Session: 21-01: Poster Session

Paper Number: 99125

99125 - Nonlinear acoustics and acoustic emission for the Non-destructive testing and structural health monitoring of a recyclable polymer matrix composite material reinforced with flax fibers using integrated piezoelectric sensors 

In this study, we present a NonLinear Resonance Acoustic Spectroscopic (NLRAS) method for damage characterization based on the nonlinear hysteretic behavior of heterogenous material. We use some Nonlinear acoustic features as Resonance frequency shift and quality Q-factor change as a function of the increasing applied excitation amplitude, to monitor damage progression in the composite material, with integrated piezoelectric sensors.

The hysteretic Nonlinear Acoustics behavior is characterized at intact and gradually damaged states with progressive static load in three point bending test. We observe that Resonance frequency shift increases and that the Q-factor decreases as a function of the increasing applied excitation amplitude with damage accumulation change. We also observe that the frequency change and Q-factor as function of applied excitation didn't follow the same path for the increasing excitation level and for the decreasing excitation level giving rise to a hysteretic behavior that is damage dependent.

Besides, damage was monitored using the Acoustic Emission (AE) generated by the material during the damage process. With the help of a classification procedure of AE hits, damage mechanisms are identified and then correlated to the hysteretic Nonlinear Acoustics behavior. More particularly, frequency shift have been found to be very sensitive to damage creation and development in the material. The NLRAS evolution as damage progress is related to the microstructure change as matrix micro-cracking, fiber matrix decohesion and fiber rupture.

This work shows the relevance of this approach in developing a new highly sensitive method for Non Destructive Testing and Structural Health Monitoring purpose as the sensors are integrated to the samples.

Presenting Author: Rachid El Guerjouma LAUM - Le Mans University - CNRS