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SSRN 2023年

作者： Ai, Weilong Liu, Yuan Jiangsu Key Laboratory of Engineering Mechanics Analysis School of Civil Engineering Southeast University Nanjing211189 China Research Centre of Structural Health Monitoring and Prognosis State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing210016 China

The rapid development of electric vehicles necessitates lithium-ion batteries with high energy densities. To gain a deeper comprehension of lithium-ion batteries, JuBat has been created in Julia programming language for battery modelling. It is an open-source framework implemented by Julia functions, with excellent execution speed and a user-friendly implementation environment. JuBat covers three battery models: P2D, SPM, and SPMe, and uses finite element method to resolve the governing equations. The results of JuBat demonstrate good agreement with that of PyBaMM. Moreover, JuBat provides additional options of quadratic element to achieve higher accuracy. These features of JuBat promote the parametric study, analysis, and design of battery cells, all of which are instrumental in advancing lithium-ion batteries. © 2023, The Authors. All rights reserved.

关键词： Finite element method

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Sp2d: Simplified Pseudo 2d Battery Model by Fitting Functions of Potential Curves

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SSRN 2023年

Pseudo 2D battery model has been widely used for studying the electrochemical behaviours of lithium-ion batteries during charge and discharge. However, a significant bottleneck is the complicated calculation of the fully coupled governing equations, which form differential algebraic equations. In this study, a simplified version of the pseudo 2D battery model has been developed. The potential distributions in solid and liquid phases are depicted by piecewise quadratic or sinusoidal functions, with coefficients determined by boundary conditions. This simplification decouples the governing equations and converts them into ordinary differential equations. Results of the proposed method show good agreement with that of the original pseudo 2D battery model for a wide range of C-rates and drive cycles. The proposed approach provides a simpler and faster solution than the pseudo 2D battery model, with negligible accuracy sacrifice. Thus, this work is of great importance for applying physics-based models to real-time battery control and management systems. © 2023, The Authors. All rights reserved.

关键词： Lithium-ion batteries

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Damage evolution analysis of rock under Uniaxial compression and Brazilian splitting based on discrete element method 10

Damage evolution analysis of rock under Uniaxial compression...

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2020 10th Chinese Geosynthetics Conference and International Symposium on Civil Engineering and Geosynthetics, ISCEG 2020

作者： De-Kang, Li Hao-Ran, Li Meng, Liu Zi-Heng, Wang Zheng, Li Structural Health Monitoring and Control Institute Shijiazhuang Tiedao University Shijiazhuang Hebei050043 China Key Laboratory for Health Monitoring and Control of Large Structures Shijiazhuang Tiedao University Shijiazhuang Hebei050043 China Second Geological Team of Hebei Coalfield Geological Bureau Xingtai Hebei054001 China

In order to better analyze the mechanical behavior of rock in uniaxial compression and Brazilian splitting, numerical model was established according to laboratory test by PFC2D particle flow program, and the simulation results were compared with the experimental results. The results show that when the rock reaches the peak stress, the failure curve of cement appears an obvious turning point, and the failure rate of cement *** compressive strength of rock is much greater than the tensile strength under compression condition. The preloading method is more detailed for experimental restoration, and it provides certain reference significance for rock simulation in the future. © The Authors, published by EDP Sciences 2020.

关键词： Rocks

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Guided wave-hidden Markov model for on-line crack evaluation of a full-scale aircraft

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Aerospace Science and Technology 2021年 117卷 106976-106976页

作者： Zhang, Jinjin Yuan, Shenfang Chen, Jian Research Centre of Structural Health Monitoring and Prognosis State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing China

