
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Yang, Lei, Ren, Fei, Wei, Gaofeng, Shan, Lichang, and Li, Anqing
- Subjects
- *
BRAIDED structures , *PIEZOELECTRIC composites , *POISSON'S ratio , *COUPLINGS (Gearing) , *MODULUS of rigidity , *FINITE element method - Abstract
In this paper, 3D braided composites are considered for high-performance piezoelectric energy harvester designing, and a 3D braided composite piezoelectric energy harvester (3D BCPEH) is proposed. The advantage of 3D BCPEH is that the natural frequency of the device can be adjusted by adjusting the stiffness of the spring, making the natural frequency of the device close to the vibration frequency of the environment, thereby achieving the best harvesting effect of the energy harvester. During the vibration process, spring support can cushion the impact and stress on the piezoelectric energy harvester, thereby protecting the device from damage and helping to improve the stability and performance of the system. Finite element analysis is used to obtain the elastic modulus, shear modulus, and Poisson's ratio of 3D braided composites with varying braiding angles. Based on Hamilton's variational principle, the vibration control equation of the spring supported 3D BCPEH is derived. The effects of spring rate, braiding angle, external excitation acceleration, external load resistance, and structure size on the output response of 3D BCPEH are simulated and analyzed. The validity of the proposed 3D BCPEH with spring support is confirmed by the simulation results. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
36. Finite Element Analysis of Eddy Current Testing of Aluminum Honeycomb Sandwich Structure with CFRP Panels Based on the Domain Decomposition Method.
- Author
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Cui, Lulu, Zeng, Zhiwei, and Jiao, Shaoni
- Subjects
- *
EDDY current testing , *DOMAIN decomposition methods , *SANDWICH construction (Materials) , *HONEYCOMB structures , *FINITE element method , *ALUMINUM , *ALGEBRAIC equations - Abstract
Aluminum honeycomb sandwich structure with panels made of carbon fiber reinforced polymer (CFRP) are widely used in aerospace and other fields. Simulation of the eddy current (EC) testing of the sandwich structure using the finite element (FE) method is challenging as the traditional FE method has difficulties in mesh division and the solution of the algebraic equations. This paper proposes to use the domain decomposition FE method to solve such problems. The top CFRP panel, the aluminum honeycomb core, and the bottom CFRP panel of the sandwich structure and the ferrite core of the coil are placed in different subdomains and the subdomains are meshed independently. This method simplifies the mesh generation and does not require regenerating the meshes when simulating the scanning testing with the ferrite-core coil. In this way, the efficiency of simulation is greatly improved. The EC distributions in the sandwich structure are computed and the influence of defect on EC distribution is analyzed. The C scans of the sandwich structures are simulated. The images of the EC responses to the defects, such as wall fracture, node disconnection, and core wrinkle, are obtained. The simulation results are validated by experiments. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
37. Numerical modeling of self-sealing in fractured clayey materials.
- Author
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Quacquarelli, Adriana, Talandier, Jean, Di Donna, Alice, and Collin, Frédéric
- Subjects
- *
UNDERGROUND construction , *FINITE element method , *PETROPHYSICS , *PERMEABILITY - Abstract
The fractures network generated during the excavation of underground research facilities can induce stress redistribution and alteration of flow and transport properties, becoming preferential paths for releasing radionuclides into the host rock. Nevertheless, in the long term, the fracture can be sealed through the resaturation of water coming from the rock as a function of its self-sealing potential. Despite the large number of experimental studies that have proven the self-sealing capacity of clay rocks, very few attempts have been made to describe and predict the phenomenon numerically. This may be due to the difficulty of measuring the initial hydro-mechanical conditions. Besides, samples artificially fractured in the laboratory can be disturbed by the preparation process itself, which can alter the hydro-mechanical state. This paper addresses that issue by bridging the gap between experiments and numerical modeling. Representative experimental tests performed on Callovo–Oxfordian Claystone (COx) are used to offer a hydro-mechanical fracture law taking into account the self-sealing capacity of the material. Implementing such a model in a finite element code allows its validation through comparison with laboratory tests. Furthermore, the role of the initial fracture size and the evolution of water permeability during the wetting/drying process is investigated. Due to its transmissivity, injected water can penetrate the rock, initially reaching the damaged zone around the fracture before spreading through the entire sample. This progression is accounted in the constitutive equation and represented numerically. Nevertheless, a larger initial crack leads to reduced recovery rates. These results match the experiments, offering a valuable perspective in the modeling of self-sealing in in situ conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
38. Finite element modeling of thermo-hydro-mechanical coupled processes in clay soils considering bound water dehydration.
