scholarly journals Noise Attenuation of a Duct-resonator System Using Coupled Helmholtz Resonator - Thin Flexible Structures

2021 ◽  
Vol 53 (6) ◽  
pp. 210605
Author(s):  
Iwan Prasetiyo ◽  
Gradi Desendra ◽  
Khoerul Anwar ◽  
Mohammad Kemal Agusta
Keyword(s):  
Material Properties ◽  
Bragg Reflection ◽  
Resonance Effect ◽  
Flexible Structures ◽  
Helmholtz Resonator ◽  
Flexible Structure ◽  
Noise Attenuation ◽  
Resonance Mechanism ◽  
Resonator System ◽  
Periodic Arrangement

Several studies have been devoted to increasing the attenuation performance of the Helmholtz resonator (HR). One way is by periodic coupling of HRs in a ducting system. In this study, we propose a different approach, where a membrane (or a thin flexible structure in general) is added to the air cavity of a periodic HR array in order to further enhance the attenuation by utilizing the resonance effect of the membrane. It is expected that three attenuation mechanisms will exist in the system that can enhance the overall attenuation, i.e. the resonance mechanism of the HR, the Bragg reflection of the periodic system, and the resonance mechanism of the membrane or thin flexible structure. This study found that the proposed system yields two adjacent attenuation peaks, related to the HR and the membrane respectively. Moreover, extension of the attenuation bandwidth was also observed as a result of the periodic arrangement of HRs. With the same HR parameters, the peak attenuation by the membrane is tunable by changing its material properties. However, such a system does not always produce a wider attenuation bandwidth; the resonance bandwidths of both mechanisms must overlap.

Nonlinear Torsional Vibration Absorber for Flexible Structures

2018 ◽  
Vol 86 (2) ◽  
Author(s):  
Xiao-Ye Mao ◽  
Hu Ding ◽  
Li-Qun Chen
Keyword(s):  
High Efficiency ◽  
Rotation Angle ◽  
Flexible Structures ◽  
Nonlinear Energy Sink ◽  
Flexible Structure ◽  
Vibration Absorber ◽  
Special Perturbation ◽  
Energy Sink ◽  
Simulation Parameters ◽  
Nonlinear Energy

A new kind of nonlinear energy sink (NES) is proposed to control the vibration of a flexible structure with simply supported boundaries in the present work. The new kind of absorber is assembled at the end of structures and absorbs energy through the rotation angle at the end of the structure. It is easy to design and attached to the support of flexible structures. The structure and the absorber are coupled just with a nonlinear restoring moment and the damper in the absorber acts on the structure indirectly. In this way, all the linear characters of the flexible structure will not be changed. The system is investigated by a special perturbation method and verified by simulation. Parameters of the absorber are fully discussed to optimize the efficiency of it. For the resonance, the maximum motion is restrained up to 90% by the optimized absorber. For the impulse, the vibration of the structure could attenuate rapidly. In addition to the high efficiency, energy transmits to the absorber uniaxially. For the high efficiency, convenience of installation and the immutability of linear characters, the new kind of rotating absorber provides a very good strategy for the vibration control.

A Determination of Material Properties of Flexible Structures Using EMA and FEM Analysis

2014 ◽  
Vol 693 ◽  
pp. 293-298 ◽  
Author(s):  
Rastislav Duris
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Low Cost ◽  
Flexible Structures ◽  
Fem Analysis ◽  
Element Analysis ◽  
Structural Dynamic ◽  
Vibration Data ◽  
Complex Interactions ◽  
Applied Forces

Dynamic behavior of mechanical structures results from complex interactions between applied forces and the stiffness properties of the structure. Currently, many problems of structural dynamic analysis are solved using Finite Element Method (FEM). However, in recent years, the implementation of the Fast Fourier Transform (FFT) in low cost computer-based signal analyzers has provided a powerful tool for acquisition and analysis of vibration data. This article discusses combination of two approaches to structural dynamics testing; the experimental part which is referred to as Experimental Modal Analysis (EMA), respectively the analytical part, which is realized by Finite Element Analysis (FEA). Main goal of the paper is calculation of material properties from experimentally determined modal frequencies.

Application of Improved Genetic Algorithms for Sensor and Actuator Placement of Active Flexible Structures

2006 ◽  
Author(s):  
Jingjun Zhang ◽  
Ji Zheng ◽  
Ruizhen Gao
Keyword(s):  
Design Principle ◽  
Fisher Information Matrix ◽  
Information Matrix ◽  
Flexible Structures ◽  
Optimization Method ◽  
Mode Shapes ◽  
Flexible Structure ◽  
Ansys Software ◽  
Piezoelectric Elements ◽  
Actuator Placement

In order to reduce the vibration of flexible structures, this paper developed an effective procedure to determine the location of multi-piezoelectric elements in active flexible structures. The D-optimal design principle is an optimization method which chosen by the maximum determinant of Fisher Information Matrix Criteria. Study on the mode shapes and dynamic characteristics of structure, and the mode shapes of selected structural are converted into unitary mode. In order to approach higher level of vibration control, piezoelectric patches are placed on the maximum mode strain locations of the structure. The mode shapes of flexible structure are extracted and analysed using the Ansys software, and an interface is completed between the GAs and Ansys software.

scholarly journals Geometry Effects on the Noise Reduction of Helmholtz Resonators

2012 ◽  
Author(s):  
M. Farooqui ◽  
A. Alhamoud ◽  
A. Aliuddin ◽  
S. Mekid
Keyword(s):  
Resonant Frequency ◽  
Noise Reduction ◽  
Degrees Of Freedom ◽  
Helmholtz Resonator ◽  
Shape Effect ◽  
Noise Attenuation ◽  
Two Degrees Of Freedom ◽  
Helmholtz Resonators ◽  
Geometry Effects

In this paper the effect of geometry shape of the Helmholtz resonator on its resonant frequency and on its noise attenuation capability is discussed. The theory of resonant frequency depending on the shape of the vessel of the resonator is verified analytical and numerically using COMSOL for one and two degrees of freedom. The simulation was validated experimentally and has shown very good agreements. Various shapes of the resonators were compared in arrays. A better understanding of the shape effect is shown through simulations.

