Double Panel Research Articles

An analytical method for the vibration characteristics of double panel structures with uniform elastic boundary supports

ABSTRACT In this paper, the methods for solving the free vibration and forced vibration of double panel structures under arbitrary boundaries are studied. Based on the Mindlin plate theory, the natural boundary between plates and plates is constrained by artificial springs, and the theoretical model of the structure is derived. The displacement function of in-plane vibration and bending vibration is expressed by a modified Fourier series expansion. The effectiveness and reliability of this method are verified by a series of numerical calculations and comparison with those of the finite element method. Through the parameter analysis, it can be seen that the vibration isolation effect can be increased by properly increasing the coupling height or making the connecting plate closer to the boundary of the bottom plate. The method presented in this paper can be used in vibration absorption and structural design of such structures.

Sound transmission of truss-based X-shaped inertial amplification metamaterial double panels

To enhance the low-frequency sound insulation performance of conventional double panels, this work proposes a truss-based X-shape inertial amplification (TXIA) metamaterial double panel. A semi-analytical method is developed for computing the sound transmission loss (STL) of the TXIA metamaterial double panel, with numerical and experimental validations confirming the convergence and accuracy of this method. To further investigate the low-frequency acoustic wave attenuation of the proposed structure, four configurations are analyzed and discussed. Numerical results indicate that, compared to conventional and equivalent mass double panels, the TXIA metamaterial double panel effectively shifts the STL peaks to lower frequencies, exhibiting higher STL amplitudes and a reduced low-STL region. Configurations incorporating different springs enhance the STL performance without altering mass or other parameters. The STL dips of the metamaterial double panel coincide with odd-odd modes of the double panel, which have higher radiation efficiencies. Parametric studies reveal that changes in the IA angle shift the dips induced by in-phase modes to lower frequencies, while increased stiffness shifts these in-phase dips to higher frequencies. The depth of the cavity between the two panels only affects the first-order anti-phase dip. Additionally, increased stiffness enhances the STL performance and introduces a new peak in the stiffness-controlled region. Due to its flexibility, the TXIA metamaterial double panel holds significant potential for industrial applications.

Improving low-frequency sound transmission loss of double panels with a plate-type acoustic metamaterial

The sound insulation performance of double-leaf partitions is crucially affected by the mass-air-mass resonance phenomenon, whose frequency reduction can shift the high sound insulation to lower frequencies. In this work, an alternative strategy for exceeding the low limit of the mass-air-mass resonance frequency of conventional double panels is proposed in terms of the effective surface mass density. An equivalent spring-mass model based on the effective medium theory is implemented to intuitively understand the characteristics. A simple double-panel metamaterial is designed by replacing one of the panels with a single-plate metamaterial attached strip masses to decrease the structural complexity. The extended semi-analytical method is applied to predict efficiently the sound transmission loss in the low-frequency range, which is verified by the coupled vibro-acoustic finite element method with excellent agreement. The results demonstrate that the proposed double-panel metamaterial can reduce the minimum of the resonant frequency without changing the areal mass density and panel spacing. The sound insulation can be significantly improved between the reduced mass-air-mass resonance and the anti-resonance frequencies. To provide a better understanding of the sound transmission loss improvement, parametric studies are conducted. The design strategy is validated through experiments conducted in an impedance tube, and the results corroborate the findings. This study is instrumental in designing double-panel partitions that require sound insulation in specific low-frequency regions.

