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Evaluation on Configuration Stiffness of Overconstrained 2R1T Parallel Mechanisms

Chinese Journal of Mechanical Engineering 2024年第3期37卷 62-82页

作者： Xuejian Ma Zhenghe Xu Yundou Xu Yu Wang Jiantao Yao Yongsheng Zhao Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan UniversityQinhuangdao 066004China Key Laboratory of Advanced Forging and Stamping Technology and Science of Ministry of National Education Yanshan UniversityQinhuangdao 066004China

Currently,two rotations and one translation(2R1T)three-degree-of-freedom(DOF)parallel mechanisms(PMs)are widely applied in five-DOF hybrid machining ***,there is a lack of an effective method to evaluate the configuration stiffness of mechanisms during the mechanism design *** is a challenge to select appropriate 2R1T PMs with excellent stiffness performance during the design *** the operational status of 2R1T PMs,the bending and torsional stiffness are considered as indices to evaluate PMs'configuration ***,a specific method is proposed to calculate these stiffness ***,the various types of structural and driving stiffness for each branch are assessed and their specific values ***,a rigid-flexible coupled force model for the over-constrained 2R1T PM is established,and the proposed evaluation method is used to analyze the configuration stiffness of the five 2R1T PMs in the entire ***,the driving force and constraint force of each branch in the whole working space are calculated to further elucidate the stiffness evaluating results by using the proposed method *** obtained results demonstrate that the bending and torsional stiffness of the 2RPU/UPR/RPR mechanism along the x and y-directions are larger than the other four mechanisms.

关键词： Parallel mechanism Stiffness Over-constrained Three degrees of freedom

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Kinetic analysis of austenite transformation for B1500HS high-strength steel during continuous heating

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International Journal of Minerals,Metallurgy and Materials 2020年第11期27卷 1508-1516页

作者： Mu-yu Li Dan Yao Liu Yang Hao-ran Wang Ying-ping Guan Key Laboratory of Advanced Forging&Stamping Technology and Science(Ministry of Education of China) Yanshan UniversityQinhuangdao 066004China School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004China

The dilatometric curves of B1500HS high-strength steel at different heating rates were measured by a Gleeble-3800 thermal simulator and analyzed to investigate the effect of heating rate on *** show that the value of starting temperature and ending temperature of austenite transformation increase with the rise of heating rates,whereas the temperature interval of austenite formation *** kinetic equation of austenite transformation was solved using the Johnson–Mehl–Avrami model,and the related parameters of the equation were analyzed by the Kissinger *** those calculations,the activation energy of austenite transformation is 1.01×10^6 J/mol,and the values of kinetic parameters n and ln k0 are 0.63 and 103.03,*** relationship between the volume fraction of austenite and the heating time at different heating rates could be predicted using the kinetic *** predicted and experimental results were compared to verify the accuracy of the kinetic *** microstructure etched by different corrosive solutions was analyzed,and the reliability of kinetic equation was further verified from the microscopic perspective.

关键词： B1500HS high-strength steel dilatometric curve austenite transformation kinetic equation Johnson-Mehl-Avuami model

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Ductilization of 2.6-GPa alloys via short-range ordered interfaces and supranano precipitates

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Science (New York, N.Y.) 2025年第6732期387卷 401-406页

作者： Yan, Yong-Qiang Cha, Wen-Hao Liu, Sida Ma, Yan Luan, Jun-Hua Rao, Ziyuan Liu, Chang Shan, Zhi-Wei Lu, Jian Wu, Ge Center for Advancing Materials Performance from the Nanoscale (CAMP-Nano) Hysitron Applied Research Center in China (HARCC) and Center for Alloy Innovation and Design (CAID) State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an China Laboratory for Multiscale Mechanics and Medical Science SV LAB School of Aerospace Xi'an Jiaotong University Xi'an China Faculty of Georesources and Materials Engineering RWTH Aachen University Aachen Germany Department of Materials Science and Engineering Delft University of Technology Delft Netherlands Inter-University 3D Atom Probe Tomography Unit Department of Mechanical Engineering City University of Hong Kong Hong Kong China Max Planck Institute for Sustainable Materials Düsseldorf Germany National Engineering Research Center of Light Alloy Net Forming Shanghai Jiao Tong University Shanghai China Centre for Advanced Structural Materials Department of Materials Science and Engineering City University of Hong Kong Hong Kong China

