共查询到19条相似文献,搜索用时 405 毫秒
1.
将电流变液等效为线性粘弹性材料,并假定在小变形情况下其储能模量和损耗因子与加在它上面的电场成正比,利用Hamilton原理和有限元方法建立电流变夹层梁的动力学方程。分析不同外加电场和厚度比情况下,电流变夹层梁的振动特性及动力稳定性。通过对单频轴向激励作用下电流变夹层悬臂梁的仿真计算显示,外加电场的增大能提高电流变夹层梁的刚度和阻尼损耗,减少不稳定区域的大小,而电流变层厚度的增加将使梁的固有频率降低,但提高了梁的稳定范围。表明合理设计电流变夹层梁可以有效抑制振动,提高系统的稳定性。 相似文献
2.
电流变材料抑振机构动态性能测试与分析 总被引:1,自引:0,他引:1
电流变材料在振动控制中表现出优良的阻尼抗振性能,但由于电流变材料在振动结构中随振动幅度、振动频率和施加电场强度的变化,其动态性能表现出明显的差异,使控制模型难于准确制定。通过对含有电流变材料的抑振机构进行动态性能测试试验,获取在不同电场强度和不同激振频率下的迟滞曲线,并结合所建立的迟滞曲线数学模型将电流变材料在结构振动控制中所表现出来的动态性能分为牛顿粘性液体、屈服前弹性体、屈服前粘弹体、非线性体和屈服后粘性体,同时,分析了电流变材料不同动态特性出现的条件及其对整个结构动态性能的影响。这种试验分析方法为有效制定电流变抑振机构的控制策略提供了科学依据。 相似文献
3.
4.
5.
6.
磁流变弹性体隔振器的设计与振动特性分析 总被引:5,自引:0,他引:5
磁流变弹性体是磁流变材料的一个新的分支,兼有磁流变液和弹性体的优点,在结构振动的主被动一体控制中有着广泛的应用前景.利用磁流变弹性体的可控刚度和阻尼特性,基于挤压式受力方式,设计一种磁流变弹性体隔振器,并对其在不同外加控制电流和激励频率下的振动响应特性进行了相关试验测试,分析和研究外加控制电流和激励频率对隔振器的振动响应特性和隔振效果的影响.试验结果发现,在外加电流的作用下,磁流变弹性体能有效增大结构阻尼,改变隔振器振动响应谱峰值的频率和幅值,提高系统的隔振效果.结果表明所设计的磁流变弹性体隔振器能在外加电流的控制下,实现对结构振动响应峰值的移频和减幅作用,具有较好的主被动一体减振效果. 相似文献
7.
设计制作了两种电流变液与压电陶瓷复合的自适应阻尼器,其特点是:压电陶瓷响应振动产生高电压,用这个高电压直接去激励固化阻尼器内的电流变液实现了阻尼的自动调节。随着振动频率,振幅的变化,电流变液的响应改变,形成对振动的自适应控制。 相似文献
8.
9.
10.
11.
H. Lu G. Meng 《The International Journal of Advanced Manufacturing Technology》2006,28(11-12):1049-1055
This paper investigates the dynamic characteristics of a sandwich plate embedded with an electrorheological (ER) fluid. A laser holographic interference experiment and modal testing were conducted to identify natural frequencies, modal damping and shapes of the composite structure, under different electric fields applied to the fluid domain. Moreover, the influence of the ER effect on the structural dynamic responses were recorded. It was found that both of the damping and natural frequencies of the sandwich plate increase monotonously with an increasing electric field; while, at the same time, the resonant peaks of the frequency response and the amplitudes of dynamic responses decrease. Furthermore, based on the special properties of the ER fluid, a discrete dynamic model of the sandwich plate containing ER fluids was developed and validated. The numerical simulation verifies the effect of the ER material on the structure, and the calculated dynamic parameters show the coincident changes with the experimental results. 相似文献
12.
On the application of an electric field, the mechanical properties of ER(Electro-rheological) fluid are very complex. The damping force of ER fluid is linear without electric field and is nonlinear when an electric field is applied. By increasing the strength of the electric field, the behavior of ER fluid changes from linear viscous to nonlinear viscoelastic-plastic. External electric fluid changes natural behavior of system with ER fluid besides the mechanical properties of ER fluid. The affect of ER fluid on the stiffness of nonlinear vibration system with ER dampers is analyzed by iterative perturbation method. The results show that the stiffness of structure would be increased with growing of the strength of the electric field. 相似文献
13.
《Measurement》2016
Damping performance of lightweight composite structures, like fibre reinforced plastics (FRPs) is more efficient than the conventional materials. This phenomena was found valuable in the aerospace and transport industries. For this reason accurate material properties of FRPs are required for precise prediction of dynamic response. However, the given properties are often burden with a significant uncertainty level due to environment influence which includes air damping, temperature changes, humidity, etc. The present study concerns with the air damping influence on the dynamic behaviour of laminated composites plates with moderate damping level. The effect on dynamic characteristics is evaluated experimentally using a vacuum chamber and a laser vibrometer. Resonant frequencies and modal loss factors changes are investigated in terms of material type, sample size and excitation amplitude. A semi-automatic and time efficient two-step testing procedure is developed for a precise measurement of loss factors of laminated composite plates. 相似文献
14.
