scholarly journals Tailoring Plate Thickness of a Helmholtz Resonator for Improved Sound Attenuation

2016 ◽  
Author(s):  
Mohammad Kurdi ◽  
Shahin Nudehi ◽  
Gregory Scott Duncan
Keyword(s):  
Transmission Loss ◽  
Plate Thickness ◽  
Helmholtz Resonator ◽  
Element Model ◽  
Flexible Plate ◽  
End Plate ◽  
Receptance Coupling ◽  
Coupling Techniques ◽  
Gradient Based ◽  
Optimization Search

A Helmholtz resonator with flexible plate attenuates noise in exhaust ducts, and the transmission loss function quantifies the amount of filtered noise at a desired frequency. In this work the transmission loss is maximized (optimized) by allowing the resonator end plate thickness to vary for two cases: 1) a non-optimized baseline resonator, and 2) a resonator with a uniform flexible endplate that was previously optimized for transmission loss and resonator size. To accomplish this, receptance coupling techniques were used to couple a finite element model of a varying thickness resonator end plate to a mass-spring-damper model of the vibrating air mass in the resonator. Sequential quadratic programming was employed to complete a gradient based optimization search. By allowing the end plate thickness to vary, the transmission loss of the non-optimized baseline resonator was improved significantly, 28 percent. However, the transmission loss of the previously optimized resonator for transmission loss and resonator size showed minimal improvement.

scholarly journals Tailoring Plate Thickness of a Helmholtz Resonator for Improved Sound Attenuation

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Mohammad Kurdi ◽  
Shahin Nudehi ◽  
Gregory Scott Duncan
Keyword(s):  
Transmission Loss ◽  
Plate Thickness ◽  
Helmholtz Resonator ◽  
Element Model ◽  
End Plate ◽  
Receptance Coupling ◽  
Coupling Techniques ◽  
Minimal Improvement ◽  
Gradient Based ◽  
Optimization Search

In this work, the transmission loss of a Helmholtz resonator is maximized (optimized) by allowing the resonator end plate thickness to vary for two cases: (1) a nonoptimized baseline resonator and (2) a resonator with a uniform flexible endplate that was previously optimized for transmission loss and resonator size. To accomplish this, receptance coupling techniques were used to couple a finite element model of a varying thickness resonator end plate to a mass-spring-damper model of the vibrating air mass in the resonator. Sequential quadratic programming was employed to complete a gradient-based optimization search. By allowing the end plate thickness to vary, the transmission loss of the nonoptimized baseline resonator was improved significantly, 28%. However, the transmission loss of the previously optimized resonator for transmission loss and resonator size showed minimal improvement.

Optimal Design of a Helmholtz Resonator With a Flexible End Plate

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Mohammad H. Kurdi ◽  
G. Scott Duncan ◽  
Shahin S. Nudehi
Keyword(s):  
Transmission Loss ◽  
Helmholtz Resonator ◽  
Design Parameters ◽  
Flexible Plate ◽  
Frequency Range ◽  
End Plate ◽  
Pareto Curve ◽  
Resonator Design ◽  
Optimization Formulation ◽  
Design Solutions

This paper describes a design process that produces a small volume Helmholtz resonator capable of achieving high transmission loss across a desired frequency range. A multiobjective optimization formulation was used to design a Helmholtz resonator with a flexible end plate. The optimization formulation generated a Pareto curve of design solutions that quantify the trade-off between the optimization goals: minimum resonator volume and maximum transmission loss across a specified frequency range. The optimization problem was formulated and solved in the following manner. First, a mathematical formulation for the transmission loss of the Helmholtz resonator with a flexible plate was completed based on the resonator design parameters. Then, the weighted transmission loss across a specified frequency range and a minimum resonator volume were defined as optimization objectives. Finally, the Pareto curve of optimum design solutions was calculated using a gradient-based approach via the ɛ-constraint method. The optimization results allow the designer to select resonator design parameters that meet the requirements for both transmission loss and resonator volume. To validate the optimization results, two optimal Helmholtz resonators were manufactured and experimentally confirmed.

