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Modeling the flukeAll anchors under consideration are equipped with a fluke. For modeling purposes the fluke can initially be considered as a flat plate with the same surface area as the real anchor. The shape, thickness and the presence of stabilizers have a big influence on the penetration behavior and must therefore be incorporated in the model. Four properties are involved in modeling the fluke:
Surface areaThe fluke area determines part of the anchors friction as well as its holding capacity. The fluke area can simply be defined by the user and used to determine its holding capacity. With the area of the fluke known it can then be use to calculate the surface friction of the anchor. ShapeThe shape of the fluke determines its form resistance; lean sharp fluke will have lower form resistance then chubby blunt ones. Nearly all flukes have a triangular or double triangular shape, and they can therefore be considered as one or two triangles.
A shape factor of one represents the best-fit triangle or double triangle with width and length corresponding to the width and length of the fluke (figure 4). By dividing the fluke area by the area of the triangle a coefficient is obtained which matches the triangle to the properties of the fluke. Because the triangle is only a rough approximation the coefficient can be larger than one if the fluke has rounded of edges. ThicknessThe thickness of the fluke will also have an influence on the drag of the anchor; a thicker fluke will have bigger resistance than a thin one. To incorporate this in the model the effect of the thickness of the anchors’ resistance will have to be investigated. Appendices
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Copyright © 2005 Project group 1
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