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Laser oscillation enables coordinated regulation of microstructure refinement and defect suppression in wire-feed laser directed energy deposited AZ91D magnesium alloy 认领 引用
1
作者 Haoyang Wang Tianlei Zhou +6 位作者 Yiyang Wang Shide Li Yujuan Wu Zhuoyun Yang Guojiang Dong Jiang Bi Dehua Liu 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2026年第7期350-368,共19页
Within the field of additive manufactured magnesium alloy,techniques such as laser powder bed fusion(LPBF),wire and arc additive manufacturing(WAAM)encounter difficulties in eliminate defects,including coarse columnar... Within the field of additive manufactured magnesium alloy,techniques such as laser powder bed fusion(LPBF),wire and arc additive manufacturing(WAAM)encounter difficulties in eliminate defects,including coarse columnar grains,porosity,and thermal cracks.To address these challenges,this study proposed an optimization framework for oscillation laser wire-feed directed energy deposited parameters tailored to AZ91D magnesium alloy.By employing a circular oscillation laser to introduce controllable molten pool agitation,the laser power was regulated to optimize the microstructure,mechanical properties,and corrosion resistance.The results showed that the porosity dropped from 1.85%to 0.12%as the laser power decreased from 1400 W to 1000 W.The grain size exhibited a tendency of initial increased followed by decreasing as the laser power ranged from 1000 W to 1400 W.Compared to the specimens at the laser power of 1000 W,grain size increased by 4.8%at 1200 W and decreased by 17.4%at 1400 W.Dispersed Al8Mn5 andβ-Mg17Al12 phases are present in the deposited specimens.Simultaneously,high-density network of dislocations formed around the uniformly dispersed Al8Mn5 phase.The corrosion rates at the laser power of 1200 W and 1400 W are 1.2 times and 3.2 times higher than that at 1000 W.The combined effects of grain refinement,dispersion strengthening by secondary phases and defect reduction enhanced the corrosion resistance in saline environments.Hence,an optimized balance of strength and ductility was achieved at a laser power of 1000 W,with an ultimate tensile strength of 303±10 MPa,a yield strength of 160±5 MPa and an elongation of 11±0.4%.This study can offer actionable guidance for customizing the lightweight Mg alloy components with low porosity and desired microstructural features. 展开更多
关键词 AZ91D magnesium alloy Wire-feed laser directed energy deposited Oscillation laser Microstructure evolution Strengthening mechanism Electrochemical corrosion
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Insight into the evolution of lamellar and block LPSO phase of Mg-Gd-Y-Zn-Zr alloy with laser welding after post-weld solution and aging treatment 认领 引用
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作者 Bing Li Xinpeng Li +4 位作者 Meng Zhang Xingkang Zheng Yujie Wang Zhaoming Yan Changcai Zhao 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2026年第3期422-438,共17页
The paper systematically investigated the effect of laser welding parameters and post-weld heat treatment on morphology microstructure evolution and mechanical properties of weld joint of Mg-13Gd-4Y-2Zn-0.6Zr alloy co... The paper systematically investigated the effect of laser welding parameters and post-weld heat treatment on morphology microstructure evolution and mechanical properties of weld joint of Mg-13Gd-4Y-2Zn-0.6Zr alloy consisting of lamellar and block long-period stacking ordered(LPSO) phases.Experimental results demonstrate that laser power and welding speed significantly influence weld geometry,with optimal parameters(600 W,25 mm/s) achieving full penetration,stable keyhole dynamics,and minimal defects,while resulting in a narrow heat-affected zone(HAZ)(<100 μm) dominated by fine grains.The eutectic(Mg,Zn)3(Gd,Y) phase formed at fusion zone(FZ) and HAZ after laser welding,which was attributed to remelting process during laser welding.Furthermore,the post-weld solution and aging treatments were conducted on Mg-Gd-Y-Zn-Zr alloy with laser welding.The rare earth(RE) atoms from eutectic(Mg,Zn)3(Gd,Y) phases and block LPSO phases dissolved into α-Mg grains in the course of solution treatment,thus lamellar 14H-LPSO phase precipitated from grain boundaries intoα-Mg grains along basal planes and equilibrium β phases precipitated at grain boundaries with reduced block LPSO.The lamellar 14H-LPSO phase precipitated across α-Mg grains as solution time further increased,and only the equilibrium β phase remained at grain boundaries.The finely dispersed β' phase precipitated inside α-Mg grains after aging treatment,thus nano-sized and densely β phase contributed to dislocation pinning,which significantly improves microhardness.The ellipsoidal β phases precipitated perpendicular to 14H-LPSO lamellae within the α-Mg grains consisting of lamellar 14H-LPSO phase.However,the β' phases precipitated in three directions with an angle of 120° to each other within α-Mg grain that is devoid of 14H-LPSO lamellae.The equilibrium β phases gradually declined with prolonged aging treatment.The precipitation of lamellar 14H-LPSO and nano-sized β' phase contributed to grain boundary migration of α-Mg grains.The results provide fundamental principle for optimizing weld integrity and mechanical response in Mg-RE-Zn alloys with LPSO phase. 展开更多