In-plane seismic performance of precast concrete hollow-core slab panels for basement walls

In building structures, exterior basement walls should resist the soil pressure type earthquake load transmitted by the ground. Thus, the structural performance of the exterior basement walls is affected by in-plane seismic performance as well as out-of-plane load resistance. In the present study, for better constructability and cost-effectiveness of the exterior basement walls, conventional reinforced concrete walls were replaced with precast hollow core slab (HCS) panels. To investigate the in-plane earthquake load resistance of HCS for exterior basement walls, cyclic lateral loading test and numerical analysis were performed on four HCS panels with in-plane double curvature. The test and analysis results showed that the structural behavior of the HCS panels was significantly affected by the panel layout. In the test specimens using a single panel, flexural compression failure occurred at the bottom of the panel, and shear friction damage occurred at the upper and lower parts of the panel. In the test specimens using double panels, failure mode was governed by direct shear. The load-carrying capacity of the test specimens using double panels was greater than two times that of the test specimens using a single panel, because the load transfer changed from flexure into direct shear in the wall specimens using double panels. Further, to use HCS panels for exterior basement walls, a design method for prediction of in-plane seismic performance and yield displacement of HCS panels was proposed.

Vibro-acoustic coupling analysis of dynamic performance of the double panel system with mechanical links

The theoretical prediction model for the dynamic performance of a double panel system that takes into account the effect of mechanical links is developed in this paper. The double panel system is established considering both the vibro-acoustic coupling and the effect of the mechanical links between two flexible panels. Firstly, the modal characteristics of the double panel system are analyzed and compared with the results calculated by the finite element method. The accuracy and efficiency of the proposed model have been validated. Subsequently, the forced response of the double panel system under different external excitations is studied. It is shown that the mechanical link resulted in less response level of the double panel system in in low frequency range due to the structural path in the energy transmission of the double panel system. Finally, the effect of the mechanical link parameters on the dynamic performance of the double panel system is discussed. The results reveal that the stiffness coefficients, location distributions, and number of mechanical links can significantly influence the dynamic behavior of the double panel system. Therefore, the theoretical model can be used in optimization techniques to improve the sound transmission characteristics of the double panel system.

The Coupled Band Gap of the Double Panel with Periodic Attached Spring-Mass Structure

The Coupled Band Gap of the Double Panel with Periodic Attached Spring-Mass Structure

Validation of the psychosocial consequences of screening in lung cancer questionnaire in the international lung screen trial Australian cohort

BackgroundEvaluation of psychosocial consequences of lung cancer screening with LDCT in high-risk populations has generally been performed using generic psychometric instruments. Such generic instruments have low coverage and low power to detect screening impacts. This study aims to validate an established lung cancer screening-specific questionnaire, Consequences Of Screening Lung Cancer (COS-LC), in Australian-English and describe early results from the baseline LDCT round of the International Lung Screen Trial (ILST).MethodsThe Danish-version COS-LC was translated to Australian-English using the double panel method and field tested in Australian-ILST participants to examine content validity. A random sample of 200 participants were used to assess construct validity using Rasch item response theory models. Reliability was assessed using classical test theory. The COS-LC was administered to ILST participants at prespecified timepoints including at enrolment, dependent of screening results.ResultsMinor linguistic alterations were made after initial translation of COS-LC to English. The COS-LC demonstrated good content validity and adequate construct validity using psychometric analysis. The four core scales fit the Rasch model, with only minor issues in five non-core scales which resolved with modification. 1129 Australian-ILST participants were included in the analysis, with minimal psychosocial impact observed shortly after baseline LDCT results.ConclusionCOS-LC is the first lung cancer screening-specific questionnaire to be validated in Australia and has demonstrated excellent psychometric properties. Early results did not demonstrate significant psychosocial impacts of screening. Longer-term follow-up is awaited and will be particularly pertinent given the announcement of an Australian National Lung Cancer Screening Program.Trial registrationNCT02871856.

IntelliCage: the development and perspectives of a mouse- and user-friendly automated behavioral test system.

