Sensitivity analysis and nonlinear programming applied to investment casting design

Finite element solidification heat transfer analysis, explicit design sensitivity analysis, and nonlinear programming are combined to examine investment casting. The theoretical formulation is presented for considering both continuous and discrete optimization. The methods are then applied to improve the design of an axisymmetric superalloy investment casting. A significant reduction in material is achieved by minimizing riser volume, while maintaining directional solidification. In a second example problem a continuous-discrete algorithm is implemented to solve a similar problem, where mold wrap having one of a set of discrete thicknesses is placed on the investment to control the solidification pattern.