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Modeling and Design of Periodic Polygonal Lattices Constructed from Microstructures with Varying Curvatures

Physical Review Applied 2022年第4期17卷 044032-044032页

作者： Le Dong Dong Wang Jinqiang Wang Chengru Jiang Hui Wang Biao Zhang Mao See Wu Guoying Gu Robotics Institute and State Key Laboratory of Mechanical System and Vibration School of Mechanical Engineering Shanghai Jiao Tong University Shanghai 200240 China Frontiers Science Center for Flexible Electronics (FSCFE) Xi’an Institute of Flexible Electronics (IFE) and Xi’an Institute of Biomedical Materials & Engineering (IBME) Northwestern Polytechnical University 127 West Youyi Road Xi’an 710072 China School of Mechanical and Aerospace Engineering Nanyang Technological University 50 Nanyang Avenue 639798 Singapore

Lattice structures can exhibit unusual mechanical properties by appropriate design and arrangement of the microstructures, and have already found applications in areas such as tissue engineering, stretchable electronics, and soft robotics. However, the designed microstructures generally follow simple geometric patterns with constant curvatures and theoretical models are developed for each geometry particularly. It lacks a universal method to model and design the periodic lattice constructed from microstructures with varying curvatures. In this paper, we develop a universal approach to design polygonal lattices with a wide range of microstructures with varying curvatures using instant curvature and parametric functions. A finite deformation model is proposed for the microstructures and the corresponding lattices, which considers the wavy or curled microstructure, hierarchical geometry, and large deformation. Experiments and finite-element simulations are conducted to validate the theoretical model. All of Young’s modulus, stretchability, and Poisson’s ratio can be inversely designed using the developed theoretical model. Results show that the stretchability of the highly stretchable lattice can be further increased by more than 4 times using densely curled microstructure. The signs of Poisson’s ratio can also change with the axial strain by rationally designing the microstructures. By combining curve fitting and curvature and parametric functions, the mechanical behaviors of lattices constructed by bioinspired microstructures can also be predicted. The lattice structures are then demonstrated to reinforce a hydrogel with modulus increased by around 2 orders and act as a biomimetic soft-strain sensor. This work could aid the design of a hierarchical lattice and have potential applications in tissue engineering, stretchable electronics, and soft robotics.

关键词： Biomimetic & bio-inspired materials Devices Elastic deformation Flexible electronics Mechanical metamaterials Origami & Kirigami Strain Smart materials

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Design and Experimental Validation of Sealing Assembly for Lunar Regolith Volatile Extraction Heating Furnace

Design and Experimental Validation of Sealing Assembly for L...

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IEEE International Conference on robotics and Biomimetics

作者： Hongan Zhang Junyue Tang Yinchao Wang Zixiao Lu Bo Wang Miaoyan Cao Shengyuan Jiang Mechanical Engineering Yanshan University Qinhuangdao P. R. China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin P. R. China Mechatronics Institute Shenyang Aerospace University Shenyang P. R. China National Center for Nanoscience and Technlogy Chinese Academy of Science Beijing P. R. China China Academy of Space Technology Beijing P. R. China

A lunar regolith in-situ analysis payload deploying a mass spectrometer is proposed to exactly detect the water ice of the South Pole of the moon for China future lunar exploration missions. In order to realize the goal, an airtight heating furnace for volatile extraction from lunar regolith is desired. In this paper, sealing methods for lunar regolith volatile in heating furnace to future proposed in-situ sampling and analysis of lunar samples were investigated based on power requirements, furnace closing accuracy requirements, dust tolerance and operation in the Lunar environment. Methods implemented include a balanced metal hollow ring seal, a double channel ferrule tab ring radial seal and a spring energized seal. Comparing the performance of sealing methods under the above conditions, a spring energized seal is selected as the heating furnace seal. The materials and structure of the seal are designed based on the rigidity requirements, leakage rate requirements and working environment requirements. In order to test the sealing performance of seals after repeated sealing in high and low temperature environments, a seal leak detection system was designed. The test results indicate that the seal can meet the sealing performance requirements after repeated sealing at various temperatures.

