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Study on the Formation and Separation Process of Droplets in the Medical Piezoelectric Atomization Device Induced by Intra‑hole Fluctuation

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Chinese Journal of Mechanical Engineering 2022年第3期35卷 285-296页

作者： Qiufeng Yan wanting sun Jianhui Zhang School of Electrical Engineering Nantong UniversityNantong 226019China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China College of Mechanical and Electrical Engineering Guangzhou UniversityGuangzhou 510006China

Traditional atomization devices always exhibit many drawbacks,such as non-uniform atomization particle sizes,instability of transient atomization quantity and uncontrollability of precise energy,which seriously restrict further practical application of atomization inhalation therapy.The formation and separation process of droplets belongs to a microphenomenon of atomization.The investigation of the droplet formation and separation process will be favorable for understanding the atomization mechanism.In present work,the Conservative Level Set Method(CLSM)is successfully applied on the simulation of the formation and separation of droplets in a medical piezoelectric atomization device induced by intra-hole fluctuation.The intra-hole fluctuation mechanism is systematically explored and analyzed,and also the expression of the volume change in the micro cone hole is built and evaluated.Both the control equation and simulation model of droplet formation and separation process have been well established by meshing the simulation model,and thereby the process of droplet formation and separation is simulated.The corresponding results demonstrate that the breaking time of droplets is decreased with the inlet velocity and liquid temperature rising,while enhanced with the liquid concentration increasing.Meanwhile,the volume of droplet is decreased with the inlet velocity and liquid concentration increasing,but increased with the liquid temperature rising.The velocity of droplet is enhanced with the inlet velocity and liquid temperature rising,and reduced with the increase of liquid concentration.When the large side diameter of micro-cone hole is set as 79μm,the breaking time of the droplet reaches a minimum value of 38.7μs,whereas the volume and the velocity of droplet reach a maximum value of 79.8 pL and 4.46 m/s,respectively.This study provides theoretical guidance for the design of medical piezoelectric atomization devices and contributes to the promotion of inhalation therapy in practical use.

关键词： CLSM Intra-hole fluctuation Piezoelectric atomization Droplet distribution

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Corrosion behavior of a Mg-Zn-Ca-La alloy in 3.5 wt%NaCl solution

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Journal of Magnesium and Alloys 2022年第2期10卷 567-580页

作者： Yuzhou Du Xin Wang Dongjie Liu wanting sun Bailing Jiang School of Materials Science and Engineering Xi’an University of TechnologyXi’an 710048China Shaanxi Province Engineering Research Center for Magnesium Alloys Xi’an University of TechnologyXi’an 710048China School of Materials Science and Engineering Dongguan University of TechnologyDongguan 523808China

The present study investigates the corrosion behavior of a Mg–Zn–Ca–La alloy.Results indicate that the corrosion resistance is enhanced by rolling deformation and subsequent annealing treatment significantly.The microstructure,distribution of second phase and grain orientation are the main factors affecting corrosion properties.The second phase with semi-continuous network in the as-cast alloy gives rise to the penetration of corrosion into the matrix.However,the dispersed second phase after deformation results in uniform corrosion.The formation of dense corrosion layer at the initial stage of corrosion is favorable for the improvement of corrosion resistance.The sample withplane oriented towards surface exhibits good corrosion resistance,which is ascribed to the homogeneous microstructure and strong basal texture.

关键词： Mg–Zn–Ca–La Rolling Second phase Texture Corrosion properties

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An extraordinary-performance gradient nanostructured Hadfield manganese steel containing multi-phase nanocrystalline-amorphous core-shell surface layer by laser surface processing

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Journal of Materials Science & Technology 2023年第3期134卷 209-222页

作者： wanting sun Jiasi Luo Yim Ying Chan J.H.Luan Xu-Sheng Yang Research Institute for Advanced Manufacturing Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHung HomHong KongChina Hong Kong Branch of National Rail Transit Electrification and Automation Engineering Technology Research Center The Hong Kong Polytechnic UniversityHung HomHong KongChina Department of Materials Science and Engineering City University of Hong KongHong KongChina

