The Improvement Of Hull Form Modification Method And Its Application In Ship Hull Optimization

In the ship hull optimization technology,the hull form modification method is the prerequisite for ship hull optimization,and it is the link between the optimization algorithm and the ship performance evaluation,which determines the size of the ship hull optimization design space.Among them,the hull form modification method based on radial basis function interpolation has the advantages of widening the design space for ship hull changes and making local line deformation more flexible.The research on this method is mainly focused on the following work:1)Derivation of radial basis function interpolation formula applicable to hull form modification method.Aiming at the problem of judging the smoothness of the curved surface after interpolation,a radial basis function interpolation formula is derived to ensure the smoothness of the curved surface by minimizing the energy of the curved surface.Firstly,the formula is derived using regularization theory,and then the smoothness of the deformed ship is evaluated by methods such as curvature comb and zebra crossing.It is verified that the curved surface deformation method based on radial basis function interpolation can ensure the smoothness of the deformed ship.2)Improvement of support radius.The existing support radius determination method does not take the distribution of variable points and the influence of coordinate changes into account at the same time,and in special cases,the support radius cannot be obtained by Delaunay triangulation.In view of the above problems,this paper proposes a dynamic method for obtaining the support radius.The idea is based on variable points.In order to prevent saddle points from appearing on the hull surface after deformation and maintain topological continuity,Delaunay triangulation method is used to calculate the support radius and the lower bound of the support radius is derived.The above method comprehensively considers the influence of the distribution of the variable point and the change of the coordinate of the variable point on the support radius.3)Radial basis function interpolation method based on spatial point cloud.To solve the problem that the radial basis function interpolation method based on NonUniform Rational B-Splines(NURBS)cannot accurately define geometric constraints,a radial basis function interpolation method based on spatial point cloud is proposed.This method focuses on improving the selection of variable points(optimization variables)when the hull surface is deformed,as to achieve the constraint of specific geometric parts during the hull surface deformation.4)The application of surface deformation method based on radial basis function interpolation in ship form optimization.The improved hull surface deformation module is embedded in the multi-disciplinary comprehensive optimization platform for ship hydrodynamic performance developed by the team(SHIPMDO-WUT V6.0),taking Series 60 ship(referred to as S60 ship),DTMB5415 ship and trimaran as the research objects.Research on ship type optimization under given constraints,to prove the feasibility and practicality of the method...