关键词 Laser welding LPSO phase Post-weld solution treatment Aging treatment
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Achieving low-porosity and high-strength 2219 aluminum alloy joints through coupling of laser beam oscillation and post-weld heat treatment 认领 引用
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作者 ZHU Liang-jin DONG Guo-jiang +1 位作者 YANG Zhuo-yun BI Jiang 《Journal of Central South University》 SCIE EI CAS CSCD 2026年第1期90-109,共20页
Laser welding is a highly promising joining method for Al alloys.However,certain limitations such as elevated thermal input and keyhole instability are associated with its application in medium-thickness aluminium all... Laser welding is a highly promising joining method for Al alloys.However,certain limitations such as elevated thermal input and keyhole instability are associated with its application in medium-thickness aluminium alloy plates.To address these issues,circular oscillating laser welding combined with post-weld heat treatment was employed to improve the formation quality and mechanical properties of the welds.The effects of the frequency of circular oscillating laser on the forming quality,microstructure,and properties of the welds were analyzed.At an oscillation frequency of 200 Hz,the grain size in the weld zone was reduced compared to single laser welding,and the maximum tensile strength of the weld was observed to reach(264.96±1.33)MPa,representing approximately 61.19%of the base metal.Following the post-weld heat treatment of"solid solution and artificial aging",the grain boundary segregation was diminished.Nanoscale precipitated phases are present in the weld zone.Furthermore,the tensile strength was augmented to(386.35±5.65)MPa,representing approximately 89.23%of the strength of the base metal.The results of this study can provide a theoretical basis and technological reference for the circular oscillating laser welding of medium-thickness 2219-T 6 aluminium alloy plates. 展开更多
关键词 2219 aluminium alloy circular oscillating laser welding parameter optimization porosity post-weld heat treatment mechanical enhancement
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Microstructure evolution of 7050 aluminum forgings during surface cumulative plastic deformation 认领 引用 被引量：3
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作者 Jian-liang HU Ze-xiong ZHANG +3 位作者 Cheng XING Xiu-jiang WU Shi-quan HUANG Hong BO 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2025年第1期45-59,共15页
To elucidate the mechanisms of regulating the microstructure uniformity in 7050 aluminum forgings through surface cumulative plastic deformation(SCPD),the microstructure under different solution treatments was investi... To elucidate the mechanisms of regulating the microstructure uniformity in 7050 aluminum forgings through surface cumulative plastic deformation(SCPD),the microstructure under different solution treatments was investigated using metallographic observation(OM),electron backscatter diffraction(EBSD),transmission electron microscopy(TEM),and X-ray diffraction(XRD).The findings demonstrate that the most uniform microstructure in the forgings is achieved with a solution treatment at 470℃for 30 min.The SCPD process generates a significant number of needle-shaped precipitates,resulting in a higher dislocation density and stored energy.Solution treatments alleviate the pinning effect of second-phase particles and facilitate static recrystallization(SRX)in forgings,leading to a reduction in grain size.Additionally,mechanical testing results demonstrate 7%−13%increase in tensile strength and more uniform elongation of the forgings in different directions. 展开更多
关键词 microstructure homogeneity surface cumulative plastic deformation(SCPD) static recrystallization(SRX) dislocation density
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Superplasticity of fine-grained Mg−Gd−Y−Zn−Zr alloy prepared via multi-directional forging 认领 引用 被引量：1
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作者 Jing-qi ZHAO Ze-zheng WANG +3 位作者 Chun KE Qiang MENG Chun-xiang ZHANG Jun-ting LUO 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2025年第8期2553-2571,共19页
