Abstract:In this research, large amplitude free vibrations of a sandwich beam with stiff core and carbon nanotube (CNT)-reinforced face sheets are analysed. The distribution of CNTs across the thickness of the face sheets may be uniform or functionally graded. The equivalent single-layer theory of Timoshenko is used to construct the Hamiltonian of the beam under the von Kármán type of geometrical nonlinearity assumptions. A uniform temperature field through the beam is also included in the formulation. The Ritz method … Show more
“…The modal analysis impact hammer is impacted in all the nine nodal points on the sandwich beams, and average values of natural frequencies and damping ratios are observed. 17–20,30–41 Figure 5.Experimental free vibration analysis setup, (a) schematic view and (b) photographic view.…”
Section: Fabrication and Dynamic Characterization Of Cgrp-pmc-mrf Cormentioning
The semi-active vibration control of sandwich beams made of chopped strand mat glass fiber reinforced polyester resin polymer matrix composite (PMC) and magnetorheological fluid (MRF) core were experimentally investigated in this study. Two-, four- and six-layered glass fiber reinforced polyester resin polymer matrix composites were prepared using the hand-layup technique. The magnetorheological fluid was prepared in-house with 30% volume of carbonyl iron powder and 70% volume of silicone oil. Nine cantilever sandwich beams of varying thicknesses of the top and bottom layers glass fiber reinforced polyester resin polymer matrix composite beams and middle magnetorheological fluid core were prepared. The magnetorheological fluid core was activated with a non-homogeneous magnetic field using permanent magnets. The first three modes, natural frequencies and damping ratios of the glass fiber reinforced polyester resin polymer matrix composite-magnetorheological fluid core sandwich beams were determined through free vibration analysis using DEWESoft modal analysis software. The amplitude frequency response of the glass fiber reinforced polyester resin polymer matrix composite-magnetorheological fluid core sandwich beams through forced vibration analysis was determined using LabVIEW. The effect of various parameters such as magnetic flux density, thickness of glass fiber reinforced polyester resin polymer matrix composite layers and magnetorheological fluid core layer on the natural frequencies, damping ratio and vibration amplitude suppressions of the glass fiber reinforced polyester resin polymer matrix composite-magnetorheological fluid core sandwich beams was investigated. Based on the results obtained, 2 mm thickness top and bottom layers glass fiber reinforced polyester resin polymer matrix composite and 5 mm thickness magnetorheological fluid core sample have achieved a high shift in increased natural frequency, damping ratio and vibration amplitude suppression under the influence of magnetic flux density.
“…The modal analysis impact hammer is impacted in all the nine nodal points on the sandwich beams, and average values of natural frequencies and damping ratios are observed. 17–20,30–41 Figure 5.Experimental free vibration analysis setup, (a) schematic view and (b) photographic view.…”
Section: Fabrication and Dynamic Characterization Of Cgrp-pmc-mrf Cormentioning
The semi-active vibration control of sandwich beams made of chopped strand mat glass fiber reinforced polyester resin polymer matrix composite (PMC) and magnetorheological fluid (MRF) core were experimentally investigated in this study. Two-, four- and six-layered glass fiber reinforced polyester resin polymer matrix composites were prepared using the hand-layup technique. The magnetorheological fluid was prepared in-house with 30% volume of carbonyl iron powder and 70% volume of silicone oil. Nine cantilever sandwich beams of varying thicknesses of the top and bottom layers glass fiber reinforced polyester resin polymer matrix composite beams and middle magnetorheological fluid core were prepared. The magnetorheological fluid core was activated with a non-homogeneous magnetic field using permanent magnets. The first three modes, natural frequencies and damping ratios of the glass fiber reinforced polyester resin polymer matrix composite-magnetorheological fluid core sandwich beams were determined through free vibration analysis using DEWESoft modal analysis software. The amplitude frequency response of the glass fiber reinforced polyester resin polymer matrix composite-magnetorheological fluid core sandwich beams through forced vibration analysis was determined using LabVIEW. The effect of various parameters such as magnetic flux density, thickness of glass fiber reinforced polyester resin polymer matrix composite layers and magnetorheological fluid core layer on the natural frequencies, damping ratio and vibration amplitude suppressions of the glass fiber reinforced polyester resin polymer matrix composite-magnetorheological fluid core sandwich beams was investigated. Based on the results obtained, 2 mm thickness top and bottom layers glass fiber reinforced polyester resin polymer matrix composite and 5 mm thickness magnetorheological fluid core sample have achieved a high shift in increased natural frequency, damping ratio and vibration amplitude suppression under the influence of magnetic flux density.
