Search results for "METODI"
showing 10 items of 940 documents
Parametric Hull Design with Rational Bézier Curves and Estimation of Performances
2021
In this paper, a tool able to support the sailing yacht designer during the early stage of the design process has been developed. Cubic Rational Bézier curves have been selected to describe the main curves defining the hull of a sailing yacht. The adopted approach is based upon the definition of a set of parameters, say the length of waterline, the beam of the waterline, canoe body draft and some dimensionless coefficients according to the traditional way of the yacht designer. Some geometrical constraints imposed on the curves (e.g., continuity, endpoint angles, curvature) have been conceived aimed to avoid unreasonable shapes. These curves can be imported into any commercial Computer Aide…
Virtual prototyping of a new intramedullary nail for tibial fractures
2012
In this work a new distal interlocking system has been developed which is easy to use, allows a reduction of the operating time and consequently the exposure to radiations both for surgeon and patient. The main goal of this study has been the design of a new intramedullary nail for tibial fractures able to simplify and speed up the distal locking operation phases. After a preliminary stage during which several candidate concepts have been proposed and analysed, the best solution has been developed and deeply investigated. The new system, called “expansion nail”, has been firstly modelled by setting up a full parametric CAD model and, then, tested by running non linear FEM analyses to evalua…
A New Approach for CAD Modelling of Customised Orthoses by Generative Design
2021
The standard method of design and manufacturing customised orthoses is still very time-consuming due to their often very complex shape. Different authors have tried to solve this problem but, unfortunately, the proposed approaches cannot be easily used in clinical practice because they require substantial interaction among medical staff and engineers or technicians. The aim of this work is to present the framework of a new design approach that could allow clinicians to easily model a customised orthosis, without a skilled technician develops the entire procedure. In particular, an automatic process based on Generative Design has been implemented. The obtained results have demonstrated that …
A preliminary method for the numerical prediction of the behavior of air bubbles in the design of Air Cavity Ships
2016
Air-cavity ships (ACS) are advanced marine vehicles that use air injection under hull to improve the vessel’s hydrodynamic characteristics. Although the concept of drag reduction by supplying gas under the ship’s bottom was proposed in the 19th century by Froude and Laval, at this time there are not many systematic studies on this subject. This paper is a preliminary work with the purpose of being a basic tool for the design of the ACS with computational fluid dynamic methods. The study aims to conduct a series of computational tests to compare the numerical models of bubble with experimental data. The first step of this study was to investigate the behavior of free bubble in water, conside…
Sailing dinghy hydrodynamic resistance by experimental and numerical assessments
2020
Abstract Hull forms of high-performance sailing dinghies are very interesting for yacht designers. After a long period in which the attention has been focused on one-design boats, in recent years a few exciting restricted classes such as International Moth, International 14′, 18’ Skiff and Class A catamaran become recognized in several countries and led to interesting advances in high-performance yacht design. “1001VELAcup R3” class is two people racing dinghy designed according to a box rule with limitation on LOA and Bmax and total sail area. The boats must be designed and built by students of European Universities and race yearly in Italy. This paper focuses on two best-ranked boats “LED…
VirDe: A new virtual reality design approach
2008
Virtual reality (VR), even if it does not represent any more a novel technology, is one of the most powerful tool to help designers during the development of new projects. This is proved by very numerous research activities related to this field. In this research, we have studied a new way to approach the development of a product. We present the ongoing development of a system, called VirDe, acronym of virtual design, which can allow the designers to perform the whole design process, from the modelling phase to the finite element method (FEM) simulation analysis, in a virtual reality environment. This new method allows remarkable time and money saving in the overall product design process, …
A Numerical Approach to the Keel Design of a Sailing Yacht
2008
This 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 centre…
Using FEM simulation to predict structural performances of a sailing dinghy
2017
The use of finite element method (FEM) tools is proposed to investigate the structural response of an eco-sustainable sailing yacht to different loading conditions, typical of those acting during regattas. The boat is, in particular, a 4.60 m dinghy with the hull and the deck made of an hybrid flaxâcork sandwich and internal reinforcements made of marine plywood. A preliminary activity has consisted in the refitting of an existing model in order to reduce the hull weight and to improve performances during manoeuvrings. These tasks have been interactively simulated in the virtual environment of the boat CAD model, where longitudinal and transversal reinforcements were enlightened and the m…
Thermal stress analysis of different full and ventilated disc brakes
2015
During the braking phase, the heat produced by friction between pads and disc cannot be entirely dissipated. Consequently, the brake disc, especially if very hard braking occur, can accumulate large amounts of heat in a short time so producing high gradients of temperature on it. Under these conditions, functionality and safety of the brake system can be compromised. The object of this study is to investigate, under extreme working conditions, the thermomechanical behaviour of different brake rotors in order to evaluate their efficiency and stability and to identify any compromising weakness on them. In particular, by means of FEM thermo-mechanical coupled analyses, one full disc and three …
A Random Dot Stereoacuity Test based on 3D Technology
2014
This paper presents a novel stereo acuity test that is realized by a software program on a PC with 3D capabilities. The 3D technology is used to provide two separate images to the two eyes. The test is a classical random dot test, but differently to other test printed on paper, the images shown to the patient can vary and there is no monocular clue. These features allow to deliver the test also in groups (instead of individuals) like school classes, and to increase the sensitivity. The system can be easily used also by not specialized personnel and this may further increase the cost efficiency of the test. Experiments carried on with a large set of children of age between five and seven yea…