Local and Global Damped Vibrations of Plates with a Viscoelastic Soft                 Flexible Core: An Improved High-order Approach

Malekzadeh, K.; Khalili, Mohammad; Mittal, Ravi Kant

doi:10.1177/1099636205053748

Cited by 63 publications

(58 citation statements)

References 25 publications

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“…Also, the present results were in good agreement with those obtained from finite element ANSYS software and the first higher order Frostig's theory. In Table 3, dimensionless natural frequencies of sandwich panel are presented with the material properties given in Table 1 As can be seen in Table 3, the results of the present theory were in good agreement with those of IHSAPT (Malekzadeh et al 2005). Considering of different displacement fields for the core layers, there was the discrepancy between the results.…”

Section: Validation Of the Resultssupporting

confidence: 69%

“…In the present theory, displacement field for the core was assumed to be a polynomial with unknown coefficients. But, Nayak et al (2002) and Malekzadeh et al (2005) used equivalent single layer Reddy's theory and 3D elasticity theory for the core, respectively. Table 4.…”

Section: Validation Of the Resultsmentioning

confidence: 99%

“…Rayleigh-Ritz method was also used to obtain natural frequencies. The improved higher order sandwich plate theory (IHSAPT), applying the first-order shear deformation theory for the face sheets, was introduced by Malekzadeh et al (2005Malekzadeh et al ( , 2006. R R Curvature radii of the top face sheet, bottom face sheet and core in x-z and y-z planes (i=t,b,c) , , k k k Zenkour (2005a, b) presented a comprehensive bending, buckling and free vibration analysis of simply supported functionally graded (FG) ceramic-metal sandwich plates.…”

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Improved high order free vibration analysis of thick double curved sandwich panels with transversely flexible cores

Fard

Livani

Ghasemi

2014

Lat. Am. j. solids struct.

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This paper dealt with free vibration analysis of thick double curved composite sandwich panels with simply supported or fully clamped boundary conditions based on a new improved higher order sandwich panel theory. The formulation used the first order shear deformation theory for composite face sheets and polynomial description for the displacement field in the core layer which was based on the displacement field of Frostig's second model. The fully dynamic effects of the core layer and face sheets were also considered in this study. Using the Hamilton's principle, the governing equations were derived. Moreover, effects of some important parameters like that of boundary conditions, thickness ratio of the core to panel, radii curvatures and composite lay-up sequences were investigated on free vibration response of the panel. The results were validated by those published in the literature and with the FE results obtained by ABAQUS software. It was shown that thicker panels with a thicker core provided greater resistance to resonant vibrations. Also, effect of increasing the core thickness in general was significant decreased fundamental natural frequency values. KeywordsFree vibration, Double curved sandwich panel, Boundary conditions, Improved higher order sandwich panel theory.Improved high order free vibration analysis of thick double curved sandwich panels with transversely flexible cores INTRODUCTIONStructural efficiency is an important attribute for aircraft structures. A higher order theory approach, used by Kant and Patil (1991), replaced sandwich structure with an equivalent higher order shear deformable structure, which lacked the ability to determine local buckling modes and imperfection effects on the overall behavior. Using the three-dimensional elasticity equations, Bhimaraddi (1993) studied the static response of orthotropic doubly curved shallow shells. He assumed that the ratio of the shell thickness to its middle surface radius is negligible as compared to unity. The high- er order sandwich panel theory was developed by Frostig et al. (1994Frostig et al. ( , 2004, who considered two types of computational models in order to express governing equations of the core layer. The second model assumed a polynomial description of the displacement fields in the core that was based on displacement fields of the first model. Their theory did not impose any restrictions on distribution of the deformation through thickness of the core. Singh (1999) studied free vibration of the open deep sandwich shells made of thin layers and a moderately thick core. Rayleigh-Ritz method was also used to obtain natural frequencies. The improved higher order sandwich plate theory (IHSAPT), applying the first-order shear deformation theory for the face sheets, was introduced by Malekzadeh et al. (2005Malekzadeh et al. ( , 2006.

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Section: Validation Of the Resultssupporting

confidence: 69%

Section: Validation Of the Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Improved high order free vibration analysis of thick double curved sandwich panels with transversely flexible cores

Fard

Livani

Ghasemi

2014

Lat. Am. j. solids struct.

