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A decoupled method for time-dependent reliability-based design optimization

Science China(Technological Sciences) 2025年第1期68卷 308-320页

作者： Dequan ZHANG Meide YANG Xu HAN State Key Laboratory of Reliability and Intelligence of Electrical Equipment School of Mechanical EngineeringHebei University of TechnologyTianjin 300401China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China

Time-dependent reliability-based design optimization(TRBDO)has received extensive attention because of its ability to achieve optimal solutions that help meet the requirement for whole lifecycle reliability by quantitatively considering dynamic ***,directly solving TRBDO problems is computationally expensive,if not prohibitive,owing to the need to repeatedly evaluate time-dependent probabilistic *** address this challenge,an efficient decoupled method called sequential optimization and time-dependent reliability assessment(SOTRA)is proposed in this *** method transforms the original TRBDO problem,initially formulated probabilistically,into a problem using percentile formulation after discretizing time-dependent performance *** adopting the equivalent minimum performance target point(EMPTP)concept,the TRBDO problem is further converted into an equivalent deterministic optimization problem,which is subsequently solved through a sequential iteration process involving deterministic optimization and time-dependent reliability *** efficiently and robustly search an EMPTP for reliability analysis,a time-dependent self-adaptive finite-step length method is *** verify the proposed SOTRA method against existing TRBDO methods,a numerical example,a benchmark structural design case of a simply supported beam,and an engineering application for flexible wheel design are exemplified in this *** results demonstrate that the proposed SOTRA method exhibits high efficiency and robustness in solving TRBDO problems.

关键词： reliability-based design optimization dynamic uncertainties time-dependent reliability analysis decoupled method sequential optimization and reliability analysis

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Safe Efficient Policy Optimization Algorithm for Unsignalized Intersection Navigation

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IEEE/CAA Journal of Automatica Sinica 2024年第9期11卷 2011-2026页

作者： Xiaolong Chen Biao Xu Manjiang Hu Yougang Bian Yang Li Xin Xu State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body the College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body the College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082 Wuxi Intelligent Control Research Institute(WICRI)of Hunan University Wuxi 214115China College of Intelligence Science and Technology Institute of Unmanned SystemsNational University of Defense TechnologyChangsha 410073China

Unsignalized intersections pose a challenge for autonomous vehicles that must decide how to navigate them safely and *** paper proposes a reinforcement learning(RL)method for autonomous vehicles to navigate unsignalized intersections safely and *** method uses a semantic scene representation to handle variable numbers of vehicles and a universal reward function to facilitate stable learning.A collision risk function is designed to penalize unsafe actions and guide the agent to avoid them.A scalable policy optimization algorithm is introduced to improve data efficiency and safety for vehicle learning at *** algorithm employs experience replay to overcome the on-policy limitation of proximal policy optimization and incorporates the collision risk constraint into the policy optimization *** proposed safe RL algorithm can balance the trade-off between vehicle traffic safety and policy learning *** intersection scenarios with different traffic situations are used to test the algorithm and demonstrate its high success rates and low collision rates under different traffic *** algorithm shows the potential of RL for enhancing the safety and reliability of autonomous driving systems at unsignalized intersections.

关键词： Autonomous driving decision-making reinforcement learning(RL) unsignalized intersection

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Greatly enhanced corrosion/wear resistances of epoxy coating for Mg alloy through a synergistic effect between functionalized graphene and insulated blocking layer

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Journal of Magnesium and Alloys 2024年第1期12卷 332-344页

作者： Z.Y.Xue X.J.Li J.H.Chu M.M.Li D.N.Zou L.B.Tong School of Metallurgical Engineering Xi’an University of Architecture and TechnologyXi’an 710055China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China

