An active constrained beam subjected to temperature was analyzed for its vibration and damping behavior under thermal environment. The loss factor variation and frequency variation in respect to temperature considering the the temperature dependent core shear modulus and temperature dependent material loss factor of the core were reported. The temperature field in the beam was calculated by using 4 noded rectangular elements. Results indicated that as core thickness increases, passive damping in the beam increases.

V. Pradeep

Natrajan Ganesan

Damping

Elastic moduli

Thermal effects

ACLD TREATED BEAMS

FREQUENCY VARIATION

Thermal environment

BEAMS AND GIRDERS

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Sound and Vibration

Purpose - The purpose of this paper is to present numerical studies on thermally induced vibrations of piezo-thermo-viscoelastic composite beam subjected to a transient thermal load using coupled finite element method. Design/methodology/approach - The thermal relaxation and viscoelastic relaxations are taken into consideration to obtain the system response. The concept of "memory load" along with the thermal relaxation is accounted for viscoelastic core material. The influence of type of core material on the response of the system also analyzed. Findings - The findings show viscoelastic behavior with relaxation times in composite sandwich structures. Originality/value - The paper shows accounting relaxation times as a memory load in composite sandwich structures. © Emerald Group Publishing Limited.

Fulltext

Multidiscipline Modeling in Materials and Structures

Thermally induced vibrations of piezo-thermo-viscoelastic composite beam with relaxation times and system response

Sandwich beam having viscoelastic core is analyzed for its buckling and vibration behavior under thermal environments, using the finite element method. Variation of natural frequencies and loss factors with respect to temperature is investigated. The formulation is based on the displacement field proposed by Khatua and Cheung [International Journal for Numerical Methods in Engineering 6 (1973) 11-24]. The behavior of the beam considering both the temperature dependent and independent shear modulus of the core is studied. A parametric study is conducted with core thickness as parameter and its influence on buckling temperatures, natural frequencies and loss factors is studied. Two different core materials are considered for the analysis to find the influence of material on buckling and vibration behaviors. © 2005 Elsevier Ltd. All rights reserved.

Buckling and vibration of sandwich beams with viscoelastic core under thermal environments

Piezoelectric composite cylindrical shells operating in a steady state axisymmetric temperature are analyzed using a semi-analytical finite element method. Numerical studies are conducted on a clamped-clamped composite cylindrical shell for three typical length to radius ratios. The static thermal buckling analysis is carried out for a single layered composite cylindrical shell with different fiber orientation and hence study its influence on thermal buckling temperature. The influence of axisymmetric temperature on the natural frequencies and active damping ratio of the piezoelectric cylindrical shell is also examined. Two configurations of composite laminates: symmetric and antisymmetric with varying the number of plies is also considered to examine the effect on thermal buckling temperature. © 2002 Elsevier Science Ltd. All rights reserved.

Composite Structures

Buckling and dynamic analysis of piezothermoelastic composite cylindrical shell

Effect of ACLD treatment configuration on damping performance of a flexible beam

This work deals with the active vibration control of beams with smart constrained layer damping (SCLD) treatment. SCLD design consists of viscoelastic shear layer sandwiched between two layers of piezoelectric sensors and actuator. This composite SCLD when bonded to a vibrating structure acts as a smart treatment. The sensor piezoelectric layer measures the vibration response of the structure and a feedback controller is provided which regulates the axial deformation of the piezoelectric actuator (constraining layer), thereby providing adjustable and significant damping in the structure. The damping offered by SCLD treatment has two components, active action and passive action. The active action is transmitted from the piezoelectric actuator to the host structure through the viscoelastic layer. The passive action is through the shear deformation in the viscoelastic layer. The active action apart from providing direct active control also adjusts the passive action by regulating the shear deformation in the structure. The passive damping component of this design eliminates spillover, reduces power consumption, improves robustness and reliability of the system, and reduces vibration response at high-frequency ranges where active damping is difficult to implement. A beam finite element model has been developed based on Timoshenko's beam theory with partially covered SCLD. The Golla-Hughes-McTavish (GHM) method has been used to model the viscoelastic layer. The dissipation co-ordinates, defined using GHM approach, describe the frequency-dependent viscoelastic material properties. Models of PCLD and purely active systems could be obtained as a special case of SCLD. Using linear quadratic regulator (LQR) optimal control, the effects of the SCLD on vibration suppression performance and control effort requirements are investigated. The effects of the viscoelastic layer thickness and material properties on the vibration control performance are investigated.

Journal	Journal of Sound and Vibration
Publisher	Academic Press
ISSN	0022460X
Open Access	No