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Thursday, 15 September 2016

DUAL ELEMENT & DELAY LINE TRANSDUCER IN ULTRASONIC TESTING.

Dual element transducer :-Contain two independently operated elements in a single housing. One of the elements transmits and the other recives the ultrasonic signal. Active elements can be chosen for their sending and receiving capabilities to provide a transducer with a cleaner signal,and transducer for special applications such as the inspection of course grained material. Dual element transducer are especially well suited for making measurements in applications where reflectors are very near the transducer since this design eliminates the ring down effect that single element transducer experience (when single -element transducer are operating in pulse echo mode, the element cannot start receiving reflected signals until the element has stopped ringing from its transmit function).Dual element transducer are very useful when making thickness measurements of thin materials and when inspecting for near surface defects. The two elements are angled towards each other to create a crossed - beam sound path in the test material.
Delay line transducers:- provide versatility with a variety of replaceable options. Removable delay line, surface conforming membrane, and protective wear cap options can make a single transducer effective for a wide range of applications. As the name implies, the primary function of a delay line transducer is to introduce a time delay between the generation of the sound wave and the arrival of any reflected waves. This allows the transducer to complete its sending function before it starts it's listening function so that near surface resolution is improved. They are designed for use in applications such as high precision thickness gauging of thin materials and delamination checks in composite materials. They are also useful in high - temperature measurement applications sine the delay line provides some insulation to the piezoelectric element from the heat.