The superplasticity of the Mg−8.59Gd−3.85Y−1.14Zn−0.49Zr alloy was investigated before and after multi-directional forging(MDF)and the mechanisms affecting superplastic deformation were analyzed.The results indicate t... The superplasticity of the Mg−8.59Gd−3.85Y−1.14Zn−0.49Zr alloy was investigated before and after multi-directional forging(MDF)and the mechanisms affecting superplastic deformation were analyzed.The results indicate that after MDF at a temperature of 350℃and strain rates of 0.1 and 0.01 s−1(1-MDFed and 2-MDFed),the superplasticity of the alloy can be significantly improved.The elongations of the MDFed alloys exceed 400%under the strain rate of 6.06×10−4s−1and temperatures of 350,375,and 400℃,and reach the maximum values of 766%(1-MDFed)and 693%(2-MDFed)at 375℃.The grain boundary sliding of the MDFed alloy is sufficient,and the energy barrier of deformation decreases.Theβphase limits the grain growth and promotes dynamic recrystallization,maintaining the stability of the fine-grained structure during superplastic deformation.Several Y-rich phases nucleate in the high-strain region(i.e.,the final fracture region)at high temperatures,accelerating the fracture of the specimen. 展开更多
关键词 Mg−Gd−Y−Zn−Zr superplasticity multi-directional forging fracture morphology Y-rich phase
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Cryogenic forging effects and mechanisms on surface coarse grain microstructure in H-shaped 7050 aluminum forgings 认领 引用
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作者 ZHAO Zi-han YI You-ping +2 位作者 HU Jian-liang HUANG Shi-quan HE Hai-lin 《Journal of Central South University》 SCIE EI CAS CSCD 2025年第6期2009-2021,共13页
This study investigates the differences in microstructural control between cryogenic forging combined with pre-deformation(PCF)and traditional thermal forging(TTF)for 7050 aluminum forgings intended for aerospace appl... This study investigates the differences in microstructural control between cryogenic forging combined with pre-deformation(PCF)and traditional thermal forging(TTF)for 7050 aluminum forgings intended for aerospace applications.The PCF process,utilizing cryogenic deformation,significantly refines the coarse grains at the surface of the forgings,resulting in a finer and more uniform microstructure,thereby effectively addressing the issue of surface coarse grains associated with traditional methods.The findings indicate that the PCF process can accumulate higher stored energy,facilitating static recrystallization(SRX)during subsequent heat treatment and enhancing the microstructural uniformity.Utilizing various analytical techniques,including optical microscopy(OM),electron backscatter diffraction(EBSD),and transmission electron microscopy(TEM).This study reveals the superiority of the PCF process in terms of strain accumulation,dislocation density,and grain refinement.In conclusion,this method offers advantages in enhancing the performance and microstructural uniformity of 7050 aluminum forgings,presenting new opportunities for applications in the aluminum forging industry. 展开更多
关键词 7050 aluminum alloy cryogenic forging coarse grains dislocation density stored energy
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Design and analysis of truss deployable antenna mechanism based on a novel symmetric hexagonal profile division method 认领 引用 被引量：15
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作者 Jinwei GUO Yongsheng ZHAO +2 位作者 Yundou XU Yongjie LI Jiantao YAO 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2021年第8期87-100,共14页
As the deployment,supporting,and stability mechanisms of satellite antennas,space-deployable mechanisms play a key role in the field of aerospace.In order to design truss deployable antenna supporting mechanisms with ... As the deployment,supporting,and stability mechanisms of satellite antennas,space-deployable mechanisms play a key role in the field of aerospace.In 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 analysis.Then,the screw theory is employed to analyze the mobility of different mechanisms.Furthermore,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 results.Finally,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 perspective.The research results provide a good theoretical reference for the design of deployable truss antenna mechanisms and their application in the aerospace field. 展开更多
关键词 Mobility Modular mechanism Profile division Screw theory Truss deployable antenna
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δ-phase precipitation regularity of cold-rolled fine-grained GH4169 alloy plate and its effect on mechanical properties 认领 引用 被引量：14
