Ultrasonic wave transmission and bandgap in multidirectional composite laminates with spring-type interlayer...

Area of Science:

• Materials Science
• Acoustics
• Solid Mechanics

Background:

• Ultrasonic wave propagation in composite materials is critical for non-destructive evaluation.
• Interlayer regions in composites can significantly affect wave transmission characteristics.
• Understanding wave-structure interactions is key to predicting material behavior.

Purpose of the Study:

• To theoretically investigate ultrasonic wave transmission in multidirectional composite laminates.
• To analyze the influence of resin-rich interlayers on wave propagation and bandgap formation.
• To validate theoretical predictions with experimental measurements.

Main Methods:

• Utilized the stiffness-matrix method for theoretical analysis.
• Employed a spring-type interface model to represent interlayer effects.
• Calculated energy transmission spectra for longitudinal waves impinging obliquely.
• Experimentally measured transmission spectra using the through-transmission technique.

Main Results:

• Identified frequency bandgaps in ultrasonic wave transmission due to interlayer effects.
• Demonstrated that incident angle, laminate lay-up, and interfacial stiffness influence bandgap characteristics.
• Observed that bandgaps arise from constructive interference of scattered waves.
• Found good agreement between theoretical predictions and experimental results.

Conclusions:

• Resin-rich interlayers significantly impact ultrasonic wave transmission and create tunable bandgaps.
• The theoretical model accurately predicts bandgap phenomena in composite laminates.
• This research provides insights into ultrasonic wave behavior for material characterization and defect detection.