The poor corrosion and wear resistances of Mg alloys seriously limit their potential applications in various *** conventional epoxy coating easily forms many intrinsic defects during the solidification process,which cannot provide sufficient *** the current study,we design a double-layer epoxy composite coating on Mg alloy with enhanced anti-corrosion/wear properties,via the spin-assisted assembly *** outer layer is functionalized graphene(FG)in waterborne epoxy resin(WEP)and the inner layer is Ce-based conversion(Ce)*** FG sheets can be homogeneously dispersed within the epoxy matrix to fill the intrinsic defects and improve the barrier *** Ce film connects the outer layer with the substrate,showing the transition *** corrosion rate of Ce/WEP/FG composite coating is 2131 times lower than that of bare Mg alloy,and the wear rate is decreased by~90%.The improved corrosion resistance is attributed to the labyrinth effect(hindering the penetration of corrosive medium)and the obstruction of galvanic coupling *** synergistic effect derived from the FG sheet and blocking layer exhibits great potential in realizing the improvement of multi-functional integration,which will open up a new avenue for the development of novel composite protection coatings of Mg alloys.

关键词： Mg alloy Functionalized graphene Epoxy coating Corrosion/wear resistance Blocking layer

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Trajectory tracking control of autonomous heavy-duty mining dump trucks with uncertain dynamic characteristics

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Science China(Information Sciences) 2023年第10期66卷 246-262页

作者： Liang CHEN Zhaobo QIN Manjiang HU Hongbo GAO Yougang BIAN Biao XU Xiaoyan PENG State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Wuxi Intelligent Control Research Institute of Hunan University Department of Automation University of Science and Technology of China

The proportion of mines using autonomous mining trucks is still very low at present. To promote the development of intelligent mining, it is urgent to proceed with the drive-by-wire modification to common mining trucks and design a motion control algorithm considering uncertain dynamic *** paper proposes a trajectory tracking control method for autonomous heavy-duty mining dump trucks(AHMDTs) with uncertain dynamic characteristics. In this method, a driving/braking force compensation algorithm based on an inverse dynamic model is designed to guarantee accurate longitudinal control with less control gain tuning. Using road curvatures, a modified rear-wheel position feedback control method is proposed to deal with reverse-path tracking, which can simultaneously reduce the lateral error and yaw angle error. A modified Stanley controller considering the collaborative preview based on speed and curvature is constructed to achieve accurate path tracking in the forward gear. Moreover, the proposed method focuses on the practice of trajectory tracking control in an open-pit mine condition with the adverse effects caused by uncertain vehicle dynamics, huge variable load, and large actuator lag. Real vehicle tests show that the proposed methodology can control AHMDTs with a low tracking error.

关键词： vehicle control trajectory tracking control driving/braking force compensation rear-wheel position feedback

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Additively manufactured fiber-reinforced composites:A review of mechanical behavior and opportunities

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Journal of Materials Science & technology 2022年第24期119卷 219-244页

作者： Jiahui Li Yvonne Durandet Xiaodong Huang Guangyong Sun Dong Ruan Department of Mechanical Engineering and Product Design Engineering School of EngineeringSwinburne University of TechnologyHawthornVIC 3122Australia State Key Laboratory of Advanced Design and Manufacture for Vehicle Body Hunan UniversityChangsha 410082China

Recent developments in additive manufacturing techniques have facilitated the fabrication of fiberreinforced composite *** this paper,the mechanical properties and deformation mechanisms of discontinuous and continuous fiber-reinforced composites fabricated by various additive manufacturing techniques are comprehensively *** effects of fiber type,orientation and weight/volume fraction,printing path,and stacking sequence on the mechanical properties of additively manufactured composites are *** addition,the applications of additively manufactured composites,the main challenges of the current additive manufacturing techniques,and recommendations for future work are also presented.

