Development of an Optimized Materials Sustainability Meta-Methodology

The 21^st century has seen increasing demand to be able to anticipate shortages in the feedstocks of critical materials. This aligns with a growing interest in sustainability, as manufacturing industries work to shift to more resilient supply chains, and the need for reliable means of measuring supply risk. To this end, The National Research Council developed a “criticality matrix” in 2007, which defined criticality as a function of two variables: “supply risk” and “impact of supply restriction.” Other organizations then expanded on this concept, with many incorporating an environmental impact dimension, and now there are many published methodologies for assessing supply chain sustainability, each with inherent advantages and disadvantages. This makes the selection of a methodology confusing and difficult. The present paper addresses this challenge by examining 16 published material criticality methodologies. Criteria for comparison were developed across a multi-dimensional framework, which included: material, geography, time scale, assessment confidence and data transparency. These were mapped to an existing framework, based on social, technical, economic, environmental, and political (STEEP) metrics, which is the basis for many sustainability evaluations at Villanova University’s Sustainable Engineering program. Of the 16 methodologies, three were identified as most appropriate for selected materials critical to modern aerospace manufacturing, which is especially challenged in this regard due to long product cycles. These materials were: epoxy resin, carbon fiber, alumina trihydrate, and copper. The results of the assessment suggested that while no single published methodology addresses all considerations, the downselected set offers unique benefits when utilized in tandem. By combining the most applicable components from each method, it was demonstrated that the STEEP metrics may be specifically tailored to the needs of a particular industry and materials set.