INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING Int. J. Numer. Meth. Engng 2003; 56:1721–1733 (DOI: 10.1002/nme.635) Analysis of nets with hexagonal mesh using triangular elements Daniel Priour ∗; † IFREMER; BP 70; 29280 Plouzane; France SUMMARY The calculation of net shapes is achieved using the nite element method. A triangular element is developed for the modelling of the net. The main hypotheses are that the strain in each triangular element is constant, that the hexagonal meshes have three directions of twine, and that the twines are elastic. The forces due to the tension in twines are described and calculated by a direct method. The results of the model based on such triangular elements are provided. The comparison with a model where each twine is described as an elastic bar, is quite good. Copyright ? 2003 John Wiley & Sons, Ltd. KEY WORDS: net; hexagonal meshes; nite element method; direct formulation INTRODUCTION Nets are used in shing m etiers especially trawling. Now, the net makers’ and shermen’s main concern is to know if the net works well or whether the stress in the net is acceptable during shing operations. Diamond and square mesh nets are mainly used in this industry but the use of hexagonal meshes is signicant. Tronstad and Larsen [1] have developed a membrane element using the nite element method for nets made of diamond and square meshes only. The element has four corners and each side is parallel to the diagonal of net meshes. The deformation along each side of the membrane element can vary and the element remains plane. Priour [2, 3] has developed also a two-dimensional element (triangular) for the calculation of a net shape made of diamond and square meshes. The strain in each triangle being constant, the forces in twines are calculated by a direct method. These two methods are not suitable for nets made of hexagonal meshes. ∗ Correspondence to: Daniel Priour, IFREMER, BP 70, 29280 Plouzane, France † E-mail: daniel.priour@ifremer.fr Contract=grant sponsor: Commission of the European Communities, Agriculture and Fisheries (FAIR) specic RTD programme; contract=grant number: CT96 1555 Received 28 June 2001 Revised 14 March 2002 Copyright ? 2003 John Wiley & Sons, Ltd. Accepted 30 April 2002