IntelliCage for mice is a rodent home-cage equipped with four corner structures harboring symmetrical double panels for operant conditioning at each of the two sides, either by reward (access to water) or by aversion (non-painful stimuli: air-puffs, LED lights). Corner visits, nose-pokes and actual licks at bottle-nipples are recorded individually using subcutaneously implanted transponders for RFID identification of up to 16 adult mice housed in the same home-cage. This allows for recording individual in-cage activity of mice and applying reward/punishment operant conditioning schemes in corners using workflows designed on a versatile graphic user interface. IntelliCage development had four roots: (i) dissatisfaction with standard approaches for analyzing mouse behavior, including standardization and reproducibility issues, (ii) response to handling and housing animal welfare issues, (iii) the increasing number of mouse models had produced a high work burden on classic manual behavioral phenotyping of single mice. and (iv), studies of transponder-chipped mice in outdoor settings revealed clear genetic behavioral differences in mouse models corresponding to those observed by classic testing in the laboratory. The latter observations were important for the development of home-cage testing in social groups, because they contradicted the traditional belief that animals must be tested under social isolation to prevent disturbance by other group members. The use of IntelliCages reduced indeed the amount of classic testing remarkably, while its flexibility was proved in a wide range of applications worldwide including transcontinental parallel testing. Essentially, two lines of testing emerged: sophisticated analysis of spontaneous behavior in the IntelliCage for screening of new genetic models, and hypothesis testing in many fields of behavioral neuroscience. Upcoming developments of the IntelliCage aim at improved stimulus presentation in the learning corners and videotracking of social interactions within the IntelliCage. Its main advantages are (i) that mice live in social context and are not stressfully handled for experiments, (ii) that studies are not restricted in time and can run in absence of humans, (iii) that it increases reproducibility of behavioral phenotyping worldwide, and (iv) that the industrial standardization of the cage permits retrospective data analysis with new statistical tools even after many years.

Analysis of the vibro-acoustic behaviors of the periodically stiffened double panel-cavity coupled system

The vibro-acoustic behaviors of the periodically stiffened double panel-cavity coupled system is analytically investigated by the energy principle, in which the coupled system is composed of double panels, cavities and stiffeners between the face panels. In the theoretical modelling, the upper and bottom panels are decomposed into incident sub-panels and radiated sub-panels, respectively. The coupling energies between the sub-panels and stiffeners are proposed in the establishment of the energy functions for the periodically stiffened double-panels structure. To ensure the convergence and continuity over the entire solution domain, the two and three dimensional improved Fourier series are respectively adopted to express the displacement functions of the structures and the sound pressure functions inside the cavities in the coupled system. The effectiveness of the theoretical modelling of the coupled system is validated by the comparision of the natural modes and vibro-acoustic responses of the periodically stiffened double panel-cavity coupled system predicted by the current method and the ones obtained from finite element method. The number of stiffened panels has great influence on the sound transmission loss of the coupled system. In addition, the effect of the coupling stiffness and the acoustic medium on the sound transmission loss of the coupled system are also discussed in the numerical analysis.

Numerical prediction of the sound transmission loss of double panel configurations with acoustic structured and poroelastic materials

The sound transmission loss of multilayer system assemblies made of Noise Control Treatments comprising metamaterials and poroelastic materials, sandwiched between two structural panels is of utmost importance in aerospace, automotive, building and several other engineering applications. The integration of acoustic metamaterials in these systems introduces a number of challenges at the level of numerical simulation in order to predict their acoustic and structural behavior. This paper presents a methodology for the numerical simulation of the sound transmission loss of structural configurations comprising acoustic metamaterials embedded in a glass wools layer, sandwiched between two elastic panels. The metamaterial is designed as a parallel assembly of four sub-metamaterials. Each of these sub-metamaterials is also a series assembly of a periodic unit cell having a neck + cavity + neck type configuration. The four sub-metamaterials are designed so that their first resonance frequencies are grouped together in order to improve the sound transmission loss at the first two natural frequencies of the double panel. The COMSOL Multiphysics finite element method solver is used. The normal incidence and diffuse field sound transmission loss numerical results are presented and discussed in comparison with results from literature for validation.