关键词： Additive manufacturing Discontinuous and continuous fiber-reinforced composites Mechanical properties Deformation mechanism Applications

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Finite element modeling and injury criteria investigation for the lower leg of the Chinese human body under impact loads

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Theoretical & Applied Mechanics Letters 2024年第4期14卷 259-269页

作者： Xianping Du Xizheng Zhao Jianyin Lei Guanjun Zhang School of Ocean Engineering and Technology Sun Yat-Sen UniversityZhuhai 519082China Institute of Applied Mechanics College of Mechanical and Vehicle EngineeringTaiyuan University of TechnologyTaiyuan 030024China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China

The widely used human body injury criteria were established based on the biomechanical response of the EuroAmerican human body,without considering the differences in anthropometry and injury characteristics among different races,particularly the Chinese human body which typically has the smaller body *** absence of such race specific design considerations negatively influences the injury prevention capability for these populations,and weakens the applicability of injury *** resolve these issues,this study aims to develop a lower leg finite element model of a 50th percentile Chinese *** model is built based on the medical images of an average size Chinese male with detailed ankle ligaments and lower leg muscles *** from sixty experiments available in the literature are used to validate its *** the validated model,the lower leg model is subjected to combined axial compression and bending loads to evaluate its injury *** with a typical Euro-American human body mode,the Chinese lower leg presents reduced mechanical tolerance,and the revised tibia index may be an appropriate injury criteria for the Chinese lower ***,the validated model reproduces the pedestrian lower leg fracture in a domestic accident.

关键词： Chinese human body Lower limb model Impact load Injury tolerance Tibia index

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Research on the Inflence Mechanism and Lightweight of Windshield on the Stiffness of BIW

Research on the Inflence Mechanism and Lightweight of Windsh...

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2023中国汽车工程学会年会暨展览会

作者： Wang Chao Yu Wanyuan Cheng Aiguo He Zhicheng State Key Laboratory of Advanced Design and Manufacture for Vehicle Body Hunan University College of Automotive Engineering Liuzhou Vocational & Technical College

ISBN: (纸本)9789819702510

The impact mechanism of the front windshield on the torsional stiffness of the body in white(BIW) was studied by using a simplified windshield model,and the lightweight design of the front windshield was ***,the influence of the front windshield on the torsional stiffness of the BIW was verified,and the mathematical model and simplified finite element model of the windshield stiffness were *** is concluded that the shear stiffness of the front windshield is the main factor affecting the torsional stiffness of ***,the relationship between the windshield stiffness and the torsional stiffness of the BIW was established,and the influences of the elastic modulus and thickness of different types of windshield on the torsional stiffness of the vehicle body were quickly analyzed using the simplified ***,two lightweight design schemes were carried out for the *** accuracy of the simulation models was verified by *** two schemes have achieved weight reduction by 17.3% and 41.4%,respectively,under the requirements of the stiffness and mode of BIW and the pedestrian protection.

关键词： lightweight mathematic model pedestrian protection simplified model torsional stiffness

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Limb-inspired bionic quasi-zero stiffness vibration isolator

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力学学报（英文版） 2021年第7期37卷 1152-1167页

作者： Rong Zeng Guilin Wen Jiaxi Zhou Gang Zhao State Key Laboratory of Advanced Design and Manufacture for Vehicle Body Hunan UniversityChangsha 410082China State Key Laboratory of Advanced Design and Manufacture for Vehicle Body Hunan UniversityChangsha 410082China School of Mechanical and Electric Engineering Guangzhou UniversityGuangzhou 510006China

Vibration reduction has always been one of hot and important topics in mechanical engineering,especially for the special measurement *** this paper,a novel limb-inspired bionic structure is proposed to generate negative stiffness and design a new quasi-zero stiffness isolator via torsion springs,distinguishing from the existing tension spring structures in the *** nonlinear mathematical model of the proposed structure is developed and the corresponding dynamic properties are further investigated by using the Harmonic Balance method and ADAMS *** evaluate the vibration isolation performance,typical three-springs quasi-zero stiffness (TS QZS) system is selected to compare with the proposed bionic *** the graphical processing unit (GPU) parallel technology is applied to perform necessary two-parameter analyses,providing more insights into the effects of parameters on the *** is shown that the proposed structure can show advantages over the typical TS QZS system in a wider vibration isolation range for harmonic excitation case and shorter decay time for the impact excitation case.

