A chirp excitation for focussing flexural waves
A chirp excitation for focussing flexural waves
复制标题
用于聚焦弯曲波的啁啾激励
DOI：
10.1016/j.jsv.2018.07.028
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发表时间：
2019
影响因子：
4.7
通讯作者：
Waters T
中科院分区：
文献类型：
--
作者：
Waters T
在本文中，利用弯曲波的色散性质在波导上的任意位置产生冲击响应。输入波形是上行线性调频脉冲，其瞬时频率经过选择以确保同步到达任意焦点。在给定色散关系的先验知识的情况下，导出了所需线性调频脉冲波形作为带宽和焦点位置的函数的解析表达式。该原理通过均匀光束的解析模型进行了说明。模拟结果表明，理论上，由于谐波激励，有可能实现比稳态响应大至少一个数量级的峰值响应。此外，当阻尼可以忽略不计时，峰值响应大约随着距激励点的距离的平方根而增加。速度、加速度、法向应变和剪切应力在性质上表现出相似的结果，但由于它们对输入的频率响应不同而在数量上有所不同。将电动振动台的单自由度模型耦合到分析梁模型，以便预测线性调频波形的每个峰值输入电压的峰值机械响应。然后通过频率响应和瞬态测量对耦合机电模型进行实验验证。该技术可能适用于需要使用最少的仪器在梁或板状结构上产生大且合理局部瞬态响应的情况。
In this paper, the dispersive nature of flexural waves is exploited to generate a shock response at an arbitrary location on a waveguide. The input waveform is an up-chirp whose instantaneous frequency is chosen to ensure synchronous arrival at an arbitrary focal point. An analytical expression is derived for the required chirp waveform as a function of bandwidth and focal point location given prior knowledge of the dispersion relation.The principle is illustrated for an analytical model of a uniform beam. Simulated results show that it is possible, in theory, to achieve peak responses that are at least an order of magnitude larger than steady state response due to harmonic excitation. Further, the peak response increases with approximately the square root of distance from the point of excitation when damping is negligible. Velocity, acceleration, normal strain and shear stress exhibit qualitatively similar results which differ quantitatively owing to their different frequency responses with respect to the input.A single degree-of-freedom model of an electrodynamic shaker is coupled to the analytical beam model in order to predict peak mechanical responses per peak input voltage of the chirp waveform. The coupled electromechanical model is then validated experimentally through both frequency response and transient measurements. The technique is potentially applicable to situations where a large and reasonably localised transient response is required on a beam or plate-like structure using minimal instrumentation.
影响因子：
3.7
作者：
Lütkenhöner B
通讯作者：
Lütkenhöner B
DOI：
--
发表时间：
2012
期刊：
影响因子：
--
作者：
Steven Dion;Louis;M. Brouillette
通讯作者：
M. Brouillette
影响因子：
4.2
作者：
Michaels, Jennifer E.;Lee, Sang Jun;Wilcox, Paul D.
通讯作者：
Wilcox, Paul D.