scholarly journals The Influence of PZT Actuators Positioning in Active Structural Acoustic Control

10.14311/968 ◽  
2007 ◽  
Vol 47 (4-5) ◽  
Author(s):  
P. Švec ◽  
V. Jandák
Keyword(s):  
Sound Field ◽  
Structural Vibration ◽  
Structural Acoustics ◽  
The Finite Element Method ◽  
Ansys Software ◽  
Structural Vibrations ◽  
Radiated Power ◽  
Acoustic Control ◽  
Radiated Sound ◽  
The Mathematical Model

This paper deals with the effect of secondary actuator positioning in an active structural acoustics control (ASAC) experiment. The ASAC approach is based on minimizing the sound radiation from structures to the far field by controlling the structural vibrations. In this article a rectangular steel plate structure was assumed with one secondary actuator attached to it. As a secondary actuator, a specially designed piezoelectric stripe actuator was used. We studied the effect of the position of the actuator on the pattern and on the radiated sound field of the structural vibration, with and without active control. The total radiated power was also measured. The experimental data was confronted with the results obtained by a numerical solution of the mathematical model used. For the solution, the finite element method in the ANSYS software package was used. 

An Efficient Approach to the Simulation of Acoustic Radiation from Large Structures with FEM

2020 ◽  
Vol 28 (04) ◽  
pp. 1950019
Author(s):  
Marc Zarnekow ◽  
Frank Ihlenburg ◽  
Thomas Grätsch
Keyword(s):  
Acoustic Radiation ◽  
High Reliability ◽  
The Finite Element Method ◽  
Practical Application ◽  
Power Functions ◽  
Structural Vibrations ◽  
Model Order ◽  
Large Structures ◽  
Radiated Power ◽  
Weakly Coupled

A new efficient method for the simulation of sound radiation from large vibrating structures with the Finite Element Method (FEM) is proposed. The acoustic radiation from the major radiating panels is simulated separately for each panel, using customized fluid domains that are weakly coupled to the vibrating structure. Thereby, a significant reduction of the model order is achieved, maintaining at the same time a high reliability of results for practical application. The pressure levels at arbitrary far-field microphone positions can be efficiently computed from the Equivalent Radiated Power functions that characterize the structural vibrations of the radiating panels.

A compact active structural acoustic control method for minimizing radiated sound power

2021 ◽  
Vol 263 (3) ◽  
pp. 3396-3406
Author(s):  
Scott Sommerfeldt
Keyword(s):  
Control Method ◽  
Acoustic Radiation ◽  
Structural Vibration ◽  
Sound Power ◽  
Flat Plates ◽  
Spatial Gradients ◽  
Acoustic Control ◽  
Radiated Sound ◽  
Radiated Sound Power ◽  
Structural Acoustic Control

Active structural acoustic control is an active control method that controls a vibrating structure in a manner that reduces the sound power radiated from the structure. Such methods focus on attenuating some metric that results in attenuated sound power, while not necessarily minimizing the structural vibration. The work reported here outlines the weighted sum of spatial gradients (WSSG) control metric as a method to attenuate structural radiation. The WSSG method utilizes a compact error sensor that is able to measure the acceleration and the acceleration gradients at the sensor location. These vibration signals are combined into the WSSG metric in a manner that is closely related to the radiated sound power, such that minimizing the WSSG also results in a minimization of the sound power. The connection between WSSG and acoustic radiation modes will be highlighted. Computational and experimental results for both flat plates and cylindrical shells will be presented, indicating that the WSSG method can achieve near optimal attenuation of the radiated sound power with a minimum number of sensors.

Active Structural Acoustic Control of an Enclosure with Multi-Flexible Plates Using Different Point Force Actuators

2014 ◽  
Vol 574 ◽  
pp. 546-550
Author(s):  
Da Lin Chen ◽  
Nan Chen
Keyword(s):  
Cooperative Control ◽  
Sound Pressure ◽  
Control Method ◽  
Sound Field ◽  
Control Effect ◽  
Acoustic Control ◽  
Flexible Plates ◽  
Point Forces ◽  
Radiated Sound ◽  
Distributed Cooperative Control

This paper analytically demonstrates the use of some point forces actuators applied on different flexible plates to reduce the radiated sound in the cavity. A rectangular enclosure involving two opposite flexible plates is considered. We want to get the dominant factors that impact the coupling effects and the noise reduction in the cavity with the ASAC method, so we make some point forces located on different plates and to compare their different control effect. The formula was derivate to calculate the sound pressure in the enclosure when there some point forces applied on the flexible plates, and then analyzed and get the simulation of the sound pressure level (SPL) response in the local cavity sound field. The paper indicated that applying distributed cooperative control method can get the better reduction of noise.