Higher strength and higher ductility are desirable for structural materials. However, ultrastrong alloys inevitably show decreased strain-hardening capacity, limiting their uniform elongation. We present a supranano (<10 nanometers) and short-range ordering design for grain interiors and grain boundary regions, respectively, in fine-grained alloys based on vanadium, cobalt, and nickel, with additions of tungsten, copper, aluminum, and boron. The pronounced grain boundary-related strengthening and ductilization mechanism is realized through segregation of the short-range ordering near the grain boundary. Furthermore, the supranano ordering with a larger size has an enhanced pinning effect for dislocations and stacking faults, multiplied and accumulated in grain interiors during plastic deformation. These mechanisms promote continuously increased flow stress until fracture of the alloy at 10% strain with 2.6-gigapascal tensile stress.

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Design and dynamic analysis of a scissors hoop-rib truss deployable antenna mechanism

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Defence technology（防务技术） 2023年第6期24卷 399-413页

作者： Bo Han Xiangkun Li Jian Sun Yundou Xu Jiantao Yao Yongsheng Zhao Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan UniversityQinhuangdao066004China Key Laboratory of Advanced Forging&Stamping Technology and Science Ministry of Education of ChinaYanshan UniversityQinhuangdao066004China

As the support mechanism of space-borne antennas,space deployable antenna mechanism belongs to complex multi-closed-loop coupling mechanism,configuration design and dynamic analysis are more difficult than general parallel *** this paper,an unequal-length scissors mechanism(ULSM)is proposed by changing the position of the internal rotational joint through a basic scissors mechanism.A scissors hoop-rib truss deployable antenna mechanism(SHRTDAM)is constructed by replacing the parabolic rib with the *** analysis of SHRTDAM is conducted,and the degree of freedom(DOF)of the whole antenna mechanism is analyzed based on screw theory,the result showed that it has only one *** and acceleration characteristics of SHRTDAM are obtained by the screw derivative and rotation *** on Lagrange equation,dynamic model of this mechanism is established,the torque required to drive the mechanism is simulated and verified by Adams and MATLAB *** addition,a ground experiment prototype of 1.5-m diameter was fabricated and a deployment test is conducted,which demonstrated the mobility and deployment performance of the whole *** mechanism proposed in this paper can provide a good reference for the design and analysis of large aperture space deployable antennas.

关键词： Scissors mechanism Deployable antenna Screw theory Kinematic analysis Dynamic analysis

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Prediction of Critical Conditions for Dynamic Recrystallization in 316LN Austenitic Steel

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Journal of Iron and Steel Research International 2016年第3期23卷 238-243页

作者： Xin-gang LIU Li-ge ZHANG Rong-sheng QI Lei CHEN Miao JIN Bao-feng GUO Key Laboratory of Advanced Forging & Stamping Technology and Science(Yanshan University) Ministry of Education of China Yanshan University Library Yanshan University National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan University

Hot compression experiments conducted on a Gleeble-3500thermo-mechanical simulator and metallographic observation tests were employed to study the critical conditions of dynamic recrystallization（DRX）of 316 LN austenitic stainless *** true stress-true strain curves of 316 LN were obtained at deformation temperatures ranging from 900℃to 1 200℃and strain rates ranging from 0.001s-1 to *** on the above tests,the critical conditions of DRX were determined and compared with those obtained from work-hardening theory and the Cingara-McQueen flow stress ***,the microstructure was observed to validate the calculated *** ratio of critical strain to peak strain（εc/εp）for 316 LN was determined,and the quantitative relationship between the critical strain and the deformation parameters of 316 LN was *** results demonstrated that the onset of DRX corresponds to the constant normalized strain hardening rate（Γ）,namely,the critical strain hardening rateΓcfor316LN is equal to 0.65.