Structural health monitoring (SHM) has been embraced as an effective method in the aerospace industry. However, one of the main problems hindering SHM for practical usages is the reliable evaluation of damages under in-service conditions that introduce various uncertainties and difficulties for effectively interpreting SHM signals. The Hidden Markov Model (HMM)-based method has been proved to be potential for improving the reliability of damage evaluation under in-service conditions since it can explicitly model the uncertainties during damage state transition and SHM process. Nonetheless, traditional HMM-based damage evaluation methods need sufficient prior data of several discrete damage levels for training. These prior data come from historical experiments or simulations, which may not be sufficient for a new target structure. In this paper, a Guided Wave (GW)-health HMM damage evaluation method with an on-line calibration strategy is proposed to realize quantitative evaluation of damage propagation under time-varying conditions. At the off-line stage, a health HMM is constructed with the prior GW-SHM data collected under the structural healthy state. The likelihood probability of the on-line monitored GW-SHM feature sequence belonging to the prior health HMM is calculated for detecting the damage initiation. A new health-HMM is trained with the health data from the current target structure once the damage is found, replacing the prior health HMM. On this basis, a calibration strategy is conducted to calibrate the likelihood probability to the damage size for quantitative damage evaluation under time-varying conditions in real-time. Finally, the proposed method is validated on the fatigue test of a full-scale aircraft under an actual flight spectrum. The fatigue crack is reliably evaluated, and the maximum error of the evaluated crack length is 0.5 mm. © 2021 Elsevier Masson SAS

关键词： Hidden Markov models

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Sparse grey forecasting model learning and applications to fatigue life prediction of aircraft lap joint structures

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ISA Transactions 2025年

作者： Yang, Lu Xu, Qiuhui Wei, Baolei Xie, Naiming Yuan, Shenfang College of Information Management Nanjing Agricultural University Nanjing China College of Economics and Management Nanjing University of Aeronautics and Astronautics Nanjing China Research Center of Structural Health Monitoring and Prognosis State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and Astronautics Nanjing China School of Economics and Management Nanjing University of Science and Technology Nanjing China

A key challenge in the study of grey forecasting models is model structure discovery: converting measurement data into equations that are not only predictive, but provide a deeper understanding of the underlying dynamics inherent in the observations. The predominant approach relies on the cumulative sum operator, a knowledge-based technique that requires a well-characterized shape and extensive empirical experience. In this work, we propose a paradigm for data-driven modelling that simultaneously learns the structures of grey forecasting models and estimates the measurement noise at each observation. First, in the context of a state-space framework utilizing the integral representation of the grey model as a state equation, a candidate feature library is designed to explicitly depict the model equation, likely in a redundant form, and solved by sparse learning. Then, by combining signal-noise decomposition and time-stepping constraints, a regularized objective function is formulated to jointly learn model structure and noise. Next, large-scale simulations are designed to investigate the finite sample performance of the proposed method, including model structural identification accuracy, forecasting accuracy, and denoising capability. The results demonstrate high accuracy in model structure learning and robustness to measurement noise. Finally, we conduct fatigue testing on aircraft lap joints to collect crack propagation data. The proposed method is then applied to uncover dynamic patterns in the evolution of fatigue cracks and predict the remaining useful life of aircraft lap joint structures. © 2025 International Society of Automation

关键词： Knowledge acquisition

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Experimental and Probabilistic Study of Fatigue Crack Growth Behavior of Steel Q345qc Under Different Stress Ratios

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SSRN 2023年

作者： Ke, Lu Li, Youlin Li, Chuanxi Feng, Zheng Zhu, Furui Liang, Longming Mei, Shuyu Key Laboratory of Disaster Prevention and Structural Safety of China Ministry of Education School of Civil Engineering and Architecture Guangxi University Guangxi Nanning530004 China Key Laboratory of Large Structure Health Monitoring and Control Shijiazhuang050043 China Department of Architectural Engineering Hanyang University 222 Wangsimni-ro Seongdonggu Seoul04763 Korea Republic of Changsha University of Science and Technology China

The stress ratio effects and the scatter of the fatigue test results are the key issues in the design of steel fatigue performance. This paper reports an experimental and probabilistic investigation of the fatigue crack growth (FCG) behavior of steel Q345qC. Firstly, the microstructural characteristics and mechanical properties of steel Q345qC were examined via an optical microscope and tensile tests. Next, the FCG behavior of steel Q345qC was investigated under different stress ratios. The fatigue crack growth rate (FCGR) equations incorporating survival probabilities were proposed based on Paris and Walker laws. Finally, the theoretical FCG life under different survival probabilities in the crack stable growth region is calculated based on the integral formulas of Paris and Walker equations and compared with the tested FCG life. The experimental results demonstrate that the larger the stress ratio, the smaller the length of stress intensity factor (SIF) amplitude experienced in the stable growth region and the smaller the SIF at the end of this region. Both Paris and Walker equations can be used for FCGR calculations when the survival probability is set as 50% and the error between them and the tested values is smaller. The FCG life is calculated using the integral formula based on the Walker law with a high safety tolerance and a wide application interval of stress ratio when the survival probability is set as 90%. © 2023, The Authors. All rights reserved.

