Out-of-plane ultrasonic velocity measurement

Patent · Tue Jul 14 00:00:00 EDT 1998

OSTI ID:871706

Hall, Maclin S ^[1]; Brodeur, Pierre H ^[2]; Jackson, Theodore G ^[3]

---

1. Marietta, GA
2. Smyrna, GA
3. Atlanta, GA

A method for improving the accuracy of measuring the velocity and time of flight of ultrasonic signals through moving web-like materials such as paper, paperboard and the like, includes a pair of ultrasonic transducers disposed on opposing sides of a moving web-like material. In order to provide acoustical coupling between the transducers and the web-like material, the transducers are disposed in fluid-filled wheels. Errors due to variances in the wheel thicknesses about their circumference which can affect time of flight measurements and ultimately the mechanical property being tested are compensated by averaging the ultrasonic signals for a predetermined number of revolutions. The invention further includes a method for compensating for errors resulting from the digitization of the ultrasonic signals. More particularly, the invention includes a method for eliminating errors known as trigger jitter inherent with digitizing oscilloscopes used to digitize the signals for manipulation by a digital computer. In particular, rather than cross-correlate ultrasonic signals taken during different sample periods as is known in the art in order to determine the time of flight of the ultrasonic signal through the moving web, a pulse echo box is provided to enable cross-correlation of predetermined transmitted ultrasonic signals with predetermined reflected ultrasonic or echo signals during the sample period. By cross-correlating ultrasonic signals in the same sample period, the error associated with trigger jitter is eliminated.

• Research Organization: Institute of Paper Chemistry
• DOE Contract Number: AC05-86CE40777
• Assignee: Institute of Paper Science and Technology, Inc. (Atlanta, GA)
• Patent Number(s): US 5780744
• OSTI ID: 871706
• Country of Publication: United States
• Language: English

Related Subjects

out-of-plane
ultrasonic
velocity
measurement
method
improving
accuracy
measuring
time
flight
signals
moving
web-like
materials
paper
paperboard
pair
transducers
disposed
opposing
material
provide
acoustical
coupling
fluid-filled
wheels
errors
due
variances
wheel
thicknesses
circumference
affect
measurements
ultimately
mechanical
property
tested
compensated
averaging
predetermined
revolutions
compensating
resulting
digitization
particularly
eliminating
trigger
jitter
inherent
digitizing
oscilloscopes
digitize
manipulation
digital
computer
particular
cross-correlate
sample
periods
determine
signal
web
pulse
echo
box
provided
enable
cross-correlation
transmitted
reflected
period
cross-correlating
error
associated
eliminated
pulse echo
ultrasonic signal
ultrasonic transducer
ultrasonic signals
moving web
digital computer
ultrasonic transducers
reflected ultrasonic
sonic signals
transducers disposed
web-like materials
sonic velocity
moving web-like
errors due
echo signals
errors resulting
velocity measurement
ultrasonic velocity
web-like material
sonic signal
/73/