1,354,226 research outputs found
A Numerical Approach to the Keel Design of a Sailing Yacht
No full textThis paper describes an approach to the keel design of a sailing yacht. The related software, which is fully automatic, permits to obtain an optimal shape by modifying the surface used to define the keel planform. B-spline curves and surfaces have been used because of their ability in following complex shapes. The algorithm integrates ad hoc implemented original software with Computational Fluid Dynamics (CFD) commercial ones. The optimisation procedure makes use of Genetic Algorithms (GAs) and a gradient – based optimiser for the refinement of the solution. A careful CAD and CFD modelling leads to a stable and efficient generalised method, which has been applied to the design of the centreboard of the 5o5 international class racing dinghy.This paper describes an approach to the keel design of a sailing yacht. The related software, which is fully automatic, leads to the optimal shape by modifying the surface used to define the keel planform. B-spline curves and surfaces have been used due to their ability in following complex shapes. The algorithm integrates ad hoc implemented original software with computational fluid dynamics (CFD) commercial ones. The optimisation procedure uses genetic algorithms (GAs) and a gradient-based optimiser for the refinement of the solution. A careful CAD and CFD modelling leads to a stable and efficient generalised method, which has been applied to the design of the centreboard of the 5o5 international class racing dinghy
ON THE EFFECTS OF A CRACK PROPAGATING TOWARD THE INTERFACE OF A BIMATERIAL SYSTEM
No full textThis paper deals with the influence of matrix cracks on the failure mode of bimaterial systems and composite materials. In order to investigate such an influence, the stress field near a crack embedded into the more yielding material and propagating perpendicularly to the interface, has been analyzed by using systematic numerical simulations. Such analysis has shown that the crack propagation give rises to transversal stresses that can damage the reinforcing materials when this has low modulus, as glass fibers, or low transversal strength, such as carbon fibers. Moreover, the longitudinal stress concentration can damage the reinforcing material only if this has high stiffness, as in the case of aramid and carbon fibers. Also, the numerical results have permitted to implement simple formulas that allows the user an accurate evaluation of the SIF as well as to predict possible debonding or fiber splitting phenomena. Finally, the SIFs evaluated numerically have been corroborated by experimental tests carried out by using an efficient procedure based on RGB digital photoelasticity. © 2005 Elsevier Ltd. All rights reserved
Study of the performances of a fluidynamic actuator
No full textAim of this paper is presented a new methodology to study how different geometric parameters affect the performance of a hydraulic actuator. Preliminarily, the real working conditions of a hydraulic machine have been simulated by means of a CFD module. After, to test the reliability of the simulations, the obtained numerical results have been compared with the experimental data of a real prototype. This comparison demonstrates a good level of agreement between numerical and experimental results. Different simulations have been setup by modifying the actuator geometry and evaluating the efficiency of every analysed configuration. The results of this study give useful guidelines for the choice of the best geometry depending on the working conditions of the actuator
Sailing Yacht Foil Design, a Comparison Between Vortice Lattice Method and CFD RANS Simulations
No full textThe increasing interest in foiling sailing yachts, recently driven by the American’s Cup, led to a wider application even in small boats such as dinghies or windsurfing. Foiling seems to be recent but since the early twenty-century years, hydrofoils has been experimented in Italy. This paper shows the complete foil design process starting from classical wing design based on theoretical consideration and illustrating the importance of modern simulation environments in design processes. Commercial CFD code Ansys Fluent® has been used and the results have been compared with those obtained through ad hoc developed vortice lattex method software, showing a substantial agreement with RANS simulation and theoretical calculation in front of incredible time reduction for simulation process that would allow a numerical planform optimization in a reasonable time. The case study focuses on the boat LED from the University of Palermo racing yearly in the framework of the 1001VELAcup® international university sailing challenge
Valutazione sperimentale della resistenza alla frattura di riabilitazioni protesiche fisse, per settori posteriori, con struttura in ossido di zirconio realizzata con tecnologia CAD/CAM: simulazione di 10 casi clinici.
No full textStudio dei fattori di intensificazione delle tensioni per cricca che avanza in un pannello forato mediante analisi fotoelastica
No full textDetermination of the Stress Intensity factor by means of the Electronic Speckle Pattern Interferometry technique
No full textMIsura del campo di spostamenti di un foro espanso a freddo mediante tecniche DSPI e DIC
No full textDisplacement measurement through DIC and DSPI techniques in cold-expanded holes
No full textIn this paper, the displacement field induced by the split-sleeve cold expansion of holes was measured using both digital image correlation (DIC) and digital speckle pattern interferometry (DSPI) techniques. Thus, the experimental results, which were evaluated on the inlet surface of a 6082-T6 aluminium plate, were compared with those from theoretical prediction. DIC provided accurate measurements up to the elastic-plastic boundary, whereas the DSPI technique highlighted the changes of displacement in the elastic domain. Prediction of the displacement based on the existing analytical model agreed with the experimental results achieved with both techniques. Possible explanations for the differences are discussed
Ottimizzazione di Forma della Deriva di una Barca a Vela: applicazione al caso della classe 5o5
No full textCon questo lavoro gli autori propongono un metodo di indagine automatizzato per la
ricerca della forma ottimale di una deriva di uno scafo a vela che garantisca la
portanza necessaria, nelle ordinarie condizioni di navigazione controvento, offrendo
al contempo la minore resistenza.
L’ampio spettro di forme adottate denuncia forse il problema dei progettisti, i quali
si rifanno alla teoria classica dell’aerodinamica, nell’interpretare il complesso
problema idrodinamico. Da questo punto di vista un valido aiuto viene offerto dai
codici di fluidodinamica computazionale (CFD) i quali permettono, con buona
approssimazione, di individuare la distribuzione delle forze e delle velocità di un
flusso attorno ad un corpo.
La fase di pre-processing (mediante il software ICEM CFD di Ansys) e la fase di
solving (mediante il software Fluent), sono state integrate in un software di
ottimizzazione originale, sviluppato in ambiente MatLab. Il metodo messo a punto,
la cui validità è generale, si è dimostrato affidabile e veloce grazie anche all’utilizzo
del calcolo parallelo per la risoluzione delle simulazioni fluidodinamicheThis paper describes an approach to the keel design of a sailing yacht. The related software, which is fully automatic, leads to the optimal shape by modifying the surface used to define the keel planform. B-spline curves and surfaces have been used due to their ability in following complex shapes. The algorithm integrates ad hoc implemented original software with computational fluid dynamics (CFD) commercial ones. The optimisation procedure uses genetic algorithms (GAs) and a gradient-based optimiser for the refinement of the solution. A careful CAD and CFD modelling leads to a stable and efficient generalised method, which has been applied to the design of the centreboard of the 5o5 international class racing dinghy
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