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“…In their theory, the shear stress in thickness directions was assumed to be uniformly distributed; but, a second order function was considered for the vertical displacement of the core. The improved higher order sandwich plate theory, applying the first order shear deformation theory for the face sheets, was introduced by Malekzadeh et al (2005a). Zenkour (2005a, b) presented the comprehensive analysis of FG sandwich plates.…”

Section: Introductionmentioning

confidence: 99%

Improved high-order bending analysis of double curved sandwich panels subjected to multiple loading conditions

Fard

Livani

Veisi

et al. 2014

Lat. Am. j. solids struct.

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For the first time, the bending analysis of a double curved sandwich panel was presented which was subjected to point load, uniform distributed load on a patch, and harmonic distributed loads and was based on a new improved higher order sandwich panel theory. Since the cross-sectional warping was accurately modeled by this theory, it did not require any shear correction factor. Also, the present analysis incorporated trapezoidal shape factor (the 1+z/R terms) of a curved panel element. Geometry was used for the consideration of different radii curvatures of the face sheets, while the core was unique. Unlike most of other reference works, the core can have non-uniform thickness. The governing equations were derived by the principle of minimum potential energy. The effects of types of boundary conditions, types of applied loads, core to panel, and radii curvatures ratios on the bending response were also studied.

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Free vibration analysis of nanocomposite sandwich plates reinforced with CNT aggregates

2017

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In this article, free vibration analysis of simply supported sandwich plates with a flexible core and two functionally graded nanocomposite face sheets resting on two-parameter elastic foundation is carried out using Navier's solution. The nanocomposite face sheets are reinforced by randomly oriented and aggregated carbon nanotube (CNT). The material properties of the nanocomposites plates are graded along the thickness and are estimated though the Eshelby-Mori-Tanaka approach. In the proposed theory, 3-D elasticity theory and first order shear deformation theory are used for core and face sheets, respectively. Also, Hamilton's variational principle is used to derive the equations of motion. IntroductionHaving lighter mass and increased rigidity against bending, sandwich structures are widely used in aerospatial, naval and industrial applications [1]. Also, recently the use of CNT in polymer/CNT composites has attracted wide attention [2]. A high aspect ratio, low weight of CNTs and their extraordinary mechanical properties (strength and flexibility) provide the ultimate reinforcement for the next generation of extremely lightweight but highly elastic and very strong advanced composite materials [3]. On the other hand, by using of the polymer/CNT composites in advanced multilayered composite materials (sandwich structures) we can achieve structures with low weight, high strength and high stiffness in many structures of civil, mechanical and space engineering [4]. But, one of the common features of CNT morphology is the formation of aggregation in the matrix. Aggregation into bundles or ropes limits the overall effectiveness of nanotubes at improving the mechanical properties of the nanocomposite. The large aspect ratio (usually >1000), nanotube volume fraction, low bending rigidity of CNTs and interfacial bonding in the inter-phase region between embedded CNT and its surrounding polymer lead to their aggregation. Also, mechanical properties of CNTRC will become worse if the volume fraction of CNTs arises beyond certain limit [5]. Therefore, due to high cost of CNTs, in the modeling of CNTRC the concept of functionally graded materials (FGMs) might be incorporated to effectively make use of the CNTs. FGMs are classified as novel composite materials with gradient compositional variation. The concept of FGMs can be utilized for the management of a material's microstructure, so that the mechanical behavior of a structure made of such material can be improved. The composites, which are reinforced by CNTs with grading distribution, are called functionally graded carbon nanotube reinforced composites (FG-CNTRCs). Due to the mismatch of stiffness properties between the face sheets and core, sandwich panels are susceptible to delaminate at interfaces of the layers. Using FG-CNTRC in the layers of sandwich panels can solve the major problem in sandwich construction.Since the first-order shear deformation theory (FSDT) does not satisfy the condition of zero transverse shear stress at the top and bottom surfaces of plates, a...

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Local and Global Damped Vibrations of Plates with a Viscoelastic Soft Flexible Core: An Improved High-order Approach

Cited by 63 publications

References 25 publications

Improved high order free vibration analysis of thick double curved sandwich panels with transversely flexible cores

Improved high order free vibration analysis of thick double curved sandwich panels with transversely flexible cores

Improved high-order bending analysis of double curved sandwich panels subjected to multiple loading conditions

Free vibration analysis of nanocomposite sandwich plates reinforced with CNT aggregates

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