| 摘要 |
<p>The invention relates to a method (300) of calibrating ultrasonic bi- wave fastener elongation measurements comprising - providing (301) a fastener (100, 200) of a tightened joint comprising a first portion(106, 206) with a primary deformation zone and a second portion (104, 205) excluding the primary deformation zone, - generating (302, 304) a longitudinal and a transversal ultrasonic wave and transmitting them into the second portion of the fastener, - detecting (303, 305) echoes of the longitudinal and transversal ultrasonic waves and measuring a longitudinal and a transversal TOF of the respective ultrasonic wave along a sound path in the second portion, and - defining(306) the measured longitudinal TOF and the measured transversal TOF as reference values for an elongation measurement in said fastener.</p> |
