The structure parameters in an actual industrial production have a great influence on the coefficient of supercharger floating bearing dynamic characteristics,but there has been little systematic study so far.In this ...The structure parameters in an actual industrial production have a great influence on the coefficient of supercharger floating bearing dynamic characteristics,but there has been little systematic study so far.In this paper,the influence of structural parameters of the turbocharger floating bearing on its dynamic characteristic coefficientsis systematically investigated based on the theories of hydrodynamic lubrication and tribology.The influence of clearance ratio on eccentricity and the influence of internal to external radius ratios,and Sommerfeld number were analyzed.A new formula of responding characteristics of the oil film force caused by the displacement or velocity disturbance was deduced near an equilibrium in the steady state.Applying the newly developed formula,the dynamic characteristic was studied for floating bearings.Regularity for change of oil film stiffness and damping was analyzed with the structural parameters of floating bearing such as radius ratios and eccentricity.It has been found that the clearance ratio increases with eccentricity when the radius ratio is unchanged.The eccentricity decreases with the internal to external radius ratio of floating rings when the clearance ratio is constant.The absolute value of total principal stiffness and total main damping decrease with the clearance ratio and radius ratio of floating rings when the total cross damping is stable.The results and findings in this paper can contribute to nonlinear dynamics designs of turbocharger rotor-bearing systems.展开更多
In order to execute geometric analysis for planar deployable mechanism of scissors unit,the dynamic analysis model of scissor planar deployable structure is created based on the Cartesian coordinate system,the influen...In order to execute geometric analysis for planar deployable mechanism of scissors unit,the dynamic analysis model of scissor planar deployable structure is created based on the Cartesian coordinate system,the influence coefficient is acquired by means of the coordinate transformation,combining the D 'Alembert 's principle with Dynamic-Static method,the dynamic characteristic analysis is completed finally. Moreover,specific calculating examples are adopted to verify the effectiveness of proposed method,and the result shows that the movement of each component of scissors unit mechanism is more smooth during initial deployment stage,however,when the configuration angle θ of unit mechanism is approaching π,some comparative large variations would appear on movement parameters and hinge constraint force.展开更多
Conical membrane structures are a typical form of tensile membrane structures. In the past, most studies focused on the static performance, but few on dynamic performance. In this paper, systematic parameter analysis ...Conical membrane structures are a typical form of tensile membrane structures. In the past, most studies focused on the static performance, but few on dynamic performance. In this paper, systematic parameter analysis of wind-induced response of conical membrane structures has been performed with nonlinear random simulation method in a time domain, by considering some parameters, such as span, rise-span ratio, prestress of membrane, and characteristic of the approaching wind flow. Moreover, formulas of the dynamic coefficient and nonlinear adjustment factor are advised, which can be conveniently used in wind-resistant design of conical membrane structures.展开更多
采用分子动力学模拟的方法,研究了LiCl-KCl-CeCl_3熔盐中CeCl_3的结构性质和热力学,获得了LiClKCl-CeCl_3熔盐中密度与组成、密度与温度的关系数据;径向分布函数g_(Ce-Cl)(r)的第一个峰位置为0.259nm,Ce^(3+)对应的第一个配位数约为6.9...采用分子动力学模拟的方法,研究了LiCl-KCl-CeCl_3熔盐中CeCl_3的结构性质和热力学,获得了LiClKCl-CeCl_3熔盐中密度与组成、密度与温度的关系数据;径向分布函数g_(Ce-Cl)(r)的第一个峰位置为0.259nm,Ce^(3+)对应的第一个配位数约为6.9;混合熔盐中计算数据与纯熔盐中数据的差异可以解释为混合熔盐中Ce^(3+)和Cl^-的相互作用比纯的CeCl_3更强;LiCl-KCl熔盐中Ce^(3+)的自扩散活化能为22.5 k J?mol^(-1),从活化能的本质来说,Ce^(3+)自扩散所需要克服的能垒要略低于U^(3+)(25.8 k J?mol^(-1))。当Ce^(3+)的摩尔分数从0.005增加到0.05时,其指前因子从31.9×10^(-5)cm^2?s^(-1)减少到21.8×10^(-5)cm^2?s^(-1);随着Ce^(3+)摩尔分数从0.005增长到0.05,单位体积内(忽略总体积的变化)Ce^(3+)的增加意味着其扩散阻力增加,而自扩散的能力降低,导致了指前因子的减小。展开更多