The electrorheological (ER) material embedded in the sandwich structure is subjected to oscillating shear as the structure is in vibration. According to this shear deformation mechanism, a testing apparatus with ER material filled in a fixture consisting of parallel plates is built in this study. With the controlled relative displacement between the parallel plates, the complex moduli, loss factor, and the dissipated energy of the ER material under oscillating shear are measured. The effects of the electric field strength, strain amplitude, and frequency on these dynamic properties are investigated. It is found that the constitutive model proposed in the previous work accurately describes the characteristics of the ER material under this loading condition. 相似文献
15.
Jae-Sung Bae Jai-Hyuk Hwang Jung-Sam Park Dong-Gi Kwag 《Journal of Mechanical Science and Technology》2009,23(11):3024-3035
Eddy currents are induced when a nonmagnetic, conductive material is moving as the result of being subjected to a magnetic
field, or if it is placed in a time-varying magnetic field. These currents circulate in the conductive material and are dissipated,
causing a repulsive force between the magnet and the conductor. With this concept, eddy current damping can be used as a form
of viscous damping. The present study investigates analytically and experimentally the characteristics of eddy current damping
when a permanent magnet is placed in a conductive tube. The theoretical model of eddy current damping as the result of a magnet
in a copper tube is developed from electromagnetics and is verified from experiments. The experiments include a drop test
whereby a magnet is dropped in a copper tube to measure the damping force in a steady-state, and a dynamic test is used to
measure the same phenomenon in a dynamic-state. The drop test shows that the present model can accurately predict the force
of steady-state damping. From the dynamic test, although predictability is not accurate at high excitation frequencies, the
present model can be used to predict damping force at low excitation frequencies. 相似文献
16.
STUDY ON ELECTRORHEOLOGICAL FLUID DAMPER FOR APPLICATION IN MACHINING CHATTER CONTROL 总被引:3,自引:0,他引:3
The electrorheological fluid(ERF)is a kind of intelligent material with bright prospects for industry applications, which has viscoelastic characteristic: under the applied electric field. The dynamic model of a milling system with an ERF damper is established, and the chatter suppression mechanism of the ER effect is discussed theoretically. Both the theoretical study and the experimental investigation show that the additional damping and additioaal stiffness produced by the ERF increase with the rise in the strength of electric field E, but their influence on the cutting stability is different. Only when both additional damping and additional stiffress cooperate, the milling chatter can be suppressed quickly and effectively. In additional, an ERF dumper used on the arbor of horizontal spindle milling machine is developed, and a series of milling shatter control experiments are performed. The experimental results show that the milling chatter can be suppressed effectively by using the ER damper. 相似文献
17.
Sungsoo Na Jaeyong Park Chul H. Park Moon K. Kwak Jae-Hong Shim 《Journal of Mechanical Science and Technology》2006,20(8):1139-1148
This paper addresses the analytical modeling and dynamic response of the advanced composite rotating blade modeled as thin-walled
beams and incorporating viscoelastic material. The blade model incorporates non-classical features such as anisotropy, transverse
shear, rotary inertia and includes the centrifugal and coriolis force fields. The dual technology including structural tailoring
and passive damping technology is implemented in order to enhance the vibrational characteristics of the blade. Whereas structural
tailoring methodology uses the directionality properties of advanced composite materials, the passive material technology
exploits the damping capabilities of viscoelastic material (VEM) embedded into the host structure. The VEM layer damping treatment
is modeled by using the Golla-Hughes-McTavish (GHM) method, which is employed to account for the frequency-dependent characteristics
of the VEM. The case of VEM spread over the entire span of the structure is considered. The displayed numerical results provide
a comprehensive picture of the synergistic implications of both techniques, namely, the tailoring and damping technology on
the dynamic response of a rotating thin-walled beam exposed to external time-dependent excitations. 相似文献
18.
Chao Huang Jia-Xu Wang Ke Xiao Min Li Jun-Yang Li 《Journal of Mechanical Science and Technology》2013,27(5):1233-1244
Aimed at an internal mesh planetary gear with small tooth number difference (PGSTD) reducer, this paper proposes dynamic characteristics analysis. First, static finite element (FE) analysis is performed to check the structural strength with the stress distribution in the gear teeth. Second, by means of the dynamic contact FE method, the internal dynamic excitations of teeth mesh are obtained, including mesh stiffness excitation, transmission error excitation and mesh impact excitation. According to the established model for dynamic FE modal analysis, the natural frequencies and mode shapes of the planetary gear apparatus (PGA) are calculated, and its structural dynamic response and acceleration noise are researched with the comprehensive consideration of internal and external excitations. Finally, the noise and vibration testing on the PGA is carried out by utilizing the vibration test equipment. The results confirm that the predicted values are consistent with the experimental results. 相似文献