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Origin of superlubricity of diamond-like carbon(DLC)

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Friction 2025年第1期13卷 85-99页

作者： Seokhoon Jang Zhe Chen Seong H.Kim Department of Chemical Engineering and Materials Research Institute Pennsylvania State UniversityUniversity ParkPA 16802USA state key laboratory of fluid power and mechatronic systems Zhejiang UniversityHangzhou 310058China

Hydrogenated diamond-like carbon(H-DLC)is typically produced as a coating or thin film through plasma-enhanced chemical vapor deposition(PE-CVD).H-DLC is relatively hard and well known to exhibit *** superlubricity an intrinsic property of H-DLC?This paper argues that H-DLC is not intrinsically superlubricious,but it has an ideal structure that allows transition of the interface region to a superlubricious structure upon frictional shear in proper ***,its superlubricity is an extrinsic *** argument is made by comparing frictional behaviors of three allotropes of carbon materials—graphite,amorphous carbon(a-C),and diamond,and carefully scrutinizing the run-in behavior as well as environment sensitivity of H-DLC *** superlubricious structure is generally known to be graphitic,but its exact structure remains elusive and is subject to further ***,accurate knowledge of how superlubricity is induced for H-DLC can guide engineering design to achieve superlubricious behaviors with other carbon materials produced via different synthetic routes.

关键词： superlubricity diamond-like carbon(DLC) run-in environmental sensitivity

BDM editors pick the most memorable moments of 2024

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Bio-Design and Manufacturing 2025年第1期8卷 166-168页

作者： Liang Ma Jun Yin Huayong Yang state key laboratory of fluid power and mechatronic systems Zhejiang UniversityHangzhou 310058China School of Mechanical Engineering Zhejiang UniversityHangzhou 310058China Editorial Office of Bio-Design and Manufacturing Zhejiang UniversityHangzhou 310058China

As the Chinese Lunar New Year-Spring Festival 2025 begins,we take an opportunity to look back at the journal Bio-Design and Manufacturing(BDM for short).The journal BDM,first published in 2018,is related not only to human life and health but also to the frontier disciplines of global scientific and technological *** we highlight a few points of interest from the past year in order to encourage more readers to pay attention to this exciting field.

关键词： journal development. frontier

Automatic and Rapid Throughflow-Based Optimal Design Method for Multi-Stage Axial-Flow Compressors

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Journal of Thermal Science 2025年第1期34卷 77-91页

作者： LEI Fan ZHANG Xiawen JU Yaping ZHANG Chuhua Department of fluid Machinery and Engineering School of Energy and Power EngineeringXi'an Jiaotong UniversityXi'an 710049China state key laboratory for Strength and Vibration of Mechanical Structures Xi'an Jiaotong UniversityXi'an 710049China Production and Environmental Department China Huaneng Group.Co.Ltd.Beijing 100031China

Throughflow design has the advantages of less time consumption and large optimization space,and thus is the corner stone of advanced design system of multi-stage axial-flow *** majority of relevant studies were limited to the throughflow inverse designs,and quite few works have been till now devoted to the throughflow optimal *** this work,an automatic and rapid throughflow-based optimal design method is proposed for axial-flow compressors in which a throughflow inverse design solver is embedded in optimal genetic algorithm to improve the design efficiency of axial-flow *** types of design parameters in the throughflow inverse design of axial-flow compressors,i.e.,swirl and shroud curve,are simultaneously used to optimize both the blade shape and flow *** proposed method is validated by the redesign optimization of the benchmark axial-flow compressor NASA Stage 35,and the CFD predictions show that the throughflow-based optimization leads to 1.18% efficiency benefit at design *** proposed method is then utilized to the two-dimensional throughflow optimal design of a large-scale 6.5-stage axial-flow industrial *** optimal design results are confirmed by CFD predictions,indicating that the proposed method can effectively improve the design adiabatic efficiency of the compressors by 1.09% within a few minutes on desk-top *** throughflow design implications are also obtained for advanced axial-flow industrial *** work could enhance the capability of throughflow design method and has engineering application value to explore the throughflow optimization space of multi-stage axial-flow compressors.

