Structural Health Management and Structural Design: An Unbridgeable Gap?

Much has been made of the potential for integrated system health management (ISHM) to influence the design of aerospace systems. Yet the examples of ISHM affecting design are often ones of using ISHM to maximize the potential of systems that have already been conventionally designed, such as maximizing a component's time on wing, minimizing the design supportability footprint of a system, or implementing autonomous failure avoidance or detection and remediation systems on a vehicle. The fact that these approaches are based on the application of SHM to "conventionally" designed systems precludes some of the more dramatic benefits of ISHM technology. A particularly compelling example involves aerospace primary structures where, for the same mission and same level of system safety and reliability, indications are that an ISHM-enabled composite design could weigh up to 20% less than a conventionally designed structure. In the space arena, a 20% structural mass savings could enable missions that are currently difficult, if not impossible, to achieve otherwise. Realizing this potential requires more than addressing and including the ISHM system in the conceptual design of the system. Rather, the ISHM system's capabilities, requirements and design must be an integral part of the design process before any preliminary design and sizing of the structure begins. This paper examines the potential benefits of truly ISHM- based structural design as opposed to conventional design- based ISHM. In the process, the practical challenges to ISHM-based design are discussed, key barriers to ISHM's ability to influence design are identified and approaches to address those barriers are outlined.