Patent ID: 8499643
Filing Date: 2013-08-06
Classification: G01M

Abstract:
1. A sensor unit which provides surrogate determination of crack development within a component of interest associated with a monitored structure comprising: sample sensor bolt having a shank with a head at one end, a threaded end opposite to the head and an exposed portion between the head and threaded end, wherein at least the shank of the sensor bolt is formed of a material serving as a surrogate of the material forming the component of interest associated with the monitored structure; a frame surrounding the shank of the sensor bolt and having fluid ports therein, wherein the exposed portion of the sensor bolt shank is positioned in registry with the fluid ports such that fluid entering the fluid ports comes into contact with the exposed portion of the sensor bolt shank in registry therewith; a pre-load nut threaded onto the threaded end of the sensor bolt shank and contacting an end of the frame so as to place the sensor bolt shank under an initial tensile stress, and a load cell operatively connected to the sensor bolt for sensing relief of the initial tensile stress of the sensor bolt shank; wherein fluid entering the fluid ports of the frame comes into contact with the exposed portion of the sensor bolt shank so as to cause crack formation therewithin, wherein the crack formation within the sensor bolt shank caused by fluid acting upon the exposed portion thereof responsively relieves the initial tensile stress of the sensor bolt which tensile stress relief is thereby sensed by the load cell to allow crack development in the sensor bolt shank to be determined and correlated to crack development occurring within the component of interest associated with the monitored structure.