- Author
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Sojoudi, Mohammadhossein, Li, Biao, and Norouzi, Emad
- Subjects
- *
CLAY soils , *FINITE element method , *NONLINEAR equations , *DEHYDRATION , *NEWTON-Raphson method - Abstract
This paper presents a new finite element method (FEM) model to simulate the thermo-hydro-mechanical (THM) responses of water-saturated clay soils. The model can account for the effects of temperature variation on bound water dehydration and the corresponding thermo-poromechanical strains. The governing equations, including mass balance, momentum balance, and energy balance, are derived based on the principles of continuum mechanics for porous media. The impact of bound water dehydration on THM behavior is incorporated into the coupled THM equations. The model is equipped with an unconventional plasticity for more accurate description of elastoplastic behavior. To solve the nonlinear system of equations, a modified Newton–Raphson method is employed. The model is validated using laboratory tests on various clay soils with different geological origins, and reasonable agreement is achieved. The thermally induced contraction behavior of clay soils at a low overconsolidation ratio and thermally induced expansion behavior at a high overconsolidation ratio are well simulated. During heating, the effect of bound water dehydration on the generation of excess pore pressure in clay soils is highlighted in our numerical results. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
39. Evaluating the exceedance probability of the runout distance of rainfall-induced landslides using a two-stage FEM-MPM approach.
- Author
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Lu, Meng, Ceccato, Francesca, Zhou, Mingliang, Yerro, Alba, and Zhang, Jie
- Subjects
- *
LANDSLIDES , *SOIL mechanics , *MATERIAL point method , *MONTE Carlo method , *FINITE element method , *RAINFALL - Abstract
Evaluating the exceedance probability within a time period (EPT) of the runout distance of rainfall-induced landslides is important for the quantitative risk assessment (QRA) of rainfall-induced landslides. However, assessing the EPT of the runout distance of rainfall-induced landslides using a mechanics-based method remains a challenging problem since it requires considering uncertainties in both soil properties and rainfall. This paper proposes a novel mechanics-based method to assess the EPT of the runout distance of rainfall-induced landslides with explicit consideration of the above two types of uncertainties. A two-stage numerical approach, which combines the finite element method (FEM) and the material point method (MPM), is first developed for the large deformation analysis to obtain runout distances of landslides under given rainfalls. To further enhance the computational efficiency, a machine learning-based surrogate model is built to predict the exceedance of the runout distance, and the EPT of the runout distance is finally estimated via Monte Carlo simulation. The proposed method is applied to a sandy slope under rainfall. The results show that the EPT increases as the time period becomes longer, and the runout distance of the landslide is controlled by the first failure of the slope caused by rainfall. This study contributes to the development of a general and efficient tool to support the QRA of rainfall-induced landslides. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
40. Coupled hydro-mechanical XFEM analysis for multi-fracturing through an excavation driven by an underlying aquifer: a forensic case study.