Reducing grain size(i.***.increasing the fraction of grain boundaries)could effectively strengthen nanograined metals but inevitably sacrifices the ductility and possibly causes a strengthening-softening transition below a critical grain size.In this work,a facile laser surface remelting-based technique was employed and optimized to fabricate a∼600μm-thick heterogeneous gradient nanostructured layer on an austenitic Hadfield manganese steel,in which the average grain size is gradually decreased from∼200μm in the matrix to only∼8 nm in the nanocrystalline-amorphous core-shell topmost surface.Atomic-scale microstructural characterizations dissected the gradient refinement processes along the gradient direction,i.***.transiting from the dislocations activities and twinning in sub-region to three kinds of martensitic transformations,and finally a multi-phase nanocrystalline-amorphous core-shell structural surface.Mechanical tests(e.***.nanoindentation,bulk-specimen tensile,and micro-pillar compression)were conducted along the gradient direction.It confirms a tensile strength of∼1055 MPa and ductility of∼10.5%in the laser-processed specimen.Particularly,the core-shell structural surface maintains ultra-strong(tensile strength of∼1.6 GPa,micro-pillar compressive strength of∼4 GPa at a strain of∼8%,and nanoindentation hardness of∼7.7 GPa)to overcome the potential strengthening-softening transition.Such significant strengthening effects are ascribed to the strength-ductility synergetic effects-induced extra work hardening ability in gradient nanostructure and the well-maintained dislocation activities inside extremely refined nanograins in the multi-phase nanocrystalline-amorphous core-shell structural surface,which are evidenced by atomic-scale observations and theoretical analysis.This study provides a unique hetero-nanostructure through a facile laser-related technique for extraordinary mechanical performance.

关键词： Laser surface processing Hadfield manganese steel Gradient nanostructure Nanocrystalline-amorphous Martensitic transformation

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Laser surface treatment-introduced gradient nanostructured TiZrHfTaNb refractory high-entropy alloy with significantly enhanced wear resistance

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Journal of Materials Science & Technology 2022年第15期110卷 43-56页

作者： Jiasi Luo wanting sun Ranxi Duan Wenqing Yang K.C.Chan Fuzeng Ren Xu-Sheng Yang Department of Industrial and Systems Engineering Advanced Manufacturing Technology Research CentreThe Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhen 518055China The Hong Kong Polytechnic University Shenzhen Research Institute Shenzhen 518060China

Heterogeneous gradient nanostructured metals have been shown to achieve the strength-ductility synergy, thus potentially possessing the enhanced tribological performance in comparison with their homogeneous nanograined counterparts. In this work, a facile laser surface remelting-based surface treatment technique is developed to fabricate a gradient nanostructured layer on a TiZrHfTaNb refractory highentropy alloy. The characterization of the microstructural evolution along the depth direction from the matrix to the topmost surface layer shows that the average grain size in the ~100 μm-thick gradient nanostructured layer is dramatically refined from the original ~200 μm to only ~8 nm in the top surface layer. The microhardness is therefore gradually increased from ~240 HV in matrix to ~650 HV in the topmost surface layer, approximately 2.7 times. Noticeably, the original coarse-grained single-phase bodycentered-cubic TiZrHfTaNb refractory high-entropy alloy is gradually decomposed into TiNb-rich bodycentered-cubic phase, TaNb-rich body-centered-cubic phase, ZrHf-rich hexagonal-close-packed phase and TiZr Hf-rich face-centered-cubic phase with gradient distribution in grain size along the depth direction during the gradient refinement process. As a result, the novel laser surface treatment-introduced gradient nanostructured TiZrHfTaNb refractory high-entropy alloy demonstrates the significantly improved wear resistance, with the wear rate reducing markedly by an order of magnitude, as compared with the as-cast one. The decomposed multi-phases and gradient nanostructures should account for the enhanced wear resistance. Our findings provide new insights into the refinement mechanisms of the laser-treated refractory high-entropy alloys and broaden their potential applications via heterogeneous gradient nanostructure engineering.

