Design, development, and modeling of a compact, field-grade civil infrastructure crack detector device.

摘要

Currently the nation's aging bridge infrastructure is approaching and in some cases exceeding its initial design life averaging more than forty years. Under these conditions steel bridges are susceptible to fatigue cracks at stress ranges below their material yield strength. In order to evaluate the remaining service life of these structures under their current operating conditions, it is important to accurately locate and identify active cracks within the material. Early detection of cracks and defects within a structure can provide inspectors and bridge maintenance personnel with viable information that can be used in the design and selection of an appropriate retrofit or repair technique that can be used to extend the service life of the bridge structure. Bridge inspections are typically conducted every two years primarily using visual inspection techniques. The active crack sensing tool designed and analyzed in this study is based on the robust and high sensing capabilities of piezoceramic materials. This dissertation presents the analytical, computational, and experimental results of a novel approach to identifying and characterizing cracks in steel bridge structural components using a piezoceramic sensor. Using the newly designed Piezoelectric Active Crack Tip Sensor (PACTS) tool, it was possible to detect an active crack with an opening displacement of 0.056 mm [0.0022 in] could be sensed under dynamic loading conditions. By using a crack opening linear trend (COLT) analysis, the crack tip position could be located within 3 mm [1/8 in] without the use of correction or modification factors. The results of the research provide a foundation in establishing an inspection tool capable of identifying damage detection within an in-service structure. The identification of an active crack and the ability to locate the crack tip of a material provides bridge inspectors and maintenance personnel with valuable information related to the current bridge condition that could be used for maintenance, repair, or replacement of bridges structures in an effort to ensure the safe passage of people and goods across the nation.