Research and applications of viscoelastic vibration damping materials: A review

The present literature review focuses on geometrically non-linear free and forced vibrations of shells made of traditional and advanced materials. Flat and imperfect plates and membranes are excluded. Closed shells and curved panels made of isotropic, laminated composite, piezoelectric, functionally graded and hyperelastic materials are reviewed and great attention is given to non-linear vibrations of shells subjected to normal and in-plane excitations. Theoretical, numerical and experimental studies dealing with particular dynamical problems involving parametric vibrations, stability, dynamic buckling, non-stationary vibrations and chaotic vibrations are also addressed. Moreover, several original aspects of non-linear vibrations of shells and panels, including (i) fluid–structure interactions, (ii) geometric imperfections, (iii) effect of geometry and boundary conditions, (iv) thermal loads, (v) electrical loads and (vi) reduced-order models and their accuracy including perturbation techniques, proper orthogonal decomposition, non-linear normal modes and meshless methods are reviewed in depth.

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Non-linear vibrations of shells: A literature review from 2003 to 2013

The objective of the research was to improve the wear resistance of titanium alloys by ball burnishing process. Burnishing process parameters such as burnishing speed, burnishing feed, burnishing force and number of pass were considered to minimize the specific wear rate and coefficient of friction. Taguchi optimization results revealed that burnishing force and number of pass were the significant parameters for minimizing the specific wear rate, whereas the burnishing feed and speed play important roles in minimizing the coefficient of friction. After burnishing surface microhardness increased from 340 to 405 Hv, surface roughness decreased from 0.45 to 0.12 μm and compressive residual stress were generated immediately below the burnished surface. The optimization results showed that specific wear rate decreased by 52%, whereas coefficient of friction was reduced by 64% as compared to the turned surface. The results confirm that, an improvement in the wear resistance of Ti–6Al–4V alloy has been achieved by the process of ball burnishing.

Wear resistance enhancement of titanium alloy (Ti–6Al–4V) by ball burnishing process

A wide range of surface modification processes has been developed over the past decades. Beside the well-established processes such as shot peening, there are other emerging surface modification processes such as machine hammer peening with a potential of applications that still needs to be evaluated. Therefore, all surface modification processes using guided tools with periodic or continuous contact to the workpiece are compared in this paper. After a classification of the processes, the paper presents a systematic description by comparing the different technologies and it explains the proposed standardized nomenclature. It identifies the relevant physical mechanisms of the surface modifications processes and it compares the influences on surface roughness, residual stresses, work hardening and microstructure. One section is dedicated to the need of an accompanying quality assurance. Furthermore, the capabilities of different process simulation approaches are analyzed with respect to process mechanisms and the resulting surface layer characteristics. The service performance such as fatigue life, corrosion resistance, friction and wear are discussed based on best practice results. Finally, the paper discusses the actual and potential applications of surface modification processes: surface strengthening, post welding treatments, smoothing of tools and molds as well as surface structuring and embedding of coating materials.

Surface modification by machine hammer peening and burnishing

A unified formulation for vibration analysis of composite laminated shells of revolution including shear deformation and rotary inertia

In the present study, Low Plasticity Burnishing (LPB®) process on the half-space specimen has been simulated using a 3D explicit nonlinear finite element model. The developed finite element model is then used to investigate the effect of main parameters including ball diameter, burnishing force, burnishing feed, and number of passes on the resultant profile of residual stress and plastic deformation. Due to high computational cost associated with the nonlinear finite element model and in order to practically conduct design optimization of the LPB process, the design of experiment combined with the response surface methodology has been used to develop smooth response functions to efficiently and accurately approximate the residual stress profile and plastic deformation over the entire design space. Finally in order to improve the LPB process, a design optimization using the developed response functions has been formulated to obtain the optimum set of parameters such that a deep residual compressive stress with small plastic deformation is generated throughout the thickness of component.

Finite element analysis and design optimization of low plasticity burnishing process

Linear and nonlinear vibration analysis of sandwich cylindrical shell with constrained viscoelastic core layer

Vibration analysis and design optimization of viscoelastic sandwich cylindrical shell

Nonlinear vibration analysis of sandwich shell structures with a constrained electrorheological (ER) fluid is investigated for different boundary conditions. To accomplish this, a nonlinear finite element model of a multi-layer shell structure with an ER fluid layer in the core of the sandwich shell has been developed. A new notation referred to as H-notation is presented, in place of the two well known notations referred to as B- and N-notation, in order to represent the nonlinear equations of motion. This notation leads to a considerable reduction in the computational costs caused by the time-consuming integrations in the nonlinear vibration analysis of the structure using a direct iteration technique. In particular, this notation is very useful for solving the nonlinear vibration analysis of sandwich layered shell structures in which large numbers of integrations are required to be repeatedly performed throughout the direct iteration technique. Finally, for different boundary conditions, the effects of small and large displacements, core thickness ratio and electric field intensity on the nonlinear vibration damping behavior of the sandwich shell structure are presented.

http://iopscience.iop.org/article/10.1088/0964-1726/21/7/075035/pdf

Nonlinear free vibration analysis of sandwich shell structures with a constrained electrorheological fluid layer

Compared with viscoelastic materials, electrorheological fluids can be effectively used to suppress the vibration over a broad frequency and temperature range. In this study, vibration analysis and damping characteristics of sandwich cylindrical panel structures using semiactive electrorheological fluid treatments have been investigated for different boundary conditions. Unconstrained viscoelastic material has been used at boundary and untreated locations to seal electrorheological fluids. First, an efficient finite element method has been formulated to investigate the effect of electric field intensity and thickness of top constrained elastic layer on the vibration and damping performance of the viscoelastic- and electrorheological-based sandwich cylindrical panel. Then, a design optimization methodology has been developed to simultaneously optimize the number of unconstrained viscoelastic and constrained electrorheological fluid patches and their distributions, thickness ratios of the electrorheological...

Farough Mohammadi

Papers

Finite element analysis and design optimization of low plasticity burnishing process

Linear and nonlinear vibration analysis of sandwich cylindrical shell with constrained viscoelastic core layer

Vibration analysis and design optimization of viscoelastic sandwich cylindrical shell

Nonlinear free vibration analysis of sandwich shell structures with a constrained electrorheological fluid layer

Vibration analysis and design optimization of sandwich cylindrical panels fully and partially treated with electrorheological fluid materials