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Long-term Dependency for 3D Reconstruction of Freehand Ultrasound Without External Tracker

arXiv

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arXiv 2023年

作者： Li, Qi Shen, Ziyi Li, Qian Barratt, Dean C. Dowrick, Thomas Clarkson, Matthew J. Vercauteren, Tom Hu, Yipeng The UCL Centre for Medical Image Computing The Wellcome/EPSRC Centre for Interventional and Surgical Sciences Department of Medical Physics and Biomedical Engineering University College London LondonWC1E 6BT United Kingdom State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China School of Biomedical Engineering & Imaging Sciences King’s College London LondonWC2R 2LS United Kingdom

Objective: Reconstructing freehand ultrasound in 3D without any external tracker has been a longstanding challenge in ultrasound-assisted procedures. We aim to define new ways of parameterising long-term dependencies, and evaluate the performance. Methods: First, long-term dependency is encoded by transformation positions within a frame sequence. This is achieved by combining a sequence model with a multi-transformation prediction. Second, two dependency factors are proposed, anatomical image content and scanning protocol, for contributing towards accurate reconstruction. Each factor is quantified experimentally by reducing respective training variances. Results: 1) The added long-term dependency up to 400 frames at 20 frames per second (fps) indeed improved reconstruction, with an up to 82.4% lowered accumulated error, compared with the baseline performance. The improvement was found to be dependent on sequence length, transformation interval and scanning protocol and, unexpectedly, not on the use of recurrent networks with long-short term modules;2) Decreasing either anatomical or protocol variance in training led to poorer reconstruction accuracy. Interestingly, greater performance was gained from representative protocol patterns, than from representative anatomical features. Conclusion: The proposed algorithm uses hyperparameter tuning to effectively utilise long-term dependency. The proposed dependency factors are of practical significance in collecting diverse training data, regulating scanning protocols and developing efficient networks. Significance: The proposed new methodology with publicly available volunteer data and code1 for parametersing the long-term dependency, experimentally shown to be valid sources of performance improvement, which could potentially lead to better model development and practical optimisation of the reconstruction application. © 2023, CC BY.

关键词： Ultrasonics

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Brightness-Enhanced Electroluminescence Driven by Triboelectric Nanogenerators Through Permittivity Manipulation and Impedance Matching

SSRN

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SSRN 2022年

作者： Gu, Mingwei Chen, Yunfeng Gu, Shaoqiang Wang, Can Chen, Liguo Shen, Hao Chen, Guanyu Sun, Xuhui Huang, Haibo Zhou, Yunlei Wen, Zhen Institute of Mechanical and Electric Engineering Jiangsu Provincial Key Laboratory of Advanced Robotics Soochow University Suzhou215123 China Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices Soochow University Suzhou215123 China College of Chemical Engineering and Technology Hebei University of Technology Tianjin300130 China Key Laboratory of Advanced Technologies of Materials Ministry of Education School of Materials Science and Engineering Southwest Jiaotong University Chengdu610031 China State Key Laboratory of Digital Manufacturing Equipment and Technology Flexible Electronics Research Center Huazhong University of Science and Technology Wuhan430074 China Guangdong Provincial Key Laboratory of Robotics and Intelligent System Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Shenzhen518055 China

Triboelectric nanogenerator-driven electroluminescence (TDEL) that can convert human kinetic energy into visible light has attracted extensive attention in wearable electronics. However, the brightness is usually low due to the low electric field strength on the phosphors caused by impedance mismatch. In this work, a TDEL system with optimal brightness has been proposed by adjusting the dielectric constant of nanocomposite and matching impedance with TENG. The circuit model of the TDEL system is established and the voltage at both ends of the EL layer is predicted through simulation, which error is within 4.7%. Finite element simulation is used to simulate the optimal field strength of phosphors under the dual effects of voltage drop and polarization enhancement of EL layer caused by the increase of dielectric constant of nanocomposites in TDEL system. When the volume ratio of ZnS:Cu is 40% and the dielectric constant of the composite increases from 12 to 22.8, the optimal brightness value increases by 172%. Finally, a patterned TDEL system driven by walking or running to realize the functions of night alarm and information exchange is demonstrated. This study opens the window to improve the brightness of TDEL system through permittivity manipulation and impedance matching, which is applicable to different types of TENG, luminescent particles and dielectric nanocomposites. © 2022, The Authors. All rights reserved.

关键词： Nanogenerators

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Anisotropy of thermal transport in phosphorene: A comparative first-principles study using different exchange-correlation functional

arXiv

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arXiv 2021年

作者： Zhang, Fa Zheng, Xiong Wang, Huimin Ding, Liang Qin, Guangzhao State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China Hunan Key Laboratory for Micro-Nano Energy Materials & Device School of Physics and Optoelectronics Xiangtan University Hunan Xiangtan411105 China

