|
چکیده
|
This research investigates the vibration characteristics, frequency response and dynamic stability of cylindrical sandwich panels comprising an electrorheological (ER) core on a visco pasternak-foundation. The sandwich panel comprises an ER core sandwiched between upper and lower layers of nanocomposite viscoelastic materials. Utilizing the Mori{Tanaka approach, the properties of these layers are determined. Separate governing equations are formulated for each layer, and the structural equations are derived based on the energy principles and Hamilton’s principle. Analytical methods and direct integration techniques are employed to solve the resulting differential equations of motion. Material properties of the core are determined using the Kelvin and Bingham models, and a novel model is proposed by comparing its results with experimental data, addressing previous shortcomings, and providing satisfactory results. Numerical findings indicate that increasing the volume fraction of carbon nanotubes (CNTs) in the surface layers, electric field intensity and stiffness/shear coefficients of the substrate enhance the natural frequency of the cylindrical panel. Moreover, heightened electric field intensity, viscoelastic coefficients of the layers, and substrate damping diminish system vibration amplitudes, damping the vibrations. Furthermore, the effects of various parameters such as layer thickness ratio, static load coefficient, boundary conditions, substrate coefficients, CNT volume fraction in surface layers, and electric field on dynamic instability regions (DIRs) are explored. The outcomes of this study hold relevance for applications in military, aerospace, maritime and automotive industries.
|