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engineering Fracture Mechanics 2025年 325卷

作者： Hongyuan Yang Yiru Ren State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle Hunan University Changsha Hunan 410082 China College of Mechanical and Vehicle Engineering Hunan University Changsha Hunan 410082 China

CFRP/aluminum hybrid structures are widely used in aerospace lightweight design. Notably, the assembly process of different material structures is crucial for crashworthiness. This study aims to modify the conventional assembly method and achieve high-performance connection between CFRP and aluminum tubes by using adhesives. A numerical simulation is conducted on the crushing behavior of CFRP/aluminum hybrid circular tubes with an adhesive interface (AdI) under lateral and oblique compressive loads. Based on the maximum stress failure criterion and traction-separation law, a finite element model that can predict mechanical response and failure modes is established. Further, the influence of the performance of the AdI on structural mechanical characteristics is analyzed. Results show that the energy absorption ( EA ) of the adhesive-reinforced hybrid tubes under lateral and oblique compression has increased by 60% and 72%, respectively. In addition, AdI properties significantly affect the peak crushing load ( PCL ) and late-stage EA . Finally, the damage mechanism of the adhesive interface is analyzed, revealing that it effectively reduces the relative slip between the CFRP and aluminum tubes during loading, enhancing crashworthiness.

关键词： Crashworthiness

C60 Filling-Enabled Tribological Improvement of Graphene in Conformal Contact with a Rough Substrate

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SSRN 2023年

作者： Li, Jiahao Bai, Lichun Liu, Bo Tang, Xianqiong Peng, Jinfeng Zhou, Runhua Tan, Liming Peng, Yong Key Laboratory of Traffic Safety on Track Ministry of Education School of Traffic & Transportation Engineering Central South University Changsha410075 China National & Local Joint Engineering Research Center of Safety Technology for Rail Vehicle Central South University Changsha410075 China School of Mechanical and Vehicle Engineering Hunan University Hunan Changsha410082 China School of Mechanical Engineering and Mechanics Xiangtan University Xiangtan411105 China Nanyang Technological University 50 Nanyang Avenue Singapore639798 Singapore State Key Laboratory of Powder Metallurgy Central South University Changsha410083 China

Graphene has great potential in the field of solid lubricity due to its superlow friction and high wear resistance. However, the excellent tribological performance of graphene is degraded when it conformally contacts with a rough substrate. This work proposes a novel method to improve the tribological performance of graphene on a rough Si/SiO2 substrate by filling grooves on the substrate surface with C60 molecules. When C60 filling is not performed, the friction force on the graphene surface increases rapidly at the groove edges where graphene presents large out-of-plane deformation due to its conformal contact with the substrate. Inspiringly, such high friction force is reduced by one order of magnitude when C60 filling is introduced to provide out-of-plane support to graphene and prevent its conformal contact with the substrate. Meanwhile, the high mechanical strength of C60 molecules enables a greater than 5-fold strengthening of the load-carrying capacity of graphene, which greatly improves its wear resistance on the rough substrate. These observations are helpful in promoting the tribological application of graphene by diminishing its conformal contact with the rough substrate. © 2023, The Authors. All rights reserved.

关键词： Molecular dynamics

A frequency domain reliability analysis method for electromagnetic problems based on univariate dimension reduction method

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Science China(Technological Sciences) 2019年第5期62卷 787-798页

作者： PING MengHao HAN Xu JIANG Chao ZHONG JianFeng XIAO XiaoYa HUANG ZhiLiang WANG ZhongHua State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan University Nanjing Research Institute of Electronics Technology

In this paper, a class of electromagnetic field frequency domain reliability problem is first defined. The frequency domain reliability refers to the probability that an electromagnetic performance indicator can meet the intended requirements within a specific frequency band, considering the uncertainty of structural parameters and frequency-variant electromagnetic *** then a frequency domain reliability analysis method based on univariate dimension reduction method is proposed, which provides an effective calculation tool for electromagnetic frequency domain reliability. In electromagnetic problems, performance indicators usually vary with frequency. The method firstly discretizes the frequency-variant performance indicator function into a series of frequency points' functions, and then transforms the frequency domain reliability problem into a series system reliability problem of discrete frequency points' functions. Secondly, the univariate dimension reduction method is introduced to solve the probability distribution functions and correlation coefficients of discrete frequency points' functions in the system. Finally, according to the above calculation results, the series system reliability can be solved to obtain the frequency domain reliability, and the cumulative distribution function of the performance indicator can also be obtained. In this study,Monte Carlo simulation is adopted to demonstrate the validity of the frequency domain reliability analysis method. Three examples are investigated to demonstrate the accuracy and efficiency of the proposed method.

