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Numerical analysis of the effects of subgrade settlement on top-down cracking in epoxy asphalt pavement

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Science China Technological Sciences 2024年第10期67卷 3308-3320页

作者： JIANG XiuJie HUANG Wei LUO Sang WEI Ya KONG WeiYi DU KaiJun School of transportation Southeast University Intelligent transportation System Research Center Southeast University department of Civil engineering Tsinghua University Nanjing Modern Multimodal transportation Laboratory

Epoxy asphalt pavement cracking caused by subgrade settlement is detrimental to the long-term safe service of roads. A threedimensional finite element model of epoxy asphalt pavement is established to investigate the effects of subgrade settlement on the propagation of top-down cracking(TDC). The contour integral method is utilized to calculate the stress intensity factor(SIF)at the crack tip, and then the extended finite element method(XFEM) is used to analyze the propagation behavior of TDC under combined subgrade settlement and traffic loading. The results of these analyses indicate that increased subgrade settlement,stiffer surface layers, and softer bases will increase the SIF, resulting in a faster crack propagation rate. It is suggested that the use of epoxy asphalt materials in pavement structures can allow more subgrade settlement than conventional asphalt ***, when the base layer modulus is higher than 12500 MPa, the increase in surface modulus can decrease crack propagation length. Sensitivity analysis results demonstrate that subgrade settlement has the most significant impact on TDC propagation. The conclusions of this study are expected to provide a theoretical basis for crack prevention in the design and maintenance of pavement structures.

关键词： epoxy asphalt pavement subgrade settlement XFEM stress intensity factor crack propagation

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Study on the mechanism and law of temperature,humidity and moisture content on the mechanical properties of molded fiber products

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Journal of Bioresources and Bioproducts 2024年第3期9卷 351-368页

作者： Zhiqiang Fu Tong Zhao Hu Wang Jingyi Wei Haozhe Liu Liying Duan Yan Wang Ruixiang Yan School of Light Industry Science and engineering Tianjin University of Science and TechnologyTianjin 300457China department of transportation and vehicle engineering Tangshan UniversityTangshan 063000HebeiChina College of Mechanical engineering Tianjin University of Science and TechnologyTianjin 300457China

The change of temperature, humidity and moisture content (MC) will lead to the change of mechanical properties of molded fiber products (MFP). However, it is difficult to decouple the effects of temperature, humidity and MC on the mechanical properties of MFP, and predict the mechanical properties of MFP during the use. In this study, the laws and mechanism of mechanical properties of MFP with ambient temperature, humidity and MC were studied. The results showed that the direct effect of temperature (20−70 °C) on mechanical properties of MFP was insignificant, and the mechanical properties of MFP were mainly changed by MC. The MC was related to ambient temperature and humidity, and the relationship between the three could be described by the modified Guggenheim-Anderson-de Boer (GAB) model (20−70 °C and 30 %–90 % relative humidity). With the increase of MC, the elastic modulus and fracture strain was increased and decreased linearly, the yield strength and failure strength were presented GaussAmp laws, and the failure strain was presented asymptotic regressed distribution law. Two fracture modes of MFP, brittle fracture and ductile fracture, were revealed by the scanning electron microscopy of the mesoscopic fiber structure of sugarcane bagasse molded fiber products. The mathematical models and the changes of fiber structure were verified by wheat straw molded fiber products and waste paper molded fiber products. This study was contributed to understand the effects and mechanism of the change of temperature, humidity and MC on the mechanical properties of MFP.

关键词： Temperature Relative humidity Moisture content Molded fiber products Mechanical properties

Chemical short-range-order induced multiscale strengthening in refractory medium entropy alloys

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Acta Mechanica Sinica 2024年第6期40卷 41-49页

作者： Weizheng Lu Yang Chen Jia Li Peter K.Liaw Qihong Fang State Key Laboratory of Advanced Design and Manufacturing for vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha410082China department of Materials Science and engineering The University of TennesseeKnoxvilleTN37996USA

High/medium entropy alloys(H/MEAs)are generally possible to exhibit chemical short-range order(SRO).However,the complex role of SRO on mechanical properties from nano-scale to meso-scale is still challenging so ***,we study the strengthening mechanism and deformation behavior in a model body-centered-cubic HfNbTa MEA by using atomic-scale molecular dynamics,micro-scale dislocation dynamics,and meso-scale crystal plasticity finite *** SRO inhibits dislocation nucleation at the atomic scale,improving the flow *** SRO-induced ultrastrong local stress fluctuation greatly improves the micro-scale dislocation-based strength by the significant dislocation forest ***,the Ta-rich locally ordered structure leads to an obvious heterogeneous strain and stress partitioning,which forms a strong strain gradient in the adjacent grain interiors and contributes to the strong back-stress-induced strain hardening.