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作者 Hao XUE Jing-qi ZHAO +2 位作者 Yong-kang LIU Chun-xiang ZHANG Jun-ting LUO 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2020年第12期3287-3295,共9页
Cold rolling and heat-treatment were used for the grain refinement of GH4169 superalloy plate.The effects of cold rolling reduction ratio and heat-treatment time on the precipitatedδphase,and the effects ofδ-phase c... Cold rolling and heat-treatment were used for the grain refinement of GH4169 superalloy plate.The effects of cold rolling reduction ratio and heat-treatment time on the precipitatedδphase,and the effects ofδ-phase content and morphology on the mechanical properties of the GH4169 alloy plates,are studied.The results demonstrate that coldrolling can promote the precipitation of theδphase and its transformation from theδ-Ni3Nb phase to theδ-NbNi4 phase.The comprehensive properties of the alloy are better when the heat treatment time is 1 h,with 132 MPa increase in the tensile strength and only 2.9%decrease in the elongation relative to those of the original material.The mechanical properties of the alloy are shown to change greatly with the change in theδ-phase morphology. 展开更多
关键词 fine-grained GH4169 alloy cold rolling δphase mechanical properties
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Design and analysis of a truss deployable antenna mechanism based on a 3UU-3URU unit 认领 引用 被引量：10
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作者 Yundou XU Jinwei GUO +3 位作者 Luyao GUO Wenlan LIU Jiantao YAO Yongsheng ZHAO 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2019年第12期2743-2754,共12页
Space deployable structures with large calibers, high accuracy, and large folding ratios are indispensable equipment in the aerospace field. Given that the single-DOF 3 RR-3 RRR deployable unit cannot be fully folded,... Space deployable structures with large calibers, high accuracy, and large folding ratios are indispensable equipment in the aerospace field. Given that the single-DOF 3 RR-3 RRR deployable unit cannot be fully folded, this study proposes a 3 UU-3 URU deployable unit with two kinds of DOF: folding movement and orientation adjustment. First, based on the G-K formula, the DOF of the 3 UU-3 URU unit is analyzed. Then, the 3 UU-3 URU unit is used to construct a deployable truss antenna with a curved surface, and the DOF of the whole deployable antenna containing multiple 3 UU-3 URU units is calculated. The structural design of a deployable antenna with two loops is carried out with specific parameters and geometric relations. Next, a DOF simulation of a basic combination unit composed of three 3 UU-3 URU units is performed. Finally, a prototype of the basic combination unit is manufactured, and the DOF of the mechanism is experimentally verified. 展开更多
关键词 Basic combination unit Degree of freedom(DOF) Deployable truss antenna Simulation analysis Structural design
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Comparative study on forming limit prediction of AA7075-T6 sheet with M−K model and Lou−Huh criterion 认领 引用 被引量：12
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作者 Guo-jiang DONG Zhi-wei CHEN +1 位作者 Zhuo-yun YANG Bo-cheng FAN 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2020年第6期1463-1477,共15页
In order to effectively predict the fracture of AA7075-T6 sheet, the forming limit curves of AA7075-T6 high-strength sheet were drawn according to Morciniak Kuczyski (M K) model and Lou Huh criterion, respectively. Th... In order to effectively predict the fracture of AA7075-T6 sheet, the forming limit curves of AA7075-T6 high-strength sheet were drawn according to Morciniak Kuczyski (M K) model and Lou Huh criterion, respectively. The errors between the predicted values of the two theoretical prediction models and experimental values were calculated by error analysis. The forming limit curves were verified by the punch stretch test to evaluate the prediction accuracy of M K model and Lou Huh criterion. The error analysis results show that the mean error of Lou Huh criterion with the optimal parameters for all tensile specimens is 25.04%, while the mean error of M K model for all tensile specimens is 74.24%. The prediction accuracy of Lou Huh criterion in predicting the fracture of AA7075-T6 sheet is higher. The punch stretch test results show that the forming limit curve drawn by Lou Huh criterion can effectively predict the fracture of AA7075-T6 sheet, but the prediction accuracy of M K model is relatively poor. 展开更多
关键词 ductile fracture criterion M K model forming limit diagram AA7075-T6 sheet
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Densification,microstructural features and tensile properties of selective laser melted AlMgSiScZr alloy from single track to block specimen 认领 引用 被引量：8
