BOLT PRELOAD MEASUREMENTS USING ULTRASONIC METHODS.

Abstract

A laboratory bolt testing program was initiated to obtain a data base of ultrasonic extensometer measurements of preload. The test results were utilized to calibrate preloads as induced by torque wrench, calibrated wrench and turn-of-the-nut procedural methods. Tests were conducted on 1-in. and 1 one quarter -in. dia. A490 high-strength bolts. The paper discusses the testing apparatus, calibration procedures, laboratory testing sequence, test results, and observed torque-tension relationships.