Two robust nonlinear controllers along with a nonlinear observer have been developed in this study to control a 1D nonlinear flexible spacecraft. The first controller is based on dynamic inversion, while the second one is composed of dynamic inversion and µ-synthesis controllers. The extension of dynamic inversion approach to flexible spacecraft is impeded by the non-minimum phase characteristi...

The purpose of this paper is concerned with the mathematical model development issues, necessary for a better prediction of dynamic responses of articulated rotor helicopters. The methodology is laid out based on mathematical model development for an articulated rotor helicopters, using the theories of aeroelastisity, finite element and the time domain compressible unsteady aerodynamics. The he...

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...

the seismic performance of hybrid braces composed of steel and shape memory alloy (sma) was investigated in this paper. six types of hybrid braces were used, constituted by sma content of 0, 20, 40, 60, 80, and 100%. a nonlinear dynamic analysis was performed under el centro earthquake records, with the maximum acceleration of 0.6g and 0.9g. our results showed that the seismic performance, i.e....

yielding elements (ye) are among those devices that not only help control structural damages, but make better seismic behavior by concentrating the frames in some removable part of the structures. ye are located at the intersection of concentric braced frame (cbf) in a rectangular shape. in this paper, seismic behavior of the frames with ye will be investigated. for this reason, 5 braced steel ...

the nonlinear discrete crack modeling of Shahid Rajaee thin arch dam is considered. The interface elements are positioned such that certain potential separated blocks can form possible failure mechanisms. The dynamic stability of theses blocks are investigated by a special finite element program "MAP-73" which its nonlinear algorithm and interface elements formulation are presented.

This paper presents a complete derivation and implementation of the Arbitrary Lagrangian Eulerian (ALE) formulation for the simulation of nonlinear static and dynamic problems in solid mechanics. While most of the previous work done on ALE for dynamic applications was mainly based on operator split and explicit calculations, this work derives the quasi-static and dynamic ALE equations in its si...

A desired dynamic behavior of constrained manipulators can be achieved by means of impedance control and various implementations of fixed controllers have been proposed. In this paper, and adaptive implementation is presented as an alternative to reduce the design sensitivity due to manipulator mismatch. The adaptive controller globally achieves the impedance objective for the nonlinear dynamic...

This paper presents the effect of preload on nonlinear dynamic behavior of a rigid rotor supported by two-lobe aerodynamic noncircular journal bearing. A finite element method is employed to solve the Reynolds equation in static and dynamical states and the dynamical equations are solved using Runge-Kutta method. To analyze the behavior of the rotor center in the horizontal and vertical directi...