Propagating, Evanescent, and Complex Wavenumber Guided Waves in High-Performance Composites.

Area of Science:

• Composite Materials Analysis
• Wave Propagation Phenomena
• Finite Element Methods

Background:

• Guided waves (GWs) are crucial for structural health monitoring in advanced materials.
• Understanding wavenumber behavior is key to interpreting GW propagation in complex structures.
• High-performance composites, like CFRP, exhibit unique wave dynamics compared to traditional materials.

Purpose of the Study:

• To investigate propagating, evanescent, and complex wavenumbers of GWs in high-performance composites.
• To compare wavenumber trajectories in CFRP composites versus isotropic aluminum alloy.
• To validate the accuracy and robustness of the semi-analytical finite element (SAFE) method for composite analysis.

Main Methods:

• Utilized a stable and robust semi-analytical finite element (SAFE) method.
• Performed an incremental material change study from aluminum to CFRP.
• Compared SAFE results for aluminum plates against exact analytical solutions.
• Analyzed wavenumber trajectories for various CFRP laminate configurations.

Main Results:

• The SAFE method with 20 elements achieved <0.5% error for evanescent wavenumbers in aluminum.
• Reducing transverse and shear moduli shifted wavenumber solutions towards composite behavior.
• Antisymmetric imaginary Lamb wave modes consistently exist in composites, unlike in aluminum.
• CFRP plates showed a smaller real wavenumber range than aluminum.
• Imaginary SH wave trajectories in laminates were distorted by ±45 plies.

Conclusions:

• The SAFE method accurately predicts GW wavenumbers in composites.
• Material properties significantly influence wavenumber trajectories, differentiating composites from isotropic materials.
• Laminated composite structures exhibit complex wave behaviors, such as distorted SH wave modes.
• The SAFE method demonstrates convergence and accuracy in CFRP laminates with increased element density.