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Keyword : beam
Results 1 - 5 of 19
A CFD-Based Wing Sail Optimisation Method Coupled to a VPP
An aerodynamic numerical optimisation procedure for an AC72 rigid wing sail was developed. The core of the method is the geometric parameterisation strategy based on a mesh morphing technique. The morphing action, which uses radial basis functions, is integrated within the Reynolds-averaged Navier-Stokes solver and provides an efficient parametric sail aerodynamic nanalysis method which is integrated in an optimisation environment based on a velocity prediction program. A hydrodynamic model is coupled to the parametric numerical solver in an iterative procedure. The shape modifiers operate on angle of attack and twist of nthe fore and aft wing element. For each true wind condition, the velocity of the boat is maximised by iterating between the solution of the velocity prediction program and the solution of the fluid dynamic solver. The effectiveness of the proposed method is demonstrated testing a range of wind speeds.
Updated Fatigue Test Methods for Structural Foams and Sandwich Beams
Foam-cored sandwich yacht hulls are subjected to high core shear stresses during slamming events. As slamming is
repetitive by nature, failures observed on boats may be due to fatigue. This study aims to investigate possible improvements to
fatigue testing of both foam core materials and sandwich specimens. In general test set-up induces differences between the ways a
material behaves in a test coupon and in a real application. One such difference is “edge effect”, as the material behaviour can change
close to a free edge. For example, the micro-structure may have been affected by the specimen machining, which may influence
failure initiation. This is exacerbated if the test set-up induces stress concentrations close to the edge. Another difference is that in a
standard core shear fatigue testing by 4 point bending, the stress field is spatially static, when in a slamming event the stress field is
spatially variable. Does the material react differently to a static and moving stress field? This study aims to develop a core shear test
method replicating a moving stress field, free of edge effect. This paper presents the finding of the initial steps of this study: The
edge effect has been investigated using modified loading fixture. The moving stress field has been investigated with a modified 4-
point bending test using asynchronous loading. The differences in test results between the modified test methods and the relevant
standard test methods indicate that both aspects affect measured fatigue life.
The performance of racing yachts has increased significantly over the past 10-15 years without significant changes to the prediction methods used in the early stages of the design. Tank testing or CFD-simulation are not always an option and especially in the early stages of design a requirement for reliable numerical methods exists...
The Influence of Heel on the Bare Hull Resistance of a Sailing Yacht
For the useful prediction of the performance of a sailing yacht using a generic Velocity Prediction Program (VPP) an accurate assessment of the hydrodynamic and aerodynamic forces and moments involved is essential...
PCLINES, A Parametric Lines Development Program for the Home Computer