A numerical shape optimisation method for blowing glass bottles

Industrial glass blowing is an essential stage of manufacturing hollow glass containers, e.g. bottles, jars. A glass preform is brought into a mould and inflated with compressed air until it reaches the mould shape. A simulation model for blowing glass containers based on finite element methods, which adopts a level set method to track the glass-air interfaces, has previously been developed [1-3]. A considerable challenge in glass blowing is the inverse problem: to determine an optimal preform from the desired container shape. In previous work of the authors [4, 5] a numerical method was introduced for optimising the shape of the preform. The optimisation method described the shape of the preform by parametric curves, e.g. Bezier-curves or splines, and employed a modified Levenberg-Marquardt algorithm to find the optimal positions of the control points of the curves. A combined finite difference and Broyden method was used to compute the Jacobian of the residual with respect to changes in the positions of the control points. The objective of this paper is to perform an error analysis of the optimisation method previously introduced and to improve its accuracy and performance. The improved optimisation method is applied to modelled containers of industrial relevance, which shows its usefulness for practical applications.