Minimum cost and weight design of fuselage frames - Part B: cost considerations, optimization, and results

An approach is presented to design fuselage frames for minimum weight, mini mum cost, or a combination of the two. The approach combines structural req uirements and manufacturing constraints into an optimization scheme that al ters the geometry of the individual frame components until the objective fu nction is minimized. In addition to the lowest weight and cost points, a ne ar-optimal Pareto set of designs is found, out of which the design that min imizes both cost and weight is determined through a penalty function approa ch. Four different fabrication processes are considered: conventional sheet metal, high speed machined metal, hand laid-up composite, and resin transf er molded composite. For lightly loaded frames, an automated resin transfer molding process gives the lowest cost and weight designs. For highly loade d frames, high speed machining gives the lowest cost design but automated r esin transfer molding gives the lowest weight design. The effects of fabric ation process and some of the design and manufacturing constraints on cost and weight are examined. (C) 1999 Elsevier Science Ltd. All rights reserved .