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Lightweight Optimization of a Variable-Thickness Silicon Carbide Ceramic Impeller and Rotor-Dynamic Stability under High-Temperature and High-Speed Conditions

Xianfa Shen, Haiqiao Wang

Journal of Ceramic Science and Technology · Early View (advance online publication) (-1), pp. 1-14

DOI: 10.4416/JCST2026-00014

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Abstract

A variable-thickness design strategy was developed for a pressureless-sintered silicon carbide ceramic impeller operating under coupled thermal and centrifugal loads. Eight impeller structures made from one common SiC composition were compared: an equal-thickness baseline, six gradient candidates, and a balanced optimum. A five-parameter B-spline thickness field was screened through 160 Latin-hypercube designs. Gaussian-process response surfaces and NSGA-II balanced mass, principal tensile stress, second critical speed, and aerodynamic loss; surrogate models were used for screening, whereas the manufactured geometries were confirmed by direct high-fidelity calculations. Three independent manufacturing batches were represented in every group. The balanced design reduced mass from 286.4 to 232.1 g (18.96 %) while decreasing the 900 °C/60 krpm maximum principal tensile stress from 306.8 to 266.5 MPa and tip deformation from 72.4 to 59.6 µm. Its second critical speed increased from 62.1 to 69.0 krpm, and vibration velocity fell from 3.44 to 2.28 mm s−¹. Direct CFD gave a 0.58 percentage-point efficiency decrease for G7, equivalent to a 0.69 % relative decrease from the G0 efficiency and below the robust 0.80 percentage-point limit. Material properties were practically equivalent across structures. A batch-aware mixed model confirmed a lower speed-dependent response for G7, while maximum-likelihood Weibull analysis and effective-volume integration reduced the predicted failure probability from 2.1 × 10−³ to 1.8 × 10−4. The results demonstrate that redistributing ceramic volume toward the blade root and backplate transition can improve lightweight efficiency and high-speed stability without a material aerodynamic penalty.

Keywords

Silicon carbide, ceramic impeller, variable thickness, rotor dynamics, Weibull reliability

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