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A novel robot capable of performing maintenance and inspection tasks for railway bridges is proposed in this paper. Termed CMBOT (climbing manipulator robot), the robot is a combination of a five-degrees-of-freedom (5-Dof) biped climbing robot with two electromagnetic feet and a redundant manipulator with 7-Dof. This capability offers important advantages for performing maintenance and inspection tasks for railway bridges. Several fundamental issues of the CMBOT, such as robotic system development and motion planning algorithms, are addressed in this paper. A series of simulations and prototype experiments were conducted to validate the proposed robotic systems and motion planning algorithm. The results of the experiments show the reliability of the robotic systems and the efficiency of the motion planning algorithm.
Qing Chang; Xiao Luo; Zhixia Qiao; Qian Li. Design and Motion Planning of a Biped Climbing Robot with Redundant Manipulator. Applied Sciences 2019, 9, 3009 .
AMA StyleQing Chang, Xiao Luo, Zhixia Qiao, Qian Li. Design and Motion Planning of a Biped Climbing Robot with Redundant Manipulator. Applied Sciences. 2019; 9 (15):3009.
Chicago/Turabian StyleQing Chang; Xiao Luo; Zhixia Qiao; Qian Li. 2019. "Design and Motion Planning of a Biped Climbing Robot with Redundant Manipulator." Applied Sciences 9, no. 15: 3009.
Hot-stamped ultra-high strength steels have been widely used in automobile structural parts. Considering the high splash tendency in resistance spot welding due to their extremely high hardness, in this work, microstructural characteristics and mechanical performance of the resistance spot welded ultra-high strength steels are investigated. The results indicate that the interface between the nugget and heat-affected zone (HAZ) is the weakest zone where fractures initiate. In tensile shearing tests, a qualified spot welding joint failed with a button-shaped fracture. Welding defects would significantly decrease the load-carrying capacity and lead to interfacial fracture, except for a button-shaped fracture. In spot welding, it was found that a specific mid-frequency alternating current (AC) input mode, in which a 6 ms cooling cycle was inserted between every two neighboring current pulses, can avoid the splash in the spot welding of hot-stamped hardened steels.
Zhixia Qiao; Huijun Li; Lianjin Li; Xiaoyu Ran; Liwen Feng. Microstructure and Properties of Spot Welded Joints of Hot-Stamped Ultra-High Strength Steel Used for Automotive Body Structures. Metals 2019, 9, 285 .
AMA StyleZhixia Qiao, Huijun Li, Lianjin Li, Xiaoyu Ran, Liwen Feng. Microstructure and Properties of Spot Welded Joints of Hot-Stamped Ultra-High Strength Steel Used for Automotive Body Structures. Metals. 2019; 9 (3):285.
Chicago/Turabian StyleZhixia Qiao; Huijun Li; Lianjin Li; Xiaoyu Ran; Liwen Feng. 2019. "Microstructure and Properties of Spot Welded Joints of Hot-Stamped Ultra-High Strength Steel Used for Automotive Body Structures." Metals 9, no. 3: 285.
: Oxide Dispersion Strengthened (ODS) steel with a composition of Fe-14Cr-2W-0.2V-0.07Ta-1Al-0.3Y2O3 was fabricated by mechanical alloying (MA) and spark plasma sintering (SPS). All of the investigations were performed on the as-SPSed ODS sample without further heat treatment. The microstructure, particles, and tensile properties of the ODS sample were analyzed. According to the results, both submicron-sized and micron-sized grains existed in the microstructure, showing a bimodal structure. The nanoparticles were homogeneously distributed in the matrix, and the nanoparticles in the ODS sample were mainly Y-Al-O composite oxides. Two kinds of Y-Al-O nanoparticles were identified: Y3Al5O12 particles with body-centered cubic structures and Y4Al2O9 particles with monoclinic structures. The size of the nanoparticles ranged from 2 nm to 61.5 nm, and the average size of the nanoparticles was 11 ± 2.7 nm. Except for the nanoparticles, large M23C6 particles that were detrimental to the ductility of the ODS sample were also identified. These large M23C6 particles possessed a long strip or rod-like morphology, and were generally distributed along the grain boundaries. The generation of cracks generally occurred in the region where the large M23C6 particles were located during the tensile test. The as-SPSed ODS steel possessed a ductile/brittle mixed fracture mode according to the fracture surfaces analysis.
Qian Zhao; Zhixia Qiao; Yongchang Liu; Liming Yu; Yuan Huang; Qianying Guo; Huijun Li. Characterization of 14Cr ODS Steel Fabricated by Spark Plasma Sintering. Metals 2019, 9, 200 .
AMA StyleQian Zhao, Zhixia Qiao, Yongchang Liu, Liming Yu, Yuan Huang, Qianying Guo, Huijun Li. Characterization of 14Cr ODS Steel Fabricated by Spark Plasma Sintering. Metals. 2019; 9 (2):200.
Chicago/Turabian StyleQian Zhao; Zhixia Qiao; Yongchang Liu; Liming Yu; Yuan Huang; Qianying Guo; Huijun Li. 2019. "Characterization of 14Cr ODS Steel Fabricated by Spark Plasma Sintering." Metals 9, no. 2: 200.