关键词： electromagnetic field frequency domain reliability system reliability random process discretization univariate dimension reduction method

Socially-Aware Autonomous Driving: Inferring Yielding Intentions for Safer Interactions

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arXiv

arXiv 2025年

作者： Wang, Jing Jin, Yan Taghavifar, Hamid Ding, Fei Wei, Chongfeng School of Mechanical and Aerospace Engineering Queen’s University Belfast Belfast United Kingdom Department of Mechanical and Industrial Engineering Concordia University MontrealQCH3G 1M8 Canada State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China James Watt School of Engineering University of Glasgow GlasgowG12 8QQ United Kingdom

Since the emergence of autonomous driving technology, it has advanced rapidly over the past decade. It is becoming increasingly likely that autonomous vehicles (AVs) would soon coexist with human-driven vehicles (HVs) on the roads. Currently, safety and reliable decision-making remain significant challenges, particularly when AVs are navigating lane changes and interacting with surrounding HVs. Therefore, precise estimation of the intentions of surrounding HVs can assist AVs in making more reliable and safe lane change decision-making. This involves not only understanding their current behaviors but also predicting their future motions without any direct communication. However, distinguishing between the passing and yielding intentions of surrounding HVs still remains ambiguous. To address the challenge, we propose a social intention estimation algorithm rooted in Directed Acyclic Graph (DAG), coupled with a decision-making framework employing Deep Reinforcement Learning (DRL) algorithms. To evaluate the method’s performance, the proposed framework can be tested and applied in a lane-changing scenario within a simulated environment. Furthermore, the experiment results demonstrate how our approach enhances the ability of AVs to navigate lane changes safely and efficiently on roads. Copyright © 2025, The Authors. All rights reserved.

关键词： Reinforcement learning

N-Doped Graphene Film Prepared by Rapid Thermal Shock for Ultra-Sensitive Temperature Reading

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SSRN 2022年

作者： Liang, Gengyuan Yu, Linfeng Qin, Guangzhao Lei, Bowen He, Yonglyu Tang, Jun Ju, Su Bai, Shuxin Zhang, Jianwei Department of Materials Science and Engineering National University of Defense Technology No. 109 Deya Road Changsha410073 China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China

Graphene is restricted by its zero band gap when applying in functional components, and the band structure of graphene can be adjusted appropriately through nitrogen doping. At present, many nitrogen doping processes have been developed, but in general these methods are time-consuming and difficult to control the nitrogen species. In this work, an in-situ rapid high-temperature thermal shock treatment, with a fast temperature rise and drop rate, is used to prepare nitrogen doped graphene (NG) films by taking advantage of reduced graphene oxide (rGO) films as the precursor. This novel N-doped process enables the preparation of NG films within 10 s, which is the fastest to the best of our knowledge. Moreover, the type and content of doped-N can be effectively regulated by controlling the oxygen content in rGO films. The electrical conductivity and the overall average Seebeck coefficient of NG film are 13870 S·m-1 and -46.5 μV/K , and the power factor reaches 30 μWm-1K-1, indicating that the in-situ N-doping increases the carrier concentration and promotes the functional application of graphene. A NG film based temperature measuring device is further developed, which shows ultra-high accuracy and sensitivity in temperature reading within a rather wide temperature range. © 2022, The Authors. All rights reserved.

