A method of measuring the load in a member subjected to longitudinal stress, a load measuring device and a fastener tightening device using the method of measuring, a load indicating member and a load indicating fastener for use in conjunction with the method of measuring, a method of making the load...http://www.google.fr/patents/US4846001?utm_source=gb-gplus-shareBrevet US4846001 - Ultrasonic load indicating member
