Stress-constrained thermo-elastic topology optimization of axisymmetric disks considering temperature-dependent material properties

Abstract

The lightweight design of turbine disks is challenging due to the extreme thermomechanical service environment which leads to high stress and temperature-dependency of material properties. The simplified engineering design method which uses uniform material properties at fixed temperature would lead to either unsafe or conservative designs. In this article, a stress-constrained thermo-elastic topology optimization method is proposed for axisymmetric disks considering temperature-dependent material properties. The temperature-dependent property functions fitted from the material test data are used to determine the material properties of each element according to the element’s average temperature. The strain energy constraint is added into the optimization formulation in order to prevent isolated material and severe violation of stress constraint caused by abrupt volume change. The Helmholtz filter and Heaviside projection are utilized to eliminate the checkerboard pattern and ensure distinct solid/void interfaces in the optimization results, respectively. The geometry extraction from the optimization results is easily implemented by the Least Square Fitting with B-spline Method. In the illustrative examples, the effectiveness of the proposed method in obtaining lighter disk designs is demonstrated in comparison to the design obtained by the simplified engineering method and the traditional single-web disk design. The ability of the proposed method to deal with arbitrary nonuniform temperature field is also demonstrated and it is learned that lighter disk design can be obtained if the temperature field has a lower radial temperature gradient at the disk hub.