Abstract

The embryonic discipline of macroscopically smart materials featuring polymeric fiberous composite laminates with embedded optical fibers provides significant technological advantages if they are incorporated in the next generation of the machines, mechanisms, and robotic systems. These technological advantages can be exploited during the manufacture, the service life, and the failure prediction phases of the part life-cycle. The embedded optical fibers permit the manufacture of the part to be optimized during autoclave processing, for example, by controlling the state of cure and temperature using a new generation of manufacturing techniques involving closed-loop control algorithms. Subsequently, the optical fibers permit the vibrational response, stresses, strains, and deflections to be continuously monitored during the service of the mechanical system, and where appropriate, embedded actuator materials can be activated to develop a more desirable response as part of a health management philosophy. Finally, the optical sensing system enables the failure of the part to be predicted, because the propagation of a crack through the structure will result in the fracturing of the embedded optical fibers, and hence, the severing of the optical light paths which can be detected by this class of photonic system. This paper introduces this potentially powerful health management philosophy to the field of mechanism design by presenting for the first time experimental results from an investigation of the dynamic response of a slider-crank mechanism with a smart graphite-epoxy laminated connecting-rod featuring a polarimetric fiber optic sensor. This investigation examines one facet of this new philosophy; namely, a health monitoring activity in which the vibrational response of a flexible machine element is monitored using a fiber optic sensor.

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