关键词： Graphene

Mechanism of Acid-Catalyzed Pyrolysis of Levoglucosan: Formation of Anhydro-Disaccharides

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SSRN 2023年

作者： He, Ben Yu, Yun Gong, Xun Liu, Shuai Tian, Hong Leng, Erwei College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China Innovation Institute of Industrial Design and Machine Intelligence Quanzhou-Hunan University Quanzhou362006 China State Key Laboratory of Coal Combustion School of Energy and Power Engineering Huazhong University of Science and Technology Wuhan430074 China Hunan province Key Laboratory of Efficient & Clean Thermal Power Generation Technologies State Grid Hunan Electric Power Corporation Research Institute Changsha410007 China School of Energy and Power Engineering Changsha University of Science & Technology Changsha410114 China

Highlights1. Pathways were proposed for levoglucosan polymerization with and without H2SO4.2. The thermodynamic and kinetic factors of each pathway were analyzed.3. The superior pathways for the generation of anhydro-disaccharides were proposed.4. H2SO4 can significantly reduce the energy barrier of the polymerization reaction. © 2023, The Authors. All rights reserved.

关键词： Polymerization

Experimental and Theoretical Study on the Evolution of Functional Groups in Cellulose Char During Oxidative Pyrolysis

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SSRN 2022年

作者： Xiao, Fan Yang, Li He, Ben Tian, Hong Cheng, Shan Yin, Yanshan Leng, Erwei College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China Innovation Institute of Industrial Design and Machine Intelligence Quanzhou-Hunan University Quanzhou362006 China School of Energy and Power Engineering Key Laboratory of Renewable Energy Electric Technology of Hunan Province Changsha University of Science & Technology Hunan Changsha410114 China

Oxidative pyrolysis of biomass is a promising substitute technology for conventional pyrolysis and is also crucial to the related degradation process of biomass materials such as aging, combustion, fire hazard, etc. The intertwining of heterogeneous oxidation and homogeneous oxidation of biomass and its derivative muffles the detailed mechanism of oxidative pyrolysis. To unravel the mechanism of heterogeneous oxidation in the cellulose condensed phase, the real-time evolution of functional groups in cellulose char during oxidative pyrolysis was probed by the in situ diffuse reflectance infrared Fourier transform technology, which is further analyzed by a homemade semi-quantitative analysis program based on the perturbation-correlation moving-window two-dimensional correlation spectroscopy and two-dimensional correlation spectroscopy. The experimental results show the obvious promotion effects of O 2 on the direct oxidation of hydroxyls to unconjugated C=O and the cleavage of C–O–C in the development stage between the temperatures of the initiation and the maximum rate of weight loss, resulting in the lowered thermostability and devolatilization of cellulose. At elevated temperatures, the hydroxyls and C=O were further oxidized by O 2 into carboxyls, and released at around 450 ºC in the last decline stage, performing the second peak of the DTG curve for oxidative stress pyrolysis. Through DFT calculation of the hydroxyl oxidation, a low-temperature oxidation mechanism competitive with the transglycosylation and other dehydration reactions was proposed. Its rate is determined by the initiating H abstraction, which highly depends on the spin density (population) for the transition state and pyrolysis temperature. © 2022, The Authors. All rights reserved.

关键词： Cellulose

A Group Theory Based Topology Optimization Scheme for the design of Inhomogeneous Waveguides with Dihedral Group Symmetries

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SSRN 2024年

作者： Chu, Peiwen Li, Yifan He, Zhicheng Li, Eric Ozgun, Ozlem Vandenbosch, Guy A.E. Zheng, Xuezhi State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle the college of Mechanical and Transportation Engineering Hunan university Changsha410082 China ESAT-WaveCoRE Research Division Department of Electrical Engineering KU Leuven Leuven3001 Belgium School of Computing Engineering & Digital Technologies Teesside University United Kingdom Electrical and Electronics Engineering Hacettepe University Beytepe AnkaraTR 06800 Turkey

In this paper, we introduce a novel topology optimization scheme dedicated to designing waveguides with inhomogeneities holding rotation and reflection symmetries. At begining, we build the scheme by first developing a new computational algorithm that combines the Finite Element Method with the group representation theory. This combination allows the decomposition of the eigenvalue problem in a classic FEM to orthogonal (decoupled) subproblems, which therefore leads to an improved solver efficiency by order of magnitude. For a targeted mode profile, the involvement of the GRT does not only enable a pre-selection of the subproblems that are to be optimized, which further improves the computational speed, but also completely avoids potential mode degeneracies, which adversely affects the convergence of the optimization. To validate, the GRT – FEM algorithm is first tested against the results from a full FEM simulation for a guide with inhomogeneities with six-fold rotation and reflection symmetries. Then, the entire scheme is applied to achieve a desired eigenmode with a targeted propagation constant. The proposed scheme does not only provide an efficient design tool for exploiting interesting wave phenomena in waveguiding structures, but also lays down a theoretical foundation for systematically integrating symmetries with classic Computational Electromagnetics algorithms. © 2024, The Authors. All rights reserved.

