Active control of a sandwich plate with reinforced magnetostrictive faces and viscoelastic core, resting on elastic foundation

The current study presents a vibration investigation of a laminated plate considering a viscoelastic core with embedded magnetostrictive layers. The simply-supported plate is supported via Pasternak’s substrate medium. Based on different plate theories and employing Hamilton’s principle, the system of governing differential equations is derived. The mechanical properties of the viscoelastic core are described depend on the time varies based on Kelvin–Voigt model. Actuating magnetostrictive layers are utilized to control the vibration damping process of the system with the assistance of feedback and constant gain distributed control. The analytical solution is obtained to investigate the influence of half wave numbers, thickness ratios, core thickness, aspect ratios, lamination schemes, elastic foundation parameters, damping coefficient, feedback coefficient magnitude, magnetostrictive layers location, on the vibrational behavior of laminated plate. Some observations about the vibration damping process of the present plate are displayed. The results refer to that the vibration suppression rate depends on the thickness of the plate, the feedback control value, the foundation constants, and the viscoelastic structural damping significantly. Moreover, the study can be providing benchmark tests to validate future contributions on the viscoelastic smart structural issues and developing the design of smart viscoelastic structures and control of their vibrations.

Buckling and Vibration Performance of a Composite Laminated Plate with Elastic Boundaries Subjected to Local Thermal Loading

In this paper, a model is established for the calculation of the vibrations of a composite laminated plate with elastic boundary conditions subjected to local thermal loading. The model is based on first-order shear deformation theory using the finite element method. The influence of boundary conditions, heating area, and heating location on buckling and vibrations of a composite laminated plate was investigated, and there were two stages in which the critical temperature increased sharply during the transition from free boundary to simply supported and rigid fixed boundaries. The thermal buckling of locally heated laminated plates is generally not checked in practical applications unless the heated area exceeds approximately 10% of the total area of the plates. The stronger the boundary constraint is, the greater the influence of the heated area is on the vibrational frequencies of the composite laminated plate.

A CRYSTAL CHEMISTRY OF HYDROXYAPATITE : A REVIEW

In chemistry of inorganic crystals, the octacalcium phosphate (OCP) is an apatite based crystals and having a hydrated layers which used in producing of needle or plate-shaped hydroxyapatite (HAP) nanocrystals. Although, the crystals is prepared by a dissolution precipitation reaction. These reaction led to a hexagonal HAP nanocrystals formation under hydrothermal condition from OCP at 180 for 3 hours with pH of solution adjusted to 5.5 and incorporating dicarboxylate e.g. succinate (OOC.(CH2)2.COO)2- ions having Ca/P molar ratio is expected to be 1.56±0.02, where the morphology of OCP are retained. During incorporating of succinate ions in OCP crystals, the hydrogen phosphate (HPO42-) ions in the hydrated layers of OCP are being substituted by succinate ions. Since the crystal system of HAP is hexagonal and its crystalline size in the longitudinal direction of various (a,b,c) axes depending on the thickness of the laminated plate-shaped HAP crystals. Here, their size as perpendicular to the (100) plane which is calculated by introducing of Scherrers equation, D100 = Kλ/(β cos ). The organically modified OCP which generated to HAP have unique nanostructure with micrometer thickness are characterized by using of SEM, FTIR and X-ray diffraction analysis.

Static Analysis of Laminated Composite Plate Using First Order Shear Deformation Theory

Composites are used comprehensively in constructional company. Instead of conventional materials engineers are experimenting new materials every day in which composites are providing solution to many structural applications. MATLAB software is used in the investigation of static performance of laminated plates. Designing of composite laminate is very complex and requires lot of computational effort. It is very difficult to solve composite numerical problems manually. Developing MATLAB code for the analysis of laminated composite plate using finite element analysis. To determine the deflection and transverse shear stress of square laminated plate which is simply supported and subjected to uniform pressure. To explore the influence of modular ratio on deflection and transverse shear stress for different materials. Development of MATLAB code for the interpretation of first order shear deformation theory. Keywords: Laminated plate, composites, MATLAB, shear deformation theories, Finite element analysis

Effect of Angle Ply On The Mechanical Performance of Jute Fibre Woven Mat /Epoxy Composites With Varying Ageing Conditions

The present work investigates the mechanical strengths retention and prediction of maximum service life of sets of laminated composites by analyzing their diffusion coefficients and activation energies, using Fick’s law and Arrhenius principle. Jute fiber woven mat reinforced epoxy laminated composites (JFMRLCs) were prepared by simple hand lay-up and compression molding methods. The layering patterns of 0º balanced laminate of [0º/0º/0º/0º/0º], 30º angle-ply laminate of [0º/+30º/0º/-30º/0º] and 45° angle-ply laminate of [0°/+45°/0°/-45°/0°] were used to prepare the composite samples, according to classical laminated plate theory (CLPT). The composites were immersed in water at different periods of 10, 20, 30 and 40 days aging. The effects of the various periods of aging on their mechanical properties were studied. The results showed that the weights of the composite samples increased by increasing the aging periods. The mechanical properties of aged (wet) composites were compared with the unaged (dry) counterparts to predict their strengths retention. The composite with 45° layering pattern exhibited the maximum strength retention. Also, the same composite sample with layering pattern of 45° produced the maximum activation energy, based on Arrhenius principle. The tensile fractured surfaces were analyzed to investigate into their fiber-matrix interfacial bonds through images obtained from scanning electron microscopy (SEM). Summarily, it was evident that optimum JFMRLCs with layering pattern of 45° exhibited best mechanical properties. Hence, they can act as suitable, sustainable, low cost and environmentally friendly composite materials for structural marine and other related engineering applications.

Nonlinear Dynamics Simulation of Bending Deflection for Composite Laminated Plate Under Varied Temperature Using Lyapunov Exponent Parameter

This paper study the nonlinear dynamics behavior of the bending deflection of composite laminated plate based on largest Lyapunov exponent parameter. Wolf algorithm is used to quantify largest Lyapunov exponent in the presence of aspect ratios and fiber volume fractions. A power spectrum analysis has been added using the amplitude of Fast Fourier Transform (FFT) to detect the non-periodic motion of the bending deflection of the composite plate. The simulation process is done using ANSYS software Ver. 18.2. The temperature gradient of thermal shock is varied between (60C° and −15C°) through the laminate thickness. The experiment setup has been done through heating and cooling rig test environment. The non-periodic motion of the bending deflection is decreased with the increasing of aspect ratios, while the non-periodic motion of the bending deflection is increased wit the increasing of fiber volume fractions.