Broadening Low-Frequency Band Gap of Double-Panel Structure Using Locally Resonant Sonic Crystal Comprised of Slot-Type Helmholtz Resonators

An approach is presented to form and broaden the low-frequency band gap of the double panel structure (DPS) by using a locally resonant sonic crystal (LRSC) in this work. The LRSC is made of cylindrical Helmholtz resonators arranged on square lattice. Their designs are similar to a slot-type resonator, but have different depths of slot. Elongating the slit neck inward and distributing the depths of slots produce a broad local resonant band gap at low frequencies: an average insertion loss (IL) of 10.9 dB covering 520 Hz to 1160 Hz with a LRSC of 12 cm width. Next, the effect of porous material filled into the resonators on the local resonant band gap is evaluated. It is shown that filling of porous material into the resonators decreases the height and width of the local resonant band gap. Finally, the transmission losses (TLs) through the DPS with LRSC are calculated as a function of the incident angle of the sound wave for LRSC embedded in porous material and not. The results show that the porous material can be significantly reduce the incident angle dependency of TL through the DPS with LRSC.

Finite element modelling of transmission of TBL-induced vibrational energy through a stiffened double panel using CFD sensitivity study

Finite element modelling of transmission of TBL-induced vibrational energy through a stiffened double panel using CFD sensitivity study

Wave Propagation in a LRPC Composite Double Panel Structure with Periodically Attached Pillars and Etched Holes

The locally resonant phononic crystal (LRPC) composite double panel structure (DPS) made of a two-dimensional periodic array of a two-component cylindrical LR pillar connected between the upper and lower composite plates is proposed. The plates are composed of two kinds of materials and periodically etched holes. In order to reveal the bandgap properties of structure theoretically, the band structures, displacement fields of eigenmodes and transmission power spectrums of corresponding 8 × 8 finite structure are calculated and displayed by using finite element method (FEM). Numerical results and further analysis demonstrate that if the excitation and response points are picked on different sides of the structure, a wide band gap with low starting frequency is opened, which can be treated as the coupling between dominant vibrations of pillars and plate modes. In addition, the influences of filled-in rubber, etched hole and viscidity of soft material on band gap are studied and understood with the help of “base-spring-mass” simplified model.

Double Panel Structure for Active Control of Noise Transmission

Passive noise reduction means are commonly used to reduce noise in the industry but, unfortunately, their effectiveness is poor in the low frequency range. By applying active structural acoustic control to the enclosure walls significant improvement of the insulating properties in this frequency range can be achieved. In this paper a model of double panel structure with ASAC is presented. The structure consists of two aluminium plates separated by an air gap. Two inertial magnetoelectric actuators and two piezoceramic MFC sensors were used for controlling the structure. A multichannel FxLMS algorithm with virtual error microphone technique is used as a control algorithm. The signal of a virtual error microphone is extrapolated basing on signals from MFC sensors. Performance of this actively controlled structure for tonal signals at selected frequencies is presented in the article. During the study, a double panel structure was mounted on one wall of sound insulating enclosure located in an acoustic chamber. During the measurements local and global reduction of noise test signal was investigated.

A metaporoelastic structure that overcomes the sound insulation weaknesses of single and double panel partitions

Single and double panel partitions are well known for their sound transmission loss weaknesses in the vicinity of their structural resonances: the first mode of the finite size panel and the mass-spring-mass resonance of the double panel. In this paper, we investigate the use of a poroelastic based metamaterial to address this problem. The metamaterial is a network of poroelastic beams, the first bending mode of which is tuned at the targeted panel resonance. The porous nature of the resonators allows taking advantage of its dissipative properties stemming from the interaction between solid and fluid phases. For the double panel application, where a porous layer is generally present, the effectiveness of the poroelastic metamaterial relies on the design of its shape and mounting conditions. First, the sound transmission loss of a finite size single panel is studied experimentally in a rectangular duct under normal incidence. It is shown that the poroelastic metamaterial increases the transmission loss up to 12 dB at the first mode of the panel. Using resonators tuned at different frequencies makes it possible to spread this gain. The attenuation mechanisms are analyzed by simulation using a finite element model. Secondly, the double panel partition is investigated with a periodic finite element model using the Floquet-Bloch theorem. Finally, the impact of several parameters like airflow resistivity and filling fraction on the efficiency of the metaporoelastic structure is illustrated considering a diffuse field excitation.

