Damage Detection using SONIC IR Imaging for Composite Laminate

Non-Destructive Testing (NDT) is a branch of scientific methods and techniques

used to evaluate the defects and irregularities in engineering materials. These methods

conduct testing without destroying or altering material’s structure and functionality. Most

of these defects are subsurface making them difficult to detect and access.

SONIC INFRARED (IR) is a relatively new and emerging vibrothermography

method under the category of NDT methods. This is a fast NDT inspection method that

uses an ultrasonic generator to pass an ultrasonic pulse through the test specimen which

results in a temperature variation in the test specimen. The temperature increase around

the area of the defect is more because of frictional heating due to the vibration of the

specimen. This temperature variation can be observed using a thermal camera.

In this research study, the temperature variation in the composite laminate during

the SONIC IR experimentation using an infrared thermal camera. These recorded data are

used to determine the location, dimension and depth of defects through SONIC IR NDT

method using existing defect detection algorithms. Probability of detection analysis is

used to determine the probability of detection under specific experimental conditions for

two different types of composite laminates. Lastly, the effect of the process parameters

such as number of pulses, pulse duration and time delay between pulses of this technique

on the detectability and probability of detection is studied in detail.