A procedure is presented for modal and damping synthesis of flexible space structures from subsystem tests and/or analyses. In view of the various damping mechanism operative in a space structure, their contribution to total system damping and its compatibility with dynamic testing procedures, the spacecraft subsystems are identified as joints and components. The dynamics of joint subsystems is...

We propose practical analysis techniques to accurately measure geometric, dynamic, and material properties of MEMS. Analytical methods and test structures are presented to extract over a dozen properties by electric probing in a minimal chip area. Geometric properties include fabrication error with respect to layout geometry such as beam widths, gap spacings, etch holes, and beam lengths. Dynam...

In the current study, the effects of Casimir force and squeeze film damping on pull-in instability and dynamic behavior of electrostatically actuated nano and micro electromechanical systems are investigated separately. Linear elastic membrane theory is used to model the static and dynamic behavior of the system for strip, annular and disk geometries. Squeeze film damping is modeled using nonli...

Dynamic viscoelastic properties of bamboo were determined in torsion and bending. Damping, measured by tan δ, in dry bamboo was relatively small, about 0.01 in bending and 0.02 to 0.03 in torsion, with little dependence on frequency in the audio range. In wet bamboo, damping was somewhat greater: 0.012 to 0.015 in bending and 0.03 to 0.04 in torsion. The anisotropy in damping implies a purely c...

In the dynamic analysis of structural engineering systems, it is common practice to introduce damping models to reproduce experimentally observed features. These models, for instance Rayleigh damping, account for the damping sources in the system altogether and often lack physical basis. We report on an alternative path for reproducing damping coming from material nonlinear response through the...

To evaluate the earth seismic response due to earthquake effects, ground response analyses are used to predict ground surface motions for development of design response spectra, to compute dynamic stresses and strains for evaluation of liquefaction hazards, and to determine the earthquake induced forces that can lead to instability of earth and earth-retaining structures. Most of the analytical...

NiCrAlY coating was prepared on a stainless steel substrate by an arc ion plating machine and the annealing experiments were carried out at different temperatures using a tube furnace. The effects of annealing temperatures on the morphology, structure, chemical composition and phase structure of the coating were characterized by SEM, EDS and XRD, respectively. The change of microstructure is di...

Micro system technology is a relatively new scientific research that deals with the development and study of properties of materials in micro dimensions. Micro-grippers are widely used in switching, positioning, and assembling micron sized components in micro-robotics. In this study, the static and dynamic behavior of visco-elastic Micro-Tweezers under the thermal and electrostatic field is...

During consolidation process of saturated cohesive soil the soil stiffness increases. Increase of the effective stress due to dissipation of excess pore pressure causes additional stiffness of soil mass. This phenomenon has a very important effect on the behavior of saturated cohesive soils during dynamic loading. In the current investigation the changes in maximum shear modulus. Gmax and dampi...