Low Frequency Pulse Compression Ultrasonic Technique for Evaluation of Thick Polyurathene Samples

The use of ultrasonic signals at sub-MHz frequencies for Non Destructive Evaluation (NDE) of thick polymer samples has been shown. It is described that the combination of low-frequency coded signals such as chirps, together with pulse compression signal processing, can provide a powerful tool for ultrasonic NDE. To achieve this goal, it is essential that the measurement system bandwidth is as wide as possible, and matched the type of waveform chosen for the measurement. In this work, the required bandwidth is achieved by using piezo-composite probes and it will be demonstrated how the combination of pulse compression techniques and broadband probes can be used to inspect highly attenuating materials such as thick polymers. It is demonstrated that the technique can be applie in evaluation of flexible riser stiffeners that has been used extensively in the offshore oil and gas industries. (author)