关键词： High/medium entropy alloys Multiscale strengthening Chemical short-range order

Adaptive state-constrained/model-free iterative sliding mode control for aerial robot trajectory tracking

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Applied Mathematics and Mechanics(English Edition) 2024年第4期45卷 603-618页

作者： Chen AN Jiaxi ZHOU Kai WANG College of Mechanical and vehicle engineering Hunan UniversityChangsha 410082China department of Mechanical engineering The Hong Kong Polytechnic UniversityHong KongChina

This paper develops a novel hierarchical control strategy for improving the trajectory tracking capability of aerial robots under parameter *** hierarchical control strategy is composed of an adaptive sliding mode controller and a model-free iterative sliding mode controller(MFISMC).A position controller is designed based on adaptive sliding mode control(SMC)to safely drive the aerial robot and ensure fast state convergence under external ***,the MFISMC acts as an attitude controller to estimate the unmodeled dynamics without detailed knowledge of aerial ***,the adaption laws are derived with the Lyapunov theory to guarantee the asymptotic tracking of the system ***,to demonstrate the performance and robustness of the proposed control strategy,numerical simulations are carried out,which are also compared with other conventional strategies,such as proportional-integralderivative(PID),backstepping(BS),and *** simulation results indicate that the proposed hierarchical control strategy can fulfill zero steady-state error and achieve faster convergence compared with conventional strategies.

关键词： aerial robot hierarchical control strategy model-free iterative sliding mode controller(MFISMC) trajectory tracking reinforcement learning

Design of quasi-zero-stiffness elastic diodes for low-frequency nonreciprocity through machine learning

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Acta Mechanica Sinica 2024年第7期40卷 137-151页

作者： Junsen He Jiaxi Zhou Kai Wang Qiang Wang College of Mechanical and vehicle engineering Hunan UniversityChangsha 410082China Key Laboratory of Advanced Design and Manufacturing Technology for vehicle Hunan UniversityChangsha 410082China department of Mechanical engineering Hong Kong Polytechnic UniversityHong KongChina

Elastic diodes with nonreciprocity have the potential to enable unidirectional modulation of elastic ***,it is a challenge to achieve nonreciprocity at low frequencies(<100 Hz)using existing elastic *** paper proposes a quasizero-stiffness(QZS)elastic diode to resolve such a tough issue and fulfill high-quality low-frequency *** proposed elastic diode is invented by combining a QZS locally resonant metamaterial with a linear one,where the beneficial nonlinearity of the QZS metamaterial facilitates opening an amplitude-dependent band gap at very low ***,the dispersion relation of the QZS metamaterial is derived theoretically based on the harmonic balance method(HBM).Then,the transmissibility of the QZS elastic diode in both the forward and backward directions is calculated through theoretical analyses and numerical ***,the influences of system parameters on the low-frequency nonreciprocal effect are *** results indicate that considerable nonreciprocity is observed at a quite low frequency(e.g.,9 Hz),which is achieved by amplitude-dependent local resonance combined with interface ***,a machine learning-based design optimization is introduced to evaluate and enhance the nonreciprocal effect of the QZS elastic *** the aid of machine learning(ML),the computational cost of predicting nonreciprocal effects during design optimization can be significantly *** design optimization,the nonreciprocal frequency bandwidth can be broadened while maintaining considerable isolation quality at low frequencies.

关键词： Nonreciprocity Low-frequency Elastic diode Quasi-zero-stiffness Nonlinear elastic metamaterials Machine learning

Subpicosecond laser ablation behavior of a magnesium target and crater evolution:Molecular dynamics study and experimental validation

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Chinese Physics B 2024年第7期33卷 613-622页

作者：江国龙周霞 State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsFaculty of Vehicle Engineering and MechanicsDalian University of TechnologyDalian 116024China

The micro-ablation processes and morphological evolution of ablative craters on single-crystal magnesium under subpicosecond laser irradiation are investigated using molecular dynamics(MD) simulations and *** simulation results exhibit that the main failure mode of single-crystal Mg film irradiated by a low fluence and long pulse width laser is the ejection of surface atoms,which has laser-induced high ***,under high fluence and short pulse width laser irradiation,the main damage mechanism is nucleation fracture caused by stress wave reflection and superposition at the bottom of the *** addition,Mg[0001] has higher pressure sensitivity and is more prone to ablation than Mg[0001].The evolution equation of crater depth is established using multi-pulse laser ablation simulation and verified by *** results show that,under multiple pulsed laser irradiation,not only does the crater depth increase linearly with the pulse number,but also the quadratic term and constant term of the fitted crater profile curve increase linearly.