关键词： multi-stage axial-flow compressor throughflow design empirical correlations genetic algorithm aerodynamic optimization

Adaptive fuzzy integral sliding mode velocity control for the cutting system of a trench cutter

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Frontiers of Information Technology & Electronic Engineering 2016年第1期17卷 55-66页

作者： Qi-yan TIAN Jian-hua WEI Jin-hui FANG Kai GUO state key laboratory of fluid power&mechatronic systems Zhejiang UniversityHangzhou 310027China

This paper presents a velocity controller for the cutting system of a trench cutter(TC). The cutting velocity of a cutting system is affected by the unknown load characteristics of rock and soil. In addition, geological conditions vary with time. Due to the complex load characteristics of rock and soil, the cutting load torque of a cutter is related to the geological conditions and the feeding velocity of the cutter. Moreover, a cutter's dynamic model is subjected to uncertainties with unknown effects on its function. In this study, to deal with the particular characteristics of a cutting system, a novel adaptive fuzzy integral sliding mode control(AFISMC) is designed for controlling cutting velocity. The model combines the robust characteristics of an integral sliding mode controller with the adaptive adjusting characteristics of an adaptive fuzzy controller. The AFISMC cutting velocity controller is synthesized using the backstepping technique. The stability of the whole system including the fuzzy inference system, integral sliding mode controller, and the cutting system is proven using the Lyapunov theory. Experiments have been conducted on a TC test bench with the AFISMC under different operating conditions. The experimental results demonstrate that the proposed AFISMC cutting velocity controller gives a superior and robust velocity tracking performance.

关键词： Cutting system, Electro-hydraulic system, Cutting velocity control, Adaptive fuzzy integral sliding mode control

Sensitivity of Influential Factors on Needle Insertion Experiments:A Quantitative Analysis on Phantom Deformations and Needle Deflections

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Chinese Journal of Mechanical Engineering 2020年第6期33卷 38-48页

作者： Murong Li Yong Lei Tian Xu state key laboratory of fluid power&mechatronic systems Zhejiang UniversityHangzhou310027China

High repeatability of needle insertion experiments is essential to the needle-phantom interaction model ***,the influential factors governing the accuracy of the phantom and needle deformations have not been systematically *** this paper,the impact of influential factors,including phantom characteristic represented by the ratio of DMSO and thawing time(TT),needle properties represented by needle external diameter(NED)and operating factors such as needle insertion velocity(IV),insertion positions(IP)and repeated insertion times(RITs)are analyzed by orthogonal experiment *** range calculation shows the most sensitive parameters to phantom deformations are RITs,IV and DMSO while the most sensitive parameters to needle deflection are DMSO,TT and *** variance analysis,the significant factors on maximum tissue deformation(MTD)are IV,followed by RITs,DMSO and *** NED and TT have nearly no significant impact on *** significant sequence on maximum needle deflection(MND)is as follows:DMSO,TT and *** show that,among all impacting factors,phantom deformation is susceptible to both material properties and operative factors while the needle deflection is more susceptible to material properties of the phantom,which can help researchers in related fields to conduct experiments in a more precise manner and better understand the needle-phantom interaction mechanism.

关键词： Needle insertion Sensitivity analysis Tissue deformation Needle deflection

Pressure Regulation for Earth Pressure Balance Control on Shield Tunneling Machine by Using Adaptive Robust Control

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Chinese Journal of Mechanical Engineering 2016年第3期29卷 598-606页

作者： XIE Haibo LIU Zhibin YANG Huayong state key laboratory of fluid power&mechatronic systems Zhejiang University.Hangzhou 310027.China

Most current studies about shield tunneling machine focus on the construction safety and tunnel structure stability during the excavation. Behaviors of the machine itself are also studied, like some tracking control of the machine. Yet, few works concern about the hydraulic components, especially the pressure and flow rate regulation components. This research focuses on pressure control strategies by using proportional pressure relief valve, which is widely applied on typical shield tunneling machines. Modeling of a commercial pressure relief valve is done. The modeling centers on the main valve, because the dynamic performance is determined by the main valve. To validate such modeling, a frequency-experiment result of the pressure relief valve, whose bandwidth is about 3 Hz, is presented as comparison. The modeling and the frequency experimental result show that it is reasonable to regard the pressure relief valve as a second-order system with two low corner frequencies. PID control, dead band compensation control and adaptive robust control（ARC） are proposed and simulation results are presented. For the ARC, implements by using first order approximation and second order approximation are presented. The simulation results show that the second order approximation implement with ARC can track 4 Hz sine signal very well, and the two ARC simulation errors are within 0.2 MPa. Finally, experiment results of dead band compensation control and adaptive robust control are given. The results show that dead band compensation had about 30° phase lag and about 20% off of the amplitude attenuation. ARC is tracking with little phase lag and almost no amplitude attenuation. In this research, ARC has been tested on a pressure relief valve. It is able to improve the valve＇s dynamic performances greatly, and it is capable of the pressure control of shield machine excavation.

