A numerical study of free and forced vibration of composite sandwich beam with viscoelastic core

Abstract In this article, higher order theory for sandwich beam with composite faces and viscoelastic core is achieved by considering independent transverse displacements on two faces and linear variations through the depth of the beam core. In addition, the effects of Young modulus, rotational inertia and core kinetic energy are considered to modify the “Mead & Markus” theory that is used frequently for sandwich beam. These assumptions have not been considered together in previous articles. A finite element code is developed for structural response analysis of the free and forced vibration. The obtained results are compared with the corresponding results of previous researches. The effects of impressive parameters including fiber angle, thickness of faces and core thickness on the loss factors and natural frequencies of the beam are examined. Frequency response of the beam for two cases, constant and frequency dependent core shear modulus are obtained. Finally, time response of the beam is presented based on the Newmark method. Obtained results show that, when the core is soft or hard, “Mead & Markus” theory cannot accurately predict the frequency responses of the system in comparison with the presented theory in this paper; whereas for moderately hard core, both methods lead to the same results. In addition, when the beam is unsymmetrical about its neutral axis, i.e. one face sheet is weaker than the other face sheet, the inaccuracy of the “Mead & Markus” theory increases, even at low frequencies.

[1]  B. E. Douglas,et al.  Transverse Compressional Damping in the Vibratory Response of Elastic-Viscoelastic-Elastic Beams. , 1978 .

[2]  Lien-Wen Chen,et al.  Vibration and damping analysis of a three-layered composite annular plate with a viscoelastic mid-layer , 2002 .

[3]  C. Cai,et al.  Vibration analysis of a beam with PCLD Patch , 2004 .

[4]  N. Ganesan,et al.  Vibration and thermal buckling of composite sandwich beams with viscoelastic core , 2007 .

[5]  L. Meirovitch.  Principles and techniques of vibrations , 1996 .

[6]  D. J. Mead,et al.  The forced vibration of a three-layer, damped sandwich beam with arbitrary boundary conditions , 1969 .

[7]  M. Sainsbury,et al.  The Galerkin element method applied to the vibration of damped sandwich beams , 1999 .

[8]  B. Jang,et al.  A study on material damping of 0° laminated composite sandwich cantilever beams with a viscoelastic layer , 2003 .

[9]  C. D. Johnson,et al.  Design of Passive Damping Systems , 1995 .

[10]  Thomas T. Baber,et al.  A FINITE ELEMENT MODEL FOR HARMONICALLY EXCITED VISCOELASTIC SANDWICH BEAMS , 1998 .

[11]  Qian Chen,et al.  Integral finite element method for dynamical analysis of elastic–viscoelastic composite structures , 2000 .

[12]  C. T. Sun,et al.  The Effect of Viscoelastic Adhesive Layers on Structural Damping of Sandwich Beams , 1995 .

[13]  Hualing Chen,et al.  A study on the damping characteristics of laminated composites with integral viscoelastic layers , 2006 .

[14]  L. Kollár,et al.  Mechanics of Composite Structures , 2003 .

[15]  C. Bert,et al.  The behavior of structures composed of composite materials , 1986 .

[16]  B. E. Douglas,et al.  Compressional damping in three-layer beams incorporating nearly incompressible viscoelastic cores , 1986 .