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Bionic superhydrophobic surfaces based on topography of copper oxides

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Biosurface and Biotribology 2022年第3期8卷 199-211页

作者： Chen Chen Haiyang Zhan Xiangge Bai Zichao Yuan Lei Zhao Yahua Liu Shile Feng key laboratory for precision&non‐traditional machining technology of ministry of education Dalian University of TechnologyDalianChina

Superhydrophobic surfaces(SHSs)exist in many biological organisms endowed by spectacular surface topographies,which provide important insights to drive a paradigm shift in design of engineering surfaces.Based on this,extensive progresses have been developed on bionic superhydrophobic strategies.Among them,SHSs based on topography of copper oxides exhibit considerable application prospects because of the steerability and diversity of topography,as well as additional performances,such as antibiosis,anticorrosion and catalysis.We first present a brief overview of the discovery of natural SHSs as well as fundamental understanding of surface wetting performance.Then,the structural effects in superhydrophobic systems based on the topographies of biological organisms and copper oxides are described.Finally,we highlight the perspectives on the novel design strategies of copper oxide‐based SHSs that adapt to various practical applications.

关键词： biological organisms bionic SHSs copper‐oxides topography wetting

Fixturing technology and system for thin-walled parts machining:a review

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Frontiers of Mechanical Engineering 2022年第4期17卷 1-32页

作者： Haibo LIU Chengxin WANG Te LI Qile BO Kuo LIU Yongqing WANG key laboratory for precision and non-traditional machining technology of ministry of education Dalian University of TechnologyDalian 116024China

During the overall processing of thin-walled parts(TWPs),the guaranteed capability of the machining process and quality is determined by fixtures.Therefore,reliable fixtures suitable for the structure and machining process of TWP are essential.In this review,the key role of fixtures in the manufacturing system is initially discussed.The main problems in machining and workholding due to the characteristics of TWP are then analyzed in detail.Afterward,the definition of TWP fixtures is reinterpreted from narrow and broad perspectives.Fixture functions corresponding to the issues of machining and workholding are then clearly stated.Fixture categories are classified systematically according to previous research achievements,and the operation mode,functional characteristics,and structure of each fixture are comprehensively described.The function and execution mode of TWP fixtures are then systematically summarized and analyzed,and the functions of various TWP fixtures are evaluated.Some directions for future research on TWP fixtures technology are also proposed.The main purpose of this review is to provide some reference and guidance for scholars to examine TWP fixtures.

关键词： thin-walled part(TWP) fixture machining fixture categories fixture function

Subsurface damage pattern and formation mechanism of monocrystalline β-Ga_(2)O_(3) in grinding process

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Frontiers of Mechanical Engineering 2022年第2期17卷 117-127页

作者： Xin YANG Renke KANG Shang GAO Zihe WU Xianglong ZHU key laboratory for precision and non-traditional machining technology of ministry of education Dalian University of TechnologyDalian 116024China

Monocrystalline beta-phase gallium oxide (β-Ga_(2)O_(3)) is a promising ultrawide bandgap semiconductor material. However, the deformation mechanism in ultraprecision machining has not yet been revealed. The aim of this study is to investigate the damage pattern and formation mechanism of monocrystalline β-Ga_(2)O_(3)in different grinding processes. Transmission electron microscopy was used to observe the subsurface damage in rough, fine, and ultrafine grinding processes. Nanocrystals and stacking faults existed in all three processes, dislocations and twins were observed in the rough and fine grinding processes, cracks were also observed in the rough grinding process, and amorphous phase were only present in the ultrafine grinding process. The subsurface damage thickness of the samples decreased with the reduction in the grit radius and the grit depth of cut. Subsurface damage models for grinding process were established on the basis of the grinding principle, revealing the mechanism of the mechanical effect of grits on the damage pattern. The formation of nanocrystals and amorphous phase was related to the grinding conditions and material characteristics. It is important to investigate the ultraprecision grinding process of monocrystalline β-Ga_(2)O_(3). The results in this work are supposed to provide guidance for the damage control of monocrystalline β-Ga_(2)O_(3)grinding process.

