We study pull-in instabilities in a functionally graded microelectromechanical system (MEMS) due to the heat produced by the electric current. Material properties of two-phase MEMS are assumed to vary continuously in the thickness direction. It is shown that the pull-in voltage strongly depends upon the variation through the thickness of the volume fractions of the two constituents. It is proba...

Abstract Acoustic underwater propulsion systems based on an ultrasonic transducer have been studied. In previous research, the self-propelled acoustic swimmer using thickness-vibration-mode is evaluated widely. The excited in thickness and radial direction. Because system driving force, vibration direction hard to provide thrust. this study, a cylindrical transducer, pure longitudinal vibrator,...

We report magnetophotoluminescence measurements of stacked layers of self-assembled InP quantum dots. With a magnetic field applied in the growth direction we have determined the exciton reduced mass from the field dependence of the photoluminescence energy. By applying a magnetic field perpendicular to the growth direction, we have analyzed the spatial confinement of the dots in the growth dir...

Free vibration characteristics of continuous grading fiber orientation (CGFO) beams resting on variable Winkler and two-parameter elastic foundations have been studied. The beam is under different boundary conditions and assumed to have arbitrary variations of fiber orientation in the thickness direction. The governing differential equations for beam vibration are being solved using Generalized...

The modern engineering structures require the advanced engineering materials to resist the high temperatures and to provide high stiffness. In particular the functionally graded porous materials (FGPMs) introduced are expected to have these desired properties, consequently eliminating local stress concentration and de-lamination. In the present paper, a new shear strains shape function is chose...

Thermo-elastic analysis of a functionally graded hollow sphere is carried out and numerical solutions of displacement, stress and thermal fields are obtained using the Polynomial differential quadrature (PDQ) method. Material properties are assumed to be graded in the radial direction according to a power law function, ho...

This paper presents a study on the use of optical fiber and a solar concentrator for a building daylighting system. Daylighting is essential for improving indoor environments and reducing electric lighting power consumption in office buildings. Traditionally, optical fiber daylighting systems were implemented only on a small scale. More complicated technologies are required for more amounts of ...

The initiation and propagation of a crack and an adiabatic shear band in three-dimensional finite coupled thermomechanical deformations of a homogeneous and isotropic thermoelastoviscoplastic rectangular 4340 steel plate containing a centrally located through-the-thickness elliptic void and deformed in simple tension are analyzed numerically by using thefinite element computer codeDYNA3D. Initi...

Similar to the very vast prior literature on analyzing laminated composite structures, “higher-order” and “layer-wise higher-order” plate and shell theories for functionally-graded (FG) materials and structures are also widely popularized in the literature of the past two decades. However, such higher-order theories involve (1) postulating very complex assumptions for plate/shell kinematics in ...