Acoustic-Structure Interaction in an Adaptive Helmholtz Resonator by Compliance and Constraint

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Shichao Cui ◽  
Ryan L. Harne
Keyword(s):  
Flexible Structures ◽  
Helmholtz Resonator ◽  
Acoustic Resonator ◽  
Acoustic Energy ◽  
Coupled Resonators ◽  
Acoustic Structure ◽  
Structure Interaction ◽  
Helmholtz Resonators ◽  
Rigid Walls ◽  
Flexible Member

Abstract The acoustic energy attenuation capabilities of traditional Helmholtz resonators are enhanced by various methods, including by coupled resonators, absorbing materials, or replacement of rigid walls with flexible structures. Drawing from these concepts to envision a new platform of adaptive Helmholtz resonator, this research studies an adaptive acoustic resonator with an internal compliant structural member. The interaction between the structure and acoustic domain is controlled by compression constraint. By applying uniaxial compression to the resonator, the flexible member may be buckled, which drastically tailors the acoustic-structure interaction mechanisms in the overall system. A phenomenological analytical model is formulated and experimentally validated to scrutinize these characteristics. It is found that the compression constraint may enhance damping capabilities of the resonator by adapting the acoustic-structure interaction between the resonator and the enclosure. The area ratio of the flexible member to the resonator opening and the ratio of the fundamental natural frequency of the flexible member to that of the enclosure are discovered to have a significant influence on the system behavior. These results reveal new avenues for acoustic resonator concepts exploiting compliant internal structures to tailor acoustic energy attenuation properties.

scholarly journals Measurement of an Analyte Concentration in Test Solution by Using Helmholtz Resonator for Biosensor Applications

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1127 ◽  
Author(s):  
Yugang Chen ◽  
Yong-Hwa Park
Keyword(s):  
Resonant Frequency ◽  
Low Frequency ◽  
Helmholtz Resonator ◽  
Acoustic Resonance ◽  
Acoustic Power ◽  
Test Solution ◽  
Frequency Change ◽  
Analyte Concentration ◽  
Resonator System ◽  
Higher Sensitivity

In this paper, an indirect method of measuring an analyte concentration in a test solution using the resonant frequency change of a Helmholtz resonator is proposed, using a novel architecture of Helmholtz resonator filled with two kinds of fluids (fixed fluid and test solution). Since the analyte concentration yields changes of density and sound speed of the test solution, the resonant frequency of the proposed Helmholtz resonator is affected by the analyte concentration of the test solution. From this effect, the analyte concentration of the test solution can be measured by the spectrum of acoustic resonance of the Helmholtz resonator. The experiment was done using a 3D-printed Helmholtz resonator system with an acoustic power source and detectors, which is consistent with analytical results and showed that the analyte concentration can be measured with higher sensitivity compared to conventional cantilever-type sensors. As an example application, the possibility of measuring glucose concentration of human blood was demonstrated, showing higher sensitivity and relatively low frequency range compared to previous resonance based methods.

Design and experimental study of a new thrown robot based on flexible structure

2015 ◽  
Vol 42 (5) ◽  
pp. 441-449 ◽  
Author(s):  
Wei Wang ◽  
Shilin Wu ◽  
Peihua Zhu ◽  
Xuepeng Li
Keyword(s):  
Design Methodology ◽  
Impact Analysis ◽  
Low Cost ◽  
Flexible Structures ◽  
Flexible Structure ◽  
New Thought ◽  
Content Type ◽  
Wheeled Robot ◽  
Material Choice ◽  
Mass Spring

Purpose – The paper aims to present a new thought for design of a thrown robot based on flexible structures. The aim of the design is to reduce the weight and improve the anti-impact capability for mini thrown robot. Design/methodology/approach – A mass-spring wheeled robot model is proposed and an impact analysis is given in this paper. Some principia were derived for configuration design and material choice to get a light and robust thrown reconnaissance robot. Based on the theoretical analysis, flexible elements like flexure hinges or rubber shell were utilized to build two generation of robots that both showed excellent performances of anti-impact ability. Findings – A second-generation thrown robot (2,050 g) was developed, which could survive dropping from the height of 6 m more than 10 times without apparent damage. Originality/value – The method based on the flexible structure provides the thrown robot with high survivability from impact, as well as light weight. It can be used in the design of the mini thrown reconnaissance robot at low cost.

scholarly journals Modelling of interaction between a snow mantle and a flexible structure using a discrete element method

2002 ◽  
Vol 2 (3/4) ◽  
pp. 163-167
Author(s):  
F. Nicot ◽  
M. Gay
Keyword(s):  
Discrete Element Method ◽  
Flexible Structures ◽  
Discrete Element ◽  
New Method ◽  
Coupled Analysis ◽  
Flexible Structure ◽  
Natural Phenomena ◽  
Snow Avalanches ◽  
Element Method

Abstract. The search of improvement of protective techniques against natural phenomena such as snow avalanches continues to use classic methods for calculating flexible structures. This paper deals with a new method to design avalanche protection nets. This method is based on a coupled analysis of both net structure and snow mantle by using a Discrete Element Method. This has led to the development of computational software so that avalanche nets can be easily designed. This tool gives the evolution of the forces acting in several parts of the work as a function of the snow situation.

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