A model of vibrating device coupling two pendulums (VDP) which is highly nonlinear was put forward to conduct vibration analysis. Based on energy analysis, dynamic equations with cubic nonlinearities were established ...A model of vibrating device coupling two pendulums (VDP) which is highly nonlinear was put forward to conduct vibration analysis. Based on energy analysis, dynamic equations with cubic nonlinearities were established using Lagrange's equation. In order to obtain approximate solution, multiple time scales method, one of perturbation technique, was applied. Cases of non-resonant and 1:1:2:2 internal resonant were discussed. In the non-resonant case, the validity of multiple time scales method is confirmed, comparing numerical results derived from fourth order Runge-Kutta method with analytical results derived from first order approximate expression. In the 1:1:2:2 internal resonant case, modal amplitudes of Aa1 and Ab2 increase, respectively, from 0.38 to 0.63 and from 0.19 to 0.32, while the corresponding frequencies have an increase of almost 1.6 times with changes of initial conditions, indicating the existence of typical nonlinear phenomenon. In addition, the chaotic motion is found under this condition.展开更多
Influence of multiple structural parameters on the performance of a gun launch system driven by highpressure reactive gases is important for structural design and performance adjustment.A coupled lumped parameter mode...Influence of multiple structural parameters on the performance of a gun launch system driven by highpressure reactive gases is important for structural design and performance adjustment.A coupled lumped parameter model was utilized to predict the propellant combustion,and a dynamic finite element method was applied to approximate the mechanical interactions between the projectile and the barrel.The combustion and the mechanical interactions were coupled through a user subroutine interface in ABAQUS.The correctness and the capability of the finite element approximations in capturing small structural changes were validated by comparing predicted resistance with experiments.Based on the coupled model,the influence of structural parameters of a medium-caliber gun on the system performance was investigated.In order to reduce the research costs,orthogonal tests were designed to investigate the comprehensive effects of the parameters.According to statistical analysis,the important order of the structural parameters on the launching process was obtained.The results indicate that the influence of the width of the rotating band stands out among the studied parameters in the gun.The work provides a method to investigate the influence of multiple parameters on system performance and gives guidance for controlling the system performance.展开更多
研究质谱的离子传输气体动力学特征对理解和提升质谱仪器灵敏度具有重要意义。基于纳维-斯托克斯(NavierStokes)方程和直接蒙特卡洛(Direct Simulation Monte Carlo)方法联用,可以计算获得气体从大气压连续流到真空稀薄流的流场特征,进...研究质谱的离子传输气体动力学特征对理解和提升质谱仪器灵敏度具有重要意义。基于纳维-斯托克斯(NavierStokes)方程和直接蒙特卡洛(Direct Simulation Monte Carlo)方法联用,可以计算获得气体从大气压连续流到真空稀薄流的流场特征,进一步与电场仿真耦合,可以获得离子的传输与空间分布信息,评价离子光学器件性能。工作基于光电离质谱,构建了毛细管进样、光电离源和取样锥的组合结构模型,建立了离子传输跨流态多物理场仿真方法,得到了两种结构光电离源电极对离子传输效率的影响,并利用自制光电离飞行时间质谱装置验证了仿真方法的可靠性。工作为复杂流场和电场环境下质谱光电离源及离子传输装置设计提供了理论指导依据。展开更多
基金Projects(50574091, 50774084) supported by the National Natural Science Foundation of ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions+1 种基金Project(CXLX12_0949) supported by Research and Innovation Project for College Graduates of Jiangsu Province, ChinaProject(2013DXS03) supported by the Fundamental Research Funds for the Central Universities, China
文摘A model of vibrating device coupling two pendulums (VDP) which is highly nonlinear was put forward to conduct vibration analysis. Based on energy analysis, dynamic equations with cubic nonlinearities were established using Lagrange's equation. In order to obtain approximate solution, multiple time scales method, one of perturbation technique, was applied. Cases of non-resonant and 1:1:2:2 internal resonant were discussed. In the non-resonant case, the validity of multiple time scales method is confirmed, comparing numerical results derived from fourth order Runge-Kutta method with analytical results derived from first order approximate expression. In the 1:1:2:2 internal resonant case, modal amplitudes of Aa1 and Ab2 increase, respectively, from 0.38 to 0.63 and from 0.19 to 0.32, while the corresponding frequencies have an increase of almost 1.6 times with changes of initial conditions, indicating the existence of typical nonlinear phenomenon. In addition, the chaotic motion is found under this condition.
基金the financial support from the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYLX_0399)
文摘Influence of multiple structural parameters on the performance of a gun launch system driven by highpressure reactive gases is important for structural design and performance adjustment.A coupled lumped parameter model was utilized to predict the propellant combustion,and a dynamic finite element method was applied to approximate the mechanical interactions between the projectile and the barrel.The combustion and the mechanical interactions were coupled through a user subroutine interface in ABAQUS.The correctness and the capability of the finite element approximations in capturing small structural changes were validated by comparing predicted resistance with experiments.Based on the coupled model,the influence of structural parameters of a medium-caliber gun on the system performance was investigated.In order to reduce the research costs,orthogonal tests were designed to investigate the comprehensive effects of the parameters.According to statistical analysis,the important order of the structural parameters on the launching process was obtained.The results indicate that the influence of the width of the rotating band stands out among the studied parameters in the gun.The work provides a method to investigate the influence of multiple parameters on system performance and gives guidance for controlling the system performance.
文摘研究质谱的离子传输气体动力学特征对理解和提升质谱仪器灵敏度具有重要意义。基于纳维-斯托克斯(NavierStokes)方程和直接蒙特卡洛(Direct Simulation Monte Carlo)方法联用,可以计算获得气体从大气压连续流到真空稀薄流的流场特征,进一步与电场仿真耦合,可以获得离子的传输与空间分布信息,评价离子光学器件性能。工作基于光电离质谱,构建了毛细管进样、光电离源和取样锥的组合结构模型,建立了离子传输跨流态多物理场仿真方法,得到了两种结构光电离源电极对离子传输效率的影响,并利用自制光电离飞行时间质谱装置验证了仿真方法的可靠性。工作为复杂流场和电场环境下质谱光电离源及离子传输装置设计提供了理论指导依据。
