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多峰超声振动系统频率自动搜索和跟踪 总被引:1,自引:0,他引:1
在大功率超声应用中,由于超声振动系统具有多峰性,超声振动系统的频率搜索和频率跟踪非常困难。文中用实验的方法研究多峰振子与振动系统的电流电压相位和电流大小关系,以及工具头的横向尺寸与振动系统主峰频宽之间的关系。根据实验规律,文中采用相位和电流双参数对振动系统的谐振状态进行判别,并在20kHz超声塑料焊接机上进行频率搜索和频率跟踪实验,实验表明双参数频率搜索和跟踪的方法是可行。 相似文献
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根据文献 [1]提出的弯曲振动变幅杆的分析方法 ,通过大量数值计算 ,对圆截面指数形、锥形和悬链线形变幅杆弯曲振动的特性进行了研究。研究结果表明 ,变幅杆弯曲振动的频率随其长度增加而降低 ,随其直径增大而升高 ;进一步研究表明 ,尽管变幅杆谐振频率与其直径大小有关 ,但只要变幅杆两端直径比值一定 ,则其谐振频率与尺寸参数间存在一定关系 ,本文用谐振曲线描述了这一关系 ,谐振曲线对变幅杆设计以及复合振动的研究是一个非常重要的工具。最后对几种变幅杆的放大能力进行了比较 ,按从大到小的顺序依次是 :悬链线形、指数形和锥形 相似文献
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《功能材料与器件学报》2015,(4)
本文建立了针对压电复合材料的压电复合换能器耦合振动有限元模型,采用有限元方法研究了压电复合材料类型对换能器振动模态与共振频率的影响,并对换能器共振频率与压电复合材料结构几何尺寸之间的关系进行研究。结果表明:压电复合材料类型不同,换能器的振动模态振型会发生改变,并且其前两阶共振频率差值会因压电复合材料的基体材料的杨氏模量和泊松比的不同而发生变化,即共振频率差值随着基体材料杨氏模量的增大而增大,但随着泊松比的增大而减小;而且共振频率与压电复合材料的结构几何尺寸有关,即随着压电复合材料厚度的增大,换能器的纵向振动频率与弯曲振动频率都会逐渐减少,但两频率之间的间距是逐渐拉大的。 相似文献
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振动噪声的抑制是近年来开关磁阻电机研究的热门领域。根据麦克斯韦张量法理论分析了径向磁拉力减小的原理,通过在定子齿顶、转子齿两侧同时开矩形槽,增大了定转子间气隙长度的同时又将一部分沿径向方向的磁通密度改变为切向方向,减小了径向磁拉力,达到抑制电磁振动的目的。利用参数化扫描的方法,对开关磁阻电机的开槽参数进行了优化,得出开槽尺寸,并对比分析开槽前后电机的径向磁拉力。运用Ansys Workbench模块分别对定转子齿开槽前后的电机定子进行模态、谐响应以及噪声分析,得到其模态固有频率、模态参与因子、振动响应频率以及声压频谱。分析结果表明:该方法有效减小了开关磁阻电机的径向磁拉力,改善了开关磁阻电机的振动和噪声。 相似文献
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深水立管两向自由度涡激振动的数值分析 总被引:2,自引:2,他引:0
对更加符合实际情况的两向自由度涡激振动进行数值分析。研究四种不同质量比(m*=14.45,8.30,3.50和m*=1.87)情况时,流向振动与横向振动幅值和频率之间的关系。结果表明,在大质量比(m*=14.45,8.30)时,流向振动频率基本可以看做横向振动频率的2倍,并且流向振动幅值相对于横向振动幅值来说可以忽略不计,符合现有实验研究结果;当质量比较小(m*=3.50,1.87)时,顺流向振动幅值并不能被忽略,尤其在顺流向处于锁频时。两向振动的主频率基本维持2倍关系,但是除主频率外还具有相同或相似的振动频率。 相似文献
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通过瑞利的近似理论假设,对大尺寸的余弦形变幅杆的纵向振动的共振频率进行了修正,得到了修正频率表达式。利用有限元软件ANSYS对一组大尺寸的余弦变幅杆进行模态分析。并发现当R1/L〉0.5时,振动时伴随有弯曲振动或扭转振动,振动较为复杂,此时瑞利理论不再适用。但需要指出的是,与一维理论相比,修正后的值适用范围更大,因此对大尺寸的余弦形超声变幅杆的工程计算具有一定的指导意义。 相似文献
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Based on the equivalent elastic method and coupled vibration theory, an analytic method is presented to study the flexural vibration of rectangular transducers consisting of piezoelectric ceramic thin plates. By introducing a mechanical coupling coefficient, the flexural vibration of the piezoelectric ceramic rectangular thin plate is reduced to two simple, one-dimensional flexural vibrations of narrow piezoelectric ceramic strips. The resonance frequency equations for the piezoelectric ceramic rectangular thin-plate transducers in flexural vibration are derived under the free and simply supported boundary conditions analytically. The relationship between the resonance frequency and the flexural vibrational order, the geometrical shape, and the dimensions of the piezoelectric ceramic rectangular thin-plate transducer is analyzed. It is demonstrated that the one-dimensional vibrational theory for the flexural vibration of a narrow piezoelectric ceramic strip and the stripe-mode flexural vibrational theory for the piezoelectric ceramic rectangular thin plate can be derived directly from the theory obtained in this paper. Experimental results show that the measured resonance frequencies of the piezoelectric ceramic rectangular thin-plate transducers in flexural vibration under free-boundary conditions are in good agreement with the calculated results. The method presented in this paper can be used in the resonance frequency analysis of vibrating systems in coupled vibration. 相似文献
