Session: Virtual Presentations in Acoustics, Vibration, and Phononics

Paper Number: 94882

94882 - Nonlinear Electro-Mechanical Impedance Spectroscopy for Comprehensive Monitoring of Carbon Fiber Reinforced Composite Laminates 

Carbon fiber reinforced composite (CFRC) laminates have been put into prevailing application due to their preferable high strength-to-weight ratio, strong corrosion resistance, and high stiffness features. However, the damage types and mechanism are complicated, rendering difficulties to the comprehensive monitoring of CFRC laminates. In recent decades, both Electromechanical Impedance Spectroscopy (EMIS) and nonlinear ultrasonic methods have been demonstrated as effective techniques for Structural Health Monitoring (SHM) of the CFRC. EMIS, which is sensitive to the local damage, utilizes the structural resonance information in the frequency domain to evaluate the structure integrity via only a single piezoelectric wafer active sensor (PWAS). Nonlinear ultrasonic techniques capture distinctive nonlinear features to conduct the detection of the incipient damage like the delamination with high sensitivity. However, EMIS is incapable of detecting incipient structural changes at very early stage while nonlinear ultrasonics requires at least two PWAS transducers to form a pitch-catch active sensing pair. In face of the unique pros and cons of the two methods, this paper strives to combine the advantages and avoid the disadvantages of these two methods, so as to achieve more efficient and comprehensive damage detection of the CFRC laminates.

In this study, the nonlinear electromechanical impedance spectroscopy, short as NEMIS, is proposed, which can obtain chirp-based impedance spectra and capture nonlinear features simultaneously with only one PWAS. This method aims to conduct a comprehensive monitoring of CFRC laminates utilizing the structural resonance information and the nonlinear ultrasonic features. In the theoretical part, various damage types of CFRC laminates are classified and introduced, followed by the mechanism behind the damage. Subsequently, a comparative illustration between the conventional EMIS and the proposed NEMIS is presented, which illuminates the differences in the mechanism and procedures between the two methods. Regarding the numerical simulation, a finite element model (FEM) of CFRC laminates is established in the commercial FEM software to verify the feasibility of the NEMIS for damage detection. The macro scale damage types are modeled by the change of material properties like density and elastic modulus, while the incipient damage like delamination is implemented by setting the contact elements between the laminates. Correspondingly, the chirp-based impedance spectra are employed to detect the macro scale damage via the deviation of resonance peaks, while the nonlinear features, such as higher harmonics and wave modulation are utilized to monitor the delamination. Linear and nonlinear damage indices are developed to quantify the severity of both the macro and micro damage types from two perspectives. This paper finishes with conclusion and suggestions for future work.

Presenting Author: Runye Lu University of Michigan-Shanghai Jiao Tong University Joint Institute,

Presenting Author Biography: The presenting author is the second year doctral student whose research focusing on structural health monitoring.

Authors:

Runye Lu University of Michigan-Shanghai Jiao Tong University Joint Institute,
Yanfeng Shen University of Michigan-Shanghai Jiao Tong University Joint Institute