Phosphorene, as a new type of two-dimensional (2D) semiconductor material, possesses unique physical and chemical properties, and thus has attracted widespread attention in recent years. With its increasing applications in nano/optoelectronics and thermoelectrics, a comprehensive study on its thermal transport properties is necessary. It has been concluded from previous studies that there exist vast difference and uncertainty in the theoretically predicted thermal conductivity, which is generally attributed to the selection of XC functional. However, there is no comprehensive investigation on this issue. In this paper, based on first-principles calculations using 12 different exchange-correlation (XC) functionals, the phonon transport properties of phosphorene are systematically studied by solving the Boltzmann transport equation (BTE). The results show noticeable differences in the phonon transport properties of phosphorene under different XC functionals. For instance, the thermal conductivity of phosphorene along the zigzag direction ranges from 0.51 to 30.48 Wm−1K-1, and that along the armchair direction ranges from 0.15 to 5.24 Wm−1K−1. Moreover, the anisotropy of thermal conductivity is between 3.4 and 6.9, which is fundamentally originated from the special hinge-like structure. This study conducts an in-depth analysis of phonon transport to reveal the effect and mechanism of different XC functionals for predicting thermal transport properties, which would provide a reference for future research on phosphorene and other novel materials. © 2021, CC BY.

关键词： Anisotropy

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Tunable unidirectional compact acoustic amplifier via space-time modulated membranes

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Physical Review B 2020年第2期102卷 024309-024309页

作者： Xiaohui Zhu Junfei Li Chen Shen Guangyu Zhang Steven A. Cummer Longqiu Li State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin Heilongjiang 150001 China Department of Electrical and Computer Engineering Duke University Durham North Carolina 27708 USA

Space-time modulation has recently attracted considerable attention as it enables new possibilities in wave manipulation and control. Here we propose a tunable unidirectional acoustic amplifier based on a space-time modulated membrane system. The transfer matrix method is applied to design this system and optimize the modulation parameters for the realization of unidirectional amplification. Efficient one-way amplification of acoustic waves is demonstrated theoretically and numerically within a frequency range from 2260 to 2520 Hz, with overall dimension being less than 1/3 of the corresponding wavelength. Across this operation band, the amplification factor in the positive direction varies smoothly from 3.0 to 5.8, while the transmitted wave energy in the negative direction does not change significantly. Our work identifies a feasible approach to realize a tunable unidirectional acoustic amplifier via space-time modulated membranes, which offers a design platform for a number of applications in sensing, imaging, and communication.

关键词： Acoustic metamaterials Acoustic wave phenomena Sound waves

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Micro-pores formation mechanism and porosity on the fatigue performance of dual laser-powder bed fusion of Ti6Al4V

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International Journal of Fatigue 2025年 199卷

作者： Li, Guotai Hu, Peichen Chen, Gang Chen, Mingjun Yu, Tianyu State Key Laboratory of Robotics and System Harbin Institute of Technology Heilongjiang Harbin150001 China Key Laboratory of Micro-systems and Micro-structures Manufacturing Ministry of Education Heilongjiang Harbin150001 China Institute of Electronic Engineering China Academy of Engineering Physics Sichuan Mianyang621000 China

Porosity significantly impacts the fatigue performance and stability of dual laser additively manufactured metallic materials. This study presents a comparative analysis of the fatigue behavior of samples fabricated by single-laser powder bed fusion (SL-PBF) and dual-laser PBF (DL-PBF). It shows that porosity defects in the overlap region reduced the fatigue strength of DL-PBF samples by nearly 20 %. Micro-CT analysis revealed that micro-pores in the SL-PBF samples were predominantly located in the contour regions. Machining with a removal depth of 0.5 mm has effectively eliminated over 90 % of internal porosity defects. For monolithic specimens, increasing the sample size and reducing the layer-wise slice area can improve the sphericity of the internal defects (0.71 to 0.85) and reduce the porosity density (0.19 % to 0.011 %). Molecular dynamics simulations further examined the influence of pore size, spacing, and quantity on fatigue behavior. Larger pore sizes promote the formation of {11 2¯ 1} twin variants, as the pore diameter increased from 20 Å to 80 Å, the proportion of variants structure increased from 3.6 % to 11.5 %. Fatigue failure initiated from a single pore, with stress propagating towards a distant pore, forming crack paths. Stress was relieved along these crack trajectories, leading to secondary crack branches that spread into low-stress zones around other defects, which resulted in fatigue cracks with vein-like morphologies. This work provides systematic insights into the fatigue degradation mechanisms induced by porosity and offers actionable strategies for improving the fatigue resistance of multi-laser PBF components through process control. © 2025 Elsevier Ltd

关键词： High-cycle fatigue

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Formation mechanism of a smooth, defectfree surface of fused silica optics using rapid CO2 laser polishing

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International Journal of Extreme Manufacturing 2019年第3期1卷 85-95页

作者： Linjie Zhao Jian Cheng Mingjun Chen Xiaodong Yuan Wei Liao Qi Liu Hao Yang Haijun Wang State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001People’s Republic of China Research Center of Laser Fusion China Academy of Engineering PhysicsMianyang 621900People’s Republic of China

