Wave Propagation and Power Flow Analysis of Sandwich Structures With Internal Absorbers

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
J. S. Chen ◽  
R. T. Wang
Keyword(s):  
Wave Propagation ◽  
Power Flow ◽  
Wave Attenuation ◽  
Sandwich Structures ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Continuum Models ◽  
Sandwich Beams ◽  
The Core ◽  
In Series

This study examines wave attenuation and power flow characteristics of sandwich beams with internal absorbers. Two types of absorbing systems embedded in the core are considered, namely, a conventional spring-mass-dashpot system having a mass with a spring and a dashpot in parallel, and a relaxation system containing an additional relaxation spring added in series with the dashpot. Analytical continuum models used for interpreting the attenuation behavior of sandwich structures are presented. Through the analysis of the power flowing into the structure, the correlation of wave attenuation and energy blockage is revealed. The reduction in the power flow indicates that some amount of energy produced by the external force can be effectively obstructed by internal absorbers. The effects of parameters on peak attenuation, bandwidth, and power flow are also studied.

Wave Propagation in Sandwich Structures With Multiresonators

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
J. S. Chen ◽  
Y. J. Huang
Keyword(s):  
Wave Propagation ◽  
Timoshenko Beam ◽  
Degrees Of Freedom ◽  
Wave Attenuation ◽  
Sandwich Beam ◽  
Sandwich Beams ◽  
Central Frequency ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
In Series

A new sandwich beam with embedded multiresonators is presented. Two continuum Timoshenko beam models are adopted for modeling sandwich beams. Numerical results show that multiple resonators can lead to multiple resonant-type bandgaps with remarkable wave attenuation. The effective mass is found to become negative for frequencies in the bandgaps where the wave is greatly attenuated. With two identical resonators connected in parallel, only one single bandgap can be found. If two resonators with equal masses and springs are connected in series, the central frequency of the second bandgap is approximated twice of the central frequency of the first gap. For the beam with series-connected resonators, a simple two degrees-of-freedom system is proposed and used for predicting the initial frequencies of the bandgaps while for the beam with resonators in parallel, two separate single degree-of-freedom systems are introduced.

Experimental investigations on the sandwich composite beams and panels with elastomeric foam core

2017 ◽  
Vol 21 (3) ◽  
pp. 865-894 ◽  
Author(s):  
AR Nazari ◽  
H Hosseini-Toudeshky ◽  
MZ Kabir
Keyword(s):  
Carrying Capacity ◽  
Sandwich Structures ◽  
Failure Mechanisms ◽  
Composite Beams ◽  
Core Material ◽  
Foam Core ◽  
Sandwich Beams ◽  
Load Carrying Capacity ◽  
The Core ◽  
Load Carrying

In this paper, the load-carrying capacity and failure mechanisms of sandwich beams and panels with elastomeric foam core and composite laminate face sheets are investigated. For this purpose, the flexural behavior of laminated composite beams and panels (applied as face sheets) is firstly investigated under three-point bending and central concentrated loads, respectively. Then, the same examination is conducted for the sandwich beams and panels, in which the proposed elastomeric foam is utilized as the core material. It is shown that the failure mechanisms which are associated to the core in the sandwich structures with crushable foams are not considered in the examined sandwich structures. The collapse of the sandwich specimens, examined here, is observed due to the failure of the skins in some steps. By multi-step collapse of these specimens via separately failure of the top and bottom skins, a considerable amount of energy is absorbed between these steps. Due to non-brittle behavior of the core material under loading, a large compression resistance is observed after failure of the top skin which led to the recovery of the load-carrying capacity in the sandwich beams. A similar behavior for the sandwich panels led to the increase of the ultimate strength after appearance of the failure lines on the top skin. The general outcomes of this investigation promise a good influence for the application of elastomeric foam as core material for sandwich structures.

Refined Theories for the Dynamic Analysis of Sandwich Structures

2017 ◽  
Author(s):  
Serge Abrate
Keyword(s):  
Wave Propagation ◽  
Dynamic Analysis ◽  
Dynamic Loading ◽  
Sandwich Structures ◽  
Harmonic Wave ◽  
Dispersion Relations ◽  
Sandwich Beams ◽  
New Models ◽  
The Individual ◽  
Selection Of

The objective of this study is to give an overview of existing theories for analyzing the behavior of sandwich beams and plates and to develop an approach for evaluating their behavior under dynamic loading. The dispersion relations for harmonic wave propagation through sandwich structures are shown to be a sound basis for evaluating whether the individual layers are modeled properly. The results provide a guide in the selection of existing models or the development of new models.