关键词： monocrystalline beta-phase gallium oxide grinding process subsurface damage nanocrystals amorphous phase

A multi-order method for predicting stability of a multi-delay milling system considering helix angle and run-out effects

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Chinese Journal of Aeronautics 2018年第6期31卷 1375-1387页

作者： Shanglei JIANG Yuwen SUN key laboratory for precision and non-traditional machining technology of the ministry of education Dalian University of Technology

In this paper, a multi-delay milling system considering helix angle and run-out effects is firstly established. An exponential cutting force model is used to model the interaction between a work-piece and a cutting tool, and a new approach is presented for accurately calibrating exponential cutting force coefficients and cutter run-out parameters. Furthermore, based on an implicit multi-step Adams formula and an improved precise time-integration algorithm, a novel stability prediction method is proposed to predict the stability of the system. The involved time delay term and periodic coefficient term are integrated as a comprehensive state term in the integral response which is approximated by the Adams formula. Then, a Floquet transition matrix with an arbitraryorder form is constructed by using a series of matrix multiplication, and the stability of the system is determined by the Floquet theory. Compared to classical semi-discretization methods and fulldiscretization methods, the developed method shows a good performance in convergence, efficiency,accuracy, and multi-order complexity. A series of cutting tests is further carried out to validate the practicability and effectiveness of the proposed method. The results show that the calibration process needs a time of less than 5 min, and the stability prediction method is effective.

关键词： Cutting force Floquet theory Milling stability Multi-delay milling system Run-out

Effect of substrate curvature on thickness distribution of polydimethylsiloxane thin film in spin coating process

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Chinese Physics B 2018年第6期27卷 479-487页

作者：闫英周平张尚雄郭晓光郭东明 key laboratory for precision and non-traditional machining technology of ministry of education Dalian University of Technology

The polymer spin coating is critical in flexible electronic manufaction and micro-electro-mechanical system（MEMS）devices due to its simple operation, and uniformly coated layers. Some researchers focus on the effects of spin coating parameters such as wafer rotating speed, the viscosity of the coating liquid and solvent evaporation on final film thickness.In this work, the influence of substrate curvature on film thickness distribution is considered. A new parameter which represents the edge bead effect ratio（re） is proposed to investigate the influence factor of edge bead effect. Several operation parameters including the curvature of the substrate and the wafer-spin speed are taken into account to study the effects on the film thickness uniformity and edge-bead ratio. The morphologies and film thickness values of the spin-coated PDMS films under various substrate curvatures and coating speeds are measured with laser confocal microscopy. According to the results, both the convex and concave substrate will help to reduce the edge-bead effect significantly and thin film with better surface morphology can be obtained at high spin speed. Additionally, the relationship between the edge-bead ratio and the thin film thickness is like parabolic curve instead of linear dependence. This work may contribute to the mass production of flexible electronic devices.

关键词： spin coating non-planar substrate film thickness distribution edge-bead effect

Recent progress of residual stress measurement methods: A review

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Chinese Journal of Aeronautics 2021年第2期34卷 54-78页

作者： Jiang GUO Haiyang FU Bo PAN Renke KANG key laboratory for precision and non-traditional machining of ministry of education Dalian University of TechnologyDalian 116024China

Residual stress is one of the main factors affecting the mechanical properties of materials, such as their strength, plasticity and surface integrity. For instance, tensile stress conditions can adversely affect material performance or component life, while compressive stress conditions can improve material fatigue strength. During the processing of integrated aviation structures, machining deformation caused by residual stress has become one of the most prominent manufacturing problems. Therefore, it is very important to measure and evaluate the stress for real applications.This paper reviews the research of residual stress measurement methods over the past five years by classifying them according to the measurement methods appearing in each stage. The existing problems and difficulties of each measurement technology are summarized, and future trends are forecasted. This paper provides a reference for further in-depth study of residual stress measurement technologies.

关键词： Destructive testing Future trends Measurement nondestructive testing Residual stress

Design of ultrasonic elliptical vibration cutting system for tungsten heavy alloy

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Frontiers of Mechanical Engineering 2022年第4期17卷 163-180页

作者： Sen YIN Yan BAO Yanan PAN Zhigang DONG Zhuji JIN Renke KANG key laboratory for precision and non-traditional machining technology of the ministry of education School of Mechanical EngineeringDalian University of TechnologyDalian 116024China

