| ABSTRACT: | WAVELET ANALYSIS BASED ULTRASONIC NONDESTRUCTIVE TESTING OF POLYMER
BONDED EXPLOSIVE
Z. Weibin, T. Yong, Y. Zhanfeng, and W. Liling
Institute Of Chemical Materials, CAEP, Mianyang, Sichuan, China
Polymer Bonded Explosives (PBX) are well-known explosives for the weapons, especially for the parts of
some important weapon. Generally, they first are molded in cylinder. One of the most important issues in
PBX cylinder properties is the detection of its flaw. Each PBX cylinder has probable flaws that influence the
security, machine-performance and other important physical or chemical performance. Its detection can be
made by ultrasonic(US) testing techniques. The ultrasonic testing is based on the fact that the ultrasonic
wave is able to distinguish different acoustic impedances when there is the different medium inside the
cylinder. The special purpose 1.25MHz*`10MHz sensors were used to emit/receive the ultrasonic signals.
When the US pulse wave propagates from the first surface in the PBX, part of the pulse is back propagated
to the transducer owed to the flaw interface. The other part of US pulse wave goes forward and reaches the
next surface, this signal eventually goes back to the transducer. These signals containing the flaw
information are recorded for analysis. Based on processing the signals by means of the wavelet transform,
we can distinguish the flaw with the frequency change of flaw echo and verify the central frequency of the
transducer, obtain the accurate part frequency of the signals with which are concerned, and also accurately
measure the signal absolute value (amplitude) depended on the effective frequency. The accuracy obtained
will encourage its implementation for nondestructive testing the PBX*fs flaws.
KEYWORDS PBX, ultrasonic nondestructive testing, wavelet transform
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