- Author
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Hong, Yi, Zhang, Jianfeng, Zhao, Yucheng, Wang, Lizhong, and Wang, Lilin
- Subjects
- *
CRACK propagation (Fracture mechanics) , *FRACTURE mechanics , *EXCAVATION , *CONTINUUM mechanics , *FINITE element method , *PLANT propagation - Abstract
This paper presents a forensic numerical study on hydro-fracturing at three locations within an excavation in a clayey till underlain by an aquifer in Ontario, Canada. The pioneering forensic studies were based on continuum mechanics using finite element method (FEM) combined with an effective medium approach, which did not explicitly simulate the physical process of fracture propagation. This has overestimated the size of the venting holes (i.e., model aperture approximately 8 m, observed approximately 0.1 m), hindering accurate assessment of the venting locations at the excavation base. For this reason, a coupled hydro-mechanical XFEM analysis, which explicitly models fracture propagation, was performed in this study to revisit the case history from the perspective of fracture mechanics. Parametric study is also performed to investigate the influence of flow rate on the direction of the fracture propagation, and thus location of venting holes. It is shown that the coupled hydro-mechanical XFEM analysis offers better predictions than previous FEM analysis for both, locations and sizes of the three observed venting holes. The parametric study reveals that an increase in the flow rate from 5 to 10 L/min (which is within the reported range) leads to a wider and less curved fracture, altering the predictions of the venting locations at the excavation base by around 8 m. This is because an increasing flow rate causes wider aperture and higher shear stress near the fracture tip, which intensifies the re-orientation of maximum principle stress that facilitates the re-direction of the propagating fractures. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
41. Research on ultrasonic bone cutting mechanism based on extended finite element method.
- Author
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Wang, Linwei, Liu, Yu, Wang, Shiwei, Li, Jinguang, Sun, Yumeng, Wang, Jingyu, and Zou, Qilei
- Subjects
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ULTRASONIC cutting , *FINITE element method , *PLANT propagation , *CRACK propagation (Fracture mechanics) , *SURGICAL equipment , *SURGICAL robots - Abstract
The research on the crack propagation mechanism of bone has important research significance and clinical medical value for the selection of cutting parameters and the development of new surgical tools. In this paper, an extended finite element method (X-FEM) model of ultrasonic bone cutting considering microstructure was developed to further study the ultrasonic bone cutting mechanism and to quantitatively analyze the effects of cutting direction, ultrasonic parameters, and cutting parameters on the mechanism of ultrasonic bone cutting crack propagation. The results show that ultrasonic bone cutting is essentially a controlled crack propagation process, in which brittle crack and fatigue crack are the main crack propagation mechanisms. In order to improve the efficiency of ultrasonic bone cutting, large amplitude and high-frequency ultrasonic vibration are preferred. Compared with the other two cutting directions, the crack propagation deflection angle in the transverse cutting direction is the largest, resulting in the worst cutting surface. Therefore, in the path planning of orthopedic surgical robots, the transverse cutting direction should be avoided as much as possible. Frequency only has a significant effect on the crack propagation rate and has a positive correlation. There is a positive correlation between the deflection angle, propagation length, propagation rate, and amplitude, which provides the possibility to control the direction and length of crack propagation by controlling the amplitude of ultrasonic. The feed speed is much lower than the ultrasonic vibration speed, which makes the influence of ultrasonic vibration speed on the crack propagation characteristics dominant. The X-FEM model of ultrasonic bone cutting provides an effective method for selecting reasonable machining parameters of orthopedic robot and optimize the design of ultrasonic osteotome. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
42. Free vibration and bending analysis of porous bi-directional FGM sandwich shell using a TSDT p-version finite element method.
