在数字化船舶设计过程中，基于插值截面线生成的船体曲面控制顶点数过多，不利于后续曲面的光顺和修改；基于非均匀有理B样条截面线生成的曲面，形状不可控.针对上述问题，提出了一种轻量化船体曲面逼近的设计方法.该方法通过对截面线进行2次逼近，生成船体曲面.在一次逼近中，应用等弦差法对截面线进行离散，得到曲线上的离散数据点；在二次逼近中，以截面线的节点矢量为设计变量，将最小化所有截面线在最小二乘意义上的逼近误差之和作为目标函数，构建截面线优化逼近模型.根据问题的性质，对自适应改变染色体长度的遗传算法进行改进，将该算法应用于模型求解.实船船体曲面逼近和设计算例表明，应用该方法对船体曲面进行逼近设计是可行的，并能满足工程设计要求，同时还可以减少船体曲面设计所需的数据量，为其他复杂曲面的轻量化设计提供参考.
During the processes of digital ship design, there are too many control points on the hull surface based on interpolation section curves, which are disadvantageous to the hull surface fairing and modification. The shape of hull surface, based on non-uniform rational B-spline section curves, is uncontrollable. To solve the forementioned problems, a design of lightweight approach of hull surface approximation is proposed. The hull surface is generated by two steps of section curves approximation. In step one, the equivalent chord deviation curve discretization method is applied to the curve approximation. In step two, the optimization approximation model is constructed with the knots of section curves as the design vari-ables. The objective function is set to minimize the sum of the approximate error of all section curves in the least-squares sense. According to the character of this problem, the genetic algorithm with adaptively alterable chromosome length is improved and applied to solve this optimization problem. The instances of the hull surface approximation and design for full-scale ship indicate that it is feasible and can satisfy the requirements of the engineering design for hull surface approximation. Applying this method, the data used for hull surface design and approximation can be reduced. And it can provide a reference for the lightweight design of other similar complex surface.
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