Analysing Mechanical Systems in Domestic and Foreign CAD Systems

2018 ◽  
pp. 10-17
Author(s):  
V. A. Martynyuk ◽  
V. A. Trudonoshin ◽  
V. G. Fedoruk
Keyword(s):  
Sheet Material ◽  
The Finite Element Method ◽  
Cad Systems ◽  
Cad System ◽  
Software Products ◽  
Foreign Products ◽  
Nonlinear Algebraic Systems ◽  
Software Product ◽  
Pipeline Design ◽  
The Mathematical Model

The article considers applications of foreign CAD-systems in creating the challenging projects at domestic enterprises and design bureaus. As stated in the article "... presently, there is no domestic CAD-system that could completely replace such foreign products as NX, CATIA, Credo". Besides, due to international cooperation in creating the challenging projects (for example, the project to create a modern wide-body aircraft, proposed jointly with China), it makes sense to use the worldwide known and popular CAD systems (the aforementioned NX, CATIA, Credo). Therefore, in the foreseeable future, we will still have to use foreign software products. Of course, there always remains a question of the reliability of the results obtained. Actually, this question is always open regardless of what software product is used - domestic or foreign. This question has been haunting both developers and users of CAD systems for the last 30 to 40 years. But with using domestic systems, it is much easier to identify the cause of inaccurate results and correct the mathematical models used, the methods of numerical integration applied, and the solution of systems of nonlinear algebraic systems. Everything is much more complicated if we use a foreign software product. All advertising conversations that there is a tool to make the detected errors available to the developers, remain only conversations in the real world. It is easily understandable to domestic users, and, especially, to domestic developers of similar software products. The existing development rates and competition for potential buyers dictate a rigid framework of deadlines for releasing all new versions of the product and introducing the latest developments into commercial product, etc. As a result, the known errors migrate from version to version, and many users have accepted it long ago. Especially, this concerns the less popular tools rather than the most popular applications (modules) of a CAD system. For example, in CAD systems, the "Modeling" module where geometric models of designed parts and assembly units are created has been repeatedly crosschecked. But most of the errors are hidden in applications related to the design of parts from sheet material and to the pipeline design, as well as in applications related to the analysis of moving mechanisms and to the strength or gas dynamic analysis by the finite element method.The article gives a concrete example of a moving mechanism in the analysis of which an error was detected using the mathematical model of external influence (a source of speed) in the NX 10.0 system of Siemens.

scholarly journals Research on the Manufacturing Quality of Co-Cured Hat-Stiffened Composite Structure

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2747
Author(s):  
Xiangwen Ju ◽  
Jun Xiao ◽  
Dongli Wang ◽  
Cong Zhao ◽  
Xianfeng Wang
Keyword(s):  
Composite Structures ◽  
Sound Pressure ◽  
Integration Method ◽  
Complex Geometry ◽  
Sound Field ◽  
Thickness Measurement ◽  
Curing Process ◽  
The Finite Element Method ◽  
Manufacturing Quality

The stringer-stiffened structure is widely used due to its excellent mechanical properties. Improving the manufacturing quality of stringer-stiffened structure which have complex geometry is important to ensure the bearing capacity of aviation components. Herein, composite hat-stiffened composite structures were manufactured by different filling forms and bladders with various properties, the deformation of silicone rubber bladder in co-curing process was studied by using the finite element method. The thickness measurement at different positions of the hat-stiffened structure was performed to determine the best filling form and bladder property. Moreover, in view of the detection difficulties in R-zone of stringer, numerical simulation was performed to get the sound pressure and impulse response of at the R-zone of stringer by Rayleigh integration method, and an effective equipment which could stably detect the manufacturing quality of R-zone was designed to verify the correctness of sound field simulation and realize the detection of stringer. With the optimum filling form and bladder properties, hat-stiffened composites can be manufactured integrally with improved surface quality and geometric accuracy, based on co-curing process.

Damping characteristics of a magneto-rheological damper with dual independent controllable ducts

2021 ◽  
pp. 1045389X2110188
Author(s):  
Jianqiang Yu ◽  
Xiaomin Dong ◽  
Tao Wang ◽  
Zhengmu Zhou ◽  
Yaqin Zhou
Keyword(s):  
Dynamic Range ◽  
Fluid Flows ◽  
Mr Damper ◽  
Viscous Damping ◽  
The Novel ◽  
The Finite Element Method ◽  
Damping Force ◽  
Damping Characteristics ◽  
Magneto Rheological ◽  
The Mathematical Model

This paper presents the damping characteristics of a linear magneto-rheological (MR) damper with dual controllable ducts based on numerical and experimental analysis. The novel MR damper consisting of a dual-rod cylinder system and a MR valve is used to reduce the influences of viscous damping force and improve dynamic range. Driven by the dual-rod cylinder system, MR fluid flows in the MR valve. The pressure drop of the MR valve with dual independent controllable ducts can be controlled by tuning the current of two independent coils. Based on the mathematical model and the finite element method, the damping characteristics of the MR damper is simulated. A prototype is designed and tested on MTS machine to evaluate its damping characteristics. The results show that the working states and damping force of the MR damper can be controlled by the two independent coils.

scholarly journals An Experimental Study of the Performance of a Crossed Rib Diffuser in Room Acoustic Control