- Author
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Lakhdar, Zeddoune, Chorfi, Sidi Mohammed, Belalia, Sid Ahmed, Khedher, Khaled Mohamed, Alluqmani, Ayed Eid, Tounsi, Adbelouahed, and Yaylacı, Murat
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FREE vibration , *FINITE element method , *SHEAR (Mechanics) , *CERAMIC materials - Abstract
Compared to the first-order shear deformation theory and other classical shell theories, the higher-order shear theory is deemed more accurate due to its superior ability to capture transverse shear effects, especially vital for precision in modeling thicker, doubly curved shell panels. Additionally, the third-order shear deformation theory (TSDT) is acknowledged for its computational efficiency compared to the 3D solution striking a balance between result precision and computational efficiency. This paper explores the static bending and free vibration analysis of a porous bi-directional functionally graded doubly curved sandwich shell. For the first time, a combination of TSDT theory with the p-version finite element method is applied, demonstrated for the analysis of bi-directional functionally graded doubly curved sandwich shell. In the initial phase, the mathematical formulation has been meticulously derived. Four models of sandwich FGM distributions, taking into account the porosity effect and comprising a blend of two ceramic materials and a metallic material, have been thoroughly explored. Subsequently, the study evaluates the effectiveness and accuracy of the formulation implemented in FORTRAN CODE through benchmark results, showcasing its adaptability for different shell panel geometries by adjusting the values of the radius of curvature. The latter part of the research delves into new findings related to bi-directional functionally graded porous sandwich FGM shell panels, investigating the effects of gradient indexes and porosity distribution on their behavior. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
43. Mechanisms of failure of aluminium-based Whipple shields under hypervelocity impact: insights from continuum simulations.
- Author
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Kamble, Arun and Tandaiya, Parag
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HYPERVELOCITY , *SPACE debris , *FINITE element method , *METEOROIDS , *ALUMINUM alloys - Abstract
Micrometeoroids and Orbital Debris (MMOD) travelling at extremely high velocities in space are a threat to the structural integrity of spacecrafts in the Low Earth Orbit. Whipple shield, consisting of a Bumper and a Rear Wall, with a stand-off distance in between, is widely used to protect spacecrafts from hypervelocity MMOD impacts. In this paper, we present numerical simulations of a set of well-known hypervelocity impact (HVI) experiments on aluminium-based Whipple shields reported in the literature. These simulations are conducted using the three-dimensional Lagrangian Finite Element Method in ABAQUS/Explicit software. In six out of the seven tests reported in the literature, the Whipple shield failed due to a detached spall from the back surface of the Rear Wall, while in the seventh test, the spall was not detached. The present work successfully replicates and favourably compares the failure mechanisms observed in these Whipple shields to the corresponding experimental results. Various critical aspects of the Whipple shield's failure mechanics and mechanisms are investigated. These include impact pressure on the projectile, Bumper and Rear Wall, Bumper hole diameter, temperature rise, and residual velocity of debris particles and spalled fragments. The predicted ballistic limit of the Whipple shield falls between 2.54 mm and 3.18 mm of Rear Wall thickness in excellent agreement with the experimental results reported in the literature. The present work provides valuable insights into Whipple shield performance. The developed methodology could be employed to optimize shield design through predictive simulations, thereby improving spacecraft protection. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
44. Design and Simulation of a Terahertz Frequency Filter Based on Plasmonic SIS Waveguide Coupled with a Split Ring Resonator for Refractive Index Sensing Applications.
- Author
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Thomas, Sherin, Singh, Mandeep, and Satyanarayan, M. N.
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REFRACTIVE index , *RESONATORS , *FINITE element method , *PLASMONICS , *POWER density - Abstract
Terahertz waveguides and resonators have brought numerous applications from biomedical to modern communications. In this paper, we have demonstrated numerically a straight semiconductor-insulator-semiconductor(SIS) waveguide attached to a split ring resonator, which acts as a terahertz frequency filter and can be used for refractive index sensing. The device's transmission properties have been studied using the finite element method. To fix the third dimension of the device, that is the depth of the waveguide the effective mode index and power density calculations are done for the propagating mode. The frequency tuning of the filter is achieved by changing the geometric parameters of the waveguide and resonator system such as ring radii and split width. Both the symmetric and antisymmetric modes of the split ring show almost the same rate of change of resonance frequency with the change in geometric parameters. To demonstrate the importance of the split position, the transmittance is studied by placing the split at different positions on the ring. We obtained the same transmittance for the split at left and right positions, whereas the split at the top and bottom shows different transmittance similar to the transmittance of a ring resonator. The symmetric and antisymmetric modes of the split ring are calculated for refractive index sensing and the highest sensitivity of 0.741 THz/ refractive index unit (RIU) for the symmetric mode as expected. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
