Search results for "Progettazione"

Influence of the distance between rivets in self-piercing riveting bonded joints made of carbon fiber panels and AA2024 blanks

2012

Abstract The increasing use of new materials alternative to steel in manufacturing industry has led to a greater emphasis on the improvement and the development of specific joining approaches allowing to get effective mechanical properties even when different materials are joined together. It should be observed that often the traditional welding techniques show several limitations as aluminum or magnesium alloys are used, and, what is more, they are not compatible with composite materials. The development of structures made of these materials has renewed the use of mechanical fastening operations. The present paper investigates the influence of the distance between rivets in self-piercing r…

CNT fibres - yarns between the extremes

2015

AbstractThe carbon nanotube community swims in the sea of superlatives. Researchers expect mechanical performance to achieve two extremes, an ultrastrong fibre taking us into space, and a superlubricant saving energy otherwise lost as heat. We examine CNT fibres in the light of traditional yarn science and present an interpretation of properties which combines aspects of these two extremes of performance.

Standard mechanical testing is inadequate for the mechanical characterisation of shape-memory alloys: Source of errors and a new corrective approach

2022

Thanks to its unique behaviour characterised by a superelastic response, Nitinol has now become the material of preference in a number of critical applications, especially in the area of medical implants. However, the reversible phase transformation producing its exceptional comportment is also responsible for a number of phenomena that make its mechanical characterisation particularly complex, by hindering the assumptions at the very basis of common uniaxial tensile testing. This necessarily reduces the level of safety and design optimization of current applications, which rely on incorrect mechanical parameters. In this study, the spurious effects introduced by the unconventional material…

Modello numerico per la simulazione e l’ottimizzazione di controlli non distruttivi con ultrasuoni

2013

I controlli non distruttivi basati sull’impiego di ultrasuoni sono ampiamente usati per la loro efficacia e affidabilità nel rilevamento di difetti. La generazione di onde ultrasonore e la propagazione in strutture di forma non regolare sono difficili da analizzare, soprattutto se la sorgente impiegata è un laser. Le tecniche numeriche per la simulazione del fenomeno reperibili in letteratura mostrano limiti di applicabilità per frequenze nel campo dei MHz e lunghezze d’onda molto corte. In questo lavoro presentiamo un metodo numerico in grado di risolvere accuratamente ed efficientemente problemi di generazione di onde ultrasonore tramite laser, con frequenze nel range dei MHz, e di propag…

IMPLEMENTAZIONE DI TECNICHE DI TERMOGRAFIA ATTIVA IRNDT SU COMPOSITI GRP MEDIANTE LA DEPOSIZIONE DI IMPULSI TERMICI DI LUNGA DURATA

2011

Nel presente lavoro viene analizzata l’implementazione di tecniche attive di termografia ad infrarossi per analisi NDT su pannelli in composito. In particolare si propone l’uso di lampade alogene come sorgente di calore esterna, le quali richiedono tempi di accensione dell’ordine di diversi secondi al fine di depositare efficaci quantità di calore. Si discutono quindi le problematiche connesse all’implementazione di tecniche di Transient Thermography e di Lock-In Thermography in presenza di tempi lunghi di deposizione di calore. Viene implementata una tecnica di modulazione della deposizione di calore mediante treni di onde quadre di lunga durata (PMLT - Pulse Modulated Lock-In Thermography…

Experimental and numerical method for nondestructive ultrasonic defect detection

2010

Ultrasonic methods are well known as powerful and reliable tool for defect detection. Conventional ultrasonic techniques rely generally on piezoelectric transducers where transmission of energy to the material is achieved with contact. In the last decades focus and interest have been directed to non-contact sensors and methods, showing many advantages over contact techniques where inspection depends on contact conditions (pressure, coupling medium, contact area). The growing interest is also due to the further development of air-coupled probes, thanks to new materials for acoustic devices and manufacturing technologies. The use of laser as tool for ultrasonic defect detection is also an eme…

Mixed Numerical-Analytical Model for Predicting the Elastic Properties of Nanocomposites with Random Distribution of CNTs

2009

Sub-Optimal Control Law for Active Magnetic Bearings Suspension

2012

This paper deals with the comparison of three types of sub-optimal control law for the stable levitation of a turbojet shaft, sustained by two radial active magnetic bearings (AMBs). Shaft is considered rigid for the procedure simplification. The utilized approach leads to development of different sub-optimal control laws to use in speed-varying simulations in the angular speed of the shaft. The first control matrix is obtained by explicit relationships of the parameters of the control law vs. speed, obtained using a curve-fitting procedure neglecting the speed-varying elements out of the main diagonal of each single block constituting the entire control matrix. The second control law is ob…

Comfort-structural analysis in product development Optimization of a motorcycle frame

2012

This work steps from a bachelor thesis, joining the results of a study about the dynamic loads to evaluate the comfort loss in the motorcycle during the usage, with the potentiality of a modern FEM software. The goal is the development of a new methodology for structural optimization of motorcycle’s frame. In many of cases the success of the structural optimization is linked with a two factors combination: the software and the strength of the engineer to condition the mathematical problem, defining parameters domain and technological constraints. A good alternative to the traditional load hypothesis linked to historical data or instrumental measurements is focused in this paper. Consistent …

Computer-aided tool path generation for robotic Non-Destructive Inspection

2013

Compared to manual Non-Destructive Testing (NDT) for inspection of engineering components, automated robotic deployment of the same NDT techniques offers an increase in accuracy, precision and speed of inspection while reducing production time and associated labour costs. Traditionally, the robot tool path is either taught or programmed manually. Automation of NDT tool path generation, as presented in this paper, offers further significant time reduction, and an increase in the flexibility of inspection planning compared to manual robot teaching and programming. Moreover, such a solution helps to maintain a controlled probe orientation with respect to the scanned surface, and thus which can…