Predictive Modeling of Smart Structures with In-situ Sensing Capability

A methodology for the predictive modeling of smart structures with in-situ sensing capability is presented and discussed. First, the smart structures concept is briefly reviewed. Then, self-sensing smart structures with in-situ sensing capabilities are introduced. Focus is placed on active sensing methods using ultrasonic guided waves in thin-wall structures. The challenges of modeling ultrasonic wave propagation in realistic structures are discussed, and the mesh-size and time-step convergence requirements are discussed. The recently developed hybrid models for modeling ultrasonic nondestructive evaluation using bulk waves are presented and their advantages are discussed. A new approach, the generic hybrid global-local (HGL) approach is presented. It builds upon previous work in hybrid methods and extends them to guided waves in thin-wall structures equipped with piezoelectric wafer active sensors (PWAS) capable of both transmission and reception of ultrasonic guided waves. The features of this proposed HGL approach, which is still under development, are discussed. SMART STRUCTURES The concept of smart structures (a.k.a., adaptive structures or intelligent structures) is usually derived through analogy with living organisms which can sense the environment, interpret the information sensed from the environment, and react to it appropriately. For example, sensors in my skin would sense the pricking of a rose’s thorns and send the information to my nervous system which will interpret it and instruct my hand to let go and retreat. In order to achieve these functions, the living organisms possess sensing, data processing, and actuation capabilities embedded into their complex bodies. Similarly, a bio-inspired smart structure would be equipped with sensing, data processing, and actuation capabilities. A smart structure is a multifunctional system with capabilities well beyond the mundane load-bearing mission of conventional structures (Figure 1). Enabling technologies are active materials, integrated active sensors, fiber optics sensors, fiber optics communication, solid-state actuators, autonomous power and energy harvesting, multifunctional composites, self healing materials, integrated electronics, reasoners, and microcontrollers, etc.