关键词： Fatigue crack propagation

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Evolution Law of Frost-Heaving Pressure of Frozen Circles in Surrounding Rock around Water-Rich Tunnels in Cold Regions

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Zhongguo Gonglu Xuebao/China Journal of Highway and Transport 2022年第9期35卷 340-351页

作者： Zheng, Xin-Yu Xu, Fei Sun, Hao-Kai Gao, Yang Wei, Li-Yuan Geotechnical and Structural Engineering Research Center Shandong University Shandong Jinan250061 China Key Laboratory of Large Structure Health Monitoring and Control Shijiazhuang Tiedao University Hebei Shijiazhuang050043 China State Key Laboratory for Geomechanics & Deep Underground Engineering China University of Mining and Technology Jiangsu Xuzhou221116 China School of Civil Engineering Southwest Jiaotong University Sichuan Chengdu610031 China

The frost-heaving evolution mechanism of frozen circles in surrounding rock around water-rich tunnel is a key scientific problem that affects the operation safety in cold regions. To explore the evolution law of frost-heaving pressure in frozen circles in such surrounding rock, scaled three-dimensional geomechanical model tests were carried out. In these tests, freezing of a water-bearing surrounding rock at low temperature was considered. The temperature field distribution characteristics of surrounding rock at the tunnel portal section was simulated by introducing ambient air into the tunnel for cooling. Micro-pressure sensors were employed to dynamically monitor the frost-heaving pressure in real time. The spatial and temporal evolution curves of the frost-heaving pressure were obtained for various water content and thickness in surrounding rock. The fitting formulas for parameters such as the frost-heaving rate of surrounding rock, thickness of the frozen circles, and water content were established utilizing multiple regression analysis. Based on this, a theoretical solution for the frost-heaving pressure of the frozen circles in surrounding rock under plain strain state was derived considering the influence of water content and proportion index of surrounding rock. The thermal stress method was used to simulate the evolution characteristics of frost-heaving pressure. Combined with numerical simulations, the test method and theoretical solution were further verified by comparing the predicted frost-heaving pressure with the theoretical and test values. The results indicate that the temperature field of surrounding rock undergoes changes in three stages. This is similar to a regular spoon with a handle-like evolution process;the temperature field of the water-bearing surrounding rock exhibits a non-linear distribution in the descending stage;the temperature field of surrounding rock shows a lagging characteristic relative to the environmental temperature. The sha

关键词： Temperature

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Ice Gathering Feature in the Soil Freezing Process and its Influence on Soil Local Deformation

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SSRN 2023年

作者： Wang, Meng Li, Xu Du, Yan-Liang Zhang, Yu-Zhi Chen, Jian-Bing Xu, Fei Gao, Yang Dong, Zhang School of Safety Engineering and Emergency Management Key Laboratory of Large Structure Health Monitoring and Control Shijiazhuang Tiedao University Shijiazhuang050043 China Key Laboratory of Urban Underground Engineering of Ministry of Education Beijing Jiaotong University Beijing100044 China Qinghai Research and Observation Base Key Laboratory of Highway Construction & Maintenance Technology in Permafrost Regions Ministry of Transport Qinghai Xining810001 China CCCC First Highway Survey and Design Research Institute Co. Ltd National Key Laboratory for Road Engineering Safety and Health in High-Cold and High-Altitude Regions Key Laboratory for Highway Construction and Maintenance Technology in Permafrost Regions