关键词： shield tunneling machine pressure regulation adaptive robust control

Effects of finite-size neutrally buoyant particles on the turbulent channel flow at a Reynolds number of 395

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Applied Mathematics and Mechanics(English Edition) 2019年第2期40卷 293-304页

作者： Zhaosheng YU Chenlin ZHU Yu WANG Xueming SHAO state key laboratory of fluid power and mechatronic system Department of MechanicsZhejiang University

A direct-forcing fictitious domain(DFFD) method is used to perform fully resolved numerical simulations of turbulent channel flows laden with large neutrally buoyant particles. The effects of the particles on the turbulence(including the mean velocity,the root mean square(RMS) of the velocity fluctuation, the probability density function(PDF) of the velocity, and the vortex structures) at a friction Reynolds number of 395 are investigated. The results show that the drag-reduction effect caused by finite-size spherical particles at low particle volumes is negligibly small. The particle effects on the RMS velocities at Re_τ = 395 are significantly smaller than those at Re_τ = 180, despite qualitatively the same effects, i.e., the presence of particles decreases the maximum streamwise RMS velocity near the wall via weakening the large-scale streamwise vortices,and increases the transverse and spanwise RMS velocities in the vicinity of the wall by inducing smaller-scale vortices. The effects of the particles on the PDFs of the fluid fluctuating velocities normalized with the RMS velocities are small, regardless of the particle size, the particle volume fraction, and the Reynolds number.

关键词： turbulent channel flow finite-size particle direct numerical simulation(DNS)

Pre-Compression Volume on Flow Ripple Reduction of a Piston Pump

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Chinese Journal of Mechanical Engineering 2013年第6期26卷 1259-1266页

作者： XU Bing SONG Yuechao YANG Huayong state key Lab of fluid power and mechatronic system Zhejiang University

Axial piston pump with pre-compression volume（PCV） has lower flow ripple in large scale of operating condition than the traditional one. However, there is lack of precise simulation model of the axial piston pump with PCV, so the parameters of PCV are difticult to be determined. A finite element simulation model for piston pump with PCV is built by considering the piston movement, the fluid characteristic（including fluid compressibility and viscosity） and the leakage flow rate. Then a test of the pump flow ripple called the secondary source method is implemented to validate the simulation model. Thirdly, by comparing results among the simulation results, test results and results from other publications at the same operating condition, the simulation model is validated and used in optimizing the axial piston pump with PCV. According to the pump flow ripples obtained by the simulation model with different PCV parameters, the flow ripple is the smallest when the PCV angle is 13~, the PCV volume is 1.3 ~ I0-4 m3 at such operating condition that the pump suction pressure is 2 MPa, the pump delivery pressure 15 MPa, the pump speed 1 000 r/min, the swash plate angle 13~. At the same time, the flow ripple can be reduced when the pump suction pressure is 2 MPa, the pump delivery pressure is 5 MPa,15 MPa, 22 MPa, pump speed is 400 r/min, 1 000 r/rain, 1 500 r/rain, the swash plate angle is ll~, 13~, 15~ and 17~, respectively. The finite element simulation model proposed provides a method for optimizing the PCV structure and guiding for designing a quieter axial piston pump.

关键词： pre-compression volume flow ripple operating condition axial piston pump

Design and analysis of an untethered micro flapping robot which can glide on the water

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Science China(Technological Sciences) 2022年第8期65卷 1749-1759页

作者： CHEN YanHong LIU YiDe LIU TaiShan LI Hua QU ShaoXing YANG Wei state key laboratory of fluid power&mechatronic system Key Laboratory of Soft Machines and Smart Devices of Zhejiang ProvincesCenter for X-MechanicsDepartment of Engineering MechanicsZhejiang UniversityHangzhou 310027China

Flapping-wing flying insects possess various advantages,such as high agility and *** design and manufacture of insect-scale flapping-wing micro aerial vehicle(FWMAV)have attracted increasing attention in recent *** to the limitations of size and weight,the FWMAV with an onboard battery which can fully mimic insect flight has not been *** this work,we design and fabricate a highly integrated flapping-wing microrobot named *** Robomoth consists of a carbon chassis,customized power and control devices,and two piezoelectric ceramic actuators symmetrically distributed in the thorax and controlled *** weighs 2.487 g,spans 5.9 cm in length,possesses 9 cm of wingspan,and carries a 0.355 g rechargeable lithium *** demonstrate the mobility of the Robomoth through untethered gliding and making turns on the water surface.A simplified dynamic model of the flapping system is proposed to explain the relationship between the driving frequency and the flapping *** Robomoth is one new untethered bioinspired flapping-wing robot that can perform stable water surface motion,which holds potential applications such as search and rescue on the *** robot can also provide insight for designing insect-scale flying vehicles.

关键词： micro/nanorobots biologically inspired robots flapping-wing flying piezoelectric ceramic actuator