Nanoscale surface roughness of tungsten heavy alloy components is required in the nuclear industry and precision instruments.In this study,a high-performance ultrasonic elliptical vibration cutting(UEVC)system is developed to solve the precision machining problem of tungsten heavy alloy.A new design method of stepped bending vibration horn based on Timoshenko’s theory is first proposed,and its design process is greatly simplified.The arrangement and working principle of piezoelectric transducers on the ultrasonic vibrator using the fifth resonant mode of bending are analyzed to realize the dual-bending vibration modes.A cutting tool is installed at the end of the ultrasonic vibration unit to output the ultrasonic elliptical vibration locus,which is verified by finite element method.The vibration unit can display different three-degree-of-freedom(3-DOF)UEVC characteristics by adjusting the corresponding position of the unit and workpiece.A dual-channel ultrasonic power supply is developed to excite the ultrasonic vibration unit,which makes the UEVC system present the resonant frequency of 41 kHz and the maximum amplitude of 14.2μm.Different microtopography and surface roughness are obtained by the cutting experiments of tungsten heavy alloy hemispherical workpiece with the UEVC system,which validates the proposed design’s technical capability and provides optimization basis for further improving the machining quality of the curved surface components of tungsten heavy alloy.

关键词： tungsten heavy alloy ultrasonic elliptical vibration cutting Timoshenko’s theory resonant mode of bending finite element method

Simulative technology for auxiliary fuel tank separation in a wind tunnel

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Chinese Journal of Aeronautics 2016年第3期29卷 608-616页

作者： Ma Xin Liu Wei Chen Ling Li Xiao Jia Zhenyuan Shang Zhiliang key laboratory for precision and non-traditional machining technology of the ministry of education Dalian University of Technology

In this paper, we propose a simulative experimental system in wind tunnel conditions lbr the separation of auxiliary fuel tanks from an aircraft. The experimental system consists of a simulative release mechanism, a scaled model and a pose measuring system. A new release mechanism was designed to ensure stability of the separation. Scaled models of the auxiliary fuel tank were designed and their moment of inertia was adjusted by installing counterweights inside the model. Pose param- eters of the scaled model were measured and calculated by a binocular vision system. Additionally, in order to achieve high brightness and high signal-to-noise ratio of the images in the dark enclosed wind tunnel, a new high-speed image acquisition method based on miniature self-emitting units was pre- sented. Accuracy of the pose measurement system and repeatability of the separation mechanism were verified in the laboratory. Results show that the position precision of the pose measurement system can reach 0.1 mm, the precision of the pitch and yaw angles is less than 0.1° and that of the roll angle can be up to 0.3°. Besides, repeatability errors of models＂ velocity and angular velocity controlled by the release mechanism remain small, satisfying the measurement requirements. Finally, experiments for the separation of auxiliary fuel tanks were conducted in the laboratory.

关键词： Aircraft auxiliary equipmentBinocular vision Position and attitude mea-surement Release mechanism Simulation experiment

Facile and Economical Fabrication of Superhydrophobic Flexible Resistive Strain Sensors for Human Motion Detection

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Nanomanufacturing and Metrology 2023年第1期6卷 15-23页

作者： Yulin Shang Bingzhen Zhang Jiyu Liu Chunwen Xia Xiaowei Yang Defeng Yan Jing Sun key laboratory for precision and non-traditional machining technology of the ministry of education Dalian University of TechnologyDalian 116024People’s Republic of China

Superhydrophobic flexible strain sensors have great application value in the fields of personal health monitoring,human motion detection,and soft robotics due to their good flexibility and high sensitivity.However,complicated preparation processes and costly processing procedures have limited their development.To overcome these limitations,in this work we develop a facile and low-cost method for fabricating superhydrophobic flexible strain sensor via spraying carbon black(CB)nanoparticles dispersed in a thermoplastic elastomer(SEBS)solution on a polydimethylsiloxane(PDMS)flexible substrate.The prepared strain sensor had a large water contact angle of 153±2.83°and a small rolling angle of 8.5±1.04°,and exhibited excellent self-cleaning property.Due to the excellent superhydrophobicity,aqueous acid,salt,and alkali could quickly roll off the flexible strain sensor.In addition,the sensor showed excellent sensitivity(gauge factor(GF)of 5.4–7.35),wide sensing ranges(stretching:over 70%),good linearity(three linear regions),low hysteresis(hysteresis error of 4.8%),and a stable response over 100 stretching-releasing cycles.Moreover,the sensor was also capable of effectively detecting human motion signals like finger bending and wrist bending,showing promising application prospects in wearable electronic devices,personalized health monitoring,etc.

关键词： Superhydrophobic Spraying Strain sensors Human motion detection