Method of recertifying a loaded bearing member

Abstract

The present invention is a method of recertifying a loaded bearing member using ultrasound testing to compensate for different equipment configurations and temperature conditions. The standard frequency F1 of a reference block is determined via an ultrasound tone burst generated by a first pulsed phase locked loop (P2L2) equipment configuration. Once a lock point number s is determined for F1, the reference frequency F1a of the reference block is determined at this lock point number via a second P2L2 equipment configuration to permit an equipment offset compensation factor Fo1=((F1-F1a)/F1)(1000000) to be determined. Next, a reference frequency F2 of the unloaded bearing member is determined using the second P2L2 equipment configuration and is then compensated for equipment offset errors via the relationship F2c=F2+F2(Fo1)/1000000. A lock point number b is also determined for F2. A resonant frequency F3 is determined for the reference block using a third P2L2 equipment configuration to determine a second offset compensation factor Fo2 (=(((F1-F3)/F1) 1000000). Next the resonant frequency F4 of the loaded bearing member is measured at lock point number b via the third P2L2 equipment configuration and the bolt load determined by the relationship load=(-1000000)Cl(((F2C-F4)/F2C)- Fo2), wherein Cl is a factor correlating measured frequency shift to the applied load. Temperature compensation is also performed at each point in the process.