이중 패널 벽체구조 무도류벽 원형 물탱크의 보강 및 구조 상세에 따른 거동특성 분석

이중 패널 벽체구조 무도류벽 원형 물탱크의 보강 및 구조 상세에 따른 거동특성 분석

Topology optimization of single and double panels for improved sound insulation in specific frequency bands

Single and double panels are commonly employed in noise control, e.g., as partitioning elements between rooms and to enclose noisy machines. In presence of narrowband disturbances, related for example to rotating machines, further improvements in sound insulation can be obtained by properly distributing the material within the area of the panels. This allows maximizing the sound Transmission Loss (TL) in the frequency band of interest by controlling structural resonances and antiresonances. In order to achieve this goal, in this work, we apply numerical topology optimization to find the optimal material thickness distribution for single and double panels. In the iterative design process, single panels are schematized through a simple mechanical Finite Element (FE) model, while double panels are modelled considering the vibroacoustic coupling between the two mechanical plates and the internal acoustic air cavity. The sound insulation properties of the designed solution are evaluated by TL computations through hybrid Finite Element-Statistical Energy Analysis (FE-SEA) simulations. The method is applied targeting different frequency bands in the audible range and focusing on practically relevant design cases, such as single and double PMMA and glazing panels.

Numerical investigation of sound transmission through single and double walls with periodic arrays of resonators

Lightweight partition walls are widely used in buildings, especially nowadays when sustainability is of a major interest. At the same time noise pollution is becoming a growing problem across the globe. All this implies the need to find possible solutions for sound insulation improvement of the lightweight partitions. This paper is focused on exploring the possibilities of exploiting the dynamic effects of periodic subwavelength arrays of resonators for sound insulation enhancement. In order to improve the sound transmission loss in a specific frequency region, periodic resonant units are tuned and introduced to single and double panels. It can be shown that the resonance mode of the resonators couples with the host plate vibration in the way of breaking the mass law and overcoming some phenomena like coincidence effect and mass-air-mass resonance. The investigation of the considered panels under acoustic field excitation is conducted using different methods. Sound transmission loss curves and dispersion diagrams are calculated. Finite element method is employed for this purpose, but also the theory of three-dimensional elasticity and well-known transfer matrix method (TMM). Several designs of resonators are proposed.

Analysis of the Vibro-Acoustic Behavior of a Stiffened Double Panel-Cavity System

An analytical solution for the vibro-acoustic behavior analysis of a stiffened double panel-cavity coupled system is presented. Unlike existing methods, this method is flexible with parameter analysis and can simulate the elastic boundary conditions of a stiffened double panel structure. The displacements of the stiffened double panel structures and the sound pressure of two inner acoustic cavities are expressed by two-dimensional (2D) and three-dimensional (3D) improved Fourier series methods, respectively. Then, the unknown coefficients of the vibro-acoustic control equation are solved by the Rayleigh–Ritz method based on the virtual works principle applied to the coupled system. In numerical results, the accuracy and effectiveness of the proposed method are validated by several comparison examples. Finally, the influence of some parameters on the vibro-acoustic behavior of the coupled system is investigated. Numerical results show that the external acoustic excitation at a certain angle can stimulate more resonant responses of the panel-cavity coupled system. This work can predict quickly the vibro-acoustic behavior of the stiffened double panel-cavity coupled system with a small truncation number. Some new results can be used as reference data for future work.

Introduction: Quo Vadis , Latin America? Human Rights, Environmental Governance and the Sustainable Development Goals

Introduction: <scp> <i>Quo Vadis</i> </scp> , Latin America? Human Rights, Environmental Governance and the Sustainable Development Goals