45. A Dual-Core Two-Parameter of RI and Temperature Photonic Crystal Fiber Sensor Based on the SPR Effect.
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Hu, Linchuan, Li, Jianshe, Li, Shuguang, Zhao, Yuanyuan, Yin, Zhiyong, Li, Kaifeng, Wang, Chun, Zhang, Sa, and Pei, Menglei
- Subjects
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PHOTONIC crystal fibers , *OPTICAL fiber detectors , *GOLD films , *FINITE element method , *REFRACTIVE index , *DETECTORS - Abstract
This paper presents a dual-core two-parameter optical fiber sensor based on the surface plasmonic resonance (SPR) effect. It is analyzed by the finite element method. The proposed sensor is a dual-channel structure designed with photonic crystal fiber (PCF) as the base material: one channel is coated with a gold film to measure the refractive index (RI) of the solution to be measured, and the other channel is coated with a gold film and polydimethylsiloxane to measure the temperature of the solution to be measured. The exposed microslot structure on both sides reduces the complexity of sensing measurements. The results show that the maximum RI sensitivity of the sensor is 19,900 nm/RIU, and the maximum sensitivity to temperature is 8.7 nm/℃. This work is conducive to realizing a PCF sensor with high sensitivity, large measurement range, real-time monitoring, and easy preparation. As a result, the sensor is expected to be widely used in fields such as biology and chemicals. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
46. Three-dimensional Darcy's reduced-order isogeometric shape optimization for cooling channels.
- Author
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Chen, Long, Wang, Xuechong, Mao, Yicheng, and Li, Baotong
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STRUCTURAL optimization , *ISOGEOMETRIC analysis , *REYNOLDS number , *POTENTIAL flow , *HEAT convection , *FINITE element method - Abstract
This paper presents a shape optimization for the three-dimensional cooling channel with high Reynolds number flow and strong convection heat transfer based on isogeometric analysis (IGA). Meanwhile, the applicability conditions of Darcy's potential flow, which is an approximate liner flow, are introduced to solve the heat-flow coupling problem. We call this method Darcy reduced-order isogeometric analysis (DRIGA). The volume parametric model is constructed by using the segmentation–mapping–merging mechanism of design features, and the model can be directly analyzed by IGA without data conversion and to eliminate discrete errors. The calculation formulas for DRIGA are derived. Then, a DRIGA-based shape optimization is achieved by applying the sensitivity analysis method with the average temperature as the objective function, the location coordinates of the fluid–solid boundary control points as the design variables, and the percentage of fluid volume and the pressure drop as the constraints. Several examples of approximate water-cooling devices show that our method can accurately describe the heat-flow coupling problem in the case of a narrow channel with a high flow velocity. The analytical results are in general agreement with those of the finite element convection–diffusion analysis, and the shape optimization results show that the average temperature is reduced, which proves the correctness of the method. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
47. Performance analysis of permanent magnet claw pole machine based on magneto-electric-thermal coupling network method.
- Author
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Liu, Chengcheng, Li, Yue, Zhang, Hongming, and Du, Handong
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PERMANENT magnets , *CLAWS , *MAGNETIC structure , *FINITE element method , *MACHINERY - Abstract
The permanent magnet claw pole machine (PMCPM) with soft magnetic composite (SMC) cores has shown better performance than the traditional transverse flux machine, and its performance can be improved by developing its stator with hybrid silicon sheet and SMC cores, and this kind of PMCPM is named as HPMCPM. Due to its complex 3D magnetic structure, analyzing its performance by using the traditional finite element method (FEM) is time-consuming. To overcome this constraint, this paper proposes a magneto-electric-thermal coupling network (METCN) model with bidirectional data transmission to calculate the electromagnetic performance and temperature distribution and the calculation results are verified by the FEM method and experimental measurement results. Compared with the 3D FEM, the proposed METCN method has the advantage of fast calculation speed and similar accuracy. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