关键词： 316LN austenitic stainless steel hot deformation dynamic recrystallization critical condition

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Design and analysis of truss deployable antenna mechanism based on a novel symmetric hexagonal profile division method

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Chinese Journal of Aeronautics 2021年第8期34卷 87-100页

作者： Jinwei GUO Yongsheng ZHAO Yundou XU Yongjie LI Jiantao YAO Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan UniversityQinhuangdao 066004China Key Laboratory of Advanced Forging&Stamping Technology and Science of Ministry of National Education Yanshan UniversityQinhuangdao 066004China

As the deployment,supporting,and stability mechanisms of satellite antennas,space-deployable mechanisms play a key role in the field of *** order to design truss deployable antenna supporting mechanisms with large folding rate,high accuracy,easy deployment and strong stability,aiming at the geometric division of the parabolic reflector,a novel method based on symmetric hexagonal division and its corresponding modular truss deployable antenna mechanism is proposed,and the original method based on asymmetric triangular division and its corresponding mechanisms are presented for comparative ***,the screw theory is employed to analyze the mobility of different ***,the improved three-dimensional mesh method is used to divide the reflector surface of a large parabolic antenna designed by the two different methods,and the profile accuracy and the type of links are taken as the evaluation indexes to quantitatively analyze the division ***,a three-dimensional model of the modular deployable mechanism based on the symmetric hexagonal design is developed,and the deployable mechanisms with different configurations based on the two design methods are compared and analyzed from the mechanical *** research results provide a good theoretical reference for the design of deployable truss antenna mechanisms and their application in the aerospace field.

关键词： Mobility Modular mechanism Profile division Screw theory Truss deployable antenna

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Development of a Wearable Upper Limb Rehabilitation Robot Based on Reinforced Soft Pneumatic Actuators

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Chinese Journal of Mechanical Engineering 2022年第4期35卷 182-190页

作者： Xinbo Chen Shuai Zhang Kaibin Cao Chunjie Wei Wumian Zhao Jiantao Yao Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan UniversityQinhuangdao 066004China Key Laboratory of Advanced Forging&Stamping Technology and Science of Ministry of National Education Yanshan UniversityQinhuangdao 066004China

Dyskinesia of the upper limbs caused by stroke,sports injury,or trafc accidents limits the ability to perform the activities of daily *** the necessary medical treatment,correct and scientifc rehabilitation training for the injured joint is an important auxiliary means during the treatment of the efected upper *** upperlimb rehabilitation robots have some disadvantages,such as a complex structure,poor compliance,high cost,and poor *** this study,a novel soft wearable upper limb rehabilitation robot(SWULRR)with reinforced soft pneumatic actuators(RSPAs)that can withstand high pressure and featuring excellent loading characteristics was *** by RSPAs,this portable SWULRR can perform rehabilitation training of the wrist and elbow *** this study,the kinematics of an SWULRR were analyzed,and the force and motion characteristics of RSPA were studied *** results provide a reference for the development and application of wearable upper limb rehabilitation *** experimental study on the rotation angle of the wrist and the pressure of the RSPA was conducted to test the efect of the rehabilitation training and verify the rationality of the theoretical *** process of wrist rehabilitation training was tested and evaluated,indicating that SWULRR with RSPAs will enhance the fexibility,comfort,and safety of rehabilitation *** work is expected to promote the development of wearable upper-limb rehabilitation robots based on modular reinforced soft pneumatic actuators.

关键词： Upper limb rehabilitation Reinforced soft pneumatic actuator Wearable rehabilitation robot Motion analysis

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Dual-Material Electron Beam Selective Melting:Hardware Development and Validation Studies

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Engineering 2015年第1期1卷 124-130页

作者： Chao Guo Wenjun Ge Feng Lin Department of Mechanical Engineering Tsinghua University Key Laboratory for Advanced Materials Processing Technology (Ministry of Education of China) Tsinghua University Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing Tsinghua University

Electron beam selective melting （EBSM） is an additive manufacturing technique that directly fabricates three-dimensional parts in a layerwise fashion by using an electron beam to scan and melt metal powder. In recent years, EBSM has been successfully used in the additive manufacturing of a variety of materials. Previous research focused on the EBSM process of a single material. In this study, a novel EBSM process capable of building a gradient structure with dual metal materials was developed, and a powder-supplying method based on vibration was put forward. Two different powders can be supplied individually and then mixed. Two materials were used in this study： Ti6AI4V powder and Ti47AI2Cr2Nb powder. Ti6AI4V has excellent strength and plasticity at room temperature, while Ti47AI2Cr2Nb has excellent performance at high temperature, but is very brittle. A Ti6AI4V/Ti47AI2Cr2Nb gradient material was successfully fabricated by the developed system. The microstructures and chemical compositions were characterized by optical microscopy, scanning microscopy, and electron microprobe analysis. Results showed that the interface thickness was about 300 μm. The interface was free of cracks, and the chemical compositions exhibited a staircase-like change within the interface.

