Research on the efficient process-oriented structural optimization method of the large-scale vacuum cryostat for fusion reactor

An efficient optimization design for large and complex components of fusion reactor is crucial to address the engineering design requirements and further promote technical standardization. Based on research status, current engineering designs for fusion reactors have some deficiencies such as time and energy wastes, inefficiency and the difficulties in covering the typical “multi-variable, multi-objective” design requirements. They are pressing and common problems that urgently need to be overcome. To deal with the aforementioned technical challenges, it is vitally important to design an efficient, precise, and normalized approach tailored for the development of future fusion reactors. Therefore, this paper proposes a process-oriented optimization design method, which involves Coupled external parameterized modeling, Experimental points design, Response surface optimization and Structural integrity validation (CERS), to improve currently inefficient design methods. And the vacuum cryostat, the largest and complex component of tokamak, is taken as an example to present the basic procedures of CERS. Firstly, the functions, basic structures, load types, analysis methods and verification criteria of the cryostat are presented in detail. And then real-time data interaction between external global parametric variables and ANSYS via coupling is established by CERS, which achieves parametric modeling of cryostat and the efficient experiment point design and optimization analysis with multi-variables and multi-objectives in an automatic way. Subsequently, this study demonstrates the significance and sensitivity of various structural parameters of cryostat from such objectives as maximum deformation, maximum equivalent stress, and total mass. And the optimal set of its structural parameters is obtained by establishing mathematical optimization model. Finally, the structural integrity is verified. The result indicates that the optimized cryostat maintains a minimum safety margin of 23% and will not suffer fatigue damage under various load events during its service. Besides, the nonlinear buckling load multiplier ∅ is 5.4, obtained by analyzing the load-displacement curve of cryostat according to the zero-curvature criterion. This shows that the designed cryostat is stable enough. The proposed method is simple, efficient and reliable which can be applied to both cryostat and other complex components of fusion reactors in the engineering design fields. It has great value of practically technical reference and can further promote the standardization of engineering design technology for future fusion reactor.