This paper investigates the frequency response of a smart SANDWICH PLATE made of magnetic face sheets and reinforced core with nanofibers. The effective elastic properties of COMPOSITE core reinforced with carbon nanotube are estimated by the extended rule of Mixture. The orthotropic visco-Pasternak foundation is examined to study orthotropic angle, damping coefficient, normal, and shear modulus. The top and bottom face sheets of the SANDWICH are magnetic and their vibrations are controlled by a feedback control system and magnetomechanical couplings. Also, the SANDWICH PLATE is subjected to the compression and extension in-plane forces in both x and y directions. Five coupled equations of motion are derived using Hamilton’, s principle. These equations are solved by the differential quadrature method. The analysis performed by the third-order shear deformation theory (Reddy’, s theory) shows useful details of the effective parameters such in-plane forces, modulus of elastic foundation, coreto-face sheet thickness ratio and controller effect of velocity feedback gain on the dimensionless frequency of the SANDWICH PLATE. The analysis of such structures can be discussed in the military, aerospace and civil industries.

SANDWICH structures are widely used in aerospace, automobile, high speed train and civil applications. SANDWICH structures consist of two thin and stiff skins and a thick and light weight core. In this study, the obligatory mandate of a SANDWICH PLATE contact constitutes a flexible foam core and COMPOSITE skins with a hemispherical rigid punch has been studied by an analytical/empirical method. In SANDWICH structures, calculation of force distribution under the punch nose is complicated, because the core is flexible and the difference between the modulus of elasticity of skin and core is large. In the present study, an exponential correlation between the contact force and indentation is proposed. The coefficient and numerical exponent were calculated using the experimental indentation results. A model based on a highorder SANDWICH panel theory was used to study the bending behavior of SANDWICH PLATE under hemispherical punch load. In the first method, the force distribution under the punch nose was calculated by the proposed method and multiplied to deformation of related point in the loading area to calculate the potential energy of the external loads.In the second method, the punch load was modeled as a point force and multiplied to deformation of maximum indented point. The results obtained from the two methods were compared with the experimental results. Indentation and bending tests were carried out on SANDWICH PLATEs with glass/epoxy skins and a styrene/acrylonitrile foam core. In the bending test, a simply support condition was set and in the indentation test the SANDWICH specimens were put on a rigid support. Indeed, in this position the punch movement was equal the indentation. The comparison between the analytical and experimental results showed that the proposed method significantly improved the accuracy of analysis.

COMPOSITE SANDWICH PLATE widely used in manufacturing of the hull of advanced fast boat. SANDWICH PLATE of the boat hull that is contact with water in one side supply the Flexural stiffness and dissipate the vibrational energy cused by internal and external factors. In this paper, COMPOSITE SANDWICH PLATE consider with two external laminate face consists of two type fiber Grphite and Glass in the epoxy resin with Polyisobutylene foam core. laminates of face have orthotropic elastic manner and core have isotropic viscoelastic manner that viscoelastic mechanical property of the core received from reference. In this paper for mechanical manner of the visoelastic core, relaxation Master Curve extract with used isothermal curves. Natural frequencies and mode shapes of the COMPOSITE SANDWICH PLATE are determined with clamped boundary conditions in the finite element software. results of natural frequencies and mode shapes of the COMPOSITE SANDWICH PLATE are compared in air and contact with water.

Free vibration characteristics of rectangular COMPOSITE PLATE with constrained layer damping and magneto-rheological fluid (MR) core are presented. Hamilton principal is used to obtain the equation of motion of the SANDWICH PLATE. Based on the Navier method, a closed-form solution is presented for free vibration analysis of MR SANDWICH PLATE under simply supported boundary conditions. The governing equation of motion is derived on the base of classical lamination theory for the facePLATEs. Only shear strain energy density of the core is considered. Using displacement continuity conditions at the interface of the layers and core, shear strain of the core is expressed in terms of displacement components of the base and constraint layers. The complex shear modulus of the MR material in the pre-yield region was described by complex modulus approach as a function of magnetic field intensity. The validity of the developed formulation is demonstrated by comparing the results in terms of natural frequencies with those in the available literature. The effects of magnetic field intensity, PLATE aspect ratio, and thickness of the MR core, base layer and constrained layer for three different stacking sequences of COMPOSITE facePLATEs on the fundamental frequency and loss factor of the first mode are discussed. The results indicate significant effect of physical and geometrical parameters on the natural frequency and loss factor associated with the first mode.

This study deals with the vibration response of SANDWICH PLATE with nano-COMPOSITE core and smart magneto-strictive face sheets. COMPOSITE core is reinforced by carbon nanotubes (CNTs) and its effective elastic properties are obtained by the rule of Mixture. Terfenol-D films are used as the face sheets of SANDWICH due to magneto-mechanical coupling in magneto-strictive material (MsM). In order to investigate the magnetization effect on the vibration characteristics of SANDWICH PLATE, a feedback control system is utilized. Also the SANDWICH PLATE undergoes the follower forces in opposite direction of x. Based on energy method, equations of motions are derived using Reddy’ s third order shear deformation theory, and Hamilton’ s principle and solved by differential quadrature method (DQM). A detailed numerical study is carried out based on third-order shear deformation theory to indicate the significant effect of follower forces, volume fraction of CNTs, temperature change, core-to-face sheet thickness ratio and controller effect of velocity feedback gain on dimensionless frequency of SANDWICH PLATE. These finding can be used to automotive industry, aerospace and building industries.

In this research a low velocity impact analysis of a SANDWICH PLATE with multilayered COMPOSITE face-sheets and flexible core under thermal conditions is investigated. In this regard, thermal effects and temperature dependent properties of the core are considered. In this study, equations of motion are derived based on a hybrid LW/ESL finite element formulation considering the thermal effects by which the number of unknowns is independent on the number of layers. This new formulation is in the framework of Carrera’ s Unified Formulation (CUF). The CUF unify many theories in a unified form such that can be differed by the order of expansion and definition of the variables in the thickness direction. In order to satisfy the interlaminar continuity of transverse stresses between the layers the Reissner Mixed Variational Theorem (RMVT) is employed. In this paper for considering the thermal effects, the nonlinear strains are used. In this research in order to modeling the low velocity impact a new modified spring-mass model is proposed using the two degree spring– mass model and also Choi linearaized law. Results of this formulation are compared with experimental results which show the high accuracy of the proposed formulation. Results show that with increasing the temperature, the impact force decreases and also impact time duration increases significantly. In this study, some new results are presented for different thermal conditions, aspect ratios, face thickness ratios and also different initial energy of impactor.

Structural SANDWICH beams are widely used because of their high specific stiffness and strength, noise reduction, thermal insulation and impact energy absorption characteristics. Conventional manufacturing method of COMPOSITE SANDWICH structures is completed by a separate adhesive joining stage by which the COMPOSITE faces are joined to the core. In this investigation, liquid phase sintering in the Al-Zn alloy system was used in order to form a diffusion bond between metallic foam and PLATE. Joining treatment was conducted at 610oC for 30 minutes in an inert atmosphere. The shear strength of the joint was measured to be about 4.8 kPa.

A novel geometrically nonlinear high order SANDWICH panel theory considering finite strains of SANDWICH components is presented in this paper. The equations are derived based on high order SANDWICH panel theory in which the Green strain and the second Piola-Kirchhoff stress tensor are used. The model uses Timoshenko beam theory assumptions for behavior of the COMPOSITE face sheets. The core is modeled as a two dimensional linear elastic continuum that possessing shear and vertical normal and also in-plane rigidities. Nonlinear equations for a simply supported SANDWICH beam are derived using Ritz method in conjunction with minimum potential energy principle. After obtaining nonlinear results based on this enhanced model, simplification was applied to derive the linear model in which kinematic relations for face sheets and core reduced based on small displacement theory assumptions. A parametric study is done to illustrate the effect of geometrical parameters on difference between results of linear and nonlinear models. Also, to verify the analytical predictions some three point bending tests were carried out on SANDWICH beams with glass/epoxy face sheets and Nomex cores. In all cases good agreement is achieved between the nonlinear analytical predictions and experimental results.

In this article, the structural performance of COMPOSITE PLATE under low velocity impact is studied. Two forms of layup sequence namely jute-epoxy laminate (JE) and jute-epoxy-rubber SANDWICH (JE-R-JE) are considered for evaluation. Special emphasis is provided for evaluating the influence of normal and oblique loading. The various dynamic parameters such as energy, peak load, and deformation are analysed in detail to study the effect of impact angle on both laminate and SANDWICH. Stress analysis of both the laminate and SANDWICH structure is carried out to discuss the effect of introducing rubber as a core material. The results reveal that using rubber as a core material has a significant effect on energy absorption. In addition, it is noticed that increasing the angle of impact yields better performance of the COMPOSITE PLATE. The results presented here may serve as benchmark for the effective utilization of COMPOSITE PLATEs in low velocity impact applications.

The honeycomb SANDWICH structures are commonly and efficiently adopted in the development of light mass satellite structures as a result of their inherent high stiffness and strength properties. Through a comprehensive study, the equivalent finite element modeling of honeycomb SANDWICH structures utilizing miscellaneous modeling approaches is introduced. For the sake of validating results, both theoretical analysis and experimental modal testing are implemented upon a honeycomb SANDWICH PLATE utilizing free-free boundary conditions. Based on the results, the SANDWICH theory and its related shell-volume-shell approach introduce a good match with the experimental results. The aforementioned approach is utilized extensively during the process of satellite structural design and modeling. In addition, a parametric study is executed so as to relate the geometric and material variations to the resonant modal frequencies. The study results indicate a crucial influence of both honeycomb core and facing sheets thicknesses on the modal frequency values.