The variation in frozen soil’s ice content is the main cause of engineering diseases in cold regions. However, currently, there is a lack of experimental data on the coupling of frozen local temperature, ice content, and local deformation. This paper focused on the frost heave process in unsaturated soil and utilized a self-developed multi-field coupled frost heave test device. In the soil column frost heave test, the temporal and spatial variations of local temperature, pore volume ice content, and local strain were synchronously collected, and the decoupling of multi-source data in a single test was realized. Based on the test data, the following conclusions were drawn: 1. In unsaturated silty clay, a critical frost segregation temperature exists. When the local temperature is between the freezing point and the critical temperature, both the deformation and ice content of the soil continue to increase. For non-bottom frost segregation cracks that meet this condition, their width can also increase continuously and slowly. When the local temperature falls below the critical frost segregation temperature, the rate of local deformation and ice content variation gradually slows down. 2. The critical temperature can be approximated from the turning point of the soil’s SFCC. 3. Segregation cracks in unsaturated frozen soil can form partially frozen cracks with a maximum ice saturation of less than 60%. The mechanism behind their formation may be related to water film thickness and freezing rate. The findings of this study contribute to the improvement of the theoretical framework of frozen soil mechanics. © 2023, The Authors. All rights reserved.

关键词： Frozen soils

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Probabilistic data mining for aircraft structural health monitoring 6

Probabilistic data mining for aircraft structural health mon...

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6th ECCOMAS European Conference on Computational Mechanics: Solids, structures and Coupled Problems, ECCM 2018 and 7th ECCOMAS European Conference on Computational Fluid Dynamics, ECFD 2018

作者： Yuan, Shenfang Chen, Jian Lei, Q.I.U. Research Center of Structural Health Monitoring and Prognosis State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics 29 Yudao Street Nanjing China

ISBN: (纸本)9788494731167

Structural health monitoring for aircraft structures has gradually turned from fundamental research to practical implementations. However, numerous uncertainties arise from practical engineering such as time-varying loads and boundary conditions may have great effects on sensor signals, which make it difficult for reliable evaluation of structural damages. To deal with these uncertainties, probabilistic data mining methods are attracting more and more attention and gradually applied to aircraft structural health monitoring. Probabilistic data mining methods quantify effects of these uncertainties and the damage with probabilistic models, and perform reliable damage evaluation with diagnosis method. This paper aims at discussing probabilistic data mining methods in aircraft structural health monitoring, as well as their applications to aircraft structures in practical engineering taking advantages of guided wave based structural health monitoring. copyright © Crown copyright (2018).All right reserved.

关键词： Structural health monitoring

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Macro-microscopic deformation evolution of thawing frozen fine-grained soil used in heavy-haul railway subgrades in cold regions

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Research in Cold and Arid Regions 2025年第02期 97-109页

作者： JianBing Chen ShaoJie Liang YuZhi Zhang XiaoDong Zhu Meng Wang MingTao Jia State Key Laboratory of Road Engineering Safety and Health in Cold and High-Altitude Regions CCCC First Highway Consultants Co.Ltd. School of Civil Engineering Shijiazhuang Tiedao University Structure Health Monitoring and Control Key Laboratory of Hebei Province Shijiazhuang Tiedao University Collaborative Innovation Center for Performance and Safety of Large-Scale Infrastructure Shijiazhuang Tiedao University School of Safety and Emergency Management Shijiazhuang Tiedao University

During the thawing process of a railway subgrade, bidirectional thawing complicates water-heat transfer, leading to serious thaw settlement issues under train loads. Focusing on the severely frozen section of the ShuozhouHuanghua port heavy-haul railway, this study conducted indoor soil-column laterally-limited compression tests on thawing fine-grained soil specimens to analyze the cumulative deformation during thawing. The deformation evolution was examined from both macroscopic and microscopic perspectives. The test results revealed a significant increase in the water content at the frozen interlayer during thawing, with minimal thaw settlement under no-load conditions. However, under dynamic loads, the thawing soil exhibited rapid settlement during the initial stages of the process. Increasing the dynamic load amplitude did not result in significant additional thaw settlement compression. Particle image velocimetry revealed substantial thaw settlement and compression at the top of thawing soil. Microscopically, the porosity at the top of the specimens significantly decreased, whereas the porosity in the frozen interlayer remained largely unchanged. Under dynamic loading, the specimens exhibited a concentrated distribution of large pores with scattered smaller pores. The phase change from ice to water,combined with dynamic loading, induced particle movement and expanded the inter-particle pore space, leading to macroscopic thaw settlement and soil compression. The findings can provide a theoretical foundation for maintaining and ensuring the safety of railway subgrades in cold regions.

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