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作者 BI Jiang CHEN Yan-bin +2 位作者 CHEN Xi STAROSTENKOV M D DONG Guo-jiang 《Journal of Central South University》 SCIE EI CAS CSCD 2021年第4期1129-1143,共15页
The selective laser melting(SLM)processed aluminum alloys have already aroused researchers’attention in aerospace,rail transport and petrochemical engineering due to the comprehensive advantages of low density,good c... The selective laser melting(SLM)processed aluminum alloys have already aroused researchers’attention in aerospace,rail transport and petrochemical engineering due to the comprehensive advantages of low density,good corrosion resistance and high mechanical performance.In this paper,an Al-14.1Mg-0.47Si-0.31Sc-0.17Zr alloy was fabricated via SLM.The characteristics of single track at different process parameters,and the influence of hatch spacing on densification,microstructural features and tensile properties of block specimens were systematically studied.The hatch spacing has an influence on the overlap ratio of single track,and further affects the internal forming quality of printed specimen.At a laser power of 160 W and scanning speed of 400 mm/s,the densification of block specimen increased first and then decreased with the increase of hatch spacing.The nearly full dense specimen(98.7%)with a tensile strength of 452 MPa was fabricated at a hatch spacing of 80μm.Typical characteristics of dimple and cleavage on the tensile fracture of the AlMgSiScZr alloy showed the mixed fracture of ductility and brittleness. 展开更多
关键词 selective laser melting aluminum alloy hatch spacing microstructural feature tensile properties
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Design and dynamic analysis of a scissors hoop-rib truss deployable antenna mechanism 认领 引用 被引量：7
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作者 Bo Han Xiangkun Li +3 位作者 Jian Sun Yundou Xu Jiantao Yao Yongsheng Zhao 《Defence Technology（防务技术）》 SCIE EI CAS CSCD 2023年第6期399-413,共15页
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 par... 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 mechanism.In 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 ULSM.Kinematic 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 DOF.Velocity and acceleration characteristics of SHRTDAM are obtained by the screw derivative and rotation transformation.Based 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 software.In 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.The mechanism proposed in this paper can provide a good reference for the design and analysis of large aperture space deployable antennas. 展开更多
关键词 Scissors mechanism Deployable antenna Screw theory Kinematic analysis Dynamic analysis
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Innovative design and optimization of a two-dimensional deployable nine-grid planar antenna mechanism with a flat reflection surface 认领 引用 被引量：7
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作者 Bo CHEN Ze JIANG +5 位作者 Xinlu WEI Luyao GUO Xin ZHOU Yundou XU Junjie QIAN Yongsheng ZHAO 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2023年第11期529-550,共22页
With the development of the aerospace industry,space missions are becoming more complicated and diversified,and there is a demand for antenna mechanisms with a larger physical aperture.In this paper,a planar deployabl... With the development of the aerospace industry,space missions are becoming more complicated and diversified,and there is a demand for antenna mechanisms with a larger physical aperture.In this paper,a planar deployable mechanism is proposed,which can form a flat reflection surface with a small gap between plates.To this end,a novel large-scale two-dimensional deployable nine-grid planar antenna mechanism is designed.First,two antenna folding schemes and four supporting mechanism schemes are proposed.Through comparison analysis,the antenna configuration scheme with the best comprehensive performance is selected.A kinematic model of the deployable mechanism is established,and its kinematic characteristics are analyzed.Then,the correctness of the kinematic model is verified by comparing the analytical and simulation results of the kinematic model.Subsequently,a finite element model of the antenna is developed.Based on the response surface method,the structural parameters of the support rods of the antenna are optimized,and a set of optimized solutions with lightweight and high fundamental frequency characteristics are obtained.Finally,a prototype of the proposed nine-grid planar antenna is fabricated.The feasibility of the deployment principle and the rationality of the designed mechanism are verified by deployment experiments. 展开更多
关键词 Design optimization Kinematics Planar antenna Structural design Two-dimensional expansion
