共查询到20条相似文献,搜索用时 46 毫秒
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《振动与冲击》2017,(12)
提出一种采用石墨自润滑球铰连接的立方体构型Stewart隔振平台,6个支腿通过可转动的球铰与基础及载荷平台相连,每个支腿由音圈作动器与力传感器构成。在假设各支腿、基础及载荷平台均为弹性体的基础上,采用子结构频响函数综合法对Stewart隔振平台进行动力学建模,并通过FEM方法进行验证,给出内嵌反馈控制的隔振平台模型,对反馈控制效果进行仿真验证;在仿真分析的基础上,对隔振平台的被动隔振性能和内嵌反馈控制的主动隔振性能进行实验。结果表明,被动隔振在30~200 Hz频段内具有约-36 d B/dec的衰减率,主动隔振在3~100 Hz频段内可获得最大20 d B的幅值衰减,200 Hz,支腿力RMS值控制后下降75%~80%。 相似文献
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为保证高精度空间光学仪器的仪器精度,采用主动隔振Stewart平台作为多维振动隔离系统。基于加速度各向同性定义,考虑负载的质量几何特性,推导了加速度各向同性的解析数学表达式,揭示了各向同性、机构结构以及负载特性之间的联系,给出了柔顺中心的数学表达式以及各向同性Stewart平台的特征不变量。为降低系统非线性及耦合影响,提出以运动正交、加速度各向同性为指标的主动隔振Stewart平台设计,建立了生成一类加速度各向同性隔振Stewart平台的设计方法 相似文献
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针对大型车载光电设备0~20 Hz低频段振动,综合考虑承载能力及车内空间,基于准零刚度系统隔振原理,提出了一种新的低频水平方向隔振方法。将一种新型的负刚度机构并入正刚度的弹簧,组成正负刚度并联的新构型隔振系统。通过对隔振系统的基本原理和动力特性进行理论分析,得到了系统处于平衡位置时的零刚度条件;并对加入了新型隔振系统的车载光电设备振动响应进行了模态仿真。理论分析和仿真结果表明,此新型准零刚度水平隔振系统在不改变承载能力的情况下,降低了固有频率,对于低频隔振有明显的效果。可将0~20 Hz频率范围内的振动幅值降低96.67%左右。通过对装有该隔振系统的车载仪器的性能进行测试,可验证该隔振系统对车载设备的隔振效果非常明显。 相似文献
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摘要:讨论主动隔振中控制器输出饱和及其抑制对振动和声辐射控制的影响。首先给出流固耦合振动的时域建模方法,采用有限元/边界元方法建立流固耦合系统的振动方程,在建模过程中通过修正流体附加质量阵得到较准确的系统模型;然后在时域模型的基础上,给出基于自适应滤波的控制和输出饱和的抑制方法。采用由单自由度隔振模型和嵌于无限大障板的简支加筋板组成的耦合系统进行仿真研究,结果显示了饱和抑制方法能够显著地改善主动隔振与远场声辐射的控制效果。 相似文献
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基于车体振动的特点提出一种应用于车载设备的三维隔振系统,建立了该系统的半主动模糊最优控制模型,并通过实验验证了该多维隔振系统的性能。该系统通过使用磁流变(MR)阻尼器与弹簧组成的隔振子系统代替3-RPC(旋转副-平移副-螺旋副)并联机构中的驱动器实现空间三维振动隔离。控制模型结合了H∞状态反馈控制方法和MR阻尼器的工作原理得到阻尼器的可输出控制力,并通过模糊模型计算得到MR阻尼器的输入电流。设计制造了一套振动隔离实验平台,并采用正弦信号和随机信号进行振动实验完成了对平台的隔振性能的验证。通过测量上平台的振动加速度表明此隔振系统具有良好的隔振效果。 相似文献
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An analytical expression is derived which describes the variation of the thermistor temperature during a relay-effect transient process following an instantaneous change in the supply voltage in an R — RT two-pole network.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 38, No. 3, pp. 465–472, March, 1980. 相似文献
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V. L. Sennitskii 《Technical Physics Letters》2005,31(10):856-858
An exact solution is obtained for the problem of interaction between the ideal liquid homogeneously moving at infinity and
streamlining a round cylinder touching a solid wall. 相似文献
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Stress analysis for a strip of which widths are different at the right and left handsides is carried out for before and after occurrence of a crack at a corner of a step. The strip is analyzed as a thin plate bending problem subject to transverse bending and torsion, and as a plane eleastic problem subject to bending in the plane and uniaxial tension. The rational mapping function of a sum of fractional expressions and complex variable method are used. Stress distribution and stress intensity factors are obtained. 相似文献
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Methods for imaging a single point source to a line image are discussed, and a design study of single spherical mirror systems that form aberration-free line images is presented. An expression forthe ray density along the line image is derived for such systems in the cases of (i) uniform beam profiles and (ii) Gaussian beam profiles. The resulting ray density profiles are illustrated for single spherical mirror systems over a wide range of design parameters. 相似文献
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C. V. Yogananda 《Acta Mechanica》1969,7(4):299-310
Summary Theoretical expressions for stresses and displacements have been derived for bending under a ring load of a free shell, a shell embedded in a soft medium, and a shell containing a soft core. Numerical work has been done for typical cases with anElliot 803 Digital Computer and influence lines are drawn therefrom.