Modeling and Experimental Investigation of a Helmholtz Resonator With a Flexible Plate

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Shahin S. Nudehi ◽  
G. Scott Duncan ◽  
Umar Farooq
Keyword(s):  
Experimental Investigation ◽  
Transmission Loss ◽  
Helmholtz Resonator ◽  
Single Frequency ◽  
Flexible Plate ◽  
Resonant Frequencies ◽  
Response Characteristics ◽  
Receptance Coupling ◽  
Frequency Response Characteristics ◽  
Plate Assembly

A Helmholtz resonator with a uniform, flexible end plate is studied in this work. This work shows that the flexible plate modifies the frequency response characteristics of the resonator, providing multiple distinct resonant frequencies instead of a single resonant frequency. Therefore, acoustical transmission loss will increase at each of the multiple resonant frequencies of the resonator and plate assembly versus at a single frequency for the unmodified Helmholtz resonator. By using receptance coupling as the modeling approach, the receptance of the Helmholtz resonator and flexible plate assembly is predicted by coupling receptance models of an unmodified Helmholtz resonator and a clamped plate. Finally, the predicted receptance of the Helmholtz resonator and flexible plate assembly is compared against experimental results.

Optimal Design of a Helmholtz Resonator With a Flexible End Plate

2012 ◽  
Author(s):  
Mohammad H. Kurdi ◽  
G. Scott Duncan ◽  
Shahin S. Nudehi
Keyword(s):  
Transmission Loss ◽  
Mathematical Formulation ◽  
Helmholtz Resonator ◽  
Design Parameters ◽  
Flexible Plate ◽  
Frequency Range ◽  
End Plate ◽  
Pareto Curve ◽  
Optimization Formulation ◽  
Design Solutions

A multi-objective optimization formulation to design a Helmholtz resonator with a flexible end plate is studied. The optimization formulation generates a Pareto curve of design solutions that quantify the trade-off between the optimization goals: minimum resonator volume and maximum transmission loss across a specified frequency range. The optimization problem is formulated and solved in the following manner. First, a mathematical formulation for the transmission loss of the Helmholtz resonator with a flexible plate is completed based on the design parameters. Then, the weighted transmission loss across a specified frequency range and a minimum resonator volume are defined as optimization objectives. Finally, the Pareto curve of optimum design solutions is calculated using a gradient-based approach via the ε-constraint method. The optimization results allow the designer to select resonator design parameters that meet the requirements for both transmission loss and resonator volume. To validate the optimization results, one optimal Helmholtz resonator is manufactured and experimentally confirmed.

scholarly journals Analysis of the Behaviour of Semi Rigid Steel End Plate Connections

2018 ◽  
Vol 149 ◽  
pp. 02058
Author(s):  
A. Bahaz ◽  
S. Amara ◽  
J.P. Jaspart ◽  
J.F. Demonceau
Keyword(s):  
Finite Element ◽  
Plate Thickness ◽  
Three Dimensional ◽  
Element Model ◽  
Rotational Behaviour ◽  
Building Structures ◽  
Element Analysis ◽  
End Plate ◽  
Plate Connections ◽  
Three Dimensional Finite Element

The analysis of steel-framed building structures with full strength beam to column joints is quite standard nowadays. Buildings utilizing such framing systems are widely used in design practice. However, there is a growing recognition of significant benefits in designing joints as partial strength/semi-rigid. The design of joints within this partial strength/semi-rigid approach is becoming more and more popular. This requires the knowledge of the full nonlinear moment-rotation behaviour of the joint, which is also a design parameter. The rotational behaviour of steel semi rigid connections can be studied using the finite element method for the following three reasons: i) such models are inexpensive; ii) they allow the understanding of local effects, which are difficult to measure accurately physically, and iii) they can be used to generate extensive parametric studies. This paper presents a three-dimensional finite element model using ABAQUS software in order to identify the effect of different parameters on the behaviour of semi rigid steel beam to column end plate connections. Contact and sliding between different elements, bolt pretension and geometric and material non-linearity are included in this model. A parametric study is conducted using a model of two end-plate configurations: flush and extended end plates. The studied parameters were as follows: bolts type, end plate thickness and column web stiffener. Then, the model was calibrated and validated with experimental results taken from the literature and with the model proposed by Eurocode3. The procedure for determining the moment–rotation curve using finite element analysis is also given together with a brief explanation of how the design moment resistance and the initial rotational stiffness of the joint are obtained.

