Determination of effective damping characteristics of fiber-reinforced viscoelastic composites

Abstract

A numerical method for the determination of effective complex moduli and vibration decrements of fiber-reinforced viscoelastic composites is proposed, which is based on the finite element modeling of representative volume element and equation of the elastic and viscous parts of the strain energy of composite and quasi-homogeneous material volumes.Keywords: composite, effective complex moduli, vibration decrement, finite element method.Introduction. The investigation of the properties of composite materials, such as polymer-based fibrous composites, indicates then to have promise in many industries, primarily thanks to the high characteristics of specific strength and internal energy dissipation and the possibility of controlling mechanical characteristics by changing structure parameters.The advantages of composites can be utilized by the rational choice of reinforcement schemes, proper choice of constituents and computing methods, which allow one to take into account discontinuous material functions throughout the composite volume and corresponding defining relations for the materials making up the composite. Exact analytical solutions of the problem which takes into account these peculiarities are possible only in few cases [1], in view of which so-called "effective" characteristics of composites, which are determined either experimentally or by computational methods, are employed in calculations [2].Since experimental and most approximate analytical methods do not permit one to accurately take into account the peculiarities of stress and strain distribution throughout the volume, the search for and use of more exact methods for the determination of effective characteristics are a topical problem, especially taking into account the possibility of optimizing constructions made of composites. Many works, e.g. [3,4], are devoted to determining effective characteristics, such as elastic moduli of unidirectional composites. There are much fewer works dealing with determining effective elastic characteristics of cross-reinforced composites (reinforced in two directions) [5, 6], composites with multidimensional reinforcement (in three, four and more directions) [7][8][9][10][11][12][13][14][15], and there are very few studies on the effective characteristics of imperfectly elastic materials, such as damping characteristics [16][17][18][19][20]. It is known that the properties of the whole material change with increasing the number of reinforcement directions in composite at constant reinforcement ratio [3,11]. In view of the fact that there are numerous spatial reinforcement schemes, the question arises whether it is expedient to use each of the schemes in the design of constructions made of tailor-made composites. The aim of this work is to develop a method for the determination of effective complex moduli and vibration decrements of composites with viscoelastic constituents and to study the effect of reinforcement peculiarities on the damping characteristics of fibrous composites.Method of Analysis. To calculate the...

Predicting the viscoelastic behavior of polymer nanocomposites

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Experimental damping ratio evaluation using Hilbert transform in filament-wound composite plates

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