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With the increasing use of additive manufacturing (AM) in diverse fields, printed structures are inevitably exposed to vibrations, which can result in fracture, fatigue, and noise. Present study aims to enhance the damping characteristics of the final part by incorporating viscoelastic materials into the primary structure using multi-material AM. The effects of process parameters on the vibration damping characteristics of printed viscoelastic structures were investigated through modal analysis and design of experiments. Results show that higher nozzle temperature, smaller layer height, lower deposition speed and smaller raster angle contribute to higher resonant frequencies and loss factors of the final parts. [ABSTRACT FROM AUTHOR]

AbstractThe present article aims at performing a global sensitivity analysis of modal properties of a frequency dependent viscoelastic sandwich plate. The latter are evaluated using a finite element model relying on Kirchhoff theory for the elastic faces and the Mindlin-Reissner approach for the viscoelastic layer. The plate’s characteristics are considered as random variables following log normal laws. Sparse polynomial chaos expansions are employed to evaluate Sobol’s indices. For high damping, the resonant frequencies and loss factors turn to be sensitive to the elastic face properties, while in the weak damping case they are mostly affected by the viscoelastic model parameters. [ABSTRACT FROM AUTHOR]

This paper presents a numerical method to solve the non-linear vibration problem of composite structures made of many unidirectional fibers/matrix layers. To take into account damping properties of structures, fractional derivative Zener model for complex moduli is used in each layer. The frequency dependence of these models leads to a non-linear vibration problem. To solve it, a High Order Newton (HON) solver based on homotopy and perturbation techniques is proposed. Thus, the initial non-linear problem turns into a set of linear systems, easier to solve. Numerical results obtained by the HON solver are compared with experimental and numerical results of literature. [ABSTRACT FROM AUTHOR]

A simple methodology for nonlinear vibration analysis of viscoelastic shell structures is established. The method is limited to periodic damped responses and couples an approximated harmonic balance method with a one mode Galerkin's procedure, which leads to an amplitude equation for free nonlinear vibration analysis of curved viscoelastic structures.

This study deals with the analysis of multilayer composite and functionally graded materials (FGM) structures. The material properties of the FGM beam are assumed to vary according to the power law distribution of its constituent's volume fraction over the cross section. The analytical analysis seems to be cumbersome. A finite element approach is investigated in this work for the static and free vibration behaviors of the 2D FGM beams with variable constituents over the cross section. The analyses are carried out in arbitrary axes and the axial, bending and shear couplings are considered. In this study, the classical beam theory, Timoshenko first-order and higher order shear models are described and implemented. The different models are compared to benchmark solutions found in the literature. Effects of boundary conditions, slenderness ratio, and the FGM power law parameter are investigated under static and free vibration analyses. FGM and multilayer sandwich beams are also analyzed. It is proven that the axial bending and shear coupling affect the behavior of the FGM beams in both statics and dynamics. In the presence of short beams, shear effect is important and leads to cross-section warping. The classical beam theory fails in this context. All models are close in the case of slender beams. [ABSTRACT FROM AUTHOR]

In this article, a modal analysis of rotating viscoelastic sandwich beams with uniform cross sections and with various viscoelastic stiffness laws is conducted. The governing equations of motion are derived using the virtual work principle and discretized by the finite element procedure. The obtained nonlinear eigenvalue problems are solved by coupling the homotopy and asymptotic numerical techniques leading to complex solutions composed of natural frequencies and loss factors. Further, the effects of the rotating speed, thickness and core layer position on the dynamic characteristics are investigated. Furthermore, the effects of the frequency dependence of the shear modulus is investigated for a beam subject to various boundary conditions. Then, numerical tests are performed and the obtained results coincide very well with the literature and those provided by the commercial software Abaqus. [ABSTRACT FROM AUTHOR]