Patent ID: 9127998
Filing Date: 2015-09-08
Classification: F16B,G01L,G01N

Abstract:
1. A method of measuring or monitoring tension in a bolt threaded into a joint having a bolt boundary formed from a real area of contact between said bolt and an underlying surface, comprising the steps of: positioning a transducer array element with a predetermined pitch and at a predetermined distance from said joint; generating an acoustic beam formed of surface acoustic waves, said acoustic beam generated by said transducer array element; directing said acoustic beam toward said bolt, wherein said surface acoustic waves reflect off of said bolt boundary at said real area of contact, thereby producing a reflected signal, said transducer array element receiving said reflected signal; determining a distance between said bolt boundary and said transducer array element based on a time of flight of said reflected signal; and generating a value of said tension based on said determination of said distance between said bolt boundary and said transducer array element, such that said distance and said value of said tension have an inverse relationship, whereby said tension is optimal at a saturation point of said real area of contact between said bolt and said underlying surface.