基金Supported by the Natural Science Foundation of Shanxi Province Project(2012011023-2)
文摘The structure parameters in an actual industrial production have a great influence on the coefficient of supercharger floating bearing dynamic characteristics,but there has been little systematic study so far.In this paper,the influence of structural parameters of the turbocharger floating bearing on its dynamic characteristic coefficientsis systematically investigated based on the theories of hydrodynamic lubrication and tribology.The influence of clearance ratio on eccentricity and the influence of internal to external radius ratios,and Sommerfeld number were analyzed.A new formula of responding characteristics of the oil film force caused by the displacement or velocity disturbance was deduced near an equilibrium in the steady state.Applying the newly developed formula,the dynamic characteristic was studied for floating bearings.Regularity for change of oil film stiffness and damping was analyzed with the structural parameters of floating bearing such as radius ratios and eccentricity.It has been found that the clearance ratio increases with eccentricity when the radius ratio is unchanged.The eccentricity decreases with the internal to external radius ratio of floating rings when the clearance ratio is constant.The absolute value of total principal stiffness and total main damping decrease with the clearance ratio and radius ratio of floating rings when the total cross damping is stable.The results and findings in this paper can contribute to nonlinear dynamics designs of turbocharger rotor-bearing systems.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51175422)
文摘In order to execute geometric analysis for planar deployable mechanism of scissors unit,the dynamic analysis model of scissor planar deployable structure is created based on the Cartesian coordinate system,the influence coefficient is acquired by means of the coordinate transformation,combining the D 'Alembert 's principle with Dynamic-Static method,the dynamic characteristic analysis is completed finally. Moreover,specific calculating examples are adopted to verify the effectiveness of proposed method,and the result shows that the movement of each component of scissors unit mechanism is more smooth during initial deployment stage,however,when the configuration angle θ of unit mechanism is approaching π,some comparative large variations would appear on movement parameters and hinge constraint force.
基金Sponsored by the National Natural Science Foundation of China(Grant No.50338010).
文摘Conical membrane structures are a typical form of tensile membrane structures. In the past, most studies focused on the static performance, but few on dynamic performance. In this paper, systematic parameter analysis of wind-induced response of conical membrane structures has been performed with nonlinear random simulation method in a time domain, by considering some parameters, such as span, rise-span ratio, prestress of membrane, and characteristic of the approaching wind flow. Moreover, formulas of the dynamic coefficient and nonlinear adjustment factor are advised, which can be conveniently used in wind-resistant design of conical membrane structures.
文摘采用分子动力学模拟的方法,研究了LiCl-KCl-CeCl_3熔盐中CeCl_3的结构性质和热力学,获得了LiClKCl-CeCl_3熔盐中密度与组成、密度与温度的关系数据;径向分布函数g_(Ce-Cl)(r)的第一个峰位置为0.259nm,Ce^(3+)对应的第一个配位数约为6.9;混合熔盐中计算数据与纯熔盐中数据的差异可以解释为混合熔盐中Ce^(3+)和Cl^-的相互作用比纯的CeCl_3更强;LiCl-KCl熔盐中Ce^(3+)的自扩散活化能为22.5 k J?mol^(-1),从活化能的本质来说,Ce^(3+)自扩散所需要克服的能垒要略低于U^(3+)(25.8 k J?mol^(-1))。当Ce^(3+)的摩尔分数从0.005增加到0.05时,其指前因子从31.9×10^(-5)cm^2?s^(-1)减少到21.8×10^(-5)cm^2?s^(-1);随着Ce^(3+)摩尔分数从0.005增长到0.05,单位体积内(忽略总体积的变化)Ce^(3+)的增加意味着其扩散阻力增加,而自扩散的能力降低,导致了指前因子的减小。
