A New Method for Experimentally Quantifying Dynamic Deflection of a Cylindrical Structure

There is a present desire to experimentally acquire resolved strain and deflection along long, slender cylinders using non-visible and minimally invasive instrument techniques. This desire supports present safety related activities within the nuclear power industry. At present, no relevant technology has been demonstrated to support this function while satisfying the above requirements. This study presents and details a new method for experimentally quantifying the deflection of a cylinder experiencing both static and dynamic loads. The method applies a distributed strain fiber-optic sensor which is helically wrapped along the axial length of the cylinder. An analytic correlation is developed and detailed herein which decomposes the helical strain into both axial strain as well as transverse deflection. This newly developed experimental method is compared against analytic solutions using ideal beam theory as well as independent and proven optical methods for the purpose of verifying the new method. The outcome of this study results in a new and verified method that quantifies the deflection profile of a cylindrical structure.