Measurement of pipe strain using an ultrasonic system

Abstract

Ultrasonic sensors can be used to measure strain occurring on an object. In this investigation, an ultrasonic signal utilized the reflected signal as a means of monitoring the condition of a pipe. This is an alternative to the strain gage which is commonly used but has a limited life span. The ultrasonic signal was transmitted to a specific location on the pipe, and then reflected by the pipe surface which experienced strain towards the ultrasonic receiver. Collimation of the transmitted and received signals is performed by aluminum probe cones attached to both ultrasonic transducers. Changes in the strain due to the pipe bending will result in changes in the electric signal due to the changes in the sound intensity. The received electric signal was processed by a signal conditioning circuit consisting of preamplifier, amplifier, band-pass filter and rectifier before being displayed. Two experiments were conducted to establish the relationship between strain on the pipe and the ultrasonic intensity. In order to verify the results, an experiment was conducted using a strain gage and the results were identical. The results show that the system is able to measure strain when the pipe bends.