[5A3] Analytic-signal ultrasonic porosity evaluation in CFRP components

N Pilashev1, R Smith2 and P Wilcox1
1University of Bristol, UK
2RCNDE Director, UK 

The currently accepted method for evaluating through-thickness average porosity in composite materials does not account for the porosity distribution, which leads to large uncertainties in the measurements. An NDE technique capable of mapping the 3D distribution of porosity could considerably improve the determination of the fitness for purpose of as-manufactured components.

This work focusses on studying the analytic signal and the instantaneous amplitude, phase and frequency, which respond to different aspects of the structure, and how they are influenced by the size, depth distribution and morphology of porosity. Two time-domain inversion methods have been developed for isolating the influence that a single effective pore has on the complex ultrasonic response. Use of a 2D Finite Element model has shown that one of these also has potential for working with multiple pores.

Both methods have been able to predict the depth and size of a single pore from simulated data, with one method showing promise for determining the depth distribution and sizes of porosity from a single waveform.