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Government Printing Office expands database access

A review of recent researches on FGM cylindrical structures under coupled physical interactions, 2000–2015

Analysis of wave propagation characteristics in piezoelectric cylindrical composite shells reinforced with carbon nanotubes

Dynamics of wave propagation in carbon nanotube (CNT)-reinforced piezocomposite cylindrical shells affected by nanotube agglomeration is investigated in this study for the first time by developing an analytical approach incorporating existing theories and models. The Mori-Tanaka micromechanics model in combination of the first-order shear deformation shell theory and wave propagation solution are employed to determine wave propagation characteristics of piezocomposite cylindrical shells reinforced with agglomerated CNTs. The effects of both partial and complete nanotube agglomerations on the effective elastic properties and wave dynamics are examined within various axial and circumferential wave numbers for different wave modes by solving an eigenvalue problem. It is found that nanotube agglomeration leads to the reduction of wave phase velocity as a result of decrease in the effective elastic properties. The developed methodology in this study can be used for analysis of the data of structural health monitoring by the non-destructive testing (NDT) in estimating the degree of nanotube agglomeration in nanocomposites.

Effects of nanotube agglomeration on wave dynamics of carbon nanotube-reinforced piezocomposite cylindrical shells

Free vibration analysis is carried out for piezoelectric coupled carbon nanotube (CNT)-reinforced composite cylindrical shells with the influences of various boundary conditions and hygrothermal environmental conditions for the first time. A simple and effective non-iterative mathematical method is used to calculate the natural frequencies. The equilibrium equations of motion are obtained based on the first-order shear deformation shell theory with the coupling effects of piezoelectricity, temperature, and moisture, respectively based on the Maxwell equation, the Fourier heat conduction equation, and the Fickian moisture diffusion equation. The Mori-Tanaka micromechanics model is used to estimate the resulting material properties for a composite shell reinforced with CNTs. Presented methodology and attained results are validated with the existing results in the literature. The effects of the boundary conditions, lamination stacking sequence, volume fraction and orientation of CNTs, piezoelectricity, and geometry of the shell on the natural frequencies of the shell are investigated. A moderate effect of temperature/moisture variation on the natural frequencies is also observed. It is found that the influence of structural boundary conditions is more significant at higher CNT volume fractions and for thicker and shorter shells, and the piezoelectricity effect is more obvious at higher circumferential mode. The model and results presented in this study can be utilized to determine vibration characteristics of smart CNT-reinforced composites subjected to hygrothermal loading as well as mechanical loading.

Free vibration analysis of smart laminated carbon nanotube-reinforced composite cylindrical shells with various boundary conditions in hygrothermal environments

The 3D piezoelasticity theory and the spatial state-space approach are used to study the steady-state non-axisymmetric sound radiation and scattering characteristics of an infinitely long, arbitrar

Acoustic radiation and active control from a smart functionally graded submerged hollow cylinder

The linear three-dimensional piezoelasticity theory in conjunction with the versatile transfer matrix approach is employed to investigate the steady-state nonaxisymmetric fluid–structure-coupled vibrations of an arbitrarily thick bilaminate simply supported hollow cylinder of finite length, composed of an inner layer of orthotropic functionally graded material perfectly bonded to an outer layer of radially/axially/circumferentially polarized functionally graded piezoceramic material. The cylinder is filled with a compressible nonviscous fluid and may be subjected to arbitrary time-harmonic on-surface mechanical drives. The analytical results are illustrated with numerical examples in which water-filled homogeneous PZT4–steel composite cylinders are driven by harmonic external concentrated or distributed radial surface loads. When the outer piezoelectric layer is operating in the receiving (sensing) mode, the frequency spectrums of the induced voltage, stress components, and on-axis acoustic pressure are c...

Vibroacoustic response and active control of a fluid-filled functionally graded piezoelectric material composite cylinder

The linear 3D piezoelasticity theory in conjunction with the versatile transfer matrix approach and the wave equation for the internal acoustic domain are employed for active non-stationary vibroacoustic response control of an arbitrarily thick, tri-laminate, fluid-filled, simply supported, piezocomposite cylindrical tank, excited by arbitrary (non-axisymmetric) time-dependent on-surface mechanical loads. The smart structure is composed of a supporting core layer of functionally graded orthotropic material perfectly bonded to inner and outer spatially distributed radially polarized functionally graded piezoceramic sensor and uniform force actuator (FGPM) layers. Active vibration damping is implemented by transferring the accumulated voltage on the sensor layer to the piezoelectric actuator layer in context of proportional and derivative control laws. Durbin's numerical inverse Laplace transform scheme is utilized to calculate the time response histories of the relevant interface displacement/stres...

Mahdi Alaei-Varnosfaderani

Papers

Acoustic radiation and active control from a smart functionally graded submerged hollow cylinder

Vibroacoustic response and active control of a fluid-filled functionally graded piezoelectric material composite cylinder

Active transient elasto-acoustic response damping of a thick-walled liquid-coupled piezolaminated cylindrical vessel