关键词： additive manufacturing electron beam selectivemelting gradient materials titanium alloy TiAI alloy

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Wetting behaviors and interfacial characteristics of molten Al_(x)CoCrCuFeNi high-entropy alloys on a WC substrate

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Journal of Materials Science & technology 2021年第19期78卷 192-201页

作者： Wenyan Luo Yunzhong Liu Cheng Tu Guangdong Provincial Key Laboratory for Processing and Forming of Advanced Metallic Materials South China University of TechnologyGuangzhou510641China National Engineering Research Center of Near-net-shape Forming for Metallic Materials South China University of TechnologyGuangzhou510641China

The wettability of molten Al_(x)CoCrCuFeNi(x is from 0 to 1.5,mol.%)high-entropy alloys(HEA)on a WC substrate was measured using a modified sessile drop method at 1823 K in an argon *** wetting behaviors and interfacial characteristics between HEAs and WC were *** wettability with final equilibrium contact angles of 0.5°-4.6°is obtained,and addition of Al deteriorates the wettability of the *** wetting of Al_(x)CoCrCuFeNi/WC system can be roughly divided into an initially sharp spreading stage and a subsequent steady-state *** the first stage,the adsorption of Cr atoms at the solid-liquid interface primarily contributes to the wetting,and the contact angle drastically ***,both the wetting behavior and interfacial microstructure are determined by the Al content of the HEA in the next *** x≤0.5,the wetting is mainly driven by the dissolution of WC,although a few reaction products of(W,Cr)_(2)C are ***,an obvious dissolution pit appears at the surface of the *** the Al content of x≥1,the interfacial reaction is dominant in competition with the dissolution of WC,and massive reaction products precipitate at the HEA/WC interface,which leads to the formation of a continuous reaction layer.

关键词： Wetting High-entropy alloy Interface Microstructure Tungsten carbide

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Force Analysis of the Overconstrained Mechanisms Based on Equivalent Stiffness Considering Limb Axial Deformation

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Chinese Journal of Mechanical Engineering 2023年第1期36卷 292-304页

作者： Jinwei Guo Yongsheng Zhao Bo Chen Guoxing Zhang Yundou Xu Jiantao Yao Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan UniversityQinhuangdao066004China Key Laboratory of Advanced Forging&Stamping Technology and Science of Ministry of National Education Yanshan UniversityQinhuangdao066004China

Overconstrained mechanism has the advantages of large bearing capacity and high motion reliability,but its force analysis is complex and difficult because the mechanism system contains *** the limb axial deformation,taking typical 2SS+P and 7-SS passive overconstrained mechanisms,2SPS+P and 7-SPS active overconstrained mechanisms,and 2SPS+P and 7-SPS passive-input overconstrained mechanisms as examples,a new force analysis method based on the idea of equivalent stiffness is *** equivalent stiffness matrix of passive overconstrained mechanism is derived by combining the force balance and deformation compatibility equations with consideration of axial elastic limb *** relationship between the constraint wrench magnitudes and the external force,limb stiffness is *** equivalent stiffness matrix of active overconstrained mechanism is derived by combining the force balance and displacement compatibility ***,the relationship between the magnitudes of the actuated wrenches and the external force,limb stiffness is *** with the equivalent stiffness of the passive overconstrained mechanism,an analytical relationship between the actuated forces of passive-input overconstrained mechanism and the output displacement,limb stiffness is ***,adaptability of the equivalent stiffness to overconstrained mechanisms is discussed,and the effect of the limb stiffness on overconstrained mechanisms force distribution is *** research results provide a theoretical reference for the design,research and practical application of overconstrained mechanism.

关键词： Active overconstrained Passive overconstrained Passive-input overconstrained Equivalent stiffness Force distribution

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