Multi Criteria Material Selection for Eco-design

In recent years, structural optimization has changed the way we think of product development. Optimizers allow to explore every possible product shape with the aim of maximizing performance, minimizing cost and accounting for environmental factors from the early phases of the design process. Material selection plays a big role, as one of the first and most binding choices of the product development. Current material selection schemes are too generic and bound to a less shape-driven design, which doesn’t take full advantage of the optimization potential. They were developed for constant or self-similar shape products and allow for a substantial degree of subjectivity, when defining weight values for non-constant shape models. This paper proposes a computer-aided material selection scheme for structurally optimized products. It aims at integrating a multi-criteria decision making approach with the product awareness of a structural optimization, in order to systematically define the ranking weight values. The procedure comprises four main steps: a) initial material screening, to obtain a list of product and process compatible materials, b) statistical analysis of the design space through a factorial DoE (Design of Experiment), to rank the effect of each material property on the environmental impact, c) Multi Criteria Decision Making, to rank materials according to each material property importance, d) structural optimization, to identify the best possible shape for the chosen material. The methodology has been tested on a simple case study concerning the design of an environmentally friendly I-beam. The results confirm the feasibility of the proposed approach in improving material selection when a relevant number of decision criteria is involved.