Techno Press

Steel and Composite Structures   Volume 29, Number 3, November10 2018, pages 319-332
Free vibration of thermo-electro-mechanically postbuckled FG-CNTRC beams with geometric imperfections
Helong Wu, Sritawat Kitipornchai and Jie Yang

Abstract     [Full Text]
    This paper investigates the free vibration of geometrically imperfect functionally graded car-bon nanotube-reinforced composite (FG-CNTRC) beams that are integrated with two sur-face-bonded piezoelectric layers and subjected to a combined action of a uniform temperature rise, a constant actuator voltage and an in-plane force. The material properties of FG-CNTRCs are assumed to be temperature-dependent and vary continuously across the thick-ness. A generic imperfection function is employed to simulate various possible imperfections with different shapes and locations in the beam. The governing equations that account for the influence of initial geometric imperfection are derived based on the first-order shear deformation theory. The postbuckling configurations of FG-CNTRC hybrid beams are determined by the differential quadrature method combined with the modified Newton-Raphson technique, after which the fundamental frequencies of hybrid beams in the postbuckled state are obtained by a standard eigenvalue algorithm. The effects of CNT distribution pattern and volume fraction, geometric imperfection, thermo-electro-mechanical load, as well as boundary condition are examined in detail through parametric studies. The results show that the fundamental frequency of an imperfect beam is higher than that of its perfect counterpart. The influence of geometric imperfection tends to be much more pronounced around the critical buckling temperature.
Key Words
    free vibration; postbuckling; functionally graded materials; carbon nanotube-reinforced composites; piezoelectric materials; thermo-electro-mechanical load
(1) Helong Wu, Sritawat Kitipornchai:
School of Civil Engineering, the University of Queensland, Brisbane, St. Lucia 4072, Australia;
(2) Jie Yang:
School of Engineering, RMIT University, P.O. Box 71, Bundoora, VIC 3083, Australia.

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