In this paper, we introduce a method that provides a nonlinear noncollocated output for trajectory tracking of a flexible one-link robot. The link is modeled as a finite-order Lagrangian system obtained from truncated modal analysis. This noncollocated output is derived based on viewing a flexible link robot arm as an underactuated mechanical system and then applying an appropriate change of co...

This paper introduces the idea of a ‘simplifying transformation’ for nonlinear structural dynamic systems. The idea simply stated; is to bring under one heading, those transformations which ‘simplify’ structural dynamic systems or responses in some sense. The equations of motion may be cast in a simpler form or decoupled (and in this sense, nonlinear modal analysis is encompassed) or the respon...

An approximate numerical mthod is presented for analysis and determination of modal characteristics in straight, pretwisted non-unifom helicopter blades. The analysis considers the coupled flapwise bending (out of plane), chordwise bending (in plane), and torsion vibration of both rotating and non-rotating blades. The proposed method is based on the integral expansion of Green functions (struct...

torsion of many symmetric structures, which were designed based on the seismic codes, is due to their asymmetricity induced during inelastic behavior. although the structure was designed symmetrically assuming elastic based criteria, different factors such as material inconsistency in structure, construction details discrepancy and construction errors may result in asymmetric behavior in inelas...

Operational Modal Analysis (OMA) is a technique of extracting modal parameters of a system from output responses only. It is an emerging field in structural dynamics and has been applied to complex structures that are often difficult to analyze using traditional Experimental Modal Analysis (EMA) techniques. Since the input information is unavailable in OMA, the technique makes use of certain as...

An approach is presented to investigate the 1:2 internal resonance of sling and beam a suspension sling–beam system. The was taken as geometrically linear Euler beam, considered be nonlinear. dynamic equilibrium equation structures derived using modal superposition method, D’Alembert principle Hamilton principle. nonlinear equations free vibration forced oscillation were solved by multiple-scal...

According to the great importance of safety in aerospace industries, identification of dynamic parameters of related equipment by experimental tests in operating conditions has been in focus. Due to the existence of noise sources in these conditions the probability of fault occurrence may increases. This study investigates the effects of noise in the process of modal parameters identification b...