关键词： laser-material interaction molecular dynamics(MD)simulation ablation crater morphology magnesium

Chaotic Aquila Optimization Algorithm for Solving Phase Equilibrium Problems and Parameter Estimation of Semi-empirical Models

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Journal of Bionic engineering 2024年第1期21卷 486-526页

作者： Oguz Emrah Turgut Mert Sinan Turgut Erhan Kırtepe department of Industrial engineering Faculty of Engineering and ArchitectureIzmir Bakircay UniversityMenemenizmirTurkey department of Mechanical engineering Faculty of EngineeringEge UniversityBornovaizmirTurkey department of Motor vehicles and transportation Technologies Sirnak UniversitySirnakTurkey

This research study aims to enhance the optimization performance of a newly emerged Aquila Optimization algorithm by incorporating chaotic sequences rather than using uniformly generated Gaussian random *** work employs 25 different chaotic maps under the framework of Aquila *** considers the ten best chaotic variants for performance evaluation on multidimensional test functions composed of unimodal and multimodal problems,which have yet to be studied in past literature *** was found that Ikeda chaotic map enhanced Aquila Optimization algorithm yields the best predictions and becomes the leading method in most of the *** test the effectivity of this chaotic variant on real-world optimization problems,it is employed on two constrained engineering design problems,and its effectiveness has been ***,phase equilibrium and semi-empirical parameter estimation problems have been solved by the proposed method,and respective solutions have been compared with those obtained from state-of-art *** is observed that CH01 can successfully cope with the restrictive nonlinearities and nonconvexities of parameter estimation and phase equilibrium problems,showing the capabilities of yielding minimum prediction error values of no more than 0.05 compared to the remaining algorithms utilized in the performance benchmarking process.

关键词： Aquila optimization algorithm Chaotic maps Parameter estimation Phase equilibrium Unconstrained optimization

Deep neural network-enabled battery open-circuit voltage estimation based on partial charging data

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Journal of Energy Chemistry 2024年第3期90卷 120-132,I0005页

作者： Ziyou Zhou Yonggang Liu Chengming Zhang Weixiang Shen Rui Xiong State Key Laboratory of Mechanical Transmission for Advanced Equipment&College of Mechanical and vehicle engineering Chongqing UniversityChongqing 400000China department of vehicle engineering School of Mechanical EngineeringBeijing Institute of TechnologyBeijing 100081China department of Electrical engineering Harbin Institute of TechnologyHarbin 150000HeilongjiangChina School of Science Computing and Engineering TechnologiesSwinburne University of TechnologyHawthornVictoria 3122Australia

Battery management systems(BMSs) play a vital role in ensuring efficient and reliable operations of lithium-ion *** main function of the BMSs is to estimate battery states and diagnose battery health using battery open-circuit voltage(OCV).However,acquiring the complete OCV data online can be a challenging endeavor due to the time-consuming measurement process or the need for specific operating conditions required by OCV estimation *** addressing these concerns,this study introduces a deep neural network-combined framework for accurate and robust OCV estimation,utilizing partial daily charging *** incorporate a generative deep learning model to extract aging-related features from data and generate high-fidelity OCV *** analysis is employed to identify the optimal partial charging data,optimizing the OCV estimation precision while preserving exceptional *** validation results,using data from nickel-cobalt-magnesium(NCM) batteries,illustrate the accurate estimation of the complete OCV-capacity curve,with an average root mean square errors(RMSE) of less than 3 *** this level of precision for OCV estimation requires only around 50 s collection of partial charging *** validations on diverse battery types operating under various conditions confirm the effectiveness of our proposed *** cases of precise health diagnosis based on OCV highlight the significance of conducting online OCV *** method provides a flexible approach to achieve complete OCV estimation and holds promise for generalization to other tasks in BMSs.

关键词： Lithium-ion battery Open-circuit voltage Health diagnosis Deep learning

Elastic three-dimensional phononic topological insulators with Dirac hierarchy

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Science China(Physics,Mechanics & Astronomy) 2024年第5期67卷 54-62页

作者： Shao-Yong Huo Qiu-Shuang Yang Jiu-Jiu Chen Hong-Kang Li Long-Chao Yao Fu-Chun He Chun-Ming Fu College of Mechanical engineering University of South ChinaHengyang 421001China State Key Laboratory of Advanced Design and Manufacturing for vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China

Three-dimensional(3D)phononic topological insulators(TIs)featuring two-dimensional(2D)surface states and one-dimensional(1D)hinge states have opened up a new route for multi-dimensional robust wave transport,providing unprecedented methods for integrated acoustic sensors and energy harvesting ***,aiming at the elastic 3D phononic TI with gapless surface states and hinge states,the realization of elastic 3D phononic TIs with gapless surface states and hinge states is a significant challenge due to the complicated multi-mode polarization of elastic waves in 3D *** this study,we demonstrate an elastic 3D phononic TI with a Dirac hierarchy by elaborately operating the corresponding spatial symmetries of the chiral honeycomb ***,a 3D double Dirac cone of elastic wave can be achieved by doubling the lattice along the outof-plane direction to fold two iso-frequency Weyl *** topological phase transitions and 2D gapless two-fold Dirac surface states of elastic wave are realized by breaking the half-lattice spatial translation ***,based on the Brillouin zone folding along the in-plane direction,the 2D gapless two-fold surface Dirac cones are folded into four-fold surface Dirac ***,by inducing the relative radius of adjacent holes to break the in-plane spatial inversion symmetry,the fourfold surface Dirac cones are gapped and associated with a surface state inversion,in which the gapless 1D hinge Dirac dispersion is *** research offers a route for engineering the hierarchies of TIs in 3D elastic wave systems and provides new possibilities for designing 3D ultrasonic devices with unconventional functions.

关键词： Dirac topological hierarchy