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Heat treatment and granule medium internal highpressure forming of AA6061 tube 认领 引用 被引量：4
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作者 BI Jiang ZHAO Chang-cai +3 位作者 BI Meng-meng DU Bing CHEN Xiao-hua DONG Guo-jiang 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第5期1040-1049,共10页
The new forming process of AA6061 alloy tube, including solution treatment, granule medium internal high-pressure forming and aging treatment, was developed. The AA6061 alloy tube via heat treatment satisfied the form... The new forming process of AA6061 alloy tube, including solution treatment, granule medium internal high-pressure forming and aging treatment, was developed. The AA6061 alloy tube via heat treatment satisfied the forming requirement, and the granule medium internal high pressure forming method for AA6061 alloy tube was also realized by using convenient implementation with low requirement of equipment and flexible design of product. At a solution temperature of 560℃ and time of 120 min, the elongation of the AA6061 extruded tube increases by 300% and the strength and the hardness dramatically decrease too. Therefore, the AA6061 alloy tube meets the requirement of internal high-pressure forming because of the improvement of formability. The experiments shows that the strength and hardness of AA6061 alloy workpiece recover to that of the as-received alloy at an aging temperature of 180℃ and time of 360 min, and the strength of AA6061 alloy workpiece is equal to the base alloy. The typical parts of convex ring tube, stepped shaft tube and hexagonal tube were successfully produced in lab by using the present forming method. The forming tests show that the maximum expansion ratio(MER) of the AA6061 extruded tube increases by 25.5% and the material properties of formed AA6061 alloy tube reached the performance of as-received alloy. 展开更多
关键词 aluminum alloy tube solution treatment aging treatment granule medium internal high pressure forming
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A New Method for Type Synthesis of 2R1T and 2T1R 3-DOF Redundant Actuated Parallel Mechanisms with Closed Loop Units 认领 引用 被引量：11
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作者 Yongquan Li Yang Zhang Lijie Zhang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2020年第6期134-157,共24页
The current type synthesis of the redundant actuated parallel mechanisms is adding active-actuated kinematic branches on the basis of the traditional parallel mechanisms,or using screw theory to perform multiple getti... The current type synthesis of the redundant actuated parallel mechanisms is adding active-actuated kinematic branches on the basis of the traditional parallel mechanisms,or using screw theory to perform multiple getting intersection and union to complete type synthesis.The number of redundant parallel mechanisms obtained by these two methods is limited.In this paper,based on Grassmann line geometry and Atlas method,a novel and effective method for type synthesis of redundant actuated parallel mechanisms(PMs)with closed-loop units is proposed.Firstly,the degree of freedom(DOF)and constraint line graph of the moving platform are determined successively,and redundant lines are added in constraint line graph to obtain the redundant constraint line graph and their equivalent line graph,and a branch constraint allocation scheme is formulated based on the allocation criteria.Secondly,a scheme is selected and redundant lines are added in the branch chains DOF graph to construct the redundant actuated branch chains with closed-loop units.Finally,the branch chains that meet the requirements of branch chains configuration criteria and F&C(degree of freedom&constraint)line graph are assembled.In this paper,two types of 2 rotational and 1 translational(2R1T)redundant actuated parallel mechanisms and one type of 2 translational and 1 rotational(2T1R)redundant actuated parallel mechanisms with few branches and closed-loop units were taken as examples,and 238,92 and 15 new configurations were synthesized.All the mechanisms contain closed-loop units,and the mechanisms and the actuators both have good symmetry.Therefore,all the mechanisms have excellent comprehensive performance,in which the two rotational DOFs of the moving platform of 2R1T redundant actuated parallel mechanism can be independently controlled.The instantaneous analysis shows that all mechanisms are not instantaneous,which proves the feasibility and practicability of the method. 展开更多
关键词 Redundant actuated Parallel mechanisms Type synthesis Atlas method Instantaneous analysis
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Life prediction and test period optimization research based on small sample reliability test of hydraulic pumps 认领 引用 被引量：6
