TSA infrared measurements for stress distribution on car elements

Abstract. Because of the continuous evolution of the market in terms of quality and performance, the car production industry is being subjected to more and more pressing technological challenges. In this framework the use of an advanced measurement technique such as thermoelasticity allows the engineers to have a fast and reliable tool for experimental investigation, optimization and validation of the finite element method (FEM) of those critical parts, such as parts of car-frame tables (Marsili and Garinei, 2013; Ju et al., 1997). In this work it is shown how the thermoelastic measurement technique can be used to optimize a Ferrari car frame, as a method of experimental investigation and as a technique of validation of numerical models.The measurement technique developed for this purpose is described together with the calibration method used in the test benches normally used for fatigue testing and qualification of this car's components. The results obtained show a very good agreement with FEM models and also the possibility of experimentally identifying the concentration levels of stress in critical parts with a very high spatial resolution and testing the effective geometry and material structure

Development of a non-contact torque transducer based on the laser speckle contrast method

Abstract. When a torque measurement is required, torque transducers show many drawbacks during their use: the usual limits are the need for contact and the effects on shaft line parameters. A new approach is proposed in this work: a non-contact torque meter for a machine shaft has been developed. It carries out torque measurements evaluating the torsional displacement between two distinct sections of the shaft, through the monitoring of their roughness. The sensing principle employed is the classical laser speckle contrast method. The outcoming intensity scattered by the rough surface is processed by a cross-correlation function. In this way, the angular torsion of two distinct sections is obtained. It is therefore possible to point out the applied torque knowing the shaft torsional stiffness

Local-field effects in silicon nanoclusters

The effect of the local fields on the absorption spectra of silicon nanoclusters (NCs), freestanding or embedded in SiO2, is investigated in the DFT-RPA framework for different size and amorphization of the samples. We show that local field effects have a great influence on the optical absorption of the NCs. Their effect can be described by two separate contributions, both arising from polarization effects at the NC interface. First, local fields produce a reduction of the absorption that is stronger in the low energy limit. This contribution is a direct consequence of the screening induced by polarization effects on the incoming field. Secondly, local fields cause a blue shift on the main absorption peak that has been explained in terms of perturbation of the absorption resonance conditions. Both contributions do not depend either on the NC diameter nor on its amorphization degree, while showing a high sensitivity to the environment enclosing the NCs

Occupational Burden of Asbestos-related Cancer in Argentina, Brazil, Colombia, and Mexico

Background: An estimate at the national level of the occupational cancer burden brought about by the industrial use of asbestos requires detailed routine information on such uses as well as on vital statistics of good quality. A causal association with asbestos exposure has been established for mesothelioma and cancers of the lung, larynx, and ovary. Objectives: The aim of this study was to provide estimates of the occupational burden of asbestos-related cancer for the Latin American countries that are or have been the highest asbestos consumers in the region: Argentina, Brazil, Colombia, and Mexico. Methods: The burden of multifactorial cancers has been estimated through the approach suggested for the World Health Organization using the population attributable fraction. The following data were used: • Proportion of workforce employed in each economic sector • Proportion of workers exposed to asbestos in each sector • Occupational turnover • Levels of exposure • Proportion of the population in the workforce • Relative risk for each considered disease for 1 or more levels of exposure Data on the proportion of workers exposed to asbestos in each sector are not available for Latin American countries; therefore, data from the European CAREX database (carcinogen exposure database) were used. Findings: Using mortality data of the World Health Organization Health Statistics database for the year 2009 and applying the estimated values for population attributable fractions, the number of estimated deaths in 5 years for mesothelioma and for lung, larynx, and ovary cancers attributable to occupational asbestos exposures, were respectively 735, 233, 29, and 14 for Argentina; 340, 611, 68, and 43 for Brazil; 255, 97, 14, and 9 for Colombia, and 1075, 219, 18, and 22 for Mexico. Conclusions: The limitations in compiling the estimates highlight the need for improvement in the quality of asbestos-related environmental and health data. Nevertheless, the figures are already usable to promote a ban on asbestos use

International scientific cooperation on asbestos-related disease prevention in Latin America.

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An Efficient Catalytic Method for Regioselective Sulfenylation of Electron-rich Aza-aromatics at RoomTtemperature

Electron-rich aza-aromatic compounds such as indoles and pyrroles represent systems of particular interest and importance in organic chemistry. An useful methodology for regioselective direct introduction of sulfenyl group on electron-rich aza-aromatics through S-alkyl and S-arylthiophthalimides as sulfenylating agents is described. Catalytic amounts of CeCl3.7H2O-NaI system are crucial to the promotion of this regioselective carbon-sulfur bond-forming Friedel-Crafts reaction. The reaction occurred in mild conditions and the products were obtained in good to excellent yields. Due to the large importance of functionalized indoles among natural compounds and pharmaceutical products, the methodology represents an efficient preparation of sulfenyl aza-aromatics, which are useful intermediates for important organic transformations

Point cloud processing techniques and image analysis comparisons for boat shapes measurements

Photomodelling is a new and fast solution for 3D modelling, based on the same principles of photogrammetry. The comparison between photomodelling and the metrological technique of structured light 3D scanning, provided by the Creaform Go Scan 50 with metrological certification, is the aim of this paper, defining performances and verifying the potential of this innovative, simple and economical technique

Optical-flow-based motion compensation algorithm in thermoelastic stress analysis using single-infrared video

Thermoelastic stress analysis (TSA) is a non-contact measurement technique for stress distribution evaluation. A common issue related to this technique is the rigid-displacement of the specimen during the test phase, that can compromise the reliability of the measurement. For this purpose, several motion compensation techniques have been implemented over the years, but none of them is provided through a single measurement and a single sample surface conditioning. Due to this, a motion compensation technique based on Optical-Flow has been implemented, which greatly increases the strength and the effectiveness of the methodology through a single measurement and single specimen preparation. The proposed approach is based on measuring the displacement field of the specimen directly from the thermal video, through optical flow. This displacement field is then used to compensate for the specimen's displacement on the infrared video, which will then be used for thermoelastic stress analysis. Firstly, the algorithm was validated by a comparison with synthetic videos, created ad hoc, and the quality of the motion compensation approach was evaluated on video acquired in the visible range. The research moved into infrared acquisitions, where the application of TSA gave reliable and accurate results. Finally, the quality of the stress map obtained was verified by comparison with a numerical model.</p