A corrected explicit method of double time steps(CEMDTS) was introduced to accurately simulate nonlinear vibration problems in engineering. The CEMDTS, the leapfrog central difference method, the Newmark method, the g...A corrected explicit method of double time steps(CEMDTS) was introduced to accurately simulate nonlinear vibration problems in engineering. The CEMDTS, the leapfrog central difference method, the Newmark method, the generalized-a method and the precise integration method were implemented in typical nonlinear examples for the purpose of comparison. Both conservative and non-conservative systems were examined. The results show that it isn't unconditionally stable for the precise integration method, the Newmark method and the generalized-a method in nonlinear systems. The stable interval of the three methods is less than that of the CEMDTS. When a small time step(?t≤T_(min)/20) is employed, the precise integration method is endowed with the highest accuracy while the CEMDTS possesses the smallest computation effort. However, the CEMDTS becomes the most accurate one when the time step is large(?t≥0.3T_(min)) or the system is strongly nonlinear. Therefore, the CEMDTS is more applicable to the nonlinear vibration systems.展开更多
在高压断路器分闸与合闸过程中,静侧传动系统的强度直接影响产品的机械寿命,550 k V断路器与以往的产品相比,提高了电压等级,意味着更难满足机械寿命要求,因此需要更加准确地预测和提高静侧传动系统的结构强度以保证寿命要求。文中建立...在高压断路器分闸与合闸过程中,静侧传动系统的强度直接影响产品的机械寿命,550 k V断路器与以往的产品相比,提高了电压等级,意味着更难满足机械寿命要求,因此需要更加准确地预测和提高静侧传动系统的结构强度以保证寿命要求。文中建立了双动自能式灭弧室静侧传动系统的柔性瞬态动力学模型,该模型基于Hypermesh进行前处理,并利用Ls-dyna进行了瞬态动力学仿真求解。在分析过程中运用了显示算法,充分考虑了网格类型、接触类型、间隙、碰撞冲击等因素的影响。应力仿真结果表明:不同速度工况下,分合闸操作过程中关键零部件存在高应力风险,文中以拉杆销为例,列出了其高应力分布图以及应力时域曲线,峰值应力达到了约380 MPa,存在优化的空间。同时还输出了零部件之间的接触力,速度曲线,以及系统能量等结果,这些仿真结果表明:接触力大小和方向以及速度变化均符合实际运动趋势,沙漏能始终未超过内能峰值的5%,接触未发生明显的滑移和穿透,这些结果确保了仿真分析的合理性。随后针对高应力区域进行了设计方案优化并和原方案进行了仿真对比。对比结果表明:各个风险点的峰值应力明显降低,横梁、导轨、小垫片上的风险点应力下降比例最高可达到50%,优化效果明显。对优化方案进行了疲劳寿命分析,寿命结果表明:关键零部件的应力风险点可以达到10 000次以上。最终进行了机械寿命实验,实验结果表明:优化方案能够满足万次机械寿命的实验要求且未发生过度磨损,验证了仿真结果以及优化设计的有效性。展开更多
基金Projects(51405402,51505390)supported by the National Natural Science Foundation of ChinaProjects(2016YFB1200404,2016YFB1200505)supported by the National Key Research and Development Program of China
文摘A corrected explicit method of double time steps(CEMDTS) was introduced to accurately simulate nonlinear vibration problems in engineering. The CEMDTS, the leapfrog central difference method, the Newmark method, the generalized-a method and the precise integration method were implemented in typical nonlinear examples for the purpose of comparison. Both conservative and non-conservative systems were examined. The results show that it isn't unconditionally stable for the precise integration method, the Newmark method and the generalized-a method in nonlinear systems. The stable interval of the three methods is less than that of the CEMDTS. When a small time step(?t≤T_(min)/20) is employed, the precise integration method is endowed with the highest accuracy while the CEMDTS possesses the smallest computation effort. However, the CEMDTS becomes the most accurate one when the time step is large(?t≥0.3T_(min)) or the system is strongly nonlinear. Therefore, the CEMDTS is more applicable to the nonlinear vibration systems.
文摘在高压断路器分闸与合闸过程中,静侧传动系统的强度直接影响产品的机械寿命,550 k V断路器与以往的产品相比,提高了电压等级,意味着更难满足机械寿命要求,因此需要更加准确地预测和提高静侧传动系统的结构强度以保证寿命要求。文中建立了双动自能式灭弧室静侧传动系统的柔性瞬态动力学模型,该模型基于Hypermesh进行前处理,并利用Ls-dyna进行了瞬态动力学仿真求解。在分析过程中运用了显示算法,充分考虑了网格类型、接触类型、间隙、碰撞冲击等因素的影响。应力仿真结果表明:不同速度工况下,分合闸操作过程中关键零部件存在高应力风险,文中以拉杆销为例,列出了其高应力分布图以及应力时域曲线,峰值应力达到了约380 MPa,存在优化的空间。同时还输出了零部件之间的接触力,速度曲线,以及系统能量等结果,这些仿真结果表明:接触力大小和方向以及速度变化均符合实际运动趋势,沙漏能始终未超过内能峰值的5%,接触未发生明显的滑移和穿透,这些结果确保了仿真分析的合理性。随后针对高应力区域进行了设计方案优化并和原方案进行了仿真对比。对比结果表明:各个风险点的峰值应力明显降低,横梁、导轨、小垫片上的风险点应力下降比例最高可达到50%,优化效果明显。对优化方案进行了疲劳寿命分析,寿命结果表明:关键零部件的应力风险点可以达到10 000次以上。最终进行了机械寿命实验,实验结果表明:优化方案能够满足万次机械寿命的实验要求且未发生过度磨损,验证了仿真结果以及优化设计的有效性。