关键词： Laser surface treatment Refractory high-entropy alloy Gradient nanostructure Wear resistance High-resolution transmission electron microscopy

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Process design and microstructure-property evolution during shear spinning of Ti_(2)AlNb-based alloy

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Journal of Materials Science & Technology 2022年第6期101卷 1-17页

作者： Sibing Wang Wenchen Xu Bin Shao Guoping Yang Yingying Zong wanting sun Zhongze Yang Debin Shan School of Materials Science and Engineering&National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of TechnologyHarbin 150001China Capital Aerospace Machinery Co.Ltd. Beijing 100076China

Rotationally symmetric workpieces of Ti_(2)AlNb-based alloys have great potential for high-temperature service condition in aviation industry,while the poor workability limits their application until now.In this study,shear spinning and heat treatment were first conducted to investigate the corresponding microstructure evolution and mechanical properties of Ti_(2)AlNb conical workpieces.The microstructure of the 1^(st) and 2^(nd) pass spun workpieces(SP1 and SP2)mainly consisted of B2+retainedα2phases.After two passes spinning,the B2 phase texture changed from//ND of as-received alloy to be//ND.The ultimate tensile stress(UTS)of SP1 and SP2 was increased to 1163 MPa and 932 MPa,respectively,compared with 782 MPa of as-received alloy at 650℃.Also,the yield stress anomaly(YSA)occurred in SP1 and SP2 because{110}and{112}cross slip systems of B2 phase were difficult to slip at or below room temperature(RT),but they became active at 650℃ and above.As an essential step for increasing the spinnability of multi-pass spinning process of the Ti_(2)AlNb alloy,the H3heat treatment scheme,i.e.960℃/2 h+850℃/12 h,was carried out between two successive passes to increase the hot workability,by which the ductility of the heat treated as-spun workpieces with the microstructure of B2+primary O+acicular secondary O+high amount spheroidizedα2phases reached 72.1%at 900℃.After being subject to the H1 heat treatment scheme,i.e.960℃-2 h,the spun workpieces with the microstructure of B2+primary O+intergranular primaryα2phases achieved an optimized comprehensive mechanical properties both at room temperature and 650℃,which should be chosen as the post-spinning heat treatment process for the service requirement.

关键词： Ti_(2)AlNb-based alloy Shear spinning Conical workpiece Microstructural evolution Mechanical property

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Exceptional thermal stability and enhanced hardness in a nanostructured Mg-Gd-Y-Zn-Zr alloy processed by high pressure torsion

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Journal of Magnesium and Alloys 2023年第12期11卷 4589-4602页

作者： wanting sun Yang He Xiaoguang Qiao Xiaojun Zhao Houwen Chen Nong Gao Marco J.Starink Mingyi Zheng School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Materials Research Group School of EngineeringUniversity of SouthamptonSouthampton SO171BJUnited Kingdom Center for Composite Materials and Structures Harbin Institute of TechnologyHarbin 150001China Department of Industrial and Systems Engineering The Hong Kong Polytechnic UniversityHung HomHong KongChina

A Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr(wt.%) alloy is processed by solution treatment and high pressure torsion(HPT) at room temperature to produce a nanostructured light material with high hardness. The stability of this alloy is subsequently tested through isochronal annealing for 0.5 h at 373 K to 673 K. The results reveal a thermal stability that is vastly superior to that of conventional Mg-based alloys processed by severe plastic deformation: the grain size remains at around 50 nm on heating to 573 K, and as the temperature is increased to 673 K,grain growth is restricted to within 500 nm. The stability of grain refinement of the present alloy/processing combination allowing grain size to be limited to 55 nm after exposure at 573 K, appears to be nearly one order of magnitude better than for the other SPD processed Mg-RE type alloys, and 2 orders of magnitude better than those of SPD processed RE-free Mg alloys. This superior thermal stability is attributed to formation of co-clusters near and segregation at grain boundaries, which cause a thermodynamic stabilization of grain size, as well as formation of β-Mg_(5)RE equilibrium phase at grain boundaries, which impede grain growth by the Zener pinning effect. The hardness of the nanostructured Mg-Gd-Y-Zn-Zr alloy increases with increasing annealing temperature up to 573 K, which is quite different from the other SPD-processed Mg-based alloys. The high hardness of 136 HV after annealing at 573 K is mainly due to solute segregation and solute clustering at or near grain boundaries.

