In this paper, the detection and the localization of a local perturbation are assessed by analysing the frequency changes only (fundamental mode and overtones). After describing the method used herein applied to the bending beam and based on the perturbation theory, experimental application to a 1D plexiglas beam is shown using frequency and modal analysis technique. The damage is considered as...

This paper describes modal testing of a wooden baseball bat with the purpose of finding the peak frequencies and vibration modes and their relation to the so-called “sweet spot”. Initial vibration testing was done by performing a tap test along a Louisville Slugger wooden baseball bat. The bat was suspended by elastic rubber bands to approximate free-free boundary conditions. The peak frequenci...

In this paper we consider the Gaussian beam mode analysis of imaging arrays on submillimetre-wave radio telescopes. We show how it is possible to describe any of the off-axis beams generated by the array in terms of the same on-axis beam mode set. The mapping process can be easily analysed using a modal approach.

This study is aimed to explore efficiency problems of using PZT patches in active vibration control of beams. The PZT patches are surface-bonded as actuators and strain gages are used as sensors. Distributed moment forcing mode is adopted to derive the control authority of actuators. Uniform beam model is applied when the mass and stiffness of PZT patches are ignored. Stepped beam model is then...

this paper describes experimental and numerical investigations on two specimens of frames composed of steel reinforced concrete beam and angle-steel concrete column under horizontal low cyclic loading. based on the test results, the relationship curves of the horizontal load-displacement and the failure modes are acquired. meanwhile the hysteretic behaviors, skeleton curves, stiffness degradati...

We call piezoelectromechanical (PEM) truss beam a truss modular beam coupled with a transmission electrical line when the coupling is obtained by piezoelectric actuators which act as bars in the module and as capacitances in the electrical line. The truss module length is assumed negligible with respect to the considered wave lengths. The transmission electrical line is assumed continuously dis...

A unique T-beam microresonator designed to operate on the principle of nonlinear modal interactions due to 1 : 2 internal resonance is introduced. Specifically, the T-structure is designed to have two flexural modes with natural frequencies in a 1 : 2 ratio, and the higher frequency mode autoparametrically excites the lower frequency mode through inertial quadratic nonlinearities. A Lagrangian ...

Initial commissioning results from the PEP-II transverse coupled-bunch feedback systems are discussed. In particular, the performance of key hardware and coupled-bunch damping results are described in some detail. Beam dynamics related measurements presented include beam transfer functions and selected modal growth and damping rates.

A modal analysis procedure is used to model suspended compressors and their excitation forces. The modal method evaluates the dynamic spring forces, modal spring forces, and modal forcing function to determine the effects of a change in suspension configuration on transmitted spring forces. Valuable design insight is gained since the modal parameters explain the behavior of suspension systems d...