共查询到19条相似文献,搜索用时 321 毫秒
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精密仪器用超低频非线性并联隔振系统研究 总被引:7,自引:0,他引:7
在分析了负刚度的形成机理基础上,设计研制了一种正负刚度并联的新型隔振系统。隔振系统采用负刚度机构在平衡点某一领域内抵消了弹性元件的部分正刚度,使隔振系统刚度呈现非线性,从而使得隔振系统总刚度趋向于零。经过设计,隔振系统具有高的支撑刚度和很低的运动刚度。在隔振系统中,可通过调节负刚度机构两端的受力情况来降低其固有频率。大量实验结果表明,该隔振系统的固有频率从10Hz降到1Hz,从而使得其隔振频带加宽,隔振能力显著提高,达到了较好的设计效果。 相似文献
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传统浮筏隔振系统为双层“质量-弹簧-阻尼”机械系统。基于机电相似理论,质量与一端接地电容对应,而惯容是与电容完全对应的双端机械元件。将惯容引入浮筏隔振系统,使浮筏动力学模型中双层质量间可产生可变惯性耦合,从而极大影响系统固有频率与隔振性能。浮筏的退化或异动会改变系统固有频率和力传递率。惯容惯质系数的增加会使浮筏固有频率降低并影响力传递率。将人工自愈的思想引入浮筏隔振系统,根据系统固有频率的监测结果来调节惯容惯质系数,将系统固有频率自主调整恢复至合适固有频率,即为基于惯容的浮筏隔振系统人工自愈技术。为验证该技术原理,搭建浮筏隔振系统实验平台,进行简谐激励扫频试验。试验结果验证基于惯容的浮筏隔振系统人工自愈技术的可行性。 相似文献
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压印光刻机是一种精密仪器,外界环境激励对压印光刻机的影响很大。橡胶空气弹簧是一种气囊减振器,用橡胶空气弹簧隔离外界环境对压印光刻机的干扰,能保护压印光刻机免受低频激励力的激励,文中阐述压印光刻机低频橡胶空气弹簧单自由度隔振系统的隔振原理,确定橡胶空气弹簧的刚度及隔振系统的固有频率,隔振系统的固有频率及隔振效率的理论结果与实际隔振系统的试验结果相吻合,表明压印光刻机的低频隔振设计是合理可行的。 相似文献
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超精密测量对环境振动要求非常严格,其仪器设备中多安装隔振装置。针对课题组圆度仪中使用的仪用小型空气弹簧隔振台,采用理论方法研究其固有频率。首先简化隔振台振动模型,根据该隔振台中约束式膜式空气弹簧的特定结构及相关理论,建立单个空气弹簧数学计算模型,获得单个空气弹簧刚度特性与其垂向变形量x的关系式,最终求得隔振系统的固有频率;同时利用压电式加速度传感器设计振动测试试验,对采集到的加速度信号进行预处理、积分运算、频谱分析,获得该系统的固有频率,两者对比,误差不超过10%,达到预期研究目标。为理论上研究该隔振平台的隔振性能及其耦合振动情况提供理论基础,也对其他类似结构的空气弹簧刚度特性的计算有一定参考意义。 相似文献
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常规的车辆动力装置隔振系统无法兼顾低频隔振性能和高承载稳定性,迫切需要新方法、新技术实现两者统一。在分析不同行程区间刚度特性对隔振率和稳定性影响的基础上,提出了预压定刚度弹簧与变刚度弹簧并联的变刚度隔振新构型,阐述了依据隔振率和负载匹配定刚度及预压参数、依据稳定性优化变刚度参数的设计方法。新型隔振器不仅支承能力强,而且隔振频域宽,尤其是低频工作域的隔振效果显著提升。实车测试结果表明,在保证足够稳定性的提前下,额定工况下新型变刚度隔振系统的隔振率由原来的30.3%提高至83.5%。 相似文献
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大型飞机的机载关键设备需要隔振系统进行振动保护,而空气弹簧在隔振性能上具有比金属弹簧更好的非线性和低频性能,对应用在大型飞机机载设备隔振系统上的空气弹簧的材料非线性、接触条件非线性等进行了分析,在对空气弹簧非线性与气体单元的实现方法进行分析的基础上,利用非线性有限元软件MSC.Marc对约束膜式空气弹簧的垂向刚度进行了数值仿真.结果表明:空气弹簧垂向刚度呈现非线性特征;空气弹簧垂向刚度与垂向位移的关系密切;随着初始内压和胶膜帘线密度的增大,空气弹簧的垂向刚度增加;胶膜帘线角与垂向刚度的关系受到约束的影响. 相似文献
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崔联合 《机械制造与自动化》2014,(2):139-143
在理论计算的基础上,采用UG软件建立减振弹簧模型,结合理论值对弹簧模型进行有限元分析,从分析结果可知:模型刚度有限元分析结果与理论计算值基本一致;对弹簧的疲劳强度分析可知,理论疲劳安全系数与有限元分析结果基本相等,模型的强度足够;弹簧静强度安全系数为1.42,静强度合格;弹簧最小固有频率大于振动机振动频率,故弹簧不会发生共振。 相似文献
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A negative stiffness vibration isolator using magnetic spring combined with rubber membrane 总被引:2,自引:0,他引:2
Qiang Li Yu Zhu Dengfeng Xu Jinchun Hu Wei Min Lacheng Pang 《Journal of Mechanical Science and Technology》2013,27(3):813-824
The most important characteristic of a passive vibration isolator is its natural frequency and load capacity. The vibration isolation performance of a passive vibration isolator in low input frequencies is considerably improved by reducing its natural frequency. This paper presents a negative stiffness magnetic suspension vibration isolator (NSMSVI) using a magnetic spring combined with rubber membranes to obtain lower natural frequency. To study the vibration isolation performance of the NSMSVI, the stretching force of the rubber membrane is measured through experiments. The stiffness of the rubber membrane comes from the derivative of the stretching force. A parametric study of load capacity, axial magnetic stiffness, and natural frequency of the magnetic spring is also performed. Consequently, as a case study, the size dimensions of the magnetic spring are determined. An NSMSVI table is set up for experimental validation, after which the transmissibility curves of the NSMSVI are calculated and tested. Experimental results show that the lowest natural frequency of the NSMSVI reaches 1.5 Hz with a maximum attenuation of -40 dB between 0 Hz and 100 Hz, whereas the NSMSVI has the maximum load capacity at the lowest stiffness. This paper essentially provides an efficient method to construct a negative stiffness vibration isolator for practical applications. 相似文献
