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J Chen - One of the best experts on this subject based on the ideXlab platform.

  • nonlinear aeroelastic flutter and dynamic response of composite laminated cylindrical shell in supersonic air flow
    Composite Structures, 2017
    Co-Authors: J Chen
    Abstract:

    Abstract Aeroelastic flutter characteristics and dynamic response of a composite laminated circular cylindrical shell under combined action of radial harmonic excitation, compressive in-Plane Force and aerodynamic pressure are studied in this paper. The first-order piston theory is employed to model the aerodynamics pressure. Partial differential equations governing the vibrations of the cylindrical shell are derived based on the Hamilton’s principle and the Donnell’s nonlinear shell theory. The Galerkin’s method is adopted to discretize the partial differential governing equations to a set of nonlinear ordinary differential equations. The four-dimensional averaged equation is obtained by applying the method of multiple scales under the case of 1:2 internal resonance. The critical free stream static pressure originating flutter of the shell is determined by solving the eigenvalue problem. The phase portrait and time history diagrams are presented to demonstrate the character of the limit cycle oscillation of the shell. The influence of different geometrical parameters, such as the radius, length and thickness of the shell, on the flutter characteristics of the composite laminated circular cylindrical shell are discussed in details. The influences of the amplitudes of the in-Plane and transverse excitations on the frequency–response curves and Force-response curves are also investigated.

  • nonlinear dynamics of initially imperfect functionally graded circular cylindrical shell under complex loads
    Journal of Sound and Vibration, 2015
    Co-Authors: Y Z Liu, Y X Hao, J Chen
    Abstract:

    Abstract The nonlinear vibration of a simply supported FGM cylindrical shell with small initial geometric imperfection under complex loads is studied. The effects of radial harmonic excitation, compressive in-Plane Force combined with supersonic aerodynamic and thermal loads are considered. The small initial geometric imperfection of the cylindrical shell is characterized in the form of the sine-type trigonometric functions. The effective material properties of this FGM cylindrical shell are graded in the radial direction according to a simple power law in terms of the volume fractions. Based on Reddy’s third-order shear deformation theory, von Karman-type nonlinear kinematics and Hamilton’s principle, the nonlinear partial differential equation that controls the shell dynamics is derived. Both axial symmetric and driven modes of the cylindrical shell deflection pattern are included. Furthermore, the equations of motion can be reduced into a set of coupled nonlinear ordinary differential equations by applying Galerkin’s method. In the study of the nonlinear dynamics responses of small initial geometric imperfect FGM cylindrical shell under complex loads, the 4th order Runge−Kutta method is used to obtain time history, phase portraits, bifurcation diagrams and Poincare maps with different parameters. The effects of external loads, geometric imperfections and volume fractions on the nonlinear dynamics of the system are discussed.

Neha Ahlawat - One of the best experts on this subject based on the ideXlab platform.

  • buckling and vibrations of two directional functionally graded circular plates subjected to hydrostatic in Plane Force
    Journal of Vibration and Control, 2017
    Co-Authors: Neha Ahlawat
    Abstract:

    Analysis and numerical results for the axisymmetric vibrations of two-directional functionally graded circular plates under the action of an in-Plane Force have been presented on the basis of classical theory of plates. The mechanical properties of the plate material are assumed to vary in both radial and transverse directions. Generalized differential quadrature method has been employed to obtain the frequency equations from the differential equation governing the motion of such simply supported and clamped plates. The lowest three roots of these frequency equations have been reported as the first three modes of vibration. The effect of volume fraction index, in-Plane Force parameter, heterogeneity parameter and density parameter has been studied on the natural frequencies of vibration. By allowing the frequencies to approach zero, the critical buckling loads for both the plates have been computed. Three-dimensional (3D) mode shapes for specified plate have been plotted. A comparison of results has been ...

S Kitipornchai - One of the best experts on this subject based on the ideXlab platform.

