Dakota Ultrasonics MINI--MAX - Manual (Page 127)

MINI-MAX Ultrasonic Bolt Tension Monitor
121
⎟
⎠
⎞
⎜
⎝
⎛
=
A
P
S
Stress
S = Stress
P = Load
A = Cross sectional error
100
∗
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
=
E
E
N
L
X
S
%Strain
S
N
= %Strain
X
E
= Elongation
L
E
= Effective Length
12.2 Display View Options
A key feature of the MINI-MAX is the versatility of the display views available to
the user. The waveform views are a graphical representation of the actual sound
reflections traveling through a fastener and returning back to the transducer. The
waveform display shows the amplitude of the signal received on the vertical (Y)
axis and time (displayed in terms of length) on the horizontal (X) axis. The two
waveform display options are RF(Full) wave, and RECT(rectified) half wave
either positive or negative. These waveform options give the user the ability to
view the actual waveform and point of detection. In this view option the user has
better control over where the MINI-MAX is detecting, selecting the proper phase
of the signal, and adjusting the gate and threshold (sensitivity) to eliminate noise
or to force a specific detection point.
The RF waveform view is recommended when initially setting up the MINI-MAX
for an application. This display view gives the user the ability to view the entire
waveform, both positive and negative cycles, to determine the appropriate phase
of the signal for measurement. The Large Digits display view is a general digital
display of the quantity selected. It’s a nice easy viewing option that is typically
used following setup of the initial application. The digits view is also equipped
with a limits bar that if the alarm status is activated and in a measurement
location other than an L-REF (reference length). If tolerance values were setup
in the MINI-MAX, the user could use the limit bar and alarm lights to view when
the fastener was in the required tolerance region, and avoid having to constantly
watch the digital readout for a target value to appear.