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Optimization of a crossbar parallel machine tool based on workspace and dexterity
Fang Xifeng,Zhang Sichong,Xu Qinhuan,Wang Tongyue,Liu Yuanwei,Chen Xiaogang 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.8
Increasing workspace and improving dexterity are important tasks for the design of parallel machine tools. The workspace of a crossbarparallel machine tool with constraints is obtained by using a 3D search method based on inverse kinematics. The new Jacobian matrixof the machine is also derived by using the natural coordinate method. Dexterity distribution of the machine tool is obtained on the basisof the workspace and the new Jacobian matrix. Influences of the structural parameters on the workspace volume index (WVI) and globaldexterity index (GDI) are analyzed. Structural optimization is conducted by treating the WVI and GDI as the global optimization goals. Unlike the initial data, the optimized results increased by 0.43 and 0.34 times.
Ultrasonic Vibration and Rheocasting for Refinement of Mg–Zn–Y Alloy Reinforced with LPSO Structure
Shulin Lü,Xiong Yang,Liangyan Hao,Shusen Wu,Xiaogang Fang,Jing Wang 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.6
In this work, ultrasonic vibration (UV) and rheo-squeeze casting was first applied on the Mg alloy reinforced with long periodstacking ordered (LPSO) structure. The semisolid slurry of Mg–Zn–Y alloy was prepared by UV and processed by rheosqueezecasting in succession. The effects of UV, Zr addition and squeeze pressure on microstructure of semisolid Mg–Zn–Yalloy were studied. The results revealed that the synergic effect of UV and Zr addition generated a finer microstructure thaneither one alone when preparing the slurries. Rheo-squeeze casting could significantly refine the LPSO structure and α-Mgmatrix in Mg96.9Zn1Y2Zr0.1alloy without changing the phase compositions or the type of LPSO structure. When the squeezepressure increased from 0 to 400 MPa, the block LPSO structure was completely eliminated and the average thickness ofLPSO structure decreased from 9.8 to 4.3 μm. Under 400 MPa squeeze pressure, the tensile strength and elongation of therheocast Mg96.9Zn1Y2Zr0.1alloy reached the maximum values, which were 234 MPa and 17.6%, respectively, due to its fineα-Mg matrix (α1-Mg and α2-Mg grains) and LPSO structure.
Sunfang Chen,Dan Cai,Qi Dong,Gaoxiang Ma,Chennan Xu,Xiaogang Ba,Wei Yuan,Bing Wu,Bin Fang 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00
Background The reconstruction of tendons with large defects requires grafts with high mechanical strength and is often hindered by complications such as infection and adhesion. Hence, grafts combining the advantages of mechanical resilience and antibacterial/antiadhesion activity are highly sought after. Methods The silver nanoparticles (GA-Ag NPs) synthesized from gallic acid and silver nitrate were attached to a decellularized extracellular matrix (Decellularized Tendon crosslinking GA-AgNPs, DT-Ag). We examined the histological structure, mechanical property, morphology, Zeta potential, cytotoxicity, antibacterial properties, antioxidant and anti-inflammatory properties, and ability of the DT-Ag to treat tendon defects in animals. Results Approximately 108.57 ± 0.94 μg GA-Ag NPs loaded per 50 mg DT, the cross-linked part of GA-Ag NPs was 65.47 ± 0.57%, which provided DT-Ag with long-lasting antibacterial activity. Meanwhile, GA endowed DT-Ag with good antioxidant and anti-inflammatory activities. Additionally, The DT-Ag facilitated M2 macrophage polarization, and suppressed fibrin deposition by hindering fibroblast adhesion. Mormore, the main advantages of DT-Ag, namely its long-lasting antibacterial activity (tested using Escherichia coli and Staphylococcus aureus as models) and the ability to prevent tissue adhesion were confirmed in vivo. Conclusion The fabricated multifunctional tendon graft was highly hydrophilic, biocompatible, and mechanically resilient, and concluded to be well suited for dealing with the main complications of surgical tendon reconstruction and has bright application prospects.