The variation in the viscous damping coefficient with carbon fiber angle can be evaluated using partial derivatives of respect to resonance frequency and modal ratio. However, direct were not effective solutions sensitivity analysis carbon-fiber-reinforced plastic (CFRP) structures because from binding matrix was changed over angle. If identified coefficients assumed equivalent values parallel ...

This paper aims to introduce two new adaptive designs of vibration control systems. First is an absorber and the second is an isolator. Absorbers are used for suppressing unwanted vibrations, while isolators isolating them. Structural parameter changes and excitation directions significantly affect the behavior of the conventional passive controllers. A Tuned Stiffness Damper (TSD), stepper mot...

There is a worldwide interest in the proper design of embankment dams to resist earthquake loadings. For the first time in Iran, a complete ambient vibration survey due to low-level loads such as wind, machinery activities, low level tectonic activities, and water exit from bottom outlet was performed on Marun embankment dam. These kinds of ambient vibration tests are suitable for manifesting t...

There is a worldwide interest in the proper design of embankment dams to resist earthquake loadings. For the first time in Iran, a complete ambient vibration survey due to low-level loads such as wind, machinery activities, low level tectonic activities, and water exit from bottom outlet was performed on Marun embankment dam. These kinds of ambient vibration tests are suitable for manifesting t...

In this paper, a new viscoelastic size-depended model developed based on a modified couple stress theory and the for nonlinear viscoelastic material in order to vibration analysis of a viscoelastic nanoplate. The material of the nanoplate is assumed to obey the Leaderman nonlinear constitutive relation and the von Kármán plate theory is employed to model the system. The viscous parts of the clas...

Studying the dynamic response of Francis turbine runners is of paramount importance in order to avoid resonance problems during operating conditions. For this purpose, the natural frequencies as well as their associated mode-shapes and damping ratios of the runner have to be determined. In this paper, an Experimental Modal Analysis (EMA) of the runner of a Francis turbine prototype has been per...

Modal parameters obtained from modal testing (such as modal vectors, natural frequencies, and damping ratios) have been used extensively in system identi"cation, "nite element model updating, and structural health monitoring. As an alternative to modal vectors, load-dependent Ritz vectors have been shown useful in various areas of structural dynamics such as model reduction and damage detection...

In this paper we develop an efficient numerical method for the finite-element model updating of damped gyroscopic systems based on incomplete complex modal measured data. It is assumed that the analytical mass and stiffness matrices are correct and only the damping and gyroscopic matrices need to be updated. By solving a constrained optimization problem, the optimal corrected symmetric damping ...

The main linacs of the Next Linear Collider (NLC) will contain several thousand X-band RDDS (Rounded Damped Detuned Structures). The transverse wakefield in the structures is reduced by detuning the modal frequencies such that they destructively interfere and by four damping manifolds per structure which provide weak damping. Errors in the fabrication of the individual cells and in the alignmen...

Whenever experimentally derived (Test) modal vectors are compared to the analytically obtained (Analysis) modal vectors, for purpose of model verification or model updating, a transformation matrix must be utilized to expand/reduce the degrees offreedom, DOF, so that the spatial dimension of the two sets of modal vectors is the same. The measured set of DOF seldom match the analytical set of DO...