关键词： Finite element method

Diff9D: Diffusion-Based Domain-Generalized Category-Level 9-DoF Object Pose Estimation

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IEEE Transactions on Pattern Analysis and Machine Intelligence 2025年第7期47卷 5520-5537页

作者： Jian Liu Wei Sun Hui Yang Pengchao Deng Chongpei Liu Nicu Sebe Hossein Rahmani Ajmal Mian National Engineering Research Center for Robot Visual Perception and Control Technology College of Electrical and Information Engineering School of Robotics and the State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Changsha China Institute of Artificial Intelligence and Robotics Xi’an Jiaotong University Xi’an China Department of Information Engineering and Computer Science University of Trento Trento Italy School of Computing and Communications Lancaster University Lancaster U.K. Department of Computer Science The University of Western Australia Crawley WA Australia

Nine-degrees-of-freedom (9-DoF) object pose and size estimation is crucial for enabling augmented reality and robotic manipulation. Category-level methods have received extensive research attention due to their potential for generalization to intra-class unknown objects. However, these methods require manual collection and labeling of large-scale real-world training data. To address this problem, we introduce a diffusion-based paradigm for domain-generalized category-level 9-DoF object pose estimation. Our motivation is to leverage the latent generalization ability of the diffusion model to address the domain generalization challenge in object pose estimation. This entails training the model exclusively on rendered synthetic data to achieve generalization to real-world scenes. We propose an effective diffusion model to redefine 9-DoF object pose estimation from a generative perspective. Our model does not require any 3D shape priors during training or inference. By employing the Denoising Diffusion Implicit Model, we demonstrate that the reverse diffusion process can be executed in as few as 3 steps, achieving near real-time performance. Finally, we design a robotic grasping system comprising both hardware and software components. Through comprehensive experiments on two benchmark datasets and the real-world robotic system, we show that our method achieves state-of-the-art domain generalization performance.

关键词： Shape Solid modeling Three-dimensional displays Pose estimation Training Robots Grasping Diffusion models Real-time systems Point cloud compression

The consistent behavior of negative Poisson's ratio with interlayer interactions

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arXiv

arXiv 2022年

作者： Wang, Yancong Yu, Linfeng Zhang, Fa Chen, Qiang Zhan, Yuqi Zheng, Xiong Wang, Huimin Qin, Zhenzhen Qin, Guangzhao State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China Hunan Key Laboratory for Micro-Nano Energy Materials & Device School of Physics and Optoelectronics Xiangtan University Hunan Xiangtan411105 China School of Physics and Microelectronics Zhengzhou University Zhengzhou450001 China

Negative Poisson's ratio (NPR) is of great interest due to the novel applications in lots of fields. Films are the most commonly used form in practical applications, which involves multiple layers. However, the effect of interlayer interactions on the NPR is still unclear. In this study, based on first principles calculations, we systematically investigate the effect of interlayer interactions on the NPR by comparably studying single-layer graphene, few-layer graphene, h-BN, and graphene-BN heterostructure. It is found that they almost have the same geometry-strain response. Consequently, the NPR in bilayer graphene, triple-layer graphene, and graphene-BN heterostructure are consistent with that in single-layer graphene and h-BN. The fundamental mechanism lies in that the response to strain of the orbital coupling are consistent under the effect of interlayer interactions. The deep understanding of the NPR with the effect of interlayer interactions as achieved in this study is beneficial for the future design and development of micro-/nanoscale electromechanical devices with novel functions based on nanostructures. © 2022, CC BY-NC-SA.

关键词： Graphene