关键词： Mg-RE alloy High pressure torsion Thermal stability Grain growth Solute segregation Phase transformation

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Combining gradient structure and supersaturated solid solution to achieve superior mechanical properties in WE43 magnesium alloy

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Journal of Materials Science & Technology 2022年第4期99卷 223-238页

作者： wanting sun Bo Wu Hui Fu Xu-Sheng Yang Xiaoguang Qiao Mingyi Zheng Yang He Jian Lu San-Qiang Shi State Key Laboratory of Ultra-precision Machining Technology Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHung HomHong KongChina Hong Kong Polytechnic University Shenzhen Research Institute ShenzhenChina Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHung HomHong KongChina School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Centre for Composite Materials and Structures Harbin Institute of TechnologyHarbin 150080China Department of Mechanical Engineering City University of Hong KongKowloonHong KongChina

In this study,surface mechanical attrition treatment was employed to sucessfully produce a gradient nanostructured layer on WE43 magnesium alloy.X-ray diffraction,energy dispersive X-ray spectrometer,and high-resolution transmission electron microscope observations were mainly performed to uncover the microstructure evolution responsible for the refinement mechanisms.It reveals that the grain refinement process consists of three transition stages along the depth direction from the core matrix to the topmost surface layer,i.e.,dislocation cells and pile-ups,ultrafine subgrains,and randomly orientated nanograins with the grain size of~40 nm.Noticeably,the original Mg;RE second phase is also experienced refinement and then re-dissolved into the α-Mg matrix phase,forming a supersaturated solid solution nanostructuredα-Mg phase in the gradient refined layer.Due to the cooperative effects of grain refinement hardening,dislocation hardening,and supersaturated solid-solution hardening,the gradient nanostructured WE43 alloy contributes to the ultimate tensile strength of~435 MPa and ductility of~11.0%,showing an extraordinary strain hardening and mechanical properties among the reported severe plastic deformation-processed Mg alloys.This work provides a new strategy for the optimization of mechanical properties of Mg alloys via combining the gradient structure and supersaturated solid solution.

关键词： Mg-RE alloy Surface mechanical attrition treatment Gradient nanostructure Supersaturated solid solution High strength and ductility Strengthening mechanisms

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Effects of Vibration Characteristics on the Atomization Performance in the Medical Piezoelectric Atomization Device Induced by Intra-Hole Fluctuation

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Chinese Journal of Mechanical Engineering 2021年第6期34卷 331-339页

作者： Qiufeng Yan wanting sun Lei Zhang Hongmei Wang Jianhui Zhang School of Electrical Engineering Nantong UniversityNantong226019China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin150001China College of Mechanical and Electrical Engineering Guangzhou UniversityGuangzhou510006China

Oral inhalation of aerosolized drugs has be widely applied in healing the affected body organs including lesions of the throat and lungs and it is more effiicient than those conventional therapies,such as intravenous drip,intramuscular injection and external topical administration in the aspects of the dosage reduction and side effects of drugs.Never-theless,the traditional atomization devices always exhibit many drawbacks.For example,non-uniformed atomization particle distribution,the instability of transient atomization quantity and difficulties in precise energy control would seriously restrict an extensive use of atomization inhalation therapy.In this study,the principle of intra-hole fluctua-tion phenomenon occurred in the hole is fully explained,and the produced volume change is also estimated.Addi-tionally,the mathematical expression of the atomization rate of the atomizing device is well established.The mecha-nism of the micro-pump is further clarified,and the influence of the vibration characteristics of the atomizing film on the atomization behavior is analyzed theoretically.The curves of sweep frequency against the velocity and amplitude of the piezoelectric vibrator are obtained by the Doppler laser vibrometer,and the corresponding mode shapes of the resonance point are achieved.The influence of vibration characteristics on atomization rate,atomization height and atomization particle size are also verified by experiments,respectively.Both the experimental results and theoretical calculation are expected to provide a guidance for the design of this kind of atomization device in the future.

关键词： Piezoelectric Intra-hole fluctuation Vibration characteristics Atomization

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Experimental and Theoretical Study on the Flexural Behavior of Recycled Concrete Beams Reinforced with GFRP Bars

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Journal of Renewable Materials 2021年第6期9卷 1169-1188页

作者： Xinzhan Chen Xiangqing Kong Ying Fu wanting sun Renguo Guan School of Civil Engineering Liaoning University of TechnologyJinzhou121001China Engineering Research Center of Continuous Extrusion Dalian Jiaotong UniversityDalian116028China

