Precise and detailed knowledge of the dynamic characteristics of structt~res has become increasingly important in recent years. As a consequence, the accuracy of experbnental data, which is often used to validate and update fmite element models, has become extremely i”lporta”t. It has been shown expetientally [II that small changes in ambient temperature can cause distinct variations in the nat...

the natural frequencies and mode shapes of pneumatic tires are predicted using a geometrically accurate, three-dimensional finite element modeling. tire rubber materials and cord layers are represented independently using “shell element” available in cosmos. the effects of some physical parameters such as the inflation pressure tread pattern, thickness of belts and ply angles to the natural fre...

A method is presented which can estimate the linear and nonlinear damping parameters in a lightly damped multidegree of freedom system which allows the system to be decomposed into a set of single degree of freedom nonlinear systems. Only a single response measurement from a free decay test is required as input ensuring that the magnitude of the damping parameters is not compromised by phase di...

the use of structural adhesives in automotive structures has been increased recently for their role in noise, vibration and harshness (nvh). therefore, the dynamic behavior of structures containing bonded joints has become an area with numerous investigations over the past decades. development of accurate formulations capable of representing adhesively bonded joint dynamics is a step forward in...

it has been proved that natural frequencies are stationary at the natural modes. also it has been shown that at the first mode it is a minimum and for systems with finite number of degrees of freedom the highest frequency is maximum (reference 1 and 2). beyond these statements nothing more can be said about the behavior of the natural frequencies without defining precisely the manner in which t...

New algorithms for estimation of the frequencies of oscillating waveform signals are described. Model of the signals is presented in the form of linear difference equation with unknown coefficients, which define the frequencies and amplitudes. Coefficients are estimated utilizing the property of the persistence of excitation of oscillating signals. Exponentially damped and oscillating signals a...

It is common for dispersion curves of damped periodic materials to be based on real frequencies versus complex wavenumbers or, conversely, real wavenumbers versus complex frequencies. The former condition corresponds to harmonic wave motion where a driving frequency is prescribed and where attenuation due to dissipation takes place only in space alongside spatial attenuation due to Bragg scatte...

Model updating concerns the modification of an existing but inaccurate model with measured data. For models characterized by quadratic pencils, themeasured data usually involve incomplete knowledge of natural frequencies, mode shapes, or other spectral information. In conducting the updating, it is often desirable tomatch only the part of observed data without tampering with the other part of u...

Phantom partials are anomalous overtones in the spectrum of the piano sound that occur at sum and difference frequencies of the natural overtones of the string. Although they are commonly assumed to be produced by forced longitudinal waves in the string, analysis of the sound of a piano produced by mechanically vibrating the soundboard while all the strings are damped indicates that phantom par...