“…It should be noted that the coefficient matrices above are all dependent on the current temperature T. Moreover, it can be seen that the solution of Equation 27is essentially a nonlinear eigenvalue problem. An direct iterative method adopted by Mirzaei and Kiani [43] is used to solve the system of nonlinear eigenvalues in Equation (27). First, to solve this equation, the nonlinear terms K g (X) are set to zero and the resulting linear eigenvalue problem is solved to obtain the linear nature frequencies ω L and the corresponding linear eigenvectors X L .…”
This paper presents a simple and effective approach based on the Haar wavelet discretization method (HWDM) for the nonlinear vibration analysis of carbon nanotube-reinforced composite (CNTRC) beams resting on a nonlinear elastic foundation in a thermal environment. Material properties are assumed to be functionally graded (FG) in the thickness direction and temperature-dependent and are evaluated through the extended rule of mixture. Based on the first-order shear deformation beam theory in conjunction with the von Kármán nonlinearity, the nonlinear governing equations of CNTRC beams on nonlinear elastic foundations are derived as well as the related boundary conditions. Moreover, the initial thermal stress due to uniform temperature rise is considered in this study. To evaluate the nonlinear natural frequencies, the obtained equations are discretized into a set of nonlinear algebraic equations through HWDM and then the direct iteration technique is employed to solve the resulting algebraic equations. The convergence and comparison studies are carried out, and the results indicate that the numerical rate of convergence of the proposed method is in agreement with the convergence theorem, and good accuracy of the present results is observed. Studies on the effects of different parameters such as CNT volume fraction, distribution type of CNTs, foundation stiffness coefficients, boundary condition, slenderness ratio, temperature rise, and initial thermal stress on the linear frequencies and the nonlinear frequency ratios are also reported. This study offers an insight into the vibration behaviors of CNTRC beams resting on nonlinear elastic foundation subjected to the uniform temperature rise.
“…The authors' have also optimized the stacking sequence using the meta‐heuristic algorithm. Kiani and his group reported the fundamental frequency and the buckling responses of CNTRC structures based on the FODT kinematics with and without thermal load.…”
In this article, the vibration characteristics of carbon nanotube reinforced sandwich curved shell panel are investigated under the elevated thermal environment. The sandwich panel component (face and core layer) properties are assumed to be temperature-dependent including various distribution of the carbon nanotube for the face sheets of the sandwich structure. The sandwich structural behavior has been modeled mathematically using the higher-order shear deformation theory. The governing differential equation of motion of the free vibrated sandwich panel is obtained using the classical Hamilton's principle and transformed to the set of algebraic form with the help of suitable finite element steps. Further, fundamental frequencies of the curved sandwich shell panel are obtained numerically by means of a generalized computer code developed in MATLAB with the help of the present higher-order mathematical model. The accuracy and the stability of the present numerical results have been checked through the proper convergence test. The model is again extended to work out the frequency responses for few more cases and compared with those available published results including the simulation responses (ANSYS). Finally, a wide variety of numerical examples have been solved for various design parameters (volume fraction of CNT, core to face thickness ratios, length to thickness ratios, aspect ratios, support conditions, curvature ratios, and types of grading) of CNT sandwich curved panel and underlined their effects in details under the uniform thermal load. POLYM. COM-POS., 00:000-000,
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