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以E型电动式激振器为基础。为抑制激振器工作频宽内的尖峰及减小对被测试件的附加刚度.对激振器的支撑弹簧板采用由碳纤维/树脂基(T300/QY8911)组成的复合材料层合板结构,并以铺层角和铺层厚度作为设计变量对其进行动态优化设计,结果表明,采用优化后的复合材料层合板结构的激振器,保证丁激振器的低频性能。且有效地抑制了工作频宽内的尖峰。 相似文献
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Xiuchang Huang Xintian Liu Hongxing Hua 《Journal of Mechanical Science and Technology》2014,28(3):813-822
A novel structured ultra-low frequency nonlinear passive isolator is presented. The isolator is composed of a knife-edge supported sliding beam which offers negative stiffness and a vertical mechanical spring in parallel to get quasi-zero dynamic stiffness. The static characteristics of the isolator are studied. Assuming light viscous damping, the dynamic behavior is investigated and the response under harmonic excitation is derived using a simple approximation. Frequency response curves (FRCs), which exhibit complex double jump phenomenon, are obtained by harmonic balance method (HBM). The limitation of the excitation force level is obtained. The force transmissibility is derived and compared with an equivalent linear system with the same damping ratio. The isolation performance of the nonlinear isolator is shown to outperform the linear system for providing a wider isolation region. The influence of system parameters on the transmissibility is examined and some useful guidelines are given. 相似文献
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A. Carrella M.I. Friswell A. Zotov D.J. Ewins A. Tichonov 《Mechanical Systems and Signal Processing》2009,23(7):2228-2235
Vibrations in rotating machinery cause many problems such as fatigue of the rotating components, excessive noise, or transmission of vibration to the supporting structure. A major source of this vibration is out-of-balance forces and this paper proposes that the rotor response is reduced by suspending the machine on nonlinear springs. In the field of vibration isolation, nonlinear mounts have been proposed which have the same static stiffness as an equivalent linear support, i.e. load bearing capability, but at the same time offer a low dynamic stiffness, i.e. a lower natural frequency. Thus the isolator is effective over an increased frequency range. These mounts are known in the literature as high-static-low-dynamic-stiffness (HSLDS) mechanisms. In this paper, the rotor is suspended on a hardening HSLDS spring to considerably reduce the critical speeds to values far away from the operating speed. The advantages of the nonlinear supports are demonstrated using a simple two degree of freedom rotating machine model consisting of a rigid disk, and shafts, bearings and supports that are flexible but have negligible mass. Following a linear analysis to highlight the benefits of a low dynamic stiffness, an approximate analytical solution of the nonlinear equation of motion is presented. A comparison between the linear and nonlinear response shows the effectiveness of the nonlinear supports. Finally, the problems that occur if the nonlinearity is too strong are highlighted. 相似文献
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对专用车空气悬置进行适应性改型,根据气体状态方程,得到膜式空气弹簧刚度与固有频率的表达式,研究了膜式空气弹簧初始气压、初始容积和有效面积对刚度特性的影响。结果表明,专用车膜式空气弹簧的刚度呈非线性,其固有频率在车桥载荷变化范围内保持基本稳定,适于载荷变化大的专用车悬置使用。 相似文献