Finite Element Analysis and Optimization of Long-Span Gantry NC Machining Center Structure

2011 ◽  
Vol 346 ◽  
pp. 379-384
Author(s):  
Shu Bo Xu ◽  
Yang Xi ◽  
Cai Nian Jing ◽  
Ke Ke Sun
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Design Method ◽  
Dynamic Performance ◽  
Plate Thickness ◽  
Element Model ◽  
Wall Structure ◽  
Characteristic Analysis ◽  
Element Analysis ◽  
Dynamic Performance Analysis

The use of finite element theory and modal analysis theory, the structure of the machine static and dynamic performance analysis and prediction using optimal design method for optimization, the new machine to improve job performance, improve processing accuracy, shorten the development cycle and enhance the competitiveness of products is very important. Selected for three-dimensional CAD modeling software-UG NX4.0 and finite element analysis software-ANSYS to set up the structure of the beam finite element model, and then post on the overall structure of the static and dynamic characteristic analysis, on the basis of optimized static and dynamic performance is more superior double wall structure of the beam. And by changing the wall thickness and the thickness of the inner wall, as well as the reinforcement plate thickness overall sensitivity analysis shows that changes in these three parameters on the dynamic characteristics of post impact. Application of topology optimization methods, determine the optimal structure of the beam ultimately.

Numerical study for increasement of low frequency sound insulation of double-panel structure using sonic crystals with distributed Helmholtz resonators

2019 ◽  
Vol 33 (14) ◽  
pp. 1950138
Author(s):  
Myong-Jin Kim
Keyword(s):  
Free Space ◽  
Transmission Loss ◽  
Numerical Study ◽  
Low Frequency ◽  
Helmholtz Resonator ◽  
Sound Insulation ◽  
The Finite Element Method ◽  
Helmholtz Resonators ◽  
Sonic Crystal ◽  
Sonic Crystals

Numerical simulations of the sound transmission loss (STL) of a double-panel structure (DPS) with sonic crystal (SC) comprised of distributed local resonators are presented. The Local Resonant Sonic Crystal (LRSC) consists of “C”-shaped Helmholtz resonator columns with different resonant frequencies. The finite element method is used to calculate the STL of such a DPS. First, the STLs of LRSC in free space and the DPS with LRSC are calculated and compared. It is shown that the sound insulations of the local resonators inserted in the double panel are higher than that in free space for the same size of the SCs and the same number of columns. Next, STL of the DPS in which the SC composed of three columns of local resonators having the same outer and inner diameters but different slot widths are calculated, and a reasonable arrangement order is determined. Finally, the soundproofing performances of DPS with distributed LRSC are compared with the case of insertion of general cylindrical SC for SC embedded in glass wool and not. The results show that the sound insulation of the DPS can be significantly improved in the low frequency range while reducing the total mass without increasing the thickness.

Investigating the Effects of Fibrous Material Compression on the Acoustical Behavior of Absorption and Barrier Materials

2006 ◽  
Vol 129 (2) ◽  
pp. 133-140 ◽  
Author(s):  
A. R. Ohadi ◽  
M. Moghaddami
Keyword(s):  
Absorption Coefficient ◽  
Fibrous Material ◽  
Transmission Loss ◽  
Element Model ◽  
Physical Parameters ◽  
Fibrous Materials ◽  
Barrier Materials ◽  
Rigid Frame ◽  
Absorbing Materials ◽  
The Galerkin Method

This paper discusses the effects of compression on acoustical performance of fibrous materials. A finite element model is used to predict the absorption coefficient and transmission loss of absorbing and barrier materials. This model is developed based on the Galerkin method and includes the equation of wave propagation in rigid frame porous material. The compression of fibrous material is entered to the model with relations that explain modifications of physical properties used in the wave equation. Acoustical behavior of absorption and barrier materials with and without compression is studied. It is shown that compression of the material leads to reduction of the transmission loss of the barrier materials and absorption coefficient of absorbing materials. In this regard, “thickness reduction” and “variations of physical parameters” due to compression are investigated.

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