Checkline TI-MINIMAX - Manual (Page 96)

Dakota Ultrasonics
90
•
A minimum of three sample bolts which are representative of the bolt
type and geometry for which the Sonic Stress Factor is to be
determined.
NOTES:
•
The Dakota Ultrasonics MINI-MAX must be calibrated, or zeroed, as
described in the Zero Calibration procedure section 8.4.
•
The Velocity Calibration should be performed prior to determining the Stress
Factor. Refer to section 10.2.
•
The sample bolts must be left to soak in the controlled temperature
environment for a period of not less than 24 hours. Care must be taken
throug h out the measurement process to avoid significant change in the bolt
temperature due to handling of the sample bolts, or the process of applying
load.
•
The mechanical apparatus for measurement of length must be calibrated in
accord with governing QA procedures. The device should be configured so
that minimum handling of the sample bolts will be required during the
measurement process.
Determination of the Sonic Stress Factor is accomplish by solving the equation:
Calibrating the Stress Factor
1) Using the mechanical measuring device, measure and record the
Mechanical Length at Zero Load “L
M0
” for each sample bolt.
SonicStressFactor
L
L
L L
L L
MECHANICAL
ULTRASONIC
Ml M
Ul U
= =
−
− ∆
∆
0
0
L MechanicalLength ZeroLoad
M 0
=
@
L UltrasonicLength Load
Ul
=
@
L UltrasonicLength ZeroLoad
U 0
=
@
L MechanicalLength Load
Ml
=
@