Materials design: A systems-based approach

Traditionally, design engineers and materials scientists have adopted very different approaches. Natural scientists are concerned with building a body of knowledge about objects or phenomena—their characteristics, behavior, and interactions. Designers, on the other hand, are concerned with how to synthesize and realize artifacts that have desired properties or functionality and fulfill a purpose or attain a goal [1]. Primarily, new materials have been developed with empirical, trial-and-error techniques prominent in the natural sciences. Integration of design engineering and materials science has been limited mostly to the selection of an appropriate material from a finite set of available materials with experimentally determined properties. In contrast, materials designers wish to tailor the material structure itself along with associated processing paths to achieve desirable material properties and performance. The structure and successful performance of a product or system is linked strongly with the properties and performance of its constituent materials; thus, performance objectives for a material and a larger system are interdependent for most applications. By concurrently designing a product and its constituent materials, innovative, high-performance, product-material systems can be realized. Moreover, as we increasingly fabricate and utilize multiphase materials, cellular materials, and heterogeneous MEMS, NEMS, and biomedical devices, it is nearly impossible to distinguish issues of materials design from those of the design of larger systems or assemblies. Certainly, it is essential to design material concurrently along with a complex product to achieve breakthroughs in robust, superior, system performance. Accordingly, systematic, effective, efficient methods are needed for designing materials along with the products and systems in which they are integrated. Many of the challenges associated with materials design motivate a systems-based design approach. For example, materials design is an inherently multi-scale activity. Desired properties and performance characteristics often depend on phenomena that span length scales from angstroms to meters and time scales from picoseconds to years. Most applications require materials that satisfy multiple functions, such as structural load bearing and thermal transport, and these requirements cannot be defined in isolation from overall system conditions and requirements. These requirements include the product in which a material is integrated and the product’s operating environment. While it is challenging to develop physics-based models that capture relevant process-structure-property relations on different scales for diverse functions, it is also difficult to link the corresponding models in a manner that facilitates exploration of the systems-level design space by a collaborative team of expert designers. The complexity and restricted domain of application of physics-based models often limit explicit integration of models across length and time scales. Therefore, critical issues include collaborative, distributed, multiobjective decision making among multiple experts and integration of heterogeneous, distributed software applications and databases for facilitating synthesis and selection of promising alternatives. Systematic communication, translation, archiving, and retrieval of design information are also important. To facilitate efficient exploration of a broad design space, model approximations may be utilized. The uncertainty associated with predictions of approximate or detailed models, the model uncertainty associated with limited data and knowledge, and the system variability associated with materials’ morphology variations must be considered, especially when information propagates through a series of models with associated assumptions, approximations, and variability and when models are utilized near the limits of their accepted domains of application.Copyright © 2004 by ASME