scholarly journals Low-Frequency Vibration Modes of Strongly Inhomogeneous Elastic Laminates

2018 ◽  
Vol 18 (4) ◽  
pp. 447-457
Author(s):  
J. D. Kaplunov ◽  
Keyword(s):  
Low Frequency ◽  
Vibration Modes ◽  
Low Frequency Vibration

Origami-Based Bistable Metastructures for Low-Frequency Vibration Control

2021 ◽  
Vol 88 (5) ◽  
Author(s):  
Mingkai Zhang ◽  
Jinkyu Yang ◽  
Rui Zhu
Keyword(s):  
Vibration Isolation ◽  
Energy Analysis ◽  
Geometrical Nonlinearity ◽  
Low Frequency ◽  
Quantitative Relationship ◽  
Vibration Modes ◽  
Two Dimensional ◽  
Low Frequency Vibration ◽  
Dynamic Experiments ◽  
Unit Cells

Abstract In this research, we aim to combine origami units with vibration-filtering metastructures. By employing the bistable origami structure as resonant unit cells, we propose metastructures with low-frequency vibration isolation ability. The geometrical nonlinearity of the origami building block is harnessed for the adjustable stiffness of the metastructure’s resonant unit. The quantitative relationship between the overall stiffness and geometric parameter of the origami unit is revealed through the potential energy analysis. Both static and dynamic experiments are conducted on the bistable origami cell and the constructed beam-like metastructure to verify the adjustable stiffness and the tunable vibration isolation zone, respectively. Finally, a two-dimensional (2D) plate-like metastructure is designed and numerically studied for the control of different vibration modes. The proposed origami-based metastructures can be potentially useful in various engineering applications where structures with vibration isolation abilities are appreciated.

Investigation of Nonlinear Vibro-Acoustic Wave Modulation Mechanisms in Composite Laminates

2013 ◽  
Vol 569-570 ◽  
pp. 96-102 ◽  
Author(s):  
Łukasz Pieczonka ◽  
Wieslaw Jerzy Staszewski ◽  
Tadeusz Uhl
Keyword(s):  
Acoustic Wave ◽  
Composite Laminates ◽  
Low Frequency ◽  
Laminate Plate ◽  
Mode Shapes ◽  
Vibration Modes ◽  
Low Frequency Vibration ◽  
Composite Laminate Plate ◽  
Thermographic Camera ◽  
Frequency Excitation

This paper investigates the effect of low-frequency vibration and the related temperature field on nonlinear vibro-acoustic wave modulations. Experimental modal analysis was used to find natural frequencies and mode shapes of a composite laminate plate with seeded delamination. Temperature distribution was analyzed with a thermographic camera in the vicinity of damage for the identified vibration modes. These frequencies of these vibration modes were then used for low-frequency excitation in nonlinear acoustic tests. The correlation between the thermal field and the observed wave modulations was analyzed.

Extremely low frequency band gaps of beam-like inertial amplification metamaterials

2017 ◽  
Vol 31 (27) ◽  
pp. 1750251 ◽  
Author(s):  
Mingming Hou ◽  
Jiu Hui Wu ◽  
Songhua Cao ◽  
Dong Guan ◽  
Yanwei Zhu
Keyword(s):  
Frequency Band ◽  
Low Frequency ◽  
Band Gaps ◽  
Vibration Modes ◽  
Resonance Theory ◽  
Local Resonance ◽  
Extremely Low Frequency ◽  
Low Frequency Vibration ◽  
Potential Applications ◽  
Amplification Mechanism

In this paper, extremely low frequency band gaps of beam-like inertial amplification metamaterials are investigated based on local resonance theory. Inertial amplification mechanism is proposed to obtain extremely low frequency band gaps by altering geometry parameters of the beam-like structures rather than modulating material properties, which allow first lower band gap (BG) to be attained easily compared to traditional local resonance structures. Band structures, frequency response functions (FRFs) plots and vibration modes of the beam-like structures are calculated and analyzed by employing finite element method. Numerical results show that first BG of the structure ranges from 23 Hz to 21 Hz. FRFs are in accordance with the dispersion relationship. It is found that interaction between inertial amplification and traveling wave modes in the proposed structure are responsible for formation of the first BG. This type of beam-like inertial amplification metamaterials has many potential applications in the field of low frequency vibration and noise reduction.

scholarly journals Enhanced Piezoelectric Shunt Design

2003 ◽  
Vol 10 (2) ◽  
pp. 127-133 ◽  
Author(s):  
Chul H. Park ◽  
Daniel J. Inman
Keyword(s):  
Vibration Mode ◽  
Vibration Suppression ◽  
Vibration Reduction ◽  
Low Frequency ◽  
Internal Resistance ◽  
Vibration Modes ◽  
Low Frequency Vibration ◽  
Design Resistance ◽  
Piezoelectric Shunt ◽  
Shunt Circuit

Piezoceramic material connected to an electronic shunt branch circuit has formed a successful vibration reduction device. One drawback of the conventional electronic shunt circuit is the large inductance required when suppressing low frequency vibration modes. Also, the large internal resistance associated with this large inductance exceeds the optimal design resistance needed for low frequency vibration suppression. To solve this problem, a modified and enhanced piezoelectric shunt circuit is designed and analyzed by using mechanical-electrical analogies to present the physical interpretation. The enhanced shunt circuit developed in this paper is proved to significantly reduce the targeted vibration mode of a cantilever beam, theoretically and experimentally.

A Study on the Fine Structure of the Lateral Line Organ of the Sea Eel

1973 ◽  
Vol 31 ◽  
pp. 648-649
Author(s):  
K. Hama
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Lateral Line ◽  
Low Frequency ◽  
Sensory Cells ◽  
Apical Surface ◽  
Voltage Electron ◽  
Sensory Epithelia ◽  
Low Frequency Vibration ◽  
Transmission Electron

The lateral line organs of the sea eel consist of canal and pit organs which are different in function. The former is a low frequency vibration detector whereas the latter functions as an ion receptor as well as a mechano receptor.The fine structure of the sensory epithelia of both organs were studied by means of ordinary transmission electron microscope, high voltage electron microscope and of surface scanning electron microscope.The sensory cells of the canal organ are polarized in front-caudal direction and those of the pit organ are polarized in dorso-ventral direction. The sensory epithelia of both organs have thinner surface coats compared to the surrounding ordinary epithelial cells, which have very thick fuzzy coatings on the apical surface.

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