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大型土石方工程无限分段起爆技术及其应用 总被引:1,自引:0,他引:1
在盐田港一期大型土石方工程爆破施工中,为控制爆破震动和扩大爆破规模,运用了严格控制单响药量、无限分段的起爆技术。本文通过理论计算得出不同距离的保护物最大单响装药量,在起爆网路布置上采取孔内、外毫秒差和炮孔分段装药技术来控制单响药量,达到减震效果。本工程通过实际监测,得出不同距离被保护物质点最大振速与理论计算的规律基本吻合。 相似文献
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Wang Yong Huang Qibai Zhou Minggang Zhang Yongbo 《International Journal of Mechanics and Materials in Design》2006,3(1):1-6
The nonlinear force induced by spring and damping of 2-degree-of-freedom locally nonlinear vibrating system is regarded as
applied force, and its mathematical model is established in this paper. Then impulse response temporal method of linear vibrating
system is applied in the system, the response of locally nonlinear vibrating system is obtained by convolution integration
between unit impulse response of corresponding linear system and equivalent nonlinear force, and numerical simulation of the
model is attained. Finally, the feasibility of the new method on the domain of locally nonlinear vibrating system is verified
by comparing the results, which supplies a new method to solve approximately vibration response of locally nonlinear vibrating
systems. 相似文献
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运用矩阵多项式的GLR理论系统地给出阻尼陀螺系统、粘性阻尼系统及无阻尼陀螺系统的谱分解定理。以粘性阻尼系统为例,应用谱分解定理的正交性结果求解时滞状态反馈下部分极点配置问题,构造性出多输入情况下解的参数表示。 相似文献
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Arkadiusz Meżyk 《工程优选》2013,45(5):503-521
This paper presents an algorithm for minimizing the resonance amplitudes of vibrating systems with dynamic vibration dampers. Damper parameters are optimised using an objective function which describes the maximum of the resonance curve for the first resonance. The algorithm described here is based on a spectral transfer function and can be applied to multi-degree-of-freedom systems. The research makes use of models of discrete as well as discrete-continuous systems. A method for formulating minimization problems is proposed which allows global optimization using gradient procedures. Sequential linear and quadratic programming methods are used. Examples of different mechanical systems with vibration dampers are also presented. 相似文献
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采用实验与数值模拟相结合的方法研究了振动管外的流动及传热特性,利用正交设计方法分析了振幅、频率等参数对换热性能的影响,得到了低频区内换热效果与振动参数间的拟合关联式,并基于场协同理论得到了管外近壁区的协同角余弦值随频率、振幅的变化规律。通过分析发现:振动强化传热的效果随着频率和振幅的升高而显著增强,共振工况下换热最强。对比不同管型的换热性能,沿椭圆管短轴方向振动的传热效果最好,圆管次之,长轴最差,证明管型也为影响振动工况下对流换热性能的重要参数。 相似文献
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Summary In the paper a coupled response–degradation problem for a nonlinear vibrating system is analyzed. The analysis allows to account
for the effect of stiffness degradation (during the vibration process) on the response and, in the same time, gives the actual
stress values for estimation of damage accumulating in the system. The paper constitutes an extension of the approach (a sequential
characterization of the degradation random process) presented in [4] to vibrating systems with nonlinear restoring term.
Dedicated to Professor Franz Ziegler on the occasion of his 70th birthday 相似文献