2021 ◽  
Vol 11 (9) ◽  
pp. 3781
Author(s):  
Takumi Yoshida ◽  
Yasutaka Ueda ◽  
Norimasa Mori ◽  
Yumi Matano
Keyword(s):  
Sound Field ◽  
Wide Band ◽  
Scattering Coefficient ◽  
Scaled Model ◽  
One Dimensional ◽  
Broadband Absorption ◽  
Acoustic Control ◽  
Absorbing Layer ◽  
Speech Clarity ◽  
Reverberation Parameters

This paper presents a crossed rib diffuser (CRD) as an effective tool for room acoustic control. We performed an experimental investigation of its effectiveness using a specimen manufactured for this trial. The CRD is constructed by overlapping two one-dimensional (1D) periodic rib diffusers with different specifications so that they are crossed at non-right angles. The CRD achieves a higher scattering coefficient than 1D periodic rib diffusers in a wide band while maintaining the simple and friendly design of 1D periodic rib diffusers applicable to various architectural spaces. Moreover, inserting an absorbing layer between upper and lower ribs of the CRD, (CRD-A) yields a high broadband absorption coefficient. We first evaluated the random-incidence scattering coefficient of CRD using a 1/5 scaled model in comparison with those of 1D periodic diffusers assessed with a numerical method. Then, absorption coefficients for the CRD and the CRD-A were measured using a reverberation room. Subsequently, an experiment on a small meeting room with a 1D periodic rib diffuser, the CRD and the CRD-A was conducted to present performance of the CRD in room acoustic control. Impulse response measurements and evaluations of reverberation parameters (T20 and EDT) and speech clarity (D50) were conducted. Additionally, we present differences in structure of reflected sounds found for the flat wall, the CRD and the CRD-A visually using a four-channel sound field microphone.

Analysis of Hydroelectric Unit’s Upper Bracket Based on Test and FEM

2014 ◽  
Vol 721 ◽  
pp. 131-134
Author(s):  
Mi Mi Xia ◽  
Yong Gang Li
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Element Model ◽  
The Finite Element Method ◽  
Ansys Software ◽  
Element Analysis ◽  
Hydroelectric Unit ◽  
The Finite Element Analysis ◽  
Strain Rosette ◽  
The Finite Element Model

To research the load upper bracket of Francis hydroelectric unit, then established the finite-element model, and analyzed the structure stress of 7 operating condition points with the ANSYS software. By the strain rosette test, acquired the data of stress-strain in the area of stress concentration of the upper bracket. The inaccuracy was considered below 5% by analyzing the contradistinction between the finite-element analysis and the test, and match the engineering precision and the test was reliable. The finite-element method could be used to judge the stress of the upper bracket, and it could provide reference for the Structural optimization and improvement too.

Cracking Response of a Concrete Wall to Cryogenic Temperature

2015 ◽  
Vol 365 ◽  
pp. 71-76
Author(s):  
Lahlou Dahmani ◽  
Rabah Hammar ◽  
Mohamed Oussalem Mechiche
Keyword(s):  
Cryogenic Temperature ◽  
Heat Conduction Problem ◽  
Outer Wall ◽  
Distribution Data ◽  
Cryogenic Temperatures ◽  
The Finite Element Method ◽  
Ansys Software ◽  
Concrete Wall ◽  
Steel Tank ◽  
Concrete Tank

Liquefied natural gas (LNG) has the cryogenic temperature of –160°C to ensure the minimum storage volume when stored in LNG containers. Among various types of LNG storage containers, the full containment above-ground type with a double safety system (outer concrete tank and inner steel tank) is very common. Normally, the inner tank contains LNG, but when the LNG leaks from the inner tank, the outer concrete tank comes into contact with LNG. Under this accidental case, it is indispensable for the outer wall to keep the liquid tightness in order to safely contain the LNG before taking any countermeasure. It is, therefore, proposed to take up a heat conduction problem using the finite element method with the ANSYS software to obtain temperature distribution data of a concrete wall at cryogenic temperatures.

Design of an Induction Glass Melting Furnace by Means of Mathematical Modelling Using the Finite Element Method

2007 ◽  
Vol 553 ◽  
pp. 124-129 ◽  
Author(s):  
Isaac Arellano ◽  
Gabriel Plascencia ◽  
Elías Carrillo ◽  
Miguel A. Barrón ◽  
Adolfo Sánchez ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Glass Melting ◽  
Melting Furnace ◽  
The Finite Element Method ◽  
Glass Melting Furnace ◽  
High Frequencies ◽  
Harmful Emissions ◽  
The Mathematical Model ◽  
Element Method

In this paper we propose the design of a novel induction furnace for glass melting. The design is based on a mathematical analysis and performed numerically by means of the Finite Element Method. Several induction coils configurations were tested. The results from the mathematical model show that it is possible to melt glass in a furnace whose hearth is no larger than half a metre by using axial induction coils and high frequencies. This furnace configuration may result in increased glass melting rates along with the elimination of harmful emissions.

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