This paper experimentally investigated the flexural behavior of reinforced recycled aggregate concrete(RAC)beams reinforced with glass fiber-reinforced polymer(GFRP)bars.A total of twelve beams were built and tested up to failure under four-point bending.The main parameters were reinforcement ratio(0.38%,0.60%,and 1.17%),recycled aggregate replacement ratio(R=0,50%,and 100%)and longitudinal reinforcement types(GFRP and steel).The flexural capacity,failure modes,flexibility deformation,reinforcement strains and crack distribution of the tested beams were investigated and compared with the calculation models of American code ACI 440.1-R-15,Canadian code CSA S806-12 and ISIS-M03-07.The tested results indicated that the reinforcement ratio has great influence on the ultimate load,crack width and deflection of GFRP-RAC beams,the recycled aggregate replacement ratio has little influence on it.However,it was found that the reinforcement ratio has no obvious influence on the cracking load which was only related to the recycled aggregate replacement ratio.The average cracking load decreased by 5%and 15%as the recycled aggregate replacement ratio increased from 0 to 50%and 100%.For the steel-RAC beams,the ultimate load was found to be about 1/2 of the ultimate load of GFRP-RAC beam under the same condition and the trend of strain,deflection and crack width were different from GFRP-RAC beams.This is due to the different material properties of GFRP bars and steel rebar.On the other hand,the calculation results showed that ACI 440.1-R-15 and CSA S806-12 underestimated the ultimate load of GFRP-RAC beams.Moreover,the deflection prediction of GFRP-RAC beams by CSA S806-12 is relatively accurate compared with ACI 440.1-R-15 and ISIS-M03-07.As for the prediction of crack width,the results of ACI 440.1-R-15 prediction were in good agreement with the experimental results at the ultimate load,with the average value of 1.09±0.28.

关键词： GFRP bars recycled aggregate concrete replacing ratio flexural capacity reinforcement ratio

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踏车训练和呼吸训练对维持性血液透析患者运动耐力、肺功能及生存质量的影响

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中国康复医学杂志 2024年第5期39卷 687-692页

作者：李淑月孙婉婷龚翔陈珺雯杨家慧曾鸣鲁俊许光旭南京医科大学康复医学院江苏省南京市210029 南京医科大学第一附属医院肾科南京医科大学第一附属医院老年康复科

目的:评估和比较踏车训练和呼吸训练对维持性血液透析(maintenance hemodialysis,MHD)患者运动耐力、肺功能及生存质量的影响。方法:2022年7月—2023年7月,本院60例MHD患者采用随机数字表法分为对照组(n=20)、踏车组(n=20)、呼吸组(n=20... 详细信息

目的:评估和比较踏车训练和呼吸训练对维持性血液透析(maintenance hemodialysis,MHD)患者运动耐力、肺功能及生存质量的影响。方法:2022年7月—2023年7月,本院60例MHD患者采用随机数字表法分为对照组(n=20)、踏车组(n=20)、呼吸组(n=20)。对照组给予常规血液透析治疗。踏车组在常规血液透析治疗基础上给予中等强度的透析中踏车训练共12周,每周3次,每次时间40min。呼吸组在常规血液透析治疗基础上给予呼吸训练(腹式呼吸训练、缩唇呼吸训练以及膈肌呼吸训练)共12周,每周3次,每次时间40min。分别于治疗前和治疗后对患者进行评估,采用峰值摄氧量(VO_(2peak))、无氧阈(AT)、峰值氧脉搏(VO_(2)/HR_(peak))评估患者的运动耐力,用力肺活量(FVC)、第一秒用力呼气量(FEV1)、每分钟最大通气量(MVV)评估患者的肺功能,肺功能指标以实测值占预计值的百分比表示,即FVC%、FEV1%、MVV%。采用健康调查简表(the MOS item short from health survey,SF-36)评估患者的生存质量,包括生理健康(PCS)、精神健康(MCS)、总分。结果:治疗前,3组患者的VO_(2peak)、AT、VO_(2)/HR_(peak)、FVC%、FEV1%、MVV%、PCS、MCS及总分均无明显差异(P>0.05);治疗12周后,踏车组VO_(2peak)、AT、VO_(2)/HR_(peak)、PCS、总分较本组治疗前增加且优于对照组(P<0.05);呼吸组FVC%、FEV1%、MCS、总分较本组治疗前增加且优于对照组(P<0.05)。结论:踏车训练和呼吸训练均能改善MHD患者的心肺功能及生存质量,其中踏车训练在提高运动耐力及生理健康方面疗效更显著,呼吸训练在提高肺功能及精神健康方面疗效更显著。

关键词：血液透析透析中踏车训练呼吸训练运动耐力肺功能生存质量

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