3
1 Introduction
1.1 Scope of applications
Ultrasonic Thickness Gauge measuring with ultrasonic wave is
applicable for measuring the thickness of any material in which ultrasonic
wave can be transmitted and reflected back from the other face.
The gauge can provide quick and accurate measurement to various
work pieces such as sheets of board and processing parts. Another
important application of the gauge is to monitor various pipes and
pressure vessels in production equipment, and monitor the thinning
degree during using. It can be widely used in petroleum, chemical,
metallurgy, shipping, aerospace, aviation and other fields.
1.2 Primary Theory
The primary theory of measuring thickness with ultrasonic wave is
similar to that of measuring thickness with optical wave. The ultrasonic
wave emitted from the probe reaches the object and transmits in it.
When the ultrasonic wave reaches the bounding surface of the material, it
is reflected back to the probe. The thickness of the material can be
determined by accurately measuring the time of the ultrasonic wave
transmitting in it.
1.3 Measuring Principle
The digital ultrasonic thickness gauge determines the thickness of a part
or structure by accurately measuring the time required for a short
ultrasonic pulse generated by a transducer to travel through the thickness
of the material, reflect from the back or inside surface, and be returned to
the transducer. The measured two-way transit time is divided by two to
account for the down-and-back travel path, and then multiplied by the
velocity of sound in the material.
The result is expressed in the well-known relationship:
Where: H- Thickness of the test piece.
v- Sound Velocity in the material.
t- The measured round trip transit time.
v
×
t
H =
2