48. Design of the long-distance wireless power transfer system with multiple relay coils based on loss optimization.
- Author
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Wu, Zhijun, Tan, Linlin, Xu, Heqi, Shen, Shuyu, and Huang, Xueliang
- Subjects
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WIRELESS power transmission , *FINITE element method , *LINEAR network coding , *ELECTRIC lines , *SUPPLY & demand , *POWER resources , *PARTICLE swarm optimization - Abstract
This paper proposes a design scheme for a wireless power transfer (WPT) system based on multi-relay coils to solve the power supply demand of 500 kV transmission line online monitoring equipment. The relationship between the operating frequency and the coil loss is established to analyze the influence of the number of relay coils and the coil distance on the transmission performance. The particle swarm optimization model is established with transmission efficiency as the optimization objective. The distribution spacing between coils, the working frequency, and the number of coils are optimized. Based on the equidistant arrangement of relay coils, an optimization scheme of non-equidistant arrangement is proposed. Under the condition of the same number of relay coils, the transmission efficiency of the system is increased by 20.56% and has been verified by experiments. In addition, finite element analysis software has simulated the surrounding high-voltage field strength of the WPT system added to the insulators. The results show that the insulators still meet the insulation standards. The simulation and experimental results show that the proposed scheme can effectively meet the power demand of high-voltage line monitoring equipment. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
49. Design and analysis of a new improved rotor structure in line-start synchronous reluctance motors.
- Author
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Mousavi-Aghdam, Seyed Reza and Azimi, Abbas
- Subjects
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RELUCTANCE motors , *SYNCHRONOUS electric motors , *FINITE element method , *MAGNETIC circuits , *ROTORS - Abstract
This paper proposes a new design for line-start operation of synchronous reluctance motors. In the past years, synchronous reluctance motors have been studied by many researchers. Due to high efficiency, they have gained increasing interest because in the synchronous operation, there is limited losses in the rotor. On the other hand, line-start operation of the synchronous reluctance motors is an important challenge that can make this type of the motors popular in many applications. However, line-start operation techniques should not considerably affect the steady-state characteristics of the motor. In the proposed design, the arrangement, size and shape of the rotor conductor bars are designed based on the rotor magnetic circuit difference between induction and reluctance synchronous motors. Complete assessment of the motor parameters are examined using finite element analysis. The proposed structure improves the starting characteristics of the motor. Moreover, power factor of the proposed motor is slightly increased in comparison to that of conventional line-start synchronous reluctance motors. The results obviously show effectiveness of the proposed line-start operation strategy for the synchronous reluctance motors. Finally, experimental verification are also included to confirm the finite element analysis results. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
50. Evolution and comparison of three typical permanent magnet machines for all-electric aircraft propulsion.
- Author
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Long, Dingbang, Wen, Honghui, Shao, Yulong, and Shuai, Zhikang
- Subjects
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PERMANENT magnets , *EDDY current losses , *FINITE element method , *MACHINERY , *ACTINIC flux - Abstract
In this paper, three typical permanent magnet machines for All-Electric aircraft propulsion are designed, optimized and compared. Firstly, the necessary performances are determined based on the requirements of high power/torque density and an aircraft with a maximum takeoff weight of 1500 kg. The initial structures of interior permanent magnet (IPM) synchronous machine, vernier permanent magnet (VPM) machine and flux-switching permanent magnet (FSPM) machine are designed with identical stator outer radius and rotor shaft length. Then, parametric sensitivity analysis and multi-objective particle swarm are combined as an optimization methodology to optimize these machines. Based on the finite element analysis, the electromagnetic performances such as no-load airgap flux density harmonic spectrum, cogging torque, average output torque, losses, efficiency and power factor, etc., are generally compared and analyzed. Subsequently, the discussions are carried out, where the strength and weakness of these three machines are concluded and the future prospects are suggested. Finally, it is concluded that if effective measures are implemented to reduce the permanent magnet eddy current loss and improve the power factor, the VPM machine would be the most suitable choice among these machines for All-Electric aircraft propulsion. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
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