Research And Application Of Whole Fairing And Approximation Algorithm Of NURBS Curve

As a research branch of curve and surface modeling technology, fairing and approximation technology of NURBS curve is applied in an extremely wide area and the researches on it have very important academic and practical value.Firstly, a whole fairing and approximation algorithm of NURBS curve is given in this paper. An objective function comprised of fairing and approximation items is constructed; all the parameters of NURBS curve are dynamically obtained in the way of combining circular judgement and dichotomy search, then the curve which has a good precision and fairing quality is gained. This algorithm has a clear theory, a regular framework and a high speed of optimization calculation.Secondly, the weights of fitting curve are optimized using nonlinear optimization method. A Gene Algorithm based on leaving elites is given; the program of this GA is compiled and its high solution efficiency is verified through some examples; this algorithm is applied in the Whole Fairing and Approximation Algorithm of NURBS Curve to optimize the weights. As a result, the algorithm of this paper has a better effect.Thirdly, the program of the Whole Fairing and Approximation Algorithm of NURBS Curve is completed and the fitting curve is checked and analysed in a visual environment. The principle of algorithm is realized using the VC++6.0; the module of NURBS curve fitting is opened based on the above programe and some tools such as UG API functions. In the visual environment of UG NX4.0 the precision and fairing quality of the algorithm are checked and analysed using UG tools. It is proved that this paper's algorithm has a good effectiveness for fairing and approximation of curve through some examples.At last, a parameterized modeling module of a compressor blade in UG system is opened based on the algorithms. In detail, the Whole Fairing and Approximation Algorithm of NURBS Curve is used to solve the blade section curve fitting in this module; this module also has the size compressing and converting format functions towards data points document; using the surface checking tools of UG it is proved that the blade model which is created by this module has a good surface quality; by this means, the aerodynamics characteristic and mechanical strength of blade products are improved.