An Investigation of Vibrational Power Flow in One-Dimensional Dissipative Phononic Structures

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
H. Al Ba'ba'a ◽  
M. Nouh
Keyword(s):  
Wave Propagation ◽  
Power Flow ◽  
Vibration Suppression ◽  
Wave Attenuation ◽  
External Disturbance ◽  
Stop Band ◽  
Bragg Scattering ◽  
Spatial Propagation ◽  
The Individual ◽  
Vibrational Power Flow

Owing to their ability to block propagating waves at certain frequencies, phononic materials of self-repeating cells are widely appealing for acoustic mitigation and vibration suppression applications. The stop band behavior achieved via Bragg scattering in phononic media is most commonly evaluated using wave propagation models which predict gaps in the dispersion relations of the individual unit cells for a given frequency range. These models are in many ways limited when analyzing phononic structures with dissipative constituents and need further adjustments to account for viscous damping given by complex elastic moduli and frequency-dependent loss factors. A new approach is presented which relies on evaluating structural intensity parameters, such as the active vibrational power flow in finite phononic structures. It is shown that the steady-state spatial propagation of vibrational power flow initiated by an external disturbance reflects the wave propagation pattern in the phononic medium and can thus be reverse engineered to numerically predict the stop band frequencies for different degrees of damping via a stop band index (SBI). The treatment is shown to be very effective for phononic structures with viscoelastic components and provides a clear distinction between Bragg scattering effects and wave attenuation due to material damping. Since the approach is integrated with finite element methods, the presented analysis can be extended to two-dimensional lattices with complex geometries and multiple material constituents.

Vibrational Power Flow Analysis of Stiffened Plate and Shell Structures

2011 ◽  
Vol 66-68 ◽  
pp. 1897-1901 ◽  
Author(s):  
Xiang Zhu ◽  
Gong Yu Xiao ◽  
Tian Yun Li ◽  
Xiao Fang Hu
Keyword(s):  
Cylindrical Shell ◽  
Power Flow ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Input Power ◽  
Shell Structures ◽  
Stiffened Plate ◽  
Simply Supported ◽  
Plate And Shell ◽  
Flow Vectors

In this paper, the vibration and power flow characteristics of stiffened plate and cylindrical shell structures are investigated by using finite element method. The power flow formulas of basic shell structural elements are given at first. Then a simply supported plate and stiffened plate’s input power flow characteristics and power flow vectors are investigated. The effects of stiffeners in plates are discussed. For a simply supported cylindrical shell, the influence of the structural damping, viscous damper and stiffeners on the cylindrical shell’s input power flow characteristics and propagated power flow characteristics are discussed in detail. The power flow vectors are visualized to reveal the distribution of energy in the shell structures. Some useful conclusions are drown and helpful for the vibration control of plate and shell structures.

scholarly journals A Three-Phase Weather-Dependent Power Flow Approach for 4-Wire Multi-Grounded Unbalanced Microgrids with Bare Overhead Conductors

2020 ◽  
Author(s):  
Evangelos Pompodakis
Keyword(s):  
Power Flow ◽  
Low Voltage ◽  
Flow Analysis ◽  
Single Layer ◽  
Distribution Networks ◽  
Medium Voltage ◽  
The Core ◽  
Magnetic Effects ◽  
Three Phase ◽  
The Impact

<p><b>Conventional power flow (CPF) algorithms assume that the network resistances and reactances remain constant regardless of the weather and loading conditions. Although the impact of the weather in power flow analysis has been recently investigated via the weather-dependent power flow (WDPF) approaches, the magnetic effects in the core of ACSR conductors have not been explicitly considered. ACSR conductors are widely used in distribution networks. Therefore, this manuscript proposes a three-phase weather-dependent power flow algorithm for 4-wire multi-grounded unbalanced microgrids (MGs), which takes into consideration the impact of weather as well as the magnetic effects in the core of ACSR conductors. It is shown that the magnetic effects in the core can significantly influence the power flow results, especially for networks composed of single-layer ACSR conductors. Furthermore, the proposed algorithm explicitly considers the multi-grounded neutral conductor, thus it can precisely simulate unbalanced low voltage (LV) and medium voltage (MV) networks. In addition, the proposed approach is generic and can be applied in both grid-connected and islanded networks. Simulations conducted in a 25-Bus unbalanced LV microgrid highlight the accuracy and benefit of the proposed approach. </b></p>

scholarly journals A Three-Phase Weather-Dependent Power Flow Approach for 4-Wire Multi-Grounded Unbalanced Microgrids with Bare Overhead Conductors