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作者 郭锐 Ning Chao +4 位作者 Zhao Jingyi Wang Ping Shi Yu Zhou Jinsheng Luo Jing 《High Technology Letters》 EI CAS 2017年第1期63-70,共8页
Hydraulic pumps belong to reliable long-life hydraulic components. The reliability evaluation includes characters such as long test period,high cost,and high power loss and so on. Based on the principle of energy-savi... Hydraulic pumps belong to reliable long-life hydraulic components. The reliability evaluation includes characters such as long test period,high cost,and high power loss and so on. Based on the principle of energy-saving and power recovery,a small sample hydraulic pump reliability test rig is built,and the service life of hydraulic pump is predicted,and then the sampling period of reliability test is optimized. On the basis of considering the performance degradation mechanism of hydraulic pump,the feature information of degradation distribution of hydraulic pump volumetric efficiency during the test is collected,so an optimal degradation path model of feature information is selected from the aspect of fitting accuracy,and pseudo life data are obtained. Then a small sample reliability test of period constrained optimization search strategy for hydraulic pump is constructed to solve the optimization problem of the test sampling period and tightening end threshold,and it is verified that the accuracy of the minimum sampling period by the non-parametric hypothes is tested. Simulation result shows it could possess instructional significance and referenced value for hydraulic pump reliability life evaluation and the test's research and design. 展开更多
关键词 hydraulic pump small sample test volumetric efficiency degradation path model life span period optimal
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Kinematic,Workspace and Force Analysis of A Five-DOF Hybrid Manipulator R(2RPR)R/SP+RR 认领 引用 被引量：4
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作者 Yundou Xu Fan Yang +3 位作者 Youen Mei Dongsheng Zhang Yulin Zhou Yongsheng Zhao 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2022年第5期232-243,共12页
In the present study,the over-constrained hybrid manipulator R(2RPR)R/SP+RR is considered as the research objective.In this paper,kinematics of the hybrid manipulator,including the forward and inverse position,are ana... In the present study,the over-constrained hybrid manipulator R(2RPR)R/SP+RR is considered as the research objective.In this paper,kinematics of the hybrid manipulator,including the forward and inverse position,are analyzed.Then,the workspace is checked based on the inverse position solution to evaluate whether the workspace of the hybrid manipulator meets the requirements,and the actual workspace of the hybrid robot is analyzed.After that,the force analysis of the over-constrained parallel mechanism is carried out,and an ADAMS-ANSYS rigid-flexible hybrid body model is established to verify the simulation.Based on the obtained results from the force analysis,the manipulator structure is designed.Then,the structure optimization is carried out to improve the robot stiffness.Finally,calibration and workspace verification experiments are performed on the prototype,cutting experiment of an S-shaped aluminum alloy workpiece is completed,and the experiment verifies the machining ability of the prototype.This work conducts kinematics,workspace,force analyses,structural optimization design and experiments on the over-constrained hybrid manipulator R(2RPR)R/SP+RR,providing design basis and technical support for the development of the novel hybrid manipulator in practical engineering. 展开更多
关键词 Hybrid manipulator Over-constrained Kinematic analysis Stiffness analysis
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Microstructure,mechanical properties and multiphase synergistic strengthening mechanisms of a novel laser additive manufactured AlNi6TiZr alloy 认领 引用 被引量：3
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作者 Jiang Bi Liukun Wu +8 位作者 Zeqi Liu Haixiang Wang Shide Li Ji Wang Zhuoyun Yang Nannan Lu Xi Chen Mikhail Dmitrievich Starostenkov Guojiang Dong 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2024年第11期59-69,共11页