  • parametric instability of thermo mechanically loaded functionally graded graphene reinForced nanocomposite plates
    International Journal of Mechanical Sciences, 2018
    Co-Authors: S Kitipornchai
    Abstract:

    This paper investigates the parametric instability of functionally graded graphene reinForced nanocomposite plates that undergo a periodic uniaxial in-Plane Force and a uniform temperature rise. The plate is composed of multiple graphene platelet reinForced composite (GPLRC) layers in which graphene platelets (GPLs) are uniformly distributed in each individual layer with GPL concentration varying layer-wise across the plate thickness. The modified Halpin–Tsai model that takes into account the GPL geometry effect is employed to calculate the Young's modulus of the GPLRC. Based on the first-order shear deformation theory, the governing equations are deduced and then are solved by using the differential quadrature approach integrated with the Bolotin's method. A parametric study is undertaken to show the influences of GPL distribution pattern, concentration and geometry, temperature change, static in-Plane Force, plate geometry and boundary condition on the parametric instability of functionally graded multilayer GPLRC plates. It is found that the addition of a small amount of GPL reinForcements considerably increases the critical buckling load and natural frequencies but reduces the size of unstable region. The reinforcing effect is the best when the surface layers of the plate are GPL-rich.

Bo Liedberg - One of the best experts on this subject based on the ideXlab platform.

  • 3d structured stretchable strain sensors for out of Plane Force detection
    Advanced Materials, 2018
    Co-Authors: Zhiyuan Liu, Wan Ru Leow, Michele Xiloyannnis, Leonardo Cappello, Yaqing Liu, Bowen Zhu, Ying Jiang, Geng Chen, Lorenzo Masia, Bo Liedberg
    Abstract:

    Stretchable strain sensors, as the soft mechanical interface, provide the key mechanical information of the systems for healthcare monitoring, rehabilitation assistance, soft exoskeletal devices, and soft robotics. Stretchable strain sensors based on 2D flat film have been widely developed to monitor the in-Plane Force applied within the Plane where the sensor is placed. However, to comprehensively obtain the mechanical feedback, the capability to detect the out-of-Plane Force, caused by the interaction outside of the Plane where the senor is located, is needed. Herein, a 3D-structured stretchable strain sensor is reported to monitor the out-of-Plane Force by employing 3D printing in conjunction with out-of-Plane capillary Force-assisted self-pinning of carbon nanotubes. The 3D-structured sensor possesses large stretchability, multistrain detection, and strain-direction recognition by one single sensor. It is demonstrated that out-of-Plane Forces induced by the air/fluid flow are reliably monitored and intricate flow details are clearly recorded. The development opens up for the exploration of next-generation 3D stretchable sensors for electronic skin and soft robotics.

K Papagelis - One of the best experts on this subject based on the ideXlab platform.

  • in Plane Force fields and elastic properties of graphene
    Journal of Applied Physics, 2013
    Co-Authors: G Kalosakas, N N Lathiotakis, C Galiotis, K Papagelis
    Abstract:

    Bond stretching and angle bending Force fields, appropriate to describe in-Plane properties of graphene sheets, are derived using first principles' methods. The obtained Force fields are fitted by analytical anharmonic potential energy functions, providing efficient means of calculations in molecular mechanics simulations. Using both molecular dynamics simulations and first principles' methods, numerical results regarding the mechanical behavior of graphene monolayers under various loads, like uniaxial tension in different directions or hydrostatic tension, are presented and compared. Graphene's response in shear stress is also investigated using molecular dynamics, where a noticeable asymmetric mechanical behavior is found. Stress-strain curves and elastic constants, such as, Young modulus, Poisson's ratio, bulk modulus, and shear modulus, are calculated. Our results are compared with available experimental estimates, as well as, with corresponding theoretical calculations. Finally, the effects of the anharmonicity of the extracted bond stretching and angle bending potentials on the mechanical properties of graphene are discussed.

  • in Plane Force fields and elastic properties of graphene
    arXiv: Materials Science, 2012
    Co-Authors: G Kalosakas, N N Lathiotakis, C Galiotis, K Papagelis
    Abstract:

    Bond stretching and angle bending Force fields, appropriate to describe in-Plane motion of graphene sheets, are derived using first principles' methods. The obtained Force fields are fitted by analytical anharmonic energy potential functions, providing efficient means of calculations in molecular mechanics simulations. Numerical results regarding the mechanical behavior of graphene monolayers under various loads, like uniaxial tension, hydrostatic tension, and shear stress, are presented, using both molecular dynamics simulations and first principles' methods. Stress-strain curves and elastic constants, such as, Young modulus, Poisson ratio, bulk modulus, and shear modulus, are calculated. Our results are compared with corresponding theoretical calculations as well as with available experimental estimates. Finally, the effect of the anharmonicity of the extracted potentials on the mechanical properties of graphene are discussed.