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...

We present a modal theory of self-trapping spatially incoherent light beams in any general nonlinear media. We find that a self-trapped incoherent beam induces a multimode waveguide which guides the beam itself by multiply populating the guided modes. The self-trapping process alters the statistics of the incoherent beam, rendering it localized. We find the conditions for self-trapping (“existe...

Crack identification is a very important issue in mechanical systems, because it is a damage that if develops may cause catastrophic failure. In the first part of this research, modal analysis of a multi-cracked variable cross-section beam is done using finite element method. Then, the obtained results are validated usingthe results of experimental modal analysis tests. In the next part, a nove...

A wave model is proposed for estimating damping loss factor as a function of frequency for a beam with arbitrary transient loading applied through the boundary conditions. In contrast to modal methods which provide measures of damping only at the modal frequencies of the test structure, the damping factor is determined over discrete, but regularly spaced, frequency values associated with the te...

We describe a polarization-selective beam splitter by a sandwiched grating, which can fulfill the high efficiency element for TE polarization and the two-port output for TM polarization. The modal method and the rigorous coupled-wave analysis (RCWA) are employed together to optimize the polarization-selective beam splitter. According to the modal method, the grating duty cycle and period are di...

In this research, the modal parameters of a beam in free-free condition are extracted by performing different experiments in laboratory. For this purpose, two different techniques are employed. The first methodology is considered as a time domain method in Operational Modal Analysis. While the other one is frequency domain impact hammer test which is categorized as an Experimental Modal Analysi...

We describe recent theoretical and experimental studies of polarization and spatial information recovery by modal dispersal and phase conjugation. We discuss the fidelity of this phase-conjugation process as a function of input-beam launching conditions. We also describe several new applications of the scheme which involve correction of nonreciprocal polarization distortions, correction of loss...

crack identification is a very important issue in mechanical systems, because it is a damage that if develops may cause catastrophic failure. in the first part of this research, modal analysis of a multi-cracked variable cross-section beam is done using finite element method. then, the obtained results are validated usingthe results of experimental modal analysis tests. in the next part, a nove...

The success of vibration-based damage identification procedures depends significantly on the accuracy and completeness of the available identified modal parameters. This paper investigates the level of confidence in the damage identification results as a function of uncertainty in the identified modal parameters through a probabilistic damage identification strategy, i.e., Bayesian finite eleme...

Control systems for shakers are necessary to remove both shaker dynamics as well as coupling effects between the shaker and the structure under test. Little attention has been given to shaker control for nonlinear structures. This paper presents the design, implementation and results of a shaker controller for a horizontal, cantilevered beam subjected to a non-uniform magnetic field. The object...