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Functionally graded (FG) materials are used in potential applications in several engineering systems mainly with their property tailoring ability. Especially, the micro FG structures possessing high strength to weight ratios, good energy efficiency and absorption ability and high thermal conductivities often have a wide usage in applications like micro-sensors and actuators, micro-resonators. The present work focuses on the static bending and vibration characterization of functionally graded porous micro-plates resting on nonlinear visco-elastic foundation under hygro-thermal loads. Bi-directional material grading with porosity distribution are considered. Material modeling and dynamic analysis are carried-out using higher order shear deformation formulation with modified couple stress theory (MCST). Navier's approach is followed to solve the equations of motion. The effects of power law indices, material length scale parameter, foundation stiffness parameters, temperature rise and moisture content on the natural frequencies and static response are studied in detail. The outcome of this study is benchmark for the design of micro-devices such as paddle like resonators, tunable micro-resonators etc. [ABSTRACT FROM AUTHOR]

High-speed rotating machines like an automotive turbocharger require precision operating components and conditions. A high-speed operating turbocharger can face catastrophic failures by minor unbalances. This has emphasized research on multiple parameters of the turbocharger system influencing its dynamic conditions. The present work encircles the dynamic analysis of a turbocharger rotor-bearing system with a thrust bearing. The analysis is carried out by using an FEA model of a rotor dynamic turbocharger system. The shaft and the disc are modelled to be considered as flexible and rigid members of the system respectively. The model consists of two hydrodynamic non-linear floating ring bearings and one thrust bearing. The nonlinear bearing forces are identified by using the short bearing theory approximation. Generally, in the actual scenario, the thrust bearing would not be considered in the analysis of the turbocharger, but the influence of the thrust bearing on the dynamics has a major role. Here the comparison of the dynamics of a turbocharger with and without thrust bearing is studied. Further, parametric studies such as various speeds and the preload effect on the dynamics of the system are carried out. It is identified that the sub-synchronous peaks are getting reducing after introducing the thrust bearing. The preload and rotor speed influencing the dynamics response of the system. [ABSTRACT FROM AUTHOR]

This paper proposes a methodology of finding effective elastic properties of nanoclay-reinforced polymer composites with aligned clay particles. When interphase regions exist between nanoclay platelets and polymer, numerical homogenization is initially required to identify the properties of effective particle consisting of both clay and interface regions. Once the elastic properties of equivalent particle are obtained, Mori-Tanaka approach is employed to identify all the effective properties of resultant composite. The methodology is implemented with a modular based computer program developed in MATLAB and the variation of longitudinal modulus as a function of weight fraction of nanoclay, aspect ratio of fibers, number of stacks, nanoclay volume fraction etc is reported. The empirical results are validated with a numerical model developed in ANSYS using a representative volume element for prediction of the elastic modulus. Results are illustrated with two cases of exfoliated morphology. [ABSTRACT FROM AUTHOR]