Patent ID: 9645025
Date: 2017-05-09
CPC Classifications: G01L

Claim:
1. A synchronous pre-tensionable fiber sensing screw apparatus providing synchronous both pre-drawing of fiber Bragg grating and pre-tightening of bolt to serve as a fastening apparatus equipped with a structure to sense strain characteristic values when subject to a force to display or output strain value, comprising: a bolt, including an embedded fiber Bragg grating; a first washer, coupled on a bolt head portion to bear the force applied to the bolt and a coupling object; a second washer, coupled on a nut to bear the force applied to the coupling object; the nut, coupled on the second washer and screwed helically on the bolt to form a self-locking connection; a fiber Bragg grating, embedded in the bolt; a setting point on the bolt head end for fiber pre-drawing; a setting point on the bolt tail end for fiber pre-drawing; and fiber chucks; wherein the bolt and the nut wrench the object to be fastened via a tightening torque to make transformation of strain for sensing an extension length in the bolt caused by the axial strain of the bolt, and the bolt with the nut becomes a sensing screw structure to measure output wavelength variations resulted from change of length of the fiber Bragg grating embedded axially on the central axis of the bolt; the fastening apparatus is not only containing a nut been forced to pretightening amount in the bolt, but also containing a pre-drawing amount in the bolt with a setting point on the bolt head end for fiber pre-drawing and a setting point on the bolt tail end for fiber pre-drawing to measure shifted Bragg wavelength, the two pre-drawing amounts being synchronously formed or formed by stages.