13th International Conference on Fracture June 16–21, 2013, Beijing, China -11- optimal value of the i th optimization, the 1J ∗ and 2J ∗ of the 1 i + th optimization is obviously smaller than them in the i th optimization (initial value in the 1 i + th time is much better), and converges faster. Each value in the database is revised by the high precise analysis in inner loop. Thus the approximation function has greater change (see figure 8). That is the main reason that this strategy needs more internal optimization, namely calling more number of the high precise analysis. 50 70 90 110 130 150 170 190 210 3… 3… 3… 3… 3… 3… 3… 3… 3… 4 4… 4… 4… 4… 4… total mass the value of a1 correct and update intial only update Figure.9 Initial target approximate function, the 8th corrected and updated, and only updated target approximate function at 9x Figure 9 shows the initial target approximate function (C1), the 8th corrected and updated approximate function (C2), and 8th only updated target approximate function (C3) at 9x . The C2 parabolic axis of symmetry has obviously offset in relative to the C1 curve, while the C3 has the almost same axis with the C1, but its parabolic top is little different. The change of the parabolic axis just comes from the high precise analysis result which corrects the lower precise analysis. Conclusion This paper firstly explores the current fluid-solid coupled algorithm on the turbine design. According to the principle of the ALE with existing commercial software, the dynamic grid technology of the blade fluid domain is realized by the small coupled step length and the mesh fairing method. Then combining with the previous remesh technology, the paper establishes the process of the turbine blade fluid-solid closely coupled analysis based on the ALE. Further the multiple-precision optimization strategy is established. The high precision of the fluid-solid coupled analysis should be applied to the turbine blade MDO to improve the design accuracy. Because of the huge cost of the high precise analysis, this paper studies the VCM methods from three aspects which are various precise models, the periodic update and the two point scale function in order to improve the efficiency and accuracy of the optimization. The VCM introduces the high, medium and low precise model into the MDO. The method of the periodic update properly employs the high precision model to reasonable correct the low precision model. The two point scale function adequately utilizes the high precise analysis of the optimization process to correct the result of the low precise model. Finally, comparing the calculated results before and after coupling, the paper detailedly analyses the influence of disciplinary couple. Introducing the structural displacement, the total efficiency of the coupled field is slightly higher than single fluid analysis; the aerodynamic force is much smaller relative to the centrifugal force, the maximum equivalent stress of the closely couple is probably equivalent to the sum of individual effects of the aerodynamic force and centrifugal force. Additionally, the paper lists the optimal value on the multiple-precision optimization strategy. The result ensures the precision and efficiency of the turbine blade MDO after the optimization method
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