关键词： Limb-inspired bionic structure Quasi-zero stiffness Torsion springs Two-parameter analyses

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Unveiling deformation behavior and damage mechanism of irradiated high entropy alloys

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Journal of Materials Science & technology 2024年第29期196卷 71-87页

作者： Shuo Wang Yang Chen Jia Li Bin Liu Ruiqian Zhang Peter K Liaw Qihong Fang State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Science and Technology on Reactor Fuel and Materials Laboratory Nuclear Power Institute of ChinaChengdu 610213China Department of Materials Science and Engineering The University of TennesseeKnoxvilleTN 37996USA

The oxide dispersion strengthening(ODS)high entropy alloy(HEA)exhibits the high elevated temperature performance and radiation resistance due to severe atomic lattice distortion and oxide particles dispersed in matrix,which is expected to become the most promising structural material in the next generation of nuclear energy ***,microstructure and damage evolution of irradiated ODS HEA under loading remain elusive at submicron scale using the existing simulations owing to a lack of atomic-lattice-distortion information from a micromechanics ***,the random field theory informed discrete dislocation dynamics simulations based on the results of high-resolution transmission electron microscopy are developed to study the dislocation behavior and damage evolution in ODS HEA considering the influence of severe lattice distortion and nanoscale oxide ***,the damage behavior shows an unusual trend of the decreasing-to-increasing transition with the continuous loading *** are two main types of damage micromechanics generated in irradiated ODS HEA:the dislocation loop damage in which the damage is controlled by irradiation-induced dislocation loops and their evolution,the strain localization damage in which the damage comes from the dislocation multiplication in the local plastic *** oxide particle hinders the dislocation movement in the main slip plane,and the lattice distortion induces the dislocation sliding to the secondary slip plane,which promotes the dislocation cross-slip and dislocation loop annihilation,and thus reduces the material damage in the elastic damage *** findings can deeply understand atomic-scale damage mechanism and guide the design of ODS HEA with high radiation resistance.

关键词： Oxide dispersion strengthening High entropy alloy Radiation Dislocation Damage model

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Trace Ca alloying enhance simultaneously strength and ductility of squeeze-cast Al-5Cu-0.5Mn-based alloys

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Journal of Materials Science & technology 2024年第24期191卷 89-105页

作者： Zhanwei Su Zhuoran Zeng Sai Zhang Xianming Meng Shiwei Xu State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China College of Materials Science and Engineering Hunan UniversityChangsha 410082China China Automotive Technology&Research Center Co.Ltd Tianjin 300300China

The strength-ductility inversion relationship of alloys is a persistent challenge in advanced materials ***-Cu series cast aluminum alloys that are considered as an exceptionally high-strength light alloy are not exclusive in structural applications due to their inherently poor *** this work,we employed a squeeze casting technique and Ca microalloying strategy for microstructure modulation to effectively address this *** addition of low concentrations of Ca(0.5 wt.%and 1 wt.%)elements to the as-cast Al-5Cu-0.5Mn alloy significantly enhances its plasticity by threefold at room ***,even after T6 treatment,which typically compromises ductility for increased strength,the low-Ca micro-alloyed Al-5Cu-0.5Mn exhibited a further increase in its strength without sacrificing its *** low-Ca addition to the alloy generates an ultrafine eutectic colony with a complex"coreshell"structure,which can serve as a carrier for localized stress transfer,effectively distributing the strain uniformly to more *** hardening of α-Al grains and spheroidization of lamellar ultrafine eutectic phases were simultaneously realized in the low-Ca alloy after T6 heat treatment,which resulted in comparable hardness of α-Al grains and eutectic *** synergistic coordination of external strains through extensive strain-hardening induced by slip line and substantial microcrack generation by ultrafine eutectic colonies is evidenced by a series of in situ characterizations of the low-Ca ***,the uniform spreading deformation due to the transfer of strain-hardening effect and the alternating plastic deformation of α-Al grains and ultrafine eutectic colonies are the critical keys to overcoming the strength-plasticity paradox in low-Ca *** study provides a perspective route for Al-Cu system cast aluminum alloys to be utilized as high-strength and tough structural materials.

关键词： Al-Cu-Mn-Ca alloy Squeeze casting Plasticity mechanism Cracking mechanism

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