Browsing by Author "Mehl, Nicholas"

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    Implementation of Infrared Non-Destructive Evaluation in Fiber-Reinforced Polymer Bouble-Web I-Beams
    Mehl, Nicholas (Virginia Tech, 2006-02-13)
    When taking steps away from tried and true designs, there is always a degree of uncertainty that arises. With the introduction of fiber-reinforced polymers (FRP) in double-web I-beams (DWIB) to replace steel beams in bridge applications, there are many benefits along with the disadvantages. A bridge has been built with this new type of beam after only short-term proof testing for validation. Nondestructive evaluation (NDE) is a way to implement health monitoring of the bridge beams and needs to be assessed. The principal underlying infrared thermal imaging (IR) nondestructive evaluation (NDE) is to induce a thermal gradient in the beam through heating and monitor how it changes. Delaminations determined by others to be the critical form of deterioration, would be expected to affect the heat conduction in these beams. This project used a halogen lamp to heat the surface of the beam followed by an observation with an IR camera. Calculations of an ANSYS finite element analysis (FEA) model were compared with a series of laboratory tests. The experimental results allowed for validation of the model and development of an IR inspection procedure. This work suggests that for high quality beams of the type considered that an IR procedure could be developed to detect delaminations as small as one inch in length; however, the size would be underestimated.