Patent ID: 6029521
Filing Date: 2000-02-29
Classification: G01B,G01H

Abstract:
A method for measuring a thickness of a cover layer of a reinforcing bar, comprising the steps of:(a) disposing an impacting device and a first receiver on a surface of the cover layer along a longitudinal axis of the reinforcing bar, with a predetermined distance H provided between the impacting device and the first receiver;(b) applying an impact on the surface of the cover layer with the impacting device to generate a dilatational wave which propagates into the cover layer and is totally refracted at an interface between the cover layer and the reinforcing bar, and is received by the first receiver;(c) determining the travel time .DELTA.t.sub.S of the dilatational wave from the impacting device through the reinforcing bar to the first receiver;(d) calculating the thickness of the cover layer of the reinforcing bar by: ##EQU6## wherein d.sub.S is the thickness of the cover layer of the reinforcing bar;.DELTA.t.sub.S is the travel time of the dilatational wave from the impacting device through the reinforcing bar to the first receiver;C.sub.PC is a first speed of the dilatational wave in the cover layer;C.sub.PS ' is a second speed of the dilatational wave in the reinforcing bar;H is the distance between the impacting device and the first receiver;.theta. is a critical angle of incidence for totally refracting the dilatational wave.