“…Figure 8 indicates the variations of STL behavior of the double-walled structure against the different values of the viscoelastic medium's damping coefficient when It is observed from this figure that by considering damping coefficient from to 2000 (see Refs. 59 , 60 for given values), STL significantly increases in the whole frequency range, expressly at the mass-air-mass resonance, it increases by 16 dB. Figure 8 STL of double-walled sandwich composite MEE plate against the viscoelastic medium's damping coefficient.…”
Section: Resultsmentioning
confidence: 95%
“…Figure 9 displays the effect of the viscoelastic medium's stiffness on the variations of STL curves when It can be inferred that from this figure that with increasing viscoelastic medium's stiffness coefficient from to (see Refs. 59 , 60 for given values), STL due to the increase in the stiffness of the structure (stiffness-hardening effect) increases by 27 dB before the mass-air-mass resonance. However, it is observed that the effect of the viscoelastic medium's stiffness on STL is less in the frequency range above the mass-air-mass resonance.…”
This study offers a comprehensive investigation into the parameters affecting the sound transmission characteristics of a double-walled sandwich magneto-electro-elastic cross-ply layered plate resting on viscoelastic medium in thermal environment. To this end, the walls of this sandwich structure are modeled based on the assumptions of the first-order shear deformation theory. The governing equations are derived via a coupled set of equations targeting vibration and acoustic aspects of the problem after the application of Hamilton’s principle. The obtained equations are then solved by the implementation of double Fourier series and the second velocity potential, giving an accurate estimation of sound transmission loss under initial magnetic and electric potentials, variations of temperature, ply angle, acoustic cavity depth, incident angle of sound waves, and viscoelastic parameters.
“…Figure 8 indicates the variations of STL behavior of the double-walled structure against the different values of the viscoelastic medium's damping coefficient when It is observed from this figure that by considering damping coefficient from to 2000 (see Refs. 59 , 60 for given values), STL significantly increases in the whole frequency range, expressly at the mass-air-mass resonance, it increases by 16 dB. Figure 8 STL of double-walled sandwich composite MEE plate against the viscoelastic medium's damping coefficient.…”
Section: Resultsmentioning
confidence: 95%
“…Figure 9 displays the effect of the viscoelastic medium's stiffness on the variations of STL curves when It can be inferred that from this figure that with increasing viscoelastic medium's stiffness coefficient from to (see Refs. 59 , 60 for given values), STL due to the increase in the stiffness of the structure (stiffness-hardening effect) increases by 27 dB before the mass-air-mass resonance. However, it is observed that the effect of the viscoelastic medium's stiffness on STL is less in the frequency range above the mass-air-mass resonance.…”
This study offers a comprehensive investigation into the parameters affecting the sound transmission characteristics of a double-walled sandwich magneto-electro-elastic cross-ply layered plate resting on viscoelastic medium in thermal environment. To this end, the walls of this sandwich structure are modeled based on the assumptions of the first-order shear deformation theory. The governing equations are derived via a coupled set of equations targeting vibration and acoustic aspects of the problem after the application of Hamilton’s principle. The obtained equations are then solved by the implementation of double Fourier series and the second velocity potential, giving an accurate estimation of sound transmission loss under initial magnetic and electric potentials, variations of temperature, ply angle, acoustic cavity depth, incident angle of sound waves, and viscoelastic parameters.
“…Meanwhile, the δV produced by external loads for this composite sandwich can be calculated as: where, hygrothermal forces and , can be determined according to [ 48 ]: …”
This analysis investigated the impact wave response and propagation on a composite sandwich shell when subjected to a low-velocity external shock, considering hygrothermal effects. The sandwich shell was crafted using face layers composed of functional gradient metal–ceramic matrix material and a core layer reinforced with negative Poisson’s honeycomb. The honeycomb layer consisted of a combination of viscoelastic polymer material and elastic material. The equivalent parameters for the functional gradient material in the face layers were determined using the Mori–Tanaka and Voigt models, and the parameters for the negative Poisson’s ratio honeycomb reinforcement core layer were obtained through Gibson’s unit cell model. Parameters relevant to a low-velocity impact were derived using a modified Hertz contact law. The internal deformations, strains, and stress of the composite sandwich shell were described based on the higher-order shear deformation theory. The dynamic equilibrium equations were established using Hamilton’s principle, and the Galerkin method along with the Newmark direct integration scheme was employed to calculate the shell’s response to impact. The validity of the analysis was confirmed through a comparison with published literature. This investigation showed that a multilayer negative Poisson’s ratio viscoelastic polymer material honeycomb-cored structure can dissipate impact wave energy swiftly and suppress shock effectively.
“…The need for modeling and analysis of structures with special conditions is increasing in many engineering fields. Analysis of beams and plates resting on an elastic or viscoelastic foundation has many important applications in mechanical and aerospace engineering [1]. While direct analysis of plates under different conditions is still an active area of research [2][3][4], inverse analysis of plates for identification of applied loads has attracted the attention of many researchers [5][6][7].…”
Dynamic identification of the intensity of the moving loads applied to structures is an important task in aerospace, marine, and transportation industries. In the present work, a general technique is presented for identification of the time variations in moving loads applied to plate structures resting on viscoelastic foundation. The identification problem is formulated as an inverse problem, which utilizes dynamic responses. The direct analyses required for the identification problem are performed by a meshfree method based on the moving node technique. In this technique, a node, which travels with the applied force, is utilized in the meshfree method. Since there is no connectivity between the nodes of meshfree methods, this technique can be implemented easily, while reducing the computational labor. Another benefit of this technique is that any simple or complicated trajectory of the moving load can be handled without any additional concerns. Two numerical example problems are solved and the effects of several parameters, including the measurement error, and number of sensors on the accuracy of the results are investigated. Through the examples, it is shown that the presented technique can identify the time variations in moving loads efficiently and accurately.
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