UC San Diego

The increasing demand for in-service structural health monitoring has stimulated efforts to integrate self and environmental sensing capabilities into materials and structures. The present work is directed towards the development of a new means of fabricating composites that allows for integrating a high density of small, advanced sensors into a laminated composite in a way that enables sensing without compromising the structural integrity of the host composite material. This work presents efforts to develop structural composite materials which include networks of embedded sensors with decision-making capabilities that extend the functionality of the composite materials to be information-aware. These structurally-integrated embedded microsensors render the composite information-based, so that it can monitor and report on the local structural environment, on request or in real-time as necessary. The integration of sensors, actuators, and their subsequent devices into a structure is vital in smart applications. Essential to the application of smart composites is the issue of the mechanical coupling of the sensor to the host composite material. Therefore, the question of the impact of such devices on the various mechanical properties of the host composite material is both relevant and important. This work characterizes the effects of introducing simulated microsensors, commonly used printed circuit board material (G-10/FR4 Garolite), and various piezo thin film sensors on the mechanical properties of the host structural composite material. Quasi-static tension tests are conducted in order to characterize the mechanical properties of the host composite material as well as the effects the embedments have upon the host material. Quasi- static three-point bending (short-beam shear) and fatigue three-point bending (short-beam shear) tests are conducted in order to characterize the effects of introducing the sensors and such devices on the short-beam shear strength and fatigue life of the host structural composite material. Furthermore, various embedding configurations are examined. The thrust of the research presented here is to characterize the effects of embedding sensors and their subsequent devices on the mechanical properties of the host structural composite material in order to select a sensor and embedding configuration that can seamlessly be integrated into the host composite without compromising the integrity of the structure