Study Of Vibrational Effects Research Articles

Study of Vibration Effects on Communication Filters in Substrate Integrated Technologies

The growing need of space communication systems forces the industry to innovate in order to provide more robust, economical and flexible solutions. The new substrate integrated technologies enable the development of on-board communications devices with less weight and volume than the traditional waveguide-based ones. However, it is necessary to analyse the performance of these devices in the particular working conditions of satellite communications. This work studies the integrity of the electrical response of advanced communication filters under mechanical stress conditions. Four realisations of a Ku-band microwave filter in different substrate integrated technologies were developed and tested. Two mechanical vibration tests were performed: sinusoidal sweep and random vibration. These tests emulate the transport and launching conditions of the satellite payload. Furthermore, the mechanical natural frequency of the filters and its variation after being exposed to the tests have been measured to evaluate the devices integrity. For all the filters, this frequency variation is lower than 5 %, the standard threshold. This proves that the developed filters can survive the launching conditions of satellite payload, thus qualifying the technology for spatial applications.

A theoretical study of vibrational effects on strong field ionization of CS2

Tunneling ionization of vibrationally excited CS2 molecules in their ground electronic state is calculated using molecular orbital Ammosov–Delone–Krainov theory (MO-ADK) considering bond length-dependence and bond angle-dependence. The tunneling ionization rates and the corresponding electron density are calculated respectively for different initial states. A relationship between laser intensity and the molecular orientation angle is determined and compared with experimental results, showing excellent agreement. Our calculations show that the primary contribution of vibration effect to CS2 in tunneling ionization is due to the symmetric expansion mode.

Influence of vibrations on interface delamination in metal-polymer composites

The main objective of this work was the study of vibration effects on the viscoelastic coating protecting the steel layer in a metal–polymer composite, with simulated conditions of the transportation of food containers. Mechanical resonance tests in metal–polymer [electrolytic chromium-coated steel–poly(ethylene terephthalate) (PET)] sheets were performed to generate vibration conditions to induce structural modifications in the viscoelastic layer covering the surface of the plates. Consequently, schematic representations of the areas affected by these modifications were made. The modified structures were later analyzed by electron microscopy to detect and evaluate alterations in the morphology of the material. In addition, vibrational Raman spectroscopy analyses were performed to assess the chemical and structural changes on the protective PET at the metal–polymer interface level. The results of this study are expected to provide basic information on the mechanisms and nature of the delamination processes taking place in metal–polymer laminates employed in food-container applications. These damages have previously been detected in some food containers made of PET materials. The study of these damages can lead to the improvement of current composites or the development of higher quality materials. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The Study of Vibration Effects on Precision Grinding Surface Quality

The paper was dedicated to surface grinding, in which axisymmetric surface and non-axisymmetric surface are presented. Machined traces deviate from the vibration waveform because of the geometrical interference between the wheel and the workpiece. Simulation and experimental results indicate that the spectrum of the machined trace is competent for the detection of the vibration source. The deviation of the machined trace from the vibration waveform is greatly influenced by operating parameters, and reasonable choice of them is beneficial to surface smoothness.

Positron annihilation in simple molecular gases: A study of vibrational effects

The dynamics of positron annihilation in molecular gases containing simple diatomics is studied within a quantum formulation and is implemented by treating the positron–molecule interaction via an ab initio, nonempirical approach for all the forces at play. The process is analysed for room temperature conditions of the ambient gas and the behaviour of the corresponding annihilation rate coefficients, Z eff, is studied in detail by considering the role of the dynamical coupling between the positron motion and the vibrational degree of freedom of the molecular partner.

A BIOMECHANICAL MODEL OF MAN FOR THE STUDY OF VEHICLE SEAT AND SUSPENSION

SUMMARY The study of vibration effects on the human body was undertaken twenty-five years ago. Biomechanical models of the human body have since been suggested as a result of several experimental findings. These models (as with any analog system) allow interacting complex phenomena to be represented more exactly and can lead to valuable ergonomic results. They enable, in particular, a dynamic evaluation of seats during steady state vibrations and shocks. Repetitive experiments on the same subject in the same conditions make it possible to obtain a numerical evaluation of the model parameters, although important differences are found between subjects and also for the same subject in varying postures. As a rule, the dynamic properties of the pelvis-table link can be obtained with a satisfactory degree of precision, but for the thorax-pelvis link the dispersion of the experimental results prevents results of general applicability. Finally, it is noted that the mechanical properties of the human body cannot b...