Impact Damage Detection in Patch-Repaired CFRP Laminates Using Nonlinear Lamb Waves

Area of Science:

• Materials Science
• Aerospace Engineering
• Non-destructive Testing

Background:

• Carbon fiber-reinforced polymer (CFRP) laminates are crucial in aircraft but vulnerable to low-velocity impact (LVI) damage.
• Effective repair strategies and methods to assess repair efficacy under LVI are critical for structural integrity.

Purpose of the Study:

• To investigate the repair effectiveness of LVI-damaged CFRP laminates using various patch sizes.
• To develop and validate an integrated numerical procedure for predicting nonlinear Lamb wave behavior in repaired CFRP.

Main Methods:

• Experimental and numerical nonlinear Lamb wave analyses were employed.
• An integrated numerical procedure combining LVI simulation and nonlinear Lamb wave detection was developed.
• Relative Acoustic Nonlinearity Parameters (RANPs) were used to evaluate damage in simulations.

Main Results:

• The integrated numerical procedure was validated against drop-weight impact tests and a nonlinear ultrasonic system.
• An optimal circular patch size (2.5r radius) was determined through interpolation, optimizing absorbed energy and delamination.
• Key parameters like RANPs demonstrated consistent trends, serving as effective indicators of impact damage.

Conclusions:

• The developed numerical procedure accurately predicts nonlinear Lamb wave behavior in repaired CFRP.
• Optimal patch design is crucial for enhancing impact resistance and repair performance in CFRP structures.
• Nonlinear Lamb wave analysis, using parameters like RANPs, is a viable method for assessing impact damage and repair effectiveness.