Active feedforward control of flexural waves in an Acoustic Black Hole terminated beam
Active feedforward control of flexural waves in an Acoustic Black Hole terminated beam
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DOI：
10.1088/1361-665x/abd90f
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发表时间：
2021-01
影响因子：
4.1
通讯作者：
J. Cheer;K. Hook;S. Daley
中科院分区：
文献类型：
--
作者：
J. Cheer;K. Hook;S. Daley
声学黑洞(ABH)是一种结构特征，通常是通过在结构中引入锥形厚度分布来实现的，这会导致局部波速降低和结构阻尼的相应增强。在理想的理论情况下，当ABH逐渐减小到零厚度时，波速为零，进入ABH的波可以被完全吸收。然而，在实际实现中，ABH锥度的厚度和波速仍然是有限的。在这种情况下，为了获得高水平的结构阻尼，ABH通常与被动阻尼材料相结合，例如粘弹性层。本文研究了在梁式ABH中用主动振动控制(AVC)系统取代互补的被动减振材料，从而产生主动ABH(AABH)的潜在性能改进。因此，所提出的智能结构由一个压电贴片致动器和一个基于波的前馈AVC策略组成，前者被集成到ABH锥体中以代替被动阻尼，后者旨在最小化宽带弯曲波反射系数。为了评估所提出的AABH的相对性能，还将相同的AVC策略应用于具有等厚度终端的梁。实验结果表明，AABH系统的宽带性能与基于等厚度梁的AVC系统相当，但计算量和控制量都较小，具有显著的实用价值。
Acoustic Black Holes (ABHs) are structural features that are typically realised by introducing a tapering thickness profile into a structure that results in local regions of wave-speed reduction and a corresponding enhancement in the structural damping. In the ideal theoretical case, where the ABH tapers to zero thickness, the wave-speed reaches zero and the wave entering the ABH can be perfectly absorbed. In practical realisations, however, the thickness of the ABH taper and thus the wave-speed remain finite. In this case, to obtain high levels of structural damping, the ABH is typically combined with a passive damping material, such as a viscoelastic layer. This paper investigates the potential performance enhancements that can be achieved by replacing the complementary passive damping material with an active vibration control (AVC) system in a beam-based ABH, thus creating an active ABH (AABH). The proposed smart structure thus consists of a piezo-electric patch actuator, which is integrated into the ABH taper in place of the passive damping, and a wave-based, feedforward AVC strategy, which aims to minimise the broadband flexural wave reflection coefficient. To evaluate the relative performance of the proposed AABH, an identical AVC strategy is also applied to a beam with a constant thickness termination. It is demonstrated through experimental implementation, that the AABH is able to achieve equivalent broadband performance to the constant thickness beam-based AVC system, but with a lower computational requirement and a lower control effort, thus offering significant practical benefits.