Nomenclature A (),B () Functions of - a, t Mean radius and thickness of the shell - E S , S Young's modulus andPoisson's ratio of the shell - G c , c Shear modulus andPoisson's ratio of the casting or core - I 0 (r),I 1 (r) ModifiedBessel functions of the first kind and order zero and one respectively - K 0 (r),K 1 (r) ModifiedBessel functions of the second kind and order zero and one respectively - p Ring load, lb/in - U, W Displacement components in the casing or core in thez andr direction - u, w Displacement components of a middle surface point in the shell - r , rz Radial and shearing stress components - Independent variable of infinite integrals - k [3(1–S 2)a 2/t 2]1/4 With 13 Figures 相似文献
Einflußlinien für die Biegung einer freien Schale, einer Schale in einer weichen Bettung und einer Schale mit weichem Kern
Zusammenfassung Für die Biegung einer freien Schale, einer weich gebetteten Schale und einer Schale mit weichem Kern unter einer Ringlast werden Ausdrücke für die Spannungen und Verschiebungen hergeleitet. Die Ergebnisse wurden für einige typische Fälle mit einem DigitalrechnerElliot 803 numerisch ausgewertet. Die sich ergebenden Einflußlinien wurden graphisch dargestellt.
Nomenclature A (),B () Functions of - a, t Mean radius and thickness of the shell - E S , S Young's modulus andPoisson's ratio of the shell - G c , c Shear modulus andPoisson's ratio of the casting or core - I 0 (r),I 1 (r) ModifiedBessel functions of the first kind and order zero and one respectively - K 0 (r),K 1 (r) ModifiedBessel functions of the second kind and order zero and one respectively - p Ring load, lb/in - U, W Displacement components in the casing or core in thez andr direction - u, w Displacement components of a middle surface point in the shell - r , rz Radial and shearing stress components - Independent variable of infinite integrals - k [3(1–S 2)a 2/t 2]1/4 With 13 Figures 相似文献
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O. P. Kornienko 《Journal of Engineering Physics and Thermophysics》1995,68(3):334-335
It is shown that the relation between the Nusselt and Reynolds numbers determined by the Reynolds analogy is linear with self-similarity of the hydrodynamic resistance coefficient.Special Design and Technology Office Element, Odessa, Ukraine. translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 68, No. 3, May–June, pp. 395–396, 1995. 相似文献
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The dynamic behavior of a cylindrical fluid-immersed shell in a pressure wave initiated by a pulsating vapor-gas bubble that develops as a result of the action of laser radiation on the absorbing medium (metal) is examined experimentally and theoretically. The results of the experiments suggest that the amplitude of the shock wave that develops as a result of complete or partial vaporization of the absorbing medium is appreciably smaller than the amplitude of the waves due to pulsations of the bubble that is formed. Experimental data on the pattern of structural deformation are confirmed by calculations. The effect of load simulation on the behavior of the shell is established according to computational data.Translated from Problemy Prochnosti, No. 6, pp. 116–120, June, 1990. 相似文献
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S. V. Vasil’chenko B. M. Mukhin 《Journal of Engineering Physics and Thermophysics》1998,71(6):1105-1108
The authors have obtained an approximate solution of the problem of the resistance of a rigid sphere in a slow flow of a Maxwell
viscoelastic fluid that is in good agreement with experimental data [1] for Weissenberg numbers We ≤ 0.7. It is shown that
the effect of a decrease in the coefficient of resistance of a sphere in the interval 0.1 ≤ We ≤ 0.7 established experimentally
is determined in full measure by the linear viscoelastic properties of the Maxwell fluid.
Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 6, pp. 1138–1140, November–December, 1998. 相似文献