Surface defects introduced by conventional mechanical processing methods can induce irreversible damage and reduce the service life of optics applied in high-power *** to mechanical processing,laser polishing with moving beam spot is a noncontact processing method,which is able to form a defect-free *** work aims to explore the mechanism of forming a smooth,defect-free fused silica surface by high-power density laser polishing with coupled multiple *** underlying mechanisms of laser polishing was revealed by numerical simulations and the theoretical results were verified by *** simulated polishing depth and machined surface morphology were in close agreement with the experimental *** obtain the optimized polishing quality,the effects of laser polishing parameters(*** rate,pulse width and polishing times)on the polishing quality were experimentally *** was found that the processing efficiency of fused silica materials by carbon dioxide(CO2)laser polishing could reach 8.68 mm2 s−1,and the surface roughness(Ra)was better than 25 ***,the cracks on pristine fused silica surfaces introduced by initial grinding process were completely removed by laser polishing to achieve a defect-free *** maximum laser polishing rate can reach 3.88μm s−1,much higher than that of the traditional mechanical polishing *** rapid CO2 laser polishing can effectively achieve smooth,defect-free surface,which is of great significance to improve the surface quality of fused silica optics applied in high-power laser facilities.

关键词： laser polishing mechanical processing smooth surface defect-free surface polishing rate

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Time-Optimal Trajectory Planning Based on Dynamics for Industrial Robot

Time-Optimal Trajectory Planning Based on Dynamics for Indus...

引用

Automation, Control and robotics Engineering (CACRE), International Conference on

作者： Rundong Wang Minxiu Kong Yanchun Cheng Marco Castellani School of Mechatronics Engineering Harbin Institute of Technology State Key Laboratory of Robotics and System University of Birmingham Department of Mechanical Engineering

ISBN: (数字)9781728198880

ISBN: (纸本)9781728198897

Given the trajectory of the industrial robot in Cartesian space, the existing methods only consider the kinematic constraints when optimizing the time trajectory planning, and ignore the maximum driving ability of the motor, which is likely to cause an overrun alarm and greatly reduce the trajectory accuracy. Therefore, this paper studies the timeoptimal trajectory planning algorithm based on dynamics. Firstly, the algorithm discretizes the path, calculates the Cartesian coordinates of each discrete point and the differential about the path length. Then, this algorithm considers the constraints of dynamics and kinematics, uses the principle of linear programming, recursively calculates the upper limit value of speed and the maximum acceleration value at each discrete point, and calculates the speed value at each discrete point and keeps it within its allowable ranges. Finally, this algorithm uses the speed to calculate the corresponding time of each discrete point, and according to the interpolation period, outputs the path position of each period, the position and orientation in the Cartesian space and joint parameters. The MATLAB program is written to verify the feasibility and efficiency of the algorithm.

关键词： industrial robot trajectory planning time-optimal dynamics multiple constraints

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HH-Net: Image driven microscope fast auto-focus with deep neural network 19

HH-Net: Image driven microscope fast auto-focus with deep ne...

引用

9th International Conference on Biomedical Engineering and Technology, ICBET 2019

作者： Ge, Yunhao Li, Bin Zhao, Yanzheng Yan, Weixin Robotics Institute Shanghai Jiao Tong University Shanghai China State Key Lab of Mechanical System and Vibration Shanghai China

ISBN: (纸本)9781450361309

Computer aid auto-focus system is necessary for accurate microscope diagnosis, especially for the high precision microscope, which leaves little physical distance for focus adjusting manually. We proposed an image-driven microscope fast auto-focus system with a deep neural network. There are two main contributions. First, combining the high-level feature learning ability advantages of convolution neural network (CNN) and the handcraft feature selection ability of statistical learning, we proposed a High-level-Handcraft Neural Network (HH-Net) to accurately determine the distance index between microscope lens and cell smear by evaluating the image focus quality. It deployed 13 layers CNN for the high-level feature extraction from image patches. While the handcraft features which provide global information from the raw image were extracted by statistical algorithms and merged into CNN features. Finally, the combined features are utilized by the fully connected layers in the network to obtain the final distance index by classifying the biomedical image focus quality. Second, cooperated with the HH-Net, we propose an end to end image driven microscope fast auto-focus system, which can learn auto-focus policies from visual input and finish at a clear spot automatically. The accuracy of our patch level focus quality prediction is 92.4% with HH-Net, while the real-time image level focus quality predication can be 99.99% with 0.025s cost time by certainty voting strategy. Our auto-focus system can also cooperate with the X-Y Micro platform to automatically scan the whole cell smear and get the real-time best-in-focus image of a microscope with fast response, accuracy, and robustness. © 2019 Association for Computing Machinery.

关键词： Deep neural networks

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