1,721,299 research outputs found
Modelling and simulation of flywheel energy storage systems for hybrid vehicle drivelines
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Caratterizzazione meccanica di frutti in guscio
No full textObiettivo del lavoro è la definizione di una procedura di caratterizzazione sperimentale di materiali biologici a geometria complessa, quali il guscio e il gheriglio delle nocciole, per la determinazione dei parametri di calibrazione di modelli numerici da utilizzarsi nell’analisi dei processi di selezione e sgusciatura. Il guscio presenta una struttura multi-strato, con fibre orientate in ciascuno strato, e una geometria a curvatura multipla. Il gheriglio è costituito da materiale isotropo se caratterizzato con provini prelevati dalla polpa, mentre esprime un comportamento anisotropo se caratterizzato sull’intero frutto. Nel lavoro è presentata la procedura di prova sviluppata che include: la definizione e l’ottenimento dei provini, le misurazioni da compiere prima e durante la prova, l’esecuzione delle prove e l’elaborazione dei dati sperimentali. Come esempio di applicazione è descritta la campagna di prove e i risultati ottenuti per una specifica varietà di nocciola (Tonda Gentile del Piemonte), con l’analisi e la discussione dei risultati ottenuti
An easy instrument and a methodology for the monitoring and the diagnosis of a rail
No full textNowadays, there are no systematic methodologies for evaluating life assessment of the rail, and few systems provide the measures of vertical and lateral forces that train exchanges with the rail. These systems are quite expensive and require the substitution of a portion of the track. In the present paper is presented a simple transducer (MPQY) for measuring, at the same time, the vertical and lateral forces. The easy installation and use of this instrument are its main characteristics. It is sufficient to put it in a hole, made in the rail web in the concurrence of the drilling axis, and connect it to the transmitting station for measuring for each convoy the vertical and lateral forces induced by each wheel. It can be also used for analysing speed and mass of trains and the specific derailment ratio. In addition, by using a damage model, it is possible to estimate the residual life of a rail. In order to do this, a linear model of rolling contact fatigue damage is implemented and tested with same experimental acquisitions. Another application of this transducer can be identified in the variation of the mechanical behaviour of ballast. In fact, by using the information coming from the MPQY and comparing it with the flexural moment measurement, it is possible to evaluate the variation of ballast behaviour with respect to time and set new parameters for ballast maintenance and train safety
Acceleration through critical speeds of an anisotropic, non-linear, torsionally stiff rotor with many degrees of freedom
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Effects of deep cryogenic treatment on static mechanical properties of 18NiCrMo5 carburized steel
No full textIn consideration of the raising interest about the application of the deep cryogenic treatment (DCT) on materials, its effects on the static mechanical properties of a commercial gear carburized steel (18NiCrMo5) are investigated through hardness and tensile tests followed by optical fractographic observations. The present study focuses on the comparison between the results given by different sequences of DCT and tempering performed after the conventional case hardening. In addition, the soaking time parameter influence is analyzed for the case of the pre-tempering DCT. A special attention is paid to the statistical analysis of the experimental data in order to avoid misinterpretations. The results point out substantial hardness increases (from +0.6 HRC to +2.4 HRC) for all the cryotreated groups and a remarkable enhancement of the tensile strength (+11%) in one case, indicating that different sequences and DCT parameters must be considered depending on the application requirements. The experimental results are then discussed in consideration of the literature about the DCT on similar steels with the aim of correlating the obtained improvements to the microstructural mechanisms that are commonly ascribed to this treatmen
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