Search results for " progettazione."
showing 10 items of 503 documents
ANALISI CFD DELLE PRESTAZIONI DI UN CATAMARANO CON SCAFI ASIMMETRICI DOTATO DI SOSTENTAMENTO IDRODINAMICO
2010
Nel presente lavoro è proposto uno studio di ottimizzazione su di un catamarano a scafi asimmetrici con murate piane esterne, grazie al progetto di due alettoni posizionati trasversalmente alla direzione del moto al di sotto del piano di galleggiamento ai quali è affidato il sostentamento idrodinamico dell’intero catamarano. L’obiettivo finale dello studio è quello di ridurre la resistenza totale all’avanzamento del catamarano dopo aver progettato in maniera opportuna le due appendici alari. Le analisi CFD, sia del catamarano senza alettoni che del catamarano con agli alettoni, hanno dato la possibilità di operare un confronto tra i due catamarani evidenziando un beneficio del 38% in termin…
Dissection Properties of Ascending Thoracic Aortic Aneurysms Associated with Bicuspid and Tricuspid Aortic Valves
2012
An optimised tapered shape of the terminal contact elements in biological attachment devices
2009
Many biological attachment devices of insects, spiders and geckoes consist of arrays of hairs (setae), which are terminated by contact elements of different shapes. However, the most frequently observed shape is a thin plate-like spatula. In spite of a rather wide range of sizes and thicknesses, most spatulae of different animals are not uniform but possess a gradient in thickness. The thickness of spatulae in the longitudinal section becomes gradually thinner close to the tip. This geometrical effect is numerically explained in the present paper, by using a numerical approach for modeling the van der Waals-like adhesion and friction between the contact element and the substrate. The approa…
Does the 5-strand-graft have superior biomechanical behaviour than 4-strand-graft during acl reconstruction?
2019
Purpose. This study aimed to compare the biomechanical proprieties of 4 and 5-strand- grafts. Methods. For the present study, fresh-frozen bovine common digital extensor tendons were used. Tendon grafts were prepared and sized to have a length of almost 27 cm and a cylinder 4 strand diameter of 8 mm. In half of all samples (Group A, n=12,), the graft was formed by 2 bundles duplicated around a metallic rod creating a 4-strand-tendon construct. In the other half of samples (Group B, n= 12,) 5-strand-tendon construct was created duplicating a single tendon around the rod, and tripling the other one. The grafts were preconditioned at 50 N for 10 min, followed by 1,000 cyclic loading between 50…
Carbon Nanotube Based Composites: Processing, Properties, Modelling and Application
2012
The object of this book is to bring together all available information on the carbon nanotube based composites. Details of the more important processing techniques for manufacturing carbon nanotubes-polymer composites are discussed in Chapter 1, including preprocessing treatments as purifi-cation, graphitization and functionalization. Chapters 2 explores the state of the art concern-ing mechanical, thermal, electrical and optical properties of CNTs composites made of the most frequently used polymer matrixes. Two tables gives quick access to a vast amount of the available data on the mechanical and electrical properties of CNTs composites. In Chapter 3 a reviews of the numerical models, whi…
Reinforcing effect of carbon nanotubes (CNT) on polymer nanocomposites – A numerical-analytical study
2012
A mixed model, numerical-analytical, is presented that allows one to predict the elastic properties of carbon nanotube (CNT)/polymer composites containing a random distribution of CNTs, while taking account of the curvature that they show when immersed in the polymer. This hybrid approach is a significant advance over micromechanical modeling and can be applied to all nanostructured composites.
Numerical model for the electromechanical characterization of carbon nanotubes
2010
Carbon nanotubes (CNTs) can be metallic or semiconductors depending simply on geometric characteristics [e.g., 1]. This peculiar electronic behavior, combined with high mechanical strength, make them potential building blocks of a new nano-electronic technology. Most discussions of the electronic structure of CNTs assume perfect cylindrical symmetry, but this is somewhat of an oversimplification. High resolution images of CNTs often disclose structural deformations such as bent, twisted, or collapsed tubes. These deformations may develop during growth, deposition, and processing, or upon interaction with other CNTs, and with surfaces and surface features such as electrodes. Deformations bre…
A mixed finite element-tight binding technique for studying the electromechanical behavior of single and multiwall carbon nanotubes
2004
Advances in Strain Gauge Measurement on Composite Materials
2010
This article gives an overview on the application of strain gauge techniques to the analysis of the strains in composite materials. The orthotropic behaviour of the composite influences the performance of strain gauges that are calibrated for use on isotropic materials. The article considers therefore the typical topics of the strain gauge technology applied to composites with particular reference to the compensation of thermal output, the measurement of the coefficients of thermal expansion, the determination of the strain and stress state, the influence of the misalignment error, the reinforcement effect, the determination of the stress intensification factor, the analysis of residual str…
OTTIMIZZAZIONE DI UNA GIUNZIONE INCOLLATA A DOPPIA SOVRAPPOSIZIONE PER SANDWICH IN COMPOSITO
2016
Grazie alle peculiari performances meccaniche, quali soprattutto l’elevata resistenza a flessione unita ad un basso peso specifico, le strutture sandwich in composito sono sempre più frequentemente utilizzate nella moderna progettazione industriale. Nel presente lavoro, considerando un composito sandwich con skins in vetroresina e core in PVC espanso, è stato eseguito uno studio numerico e sperimentale al fine di individuare la configurazione ottimale di una giunzione incollata a doppia sovrapposizione avente quali aderendi esterni le stesse skins del sandwich e aderendo interno costituito da un inserto in metallo o in composito. In dettaglio, previa preliminare ottimizzazione teorica della…