Vibroacoustic behavior of orthotropic aerospace composite structure in the subsonic flow considering the Third order Shear Deformation Theory

Lat. Am. j. solids struct.

Rouhani

2019

This paper applies acoustic analysis of Sound Transmission Loss (STL) through infinite Functionally Graded (FG) thick plate employing Hyperbolic Shear Deformation Theory (HSDT). The procedure for applying a FG plate is followed by considering the material properties are changed continually based on power-law distribution of the materials in terms of volume fraction. The main benefit of HSDT can be justified knowing the fact that, it uses parabolic transverse shear strain across thickness direction. Therefore, no need to enter the extra effect of shear correction coefficient factor. Besides, the displacement field is extended as a combination of polynomial as well as hyperbolic tangent function by neglecting the effect of thickness stretching. Furthermore, the equations of motion are obtained employing Hamilton's Principle. To provide an analytical solution based on HSDT, equations of motion are combined with acoustic wave equations. Moreover, some comparisons are made with the known theoretical and experimental results available in literature to verify the accuracy and efficiency of the current formulation. These comparisons reveal an excellent agreement. Consequently, some configurations are presented to demonstrate which parameters appear to be effective to improve the behavior of STL including the effects of modulus of elasticity and density in the thickness direction with respect to various power-law distributions.

“…The power transmission coefficient can be obtained as a ratio of transmitted power and incident power per unit area of the structure as follow (Talebitooti et al, 2018e):…”

Section: Sound Transmission Lossmentioning

confidence: 99%

Investigating Hyperbolic Shear Deformation Theory on vibroacoustic behavior of the infinite Functionally Graded thick plate

Lat. Am. j. solids struct.

Rouhani

2019

“…They also added a porous material into an infinite cylinder under various boundary configurations (Talebitooti et al, 2018a). In other works (Talebitooti et al, 2018d; Talebitooti and Zarastvand, 2018c), the focus was specially placed on the vibroacoustic behavior of the infinite shells based on the first and third order shear deformation theories. They also inspected the effect of a porous material on the sound insulation property of the infinite and finite doubly curved shells (Talebitooti and Zarastvand, 2018b; Talebitooti et al, 2018e).…”

Section: Introductionmentioning

confidence: 99%

Acoustic performance prediction of a multilayered finite cylinder equipped with porous foam media

Gohari

Journal of Vibration and Control

2020

This paper presents an analytical model to embed porous materials in a finite cylindrical shell in order to obtain the sound transmission loss coefficient. Although the circumferential modes are considered only for calculating the amount of the transmitted noise through an infinitely long cylinder, the present study employs the longitudinal modes in addition to circumferential ones to analyze the vibroacoustic performance of a simply supported cylinder subjected to the porous core based on the first order shear deformation theory. To achieve this goal, the structure is immersed in a fluid and excited by an acoustic wave. In addition, the acoustic pressures and the displacements are developed in the form of double Fourier series. Since these series consist of infinite modes, it is essential to terminate this process by considering adequate modes. Hence, the convergence checking algorithm is employed in the form of some three-dimensional configurations with respect to length, frequency and radius. Afterwards, some figures are plotted to confirm the accuracy of the present formulation. In these configurations, the obtained sound transmission loss from the present study is compared with that of the infinite one. It is shown that by increasing the length of the structure, the results are approached to sound transmission loss of the infinite shells. Moreover, a new approach is proposed to show the transverse displacement of a finite poroelastic cylinder at different frequencies. Based on the outcomes, it is found that by enhancing the length of the poroelastic cylinder, the amount of the transmitted sound into the structure is reduced at the high frequency domain. However, the sound insulation property of the structure is improved at the low frequency region when the radius of the shell is decreased.

“…Note that the sound insulation study of the doubly curved shells is a new approach which should be considered. Herewith, the authors have been presented power transmission of the doubly curved shells without porous core in two their previous publications [56,57]. Meanwhile, in this paper, a new approach is made through vibroacoustic optimization of the poroelastic composite sandwich structures in a diffuse field.…”

Section: Introductionmentioning

confidence: 99%

Multi-objective optimization approach on diffuse sound transmission through poroelastic composite sandwich structure

Jnl of Sandwich Structures & Materials

Darvishgohari

2019

Multi-objective vibroacoustic optimization of the double-walled doubly curved composite shells having poroelastic lining in its core in a diffuse field is performed based on Non-dominated sorting Genetic Algorithm-II. To present an analytical model on the basis of multi-objective optimization, the summation of sound transmission loss and transverse displacement along with weight of the structure are considered as two cost functions, which should be optimized in a diffuse field. In fact, the significant achievement of this work is to design an optimization algorithm to improve vibroacoustic fitness and weight of the sandwich doubly curved shells. In the first part of the paper, a general formulation is prepared to analyze the dynamic of the poroelastic composite sandwich structures. Likewise, some validation configurations are presented to confirm the accuracy of the current formulation. Consequently, an optimization algorithm is provided on the basis of considering some appropriate design variables including material and porous types as well as stacking sequences. In this regard, a batch of 19 benchmarks of porous core is investigated. Furthermore, a configuration of optimized points in the Pareto front is plotted in which the simultaneous effects of optimizing the weight and vibroacoustic fitness can be observed. As a result, a new approach is made through optimization of the transverse displacement of the structure as a function of various incidence and azimuth angles in three dimensional configurations with respect to different frequencies.