Abstract：Concerning the safety and stability in operation of Roots pumps which are featured with large flow rate and high speed, the topology of lobe in a two-lobe Roots pump was optimized by means of e-volutionary structural optimization(ESO)method. Since a structural mutation phenomenon occurs du-ring the optimization process, the screening and deletion algorithms are proposed based on the connection traits between singular elements to improve the ESO method, eventually the stability and continuity of the optimization process are ensured. The improved ESO method was realized by using Ansys mechanical parametric design language(APDL). At first, the allowable interval of initial rejection rate was ascertained by using interval approximation and combining with the visual process of program. Then, the topology of lobe in a two-lobe Roots pump was optimized with five kinds of initial rejection rates when it was subject to the 1 500 r/min inertial load. Finally, a reasonably topological structure for the lobe was decided by analyzing maximum stress, strain and displacements in different design cases and sifting among them. Comparing the results of finite element analysis shows that the optimized structure not only experiences more even stress distribution under the inertial load but the material utilization ratio is also improved considerably. The maximum stress, strain and displacement are reduced by 17.7%, 17.5% and 18.7%, respectively, the mass of rotor is decreased by 55%; as a result, the safety and stability can be improved greatly for this Roots pump operating at a high speed and large flow rate.
[1]Xie Y M,Steven G P. A simple evolutionary procedure for structural optimization [J]. Computers and Structures,1993, 49(5):885-896.[2]荣见华,谢忆民,姜节胜,等. 渐进结构优化设计的现状与进展[J]. 长沙交通学院学报,2001,17(3):16-23. Rong Jianhua,Xie Yimin,Jiang Jiesheng, et al. Present situation and development of evolutionary structural optimization method[J]. Journal of Changsha Communications University,2001,17(3):16-23.(in Chinese)[3]Xie Yimin,Huang Xiaodong. Recent developments in evolutionary structural optimization(ESO)for conti-nuum structures [J]. Materials Science and Enginee-ring, 2010,10(1): 012196.[4]Huang Xiaodong,Xie Yimin. A further review of ESO methods for topology optimization[J]. Structural and Multidisciplinary Optimization,2010,41(5):671-683.[5]Steven G P,Querin O,Xie Y M. Evolutionary structural optimization(ESO)for combined topology and size optimization of discrete structures [J]. Computer Methods in Applied Mechanics and Engineering,2000,188(4):743-754.[6]Marckmann G,Bettess P,Peseux B. Self-designing structures: A new evolutionary rule for thickness distribution in 2D problems[J]. Communications in Numerical Methods in Engineering, 2002,18(10):743-755.[7]刘丰睿,赵丽滨,韩邦成,等. 磁悬浮控制力矩陀螺框架结构的拓扑优化设计[J]. 北京航空航天大学学报,2010,36(4):455-458. Liu Fengrui,Zhao Libin, Han Bangcheng, et al. Topo-logy optimization design of frame structure for magnetic suspension control moment gyroscope [J]. Journal of Beijing University of Aeronautics and Astronautics,2010,36(4):455-458.(in Chinese)[8]Ren G,Xie Y M. Optimization of underground excavation in rock masses using ESO techniques [C]//Proceedings of the 12th International Conference on Optimum Design of Structures and Materials in Engineering. [S.l.]:WIT Press,2012:165-174.[9]Ansola R,Vegueria E,Canales J,et al. A simple evolutionary topology optimization procedure for compliant mechanism design [J]. Finite Elements in Analysis and Design,2007,44(1/2):53-62.[10]范文杰,徐进永,张子达. 基于双向渐进结构优化法的装载机动臂拓扑优化[J]. 农业机械学报,2006,37(11):24-27. Fan Wenjie,Xu Jinyong,Zhang Zida. Topology optimization on arm of loader based on BESO [J]. Transactions of the Chinese Society for Agricultural Machinery,2006,37(11):24-27.(in Chinese)[11]Huang Xiaodong,Xie Yimin. Bi-directional evolutionary topology optimization of continuum structures with one or multiple materials[J]. Computational Mechanics,2009,43:393-401.[12]Huang Xiaodong,Xie Yimin. A new look at ESO and BESO optimization methods [J]. Structural and Multidisciplinary Optimization,2008,35:89-92.[13]Querin O,Yong V,Steven G P,et al. Computational efficiency and validation of bi-directional evolutionary structural optimization [J]. Computer Methods in Applied Mechanics and Engineering,2000,189(2):559-573.[14]孙圣权,张大可,徐云岳,等. 基于应力突变率的双向进化结构优化算法[J]. 机械设计与研究,2008,24(2):6-10. Sun Shengquan,Zhang Dake,Xu Yunyue,et al. A bi-directional evolutionary structural optimization method based on ratio of stress change [J]. Machine Design and Research,2008,24(2):6-10.(in Chinese)[15]许强,李湘沅,陈庆,等. 基于ANSYS平台的连续体渐进结构优化设计及其应用[J]. 建筑科学与工程学报,2008,25(1):23-31. Xu Qiang,Li Xiangyuan,Chen Qing, et al. Evolutionary structural optimization design of continuum based on ANSYS platform and its application [J]. Journal of Architecture and Civil Engineering,2008,25(1):23-31.(in Chinese)
