Flapping plates of typical fishlike tail shapes are simulated to investigate their locomotion performance using the multi-block Lattice Boltzmann Method （LBM） and Immersed Boundary （IB） method. Numerical results s...Flapping plates of typical fishlike tail shapes are simulated to investigate their locomotion performance using the multi-block Lattice Boltzmann Method （LBM） and Immersed Boundary （IB） method. Numerical results show that fishlike forked configurations have better locomotion performance compared with unforked plates. Based on our results, the caudal fin in carangi- form mode has greater thrust, and the lunate tail fin in thtmniform mode has higher efficiency. These findings are qualitatively con- sistent with biological observations of fish swimming. Analysis of wake topology shows that the wake of the forked plate consists of a chain of alternating reverse horseshoe-like vortical structures. These structures induce a backward jet and generate a positive thrust. Moreover, this backward jet has a more favorable direction compared with that behind an unforked plate.展开更多
A methodology is implemented to find the optimum reduced weight configuration design of an operating structure of a civil aircraft vertical tail fin. FE （finite element） based topology optimization is executed to fi...A methodology is implemented to find the optimum reduced weight configuration design of an operating structure of a civil aircraft vertical tail fin. FE （finite element） based topology optimization is executed to find the optimum material distribution of initial design space of rib by maximizing the stiffness. Loads pertinent to the operating and ground conditions are estimated and applied, considering the orientation of structural assembly members and built-in supports offered in the main structure. Manufacturing constraints are incorporated into the optimization loop to generate pragmatic and manufacturable design configuration. The topologically optimized configuration is then converted to CAD viable design through data reduction and smoothing by converting to ISO-surfaces. A methodology is also devised to modify the topological optimized voids and material layout precisely with splines and fillets to construct manufacturable features and avoid stress concentrations. The resulting novel design proposal is then analyzed and validated against stipulated loads, constraints and other design needs. Results validate the new design proposal as more reliable, having reduced weight and enhanced structural performance.展开更多
目的为提高尾鳍驱动型水下机器人的工作效率,优化尾鳍驱动装置的硬件和软件提供理论支撑。方法将中国知网数据库与Web of Science数据库作为研究数据来源,对相关文献进行系统梳理,使用Citespace和VOSviewer软件对文献作者、所属机构、...目的为提高尾鳍驱动型水下机器人的工作效率,优化尾鳍驱动装置的硬件和软件提供理论支撑。方法将中国知网数据库与Web of Science数据库作为研究数据来源,对相关文献进行系统梳理,使用Citespace和VOSviewer软件对文献作者、所属机构、关键词和研究热点进行可视化图谱绘制。结果通过对文献的分析,确定三个热点研究方向,分别是尾鳍驱动装置的外形结构设计、驱动方式和控制系统设计、材料设计,并根据各研究方向提炼出对应的研究方法:基于设计形态学、结构仿生学和工程优化的外形结构设计方法,基于自下而上和模块化的驱动方式设计方法,基于滑模控制、模糊控制和PID控制系统设计方法,以及基于仿生材料、智能材料和计算机模拟的材料设计方法等。结论对目前尾鳍驱动型机器人的主要研究内容、优势特点、存在问题、设计方法和未来趋势进行总结,为相关领域的发展提供参考和依据。展开更多
基金the National Natural Science Foundation of China (Grant No. 10832010)the Innovation Project of the Chinese Academy of Sciences (Grant No. KJCX2-YW-L05)the 111 Project (Grant No. B07033)
文摘Flapping plates of typical fishlike tail shapes are simulated to investigate their locomotion performance using the multi-block Lattice Boltzmann Method （LBM） and Immersed Boundary （IB） method. Numerical results show that fishlike forked configurations have better locomotion performance compared with unforked plates. Based on our results, the caudal fin in carangi- form mode has greater thrust, and the lunate tail fin in thtmniform mode has higher efficiency. These findings are qualitatively con- sistent with biological observations of fish swimming. Analysis of wake topology shows that the wake of the forked plate consists of a chain of alternating reverse horseshoe-like vortical structures. These structures induce a backward jet and generate a positive thrust. Moreover, this backward jet has a more favorable direction compared with that behind an unforked plate.
文摘A methodology is implemented to find the optimum reduced weight configuration design of an operating structure of a civil aircraft vertical tail fin. FE （finite element） based topology optimization is executed to find the optimum material distribution of initial design space of rib by maximizing the stiffness. Loads pertinent to the operating and ground conditions are estimated and applied, considering the orientation of structural assembly members and built-in supports offered in the main structure. Manufacturing constraints are incorporated into the optimization loop to generate pragmatic and manufacturable design configuration. The topologically optimized configuration is then converted to CAD viable design through data reduction and smoothing by converting to ISO-surfaces. A methodology is also devised to modify the topological optimized voids and material layout precisely with splines and fillets to construct manufacturable features and avoid stress concentrations. The resulting novel design proposal is then analyzed and validated against stipulated loads, constraints and other design needs. Results validate the new design proposal as more reliable, having reduced weight and enhanced structural performance.
文摘目的为提高尾鳍驱动型水下机器人的工作效率,优化尾鳍驱动装置的硬件和软件提供理论支撑。方法将中国知网数据库与Web of Science数据库作为研究数据来源,对相关文献进行系统梳理,使用Citespace和VOSviewer软件对文献作者、所属机构、关键词和研究热点进行可视化图谱绘制。结果通过对文献的分析,确定三个热点研究方向,分别是尾鳍驱动装置的外形结构设计、驱动方式和控制系统设计、材料设计,并根据各研究方向提炼出对应的研究方法:基于设计形态学、结构仿生学和工程优化的外形结构设计方法,基于自下而上和模块化的驱动方式设计方法,基于滑模控制、模糊控制和PID控制系统设计方法,以及基于仿生材料、智能材料和计算机模拟的材料设计方法等。结论对目前尾鳍驱动型机器人的主要研究内容、优势特点、存在问题、设计方法和未来趋势进行总结,为相关领域的发展提供参考和依据。