In this work,selective laser melting(SLM)process is used to prepare the AlNi6TiZr alloy.By analyzing the printing quality and mechanical properties of the printed specimens with different process parameters,the SLM fo... In this work,selective laser melting(SLM)process is used to prepare the AlNi6TiZr alloy.By analyzing the printing quality and mechanical properties of the printed specimens with different process parameters,the SLM forming window of AlNi6TiZr is obtained.The relative density of the sample printed with 270 W-1100 mm/s(laser energy density:82 J/mm3)reaches 99.7%,exhibiting excellent mechanical properties(yield strength(YS):421.7 MPa;ultimate tensile strength(UTS):480.4 MPa).After an aging treatment of 325 ℃-12 h,the YS and UTS of the sample increased to 494 MPa and 550.7 MPa,respectively.Adding Ni,Ti,and Zr components promoted the generation of multi-phase precipitates in the Al alloy and improved the synergistic strengthening effect of multi-phases.The hard-shell structure(HSS)formed by the Al3Ni phase at the grain boundary significantly strengthened the grain boundary strength.The precipitated Al3(Ti,Zr)phases at the grain boundaries prevent grain growth and dislocation movement.The Al3Ni and Al3(Ti,Zr)phases have good thermal stability that can still maintain excellent enhancement effects at high temperature.AlNi6TiZr alloy has great application prospects in medium and high-temperature environments. 展开更多
关键词 Selective laser melting Al6NiTiZr alloy Microstructure Mechanical properties Thermal stability Strengthening mechanism
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Finite element simulation and microstructure of two-pass inner spinning process of curved-generatrix cone cylindrical parts with annealing/quenching 认领 引用 被引量：3
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作者 HAO Zeng-liang YANG Zhe-yi) +3 位作者 WEI Wei LIU Lei LUO Jun-ting LIU Jin-heng 《Journal of Central South University》 SCIE EI CAS CSCD 2019年第12期3305-3314,共10页
A two-pass annealing/quenching internal spinning process with small-end rotations is proposed to form a curved generatrix conical thin-walled shell.That is,annealing at 360°C for 2 h followed by the 1st pass spin... A two-pass annealing/quenching internal spinning process with small-end rotations is proposed to form a curved generatrix conical thin-walled shell.That is,annealing at 360°C for 2 h followed by the 1st pass spinning,and finally quenching in ice water after holding for 1 h at 498°C followed by the 2nd pass spinning.ABAQUS finite element software is used to simulate the internal spinning process of the products formed under different forming parameters.The distribution laws of spinning force,the stress and strain under different forming processes were compared and analyzed.The mechanical properties and microstructure of the products are subsequently analyzed.The results show that the strain and the residual stress in the skin area of the formed products under two-pass spinning process more uniform,and the hardness and the mechanical performance are improved.The microstructure of the products formed with the 0.15 mm thickness reduction at the 2nd pass is excellent.And the second phase grain size distributed uniformly in the range of 36μm.Whereas,the second phase particles are broken seriously and the size distribution inhomogeneity is increased when the thickness reduction in the skin area is greater than 0.20 mm at the 2nd pass spinning process. 展开更多
关键词 curved generatrix conical internal spinning process annealing/quenching small-end rotations finite element simulation
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High temperature stress–strain curves of MnS and their applications in finite element simulation 认领 引用 被引量：3
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作者 Miao JIN Lin-lin YU +1 位作者 Xin-gang LIU Bao-feng GUO 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2018年第10期2082-2093,共12页
A novel method for testing stress–strain curves of non-metallic materials was presented.The high temperature stress-strain curves of MnS were preliminarily obtained and corrected to account for the influence of frict... A novel method for testing stress–strain curves of non-metallic materials was presented.The high temperature stress-strain curves of MnS were preliminarily obtained and corrected to account for the influence of friction.Using the finite element method,the influence of deformation parameters on the deformation evolution of MnS inclusions was investigated based on the experimental reference data.The corresponding physical experiment was designed for comparative analysis.The results indicate that the experimental high-temperature deformation data of MnS are highly reliable.In the process of matrix deformation,the shapes of MnS inclusions change from spherical to ellipsoidal and even to lamellar.There are some differences in the morphological deformation of MnS inclusions located at different positions.With the increase in the initial size of MnS inclusions,the risk of failing the inclusion-flaw inspection increases and the forging quality further deteriorates. 展开更多
关键词 inclusion MnS stress-strain curve finite element method morphology
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