Expanding the teaching of single frequency vibration absorption to broadband attenuation using subordinate oscillator arrays via fettuccine pasta

Expanding the Teaching of Single Frequency Vibration Absorption to Broadband Attenuation using Subordinate Oscillator Arrays via Fettuccine Pasta

10.31224/osf.io/qb4up ◽

2020 ◽

Author(s):

Sai Tej Paruchuri ◽

Vijaya V. N. Sriram Malladi ◽

Pablo A. Tarazaga ◽

Andrew J. Kurdila

Keyword(s):

Frequency Response ◽

Degrees Of Freedom ◽

Vibration Isolation ◽

Dynamic Properties ◽

Current Work ◽

Single Frequency ◽

Engineering Structures ◽

Vibration Absorption ◽

Oscillator Arrays ◽

Modeling Clay

Dynamic vibration absorbers (DVAs) and tuned mass-dampers (TVAs) have wide-spread applications in the aerospace industry, the automotive sector, and in civil engineering structures. There are numerous designs of active and passive vibration attenuators or absorbers that isolate structural vibrations at or around the desired frequency. All these design approaches are fundamentally different ways to modify and tune the placement of the resonant frequencies of the host structure. The current work presents a novel method to passively attenuate vibration over a broad frequency bandwidth in the presence of uncertainty. An array of linear oscillators, also referred to as subordinate oscillator arrays (SOAs), are attached to a two-degrees-of-freedom structure to produce an attenuated broadband frequency response around a target frequency. SOAs can also be interpreted as an array of DVAs and in some categories, they can be considered as an approach to meta-structures. Another objective of the current work is to develop a hands-on approach to extend classroom teaching of vibration-isolation using SOAs made out of fettuccine strands and modeling clay. The frequencies of the oscillators in the array are tuned by varying the length of each strand and the mass of the modeling clay attached to its tip. Uncertainty in dynamic properties of such oscillators often results in mistuned SOAs with non-uniform frequency response function. Therefore, designing and testing fettuccine-based SOAs allows students to handle cases when structural uncertainties arise in engineering systems. Additionally, some of the work in the field of meta-structures can be modeled and represented by SOAs and this will provide a straight forward way to teach students some of these contemporary concepts.

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Stochastisation of microwave oscillations in microstrip log-periodic antenna-generator with LF noise-like modulation.

Journal of Radio Electronics ◽

10.30898/1684-1719.2021.11.12 ◽

2021 ◽

Vol 2021 (11) ◽

Author(s):

E.O. Yunevich ◽

◽

V.I. Kalinin ◽

V.D. Kotov ◽

V.E. Lyubchenko ◽

...

Keyword(s):

Field Effect ◽

Field Effect Transistors ◽

Single Frequency ◽

Power Combining ◽

Electronic Warfare ◽

Active Antennas ◽

Telecommunication Systems ◽

Wireless Telecommunication ◽

Effect Transistor ◽

Oscillator Arrays

Microwave solid-state oscillators of noise-like signals are of the great interest for wireless telecommunication systems, imaging systems and electronic warfare. In the paper, the possibility of power combining in the array of three independent noise-like oscillators is investigated. The noise-like oscillators are based on the microstrip log-periodic antennas which are integrated with field-effect transistors. As an active element, NE350184С field-effect transistor with 13.5 dB gain at 12 GHz is chosen. It was previously shown that single-frequency, multifrequency or noise-like generations are possible in the active antennas. The main factors that affect the generation type are the current in the drain-source circuit of the transistor and the distance between the antenna plane and reflecting screen. It is experimentally shown, that using of the noise-like oscillator arrays makes possible the spectrum and power combining, but the construction is not enough stable and reliable.

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An Active Dynamic Vibration Absorber for a Hand-Held Vibro-Elastography Probe

Journal of Vibration and Acoustics ◽

10.1115/1.2424982 ◽

2006 ◽

Vol 129 (1) ◽

pp. 101-112 ◽

Cited By ~ 15

Author(s):

Hassan Rivaz ◽

Robert Rohling

Keyword(s):

Single Frequency ◽

Vibration Absorber ◽

Imaging Method ◽

Vibration Source ◽

Dynamic Vibration Absorber ◽

Tissue Properties ◽

Vibration Absorption ◽

Dynamic Vibration ◽

High Level ◽

Tissue Motion

Vibro-elastography is a new medical imaging method that identifies the mechanical properties of tissue by measuring tissue motion in response to a multi-frequency external vibration source. Previous research on vibro-elastography used ultrasound to measure the tissue motion and system identification techniques to identify the tissue properties. This paper describes a hand-held probe with a combined vibration source and ultrasound transducer to implement the new method as a practical device. The device uses a proportional integral active dynamic vibration absorber with an electromagnetic actuator to counterbalance the reaction forces from contact with the tissue. Experiments show an operational frequency range of 5-20Hz, with at least 15dB vibration absorption in 0.4s for single frequency excitation. Experiments with variable frequency and amplitude excitation also show a high level of vibration absorption.

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