Showing papers by "Gian Marco Revel published in 2004"
TL;DR: In this paper, the authors focused on the experimental evaluation of uncertainty sources in modal parameter measurement, when high-energy laser pulses are used to excite the vibration of the structure.
33 citations
22 Jun 2004
TL;DR: In this paper, a non-contact measurement system, a Scanning Laser Doppler Vibrometer, has been used to detect delaminations in a composite material plate.
Abstract: In recent years, a great effort has been done to improve damage detection techniques in structures by using vibration measurements. This paper presents a case where a non-contact measurement system, a Scanning Laser Doppler Vibrometer, has been used to detect delaminations in a composite material plate. The diagnostic technique is the evolution of a methodology previously approached by the authors. An in-house made software has been produced for data acquisition and vibrometer control. The maps of the detected defects are presented, thus allowing the assessment of the performances of this methodology to detect damages. This analysis permitted to outline the main points to be improved in the future investigations.
14 citations
Patent•
07 Sep 2004
TL;DR: In this article, a method for continuously controlling the particle size distribution of ceramic powders leaving the powder forming plant is presented, comprising at least the following steps: withdrawing at least one powder sample at predetermined intervals, measuring the particle sizes distribution of the withdrawn sample, and comparing the measured particle sizes with a reference particle size distributions by means of a processor.
Abstract: Method for continuously controlling the particle size distribution of ceramic powders leaving the powder forming plant, comprising at least the following steps: withdrawing at least one powder sample at predetermined intervals; measuring the particle size distribution of the withdrawn sample; comparing the measured particle size distribution with a reference particle size distribution by means of a processor; regulating at least one parameter of said powder forming plant influencing the particle size distribution, on the basis of the differences between the measured particle size distribution and the reference particle size distribution; and plant for its implementation.
6 citations
22 Jun 2004
TL;DR: In this article, an algorithm has been developed for taking into consideration the fluctuation of the sound wavelength, and the results accuracy has been checked by comparing them to the surface velocity measured in the vibrating source by means of Scanning Laser Doppler Vibrometry (SLDV).
Abstract: Near-field Acoustic Holography (NAH) is one of the most promising and interesting tool for the investigation of vibro-acoustic problems. This hybrid tool is based on array microphones pressure cross-spectra acquisitions from which the acoustic field on the 3D space can be calculated. The reconstruction procedure involves numerical computations where the effect of many uncertainty sources can be propagated. One of these is the temperature factor: if the vibrating object is undergoing a high temperature gradient, the wavelength of sound propagation will change within the surrounding space. The conventional instruments applying NAH do not take into account this effect since they are based on the hypothesis of constant sound speed along the reconstruction path. In order to appreciate the influence of noteworthy temperature gradients on NAH calculations, an algorithm has been developed for taking into consideration the fluctuation of the sound wavelength. Hence, the results accuracy have been checked by comparing them to the surface velocity measured in the vibrating source by means of Scanning Laser Doppler Vibrometry (SLDV). This research work has been performed within the European Growth Project "ACES" (Optimal Acoustic Equivalent Source Descriptors for Automotive Noise Problems) GRD1-1999-11202.