2020 ◽  
Author(s):  
Evangelos Pompodakis
Keyword(s):  
Power Flow ◽  
Low Voltage ◽  
Flow Analysis ◽  
Single Layer ◽  
Distribution Networks ◽  
Medium Voltage ◽  
The Core ◽  
Magnetic Effects ◽  
Three Phase ◽  
The Impact

<p><b>Conventional power flow (CPF) algorithms assume that the network resistances and reactances remain constant regardless of the weather and loading conditions. Although the impact of the weather in power flow analysis has been recently investigated via the weather-dependent power flow (WDPF) approaches, the magnetic effects in the core of ACSR conductors have not been explicitly considered. ACSR conductors are widely used in distribution networks. Therefore, this manuscript proposes a three-phase weather-dependent power flow algorithm for 4-wire multi-grounded unbalanced microgrids (MGs), which takes into consideration the impact of weather as well as the magnetic effects in the core of ACSR conductors. It is shown that the magnetic effects in the core can significantly influence the power flow results, especially for networks composed of single-layer ACSR conductors. Furthermore, the proposed algorithm explicitly considers the multi-grounded neutral conductor, thus it can precisely simulate unbalanced low voltage (LV) and medium voltage (MV) networks. In addition, the proposed approach is generic and can be applied in both grid-connected and islanded networks. Simulations conducted in a 25-Bus unbalanced LV microgrid highlight the accuracy and benefit of the proposed approach. </b></p>

Power Flow Analysis for Complicated System

2003 ◽  
Author(s):  
Lingling Sun ◽  
Kongjie Song
Keyword(s):  
Structural Analysis ◽  
Power Flow ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Theoretical Models ◽  
Rigid Foundation ◽  
Analysis Method ◽  
Power Flow Control ◽  
Reasonable Choice ◽  
Isolation Systems

The generalized theoretical models for vibrating machines isolated by multiple elastic mounts or by a mount-raft-mount system from non-rigid foundation were proposed. The structural analysis method was developed based on the power flow control perspectives. The dynamic transmission equations were derived to predict the power flow characteristics between subsystems. Numerical calculations of power flow for practical isolation systems were carried out to explore the interaction between the mounting frequency and the flexibility of supporting structure. The effects of mounting frequency on the power transmitted to the foundation were discussed. It is shown that the power flow can be reduced effectively by reasonable choice of mounting frequency.

scholarly journals A Three-Phase Weather-Dependent Power Flow Approach for 4-Wire Multi-Grounded Unbalanced Microgrids with Bare Overhead Conductors

2020 ◽  
Author(s):  
Evangelos Pompodakis
Keyword(s):  
Power Flow ◽  
Low Voltage ◽  
Flow Analysis ◽  
Single Layer ◽  
Distribution Networks ◽  
Medium Voltage ◽  
The Core ◽  
Magnetic Effects ◽  
Three Phase ◽  
The Impact

<p><b>Conventional power flow (CPF) algorithms assume that the network resistances and reactances remain constant regardless of the weather and loading conditions. Although the impact of the weather in power flow analysis has been recently investigated via the weather-dependent power flow (WDPF) approaches, the magnetic effects in the core of ACSR conductors have not been explicitly considered. ACSR conductors are widely used in distribution networks. Therefore, this manuscript proposes a three-phase weather-dependent power flow algorithm for 4-wire multi-grounded unbalanced microgrids (MGs), which takes into consideration the impact of weather as well as the magnetic effects in the core of ACSR conductors. It is shown that the magnetic effects in the core can significantly influence the power flow results, especially for networks composed of single-layer ACSR conductors. Furthermore, the proposed algorithm explicitly considers the multi-grounded neutral conductor, thus it can precisely simulate unbalanced low voltage (LV) and medium voltage (MV) networks. In addition, the proposed approach is generic and can be applied in both grid-connected and islanded networks. Simulations conducted in a 25-Bus unbalanced LV microgrid highlight the accuracy and benefit of the proposed approach. </b></p>

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