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The bending behavior of COMPOSITEs SANDWICH PLATES with multi-layered laminated face sheets has been investigated, using a new four-nodded rectangular finite element formulation based on a layer-wise theory. Both, first order and higher-order shear deformation, theories are used in order to model the face sheets and the core, respectively. Unlike any other layer-wise theory, the number of degrees of freedom in this present model is independent of the number of layers. The compatibility conditions as well as the displacement continuity at the interface ‘face sheets–core’ are satisfied. In the proposed model, the three translation components are common for the all SANDWICH layers, and are located at the mid-plane of the SANDWICH plate. The obtained results show that the developed model is able to give accurate transverse shear stresses directly from the constitutive equations. Moreover, a parametric study was also conducted to investigate the effect of certain characteristic parameters (core thickness to total thickness ratio, side-to-thickness ratio, boundary conditions, plate aspect ratio, core-to-face sheet anisotropy ratio, core shear modulus to the flexural modulus ratio and degree of orthotropy of the face sheet) on the transverse displacement variation. The numerical results obtained by our model are compared favorably with those obtained via analytical solution and numerical/experimental, results obtained by other models. The results obtained from this investigation will be useful for a more comprehensive understanding of the behavior of SANDWICH laminates.

A new computational procedure based on two Spring-Mass-Damper-Dashpot (SMDD) and Spring-Mass- Damper (SMD) models representing contact behavior between the impactor and the plate are presented to study the low velocity impact phenomenon of SANDWICH PLATES comprising of a transversely flexible core and laminated COMPOSITE face-sheets. The interaction between the impactor and the plate is modeled with the help of a new system having three-degree of-freedom, consisting of spring-mass-damper-dashpot or spring mass- damper. The plate may be subjected to initial in-plane biaxial normal and shear stresses along the edges of the plate. Impact is assumed to occur normally over the top or the bottom face-sheets, at arbitrary location. The boundary conditions of the top and the bottom face-sheets are independent. The effects of transverse flexibility of the core and structural damping of the plate are considered in the proposed models. Based on these models, the analytic functions describing the contact force, the transverse deflections of the impactor and the plate are derived. The effects of some parameters such as plate aspect ratio, boundary conditions, initial in-plane biaxial stresses, and impact location are examined in details.

In this paper, natural frequencies of the SANDWICH PLATES with soft flexible core and COMPOSITE face sheets are obtained. Three-Dimensional (3D) finite element method (FEM) is used for constructing and analyzing of the SANDWICH PLATES to obtain their natural frequencies. Continuity conditions for transverse shear stresses at the interfaces as well as transverse flexibility and transverse normal strain and stress of the core are considered. The effects of plate dimensions such as aspect ratio and thickness ratio are studied. Also, different boundary conditions such as all edges clamped (CCCC), all edges simply supported (SSSS) and combined boundary conditions including (CFCF) are applied to the SANDWICH PLATES. Comparison of the present results in special case with those of the accurate plate theories confirms the accuracy of the proposed model.

SANDWICH structures are COMPOSITEs comprising a core layer SANDWICHed between two face layers; each layer has a distinctive characteristic, and the structure can also include COMPOSITE layers. This study presents an investigation of the free vibration behavior of a cored hybrid SANDWICH plate. The research demonstrates an analytical and numerical analysis. SANDWICH plate models made of aluminum face sheets with reinforced cores are used in this study. The analytical analysis used in this study of a three-layer SANDWICH plate is based on Kirchhoff's theorem. An additional mathematical model is constructed by dividing the core layer into two parts to form four layers with a hybrid structure. The governing equations to obtain the mechanical properties and natural frequency of the foam COMPOSITE, as well as open structural and hybrid cores, were used in this study. The numerical analysis of the various COMPOSITE structures using the modal analysis was performed through ANSYS version 2021-R1. Analytical outcomes reveal that replacing the foam core with an open-cell structure reduces the natural frequency by 25%. However, the hybrid core structure reduces the natural frequency by 27.6%. Also, the ultimate flexural load in the hybrid structure is increased by 127.7% compared to